US20010007070A1 - Ablation catheter assembly and method for isolating a pulmonary vein - Google Patents

Abstract

A catheter assembly and method for treatment of cardiac arrhythmia. In one preferred embodiment, the catheter assembly includes a catheter body, at least one electrode, and a fluid source. The catheter body includes a proximal portion, an intermediate portion, a distal portion, a first lumen, and an ablation section. The intermediate portion extends from the proximal portion and defines a longitudinal axis. The distal portion extends from the intermediate portion and forms a helix or coil. The first lumen extends from the proximal portion to the distal portion. Finally, the ablation section is formed along the helix of the distal portion and defines a loop transverse to the longitudinal axis. The ablation section is, in one preferred embodiment, comprised of a microporous material in fluid communication with the first lumen so as to irrigate fluid from the first lumen to an exterior surface of the ablation section. The electrode is associated with the ablation section. Finally, the fluid source is provided to supply a conductive fluid to the first lumen. With this configuration, upon activation, the electrode supplies an ablation energy to fluid irrigated to the exterior surface of the ablation section, thereby ablating a continuous, closed lesion pattern. During use, for example, the catheter assembly can ablate a closed lesion pattern corresponding with the loop defined by the ablation section on a chamber wall about a pulmonary vein ostium to electrically isolate the pulmonary vein from the left atrium. In one preferred embodiment, the ablation section is comprised of a high density, expanded PTFE material. In another preferred embodiment, a shaping wire is slidably disposed within the catheter body to selectively dictate the desired helical shape of the distal portion

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation-in-part of U.S. patent application Ser. No. 09/286,048, entitled “Ablation Catheter and Method for Isolating a Pulmonary Vein” filed on Apr. 5, 1999. In addition, this application is related to U.S. Patent Application entitled “Medical Device Delivery Catheter with Distal Locator” filed on even date herewith, assigned to the same assignee, and incorporated herein by reference thereto.[0001]
BACKGROUND OF THE INVENTION
• The present invention relates to an ablation catheter for treatment of cardiac arrhythmia, for example atrial fibrillation. More particularly, it relates to an ablation catheter configured to electrically isolate a vessel, such as a puhnonary vein, from a chamber, such as the left atrium with a continuous lesion pattern and a method for forming such a lesion pattern.[0002]
• The heart includes a number of pathways that are responsible for the propagation of signals necessary to produce continuous, synchronized contractions. Each contraction cycle begins in the right atrium where a sinoatral node initiates an electrical impulse. This impulse then spreads across the right atrium to the left atrium, stimulating the atria to contract. The chain reaction continues from the atria to the ventricles by passing through a pathway known as the atrioventricular (AV) node or junction, which acts as an electrical gateway to the ventricles. The AV junction delivers the signal to the ventricles while also slowing it, so the atria can relax before the ventricles contract.[0003]
• Disturbances in the heart's electrical system may lead to various rhythmic problems that can cause the heart to beat irregularly, too fast or too slow. Irregular heart beats, or arrhythmia, are caused by physiological or pathological disturbances in the discharge of electrical impulses from the sinoatrial node, in the transmission of the signal through the heart tissue, or spontaneous, unexpected electrical signals generated within the heart. One type of arrhythmia is tachycardia, which is an abnormal rapidity of heart action. There are several different forms of atrial tachycardia, including atrial fibrillation and atrial flutter. With atrial fibrillation, instead of a single beat, numerous electrical impulses are generated by depolarizing tissue at one or more locations in the atria (or possibly other locations). These unexpected electrical impulses produce irregular, often rapid heartbeats in the atrial muscles and ventricles. Patients experiencing atrial fibrillation may suffer from fatigue, activity intolerance, dizziness and even strokes.[0004]
• The precise cause of atrial fibrillation, and in particular the depolarizing tissue causing “extra” electrical signals, is currently unknown. As to the location of the depolarizing tissue, it is generally agreed that the undesired electrical impulses often originate in the left atrial region of the heart. Recent studies have expanded upon this general understanding, suggesting that nearly 90% of these “focal triggers” or electrical impulses are generated in one (or more) of the four pulmonary veins (PV) extending from the left atrium. In this regard, as the heart develops from an embryotic stage, left atrium tissue may grow or extend a short distance into one or more of the PVs. It has been postulated that this tissue may spontaneously depolarize, resulting in an unexpected electrical impulse(s) propagating into the left atrium and along the various electrical pathways of the heart.[0005]
• A variety of different atrial fibrillation treatment techniques are available, including drugs, surgery, implants, and catheter ablation. While drugs may be the treatment of choice for some patients, drugs typically only mask the symptoms and do not cure the underlying cause. Implantable devices, on the other hand, usually correct an arrhythmia only after it occurs. Surgical and catheter-based treatments, in contrast, will actually cure the problem by ablating the abnormal tissue or accessory pathway responsible for the atrial fibrillation. The catheter-based treatments rely on the application of various destructive energy sources to the target tissue, including direct current electrical energy, radiofrequency electrical energy, laser energy, and the like. The energy source, such as an ablating electrode, is normally disposed along a distal portion of a catheter.[0006]
• Most ablation catheter techniques employed to treat atrial fibrillation focus upon locating the ablating electrode, or a series of ablating electrodes, along extended target sections of the left atrium wall. Because the atrium wall, and thus the targeted site(s), is relatively tortuous, the resulting catheter design includes multiple curves, bends, extensions, etc. In response to recent studies indicating that the unexpected electrical impulses are generated within a PV, efforts have been made to ablate tissue within the PV itself. Obviously, the prior catheter designs incorporating convoluted, multiple bends are not conducive to placement within a PV. Instead, a conventional “straight ended” ablation catheter has been employed. While this technique of tissue ablation directly within a PV has been performed with relatively high success, other concerns may arise.[0007]
• More particularly, due to the relatively small thickness of atrial tissue formed within a PV, it is likely that ablation of this tissue may in fact cause the PV to shrink or constrict Because PV's have a relatively small diameter, a stenosis may result. Even further, other vital bodily structures are directly adjacent each PV. These structures may be undesirably damaged when ablating within a PV.[0008]
• In light of the above, an alternative technique has been suggested whereby a continuous ablation lesion pattern is formed in the left atrium wall about the ostium associated with the PV in question. In other words, the PV is electrically isolated from the left atrium by forming an ablation lesion pattern that surrounds the PV ostium. As a result, any undesired electrical impulse generated within the PV could not propagate into the left atrium, thereby eliminating unexpected atria contraction.[0009]
• Unfortunately, while PV isolation via a continuous ablation lesion pattern about the PV ostium appears highly viable, no acceptable ablation catheter configuration exists. Most atrial fibrillation ablation catheters have linear distal ends, designed for manipulation in a sliding fashion along the atrial wall. That is to say, the distal, electrode-carrying end of the catheter is typically slid along (or parallel to) the atrial wall. With this generally accepted configuration in mind, it may be possible to shape the distal, electrode-carrying end into a small ring sized in accordance with the PV ostium. For example, U.S. Pat. No. 5,617,854 discloses one such possibility. More particularly, the described ablation catheter includes a substantially ring-shaped portion sized to contact the ostium of the coronary sinus. Pursuant to conventional designs, the ring extends linearly from the catheter body. In theory, the ring-shaped portion may be placed about a PV ostium. However, proper positioning would be extremely difficult and time consuming. More particularly, it would be virtually impossible to locate and then align the ring about a PV ostium when sliding the catheter along the atrium wall. The ring must be directed toward the ostium in a radial direction (relative to a central axis of the ostium). Even if the electrophysiologist were able to direct the ring to the ostium, the periodic blood flow through the PV would likely force the ring away from the atrium wall, as the catheter body would not provide any support.[0010]
• A related concern entails mapping of a PV prior to ablation. In cases of atrial fibrillation, it is necessary to identify the origination point of the undesired electrical impulses prior to ablation. Thus, it must first be determined if the electrical impulse originates within one or more PVs. Once the depolarizing tissue has been identified, necessary ablation steps can be taken. Mapping is normally accomplished by placing one or more mapping electrodes into contact with the tissue in question. In order to map tissue within a PV, therefore, a relatively straight catheter section maintaining two or more mapping electrodes must be extended axially within the PV. Ablation catheters configured to slide along the atrial wall cannot include a separate, distal extension for placement within the PV. Instead, an entirely separate mapping catheter must be provided and then removed for subsequent replacement with the ablation catheter. Obviously, these additional steps greatly increase the overall time required to complete the procedure.[0011]
• Electrical isolation of a pulmonary vein via an ablation lesion pattern surrounding the pulmonary vein ostium presents a potentially revolutionary technique for treatment of atrial fibrillation. However, the unique anatomical characteristics of a pulmonary vein and left atrium render currently available ablation catheters minimally useful. Therefore, a substantial need exists for an ablation catheter designed for consistent positioning of one or more ablation electrodes about a pulmonary vein ostium, as well as for providing pulmonary vein mapping information.[0012]
SUMMARY OF THE INVENTION
• One aspect of the present invention provides a catheter assembly for treatment of cardiac arrhythmia. The catheter assembly includes a catheter body, at least one electrode, and a fluid source. The catheter body includes a proximal portion, an intermediate portion, a distal portion, a first lumen, and an ablation section. The intermediate portion extends from the proximal portion and defines a longitudinal axis. The distal portion extends from the intermediate portion and forms a helix. The first lumen extends from the proximal portion to the distal portion. Finally, the ablation section is formed along the helix of the distal portion and defines a loop transverse to the longitudinal axis. The ablation section is comprised of a microporous material in fluid communication with the first lumen so as to irrigate liquid from the first lumen to an exterior surface of the ablation section. The at least one electrode is associated with the ablation section. Finally, the fluid source is provided to supply a liquid to the first lumen. With this configuration, upon activation, the electrode supplies an ablation energy to fluid irrigated to the exterior surface of the ablation section, thereby ablating a continuous, closed lesion pattern. During use, for example, the catheter assembly can ablate a closed lesion pattern corresponding with the loop defined by the ablation section about a pulmonary vein ostium to electrically isolate the pulmonary vein from the left atrium. In one preferred embodiment, the ablation section is formed of microporous PTFE.[0013]
• Another aspect of the present invention relates to a catheter assembly for treatment of cardiac arrhythmia. The catheter assembly comprises a catheter body, at least one electrode and a shaping wire. The catheter body includes a proximal portion, a distal portion, an ablation section and a first lumen. The distal portion extends from the proximal portion and is comprised of a flexible material. The ablation section is defined along the distal portion. The first lumen extends from the proximal portion to the distal portion. The at least one electrode is associated with the ablation section. Finally, the shaping wire is moveably disposed within the first lumen and includes a proximal segment and a distal segment. In this regard, the distal segment is comprised of a shape memory material formed to revert to a helix shape. With this configuration, upon advancement of the distal segment within the distal portion, the distal portion assumes the helical shape of the distal segment and the ablation section forms a loop. During use, the loop formed by the ablation section, as otherwise dictated by the distal segment of the shaping wire, is placed, for example, about an ostium of a pulmonary vein. Upon activation of the electrode, the ablation section ablates a continuous, closed lesion pattern about the ostium, thereby electrically isolating the pulmonary vein from a remainder of the associated left atrium. In one preferred embodiment, a plurality of shaping wires, each configured to form differently sized and shaped helixes, are provided. To this end, a user can select the shaping wire most closely conforming in size and shape to the pulmonary vein ostium in question.[0014]
• Yet another aspect of the present invention relates to a method for forming an ablation pattern to electrically isolate a vessel from a chamber, the vessel having an ostium formed at a chamber wall, for treatment of cardiac arrhythmia. The method includes selecting a catheter assembly including a catheter body, a first shaping wire, and at least one electrode. The catheter body includes a proximal portion, a distal portion and a first lumen extending from the proximal portion through the distal portion. Further, the distal portion includes an ablation section. The shaping wire is selectively disposed within the first lumen and includes a proximal segment and a distal segment. The distal segment is formed to selectively assume a first helical shape. Finally, the at least one electrode is associated with the ablation section. The distal portion of the catheter body is guided into the chamber. The distal portion is then formed to a helical configuration with the distal segment of the shaping wire, including formation of the ablation section as a loop. The distal portion is directed toward the ostium such that the ablation section contacts the chamber wall about the ostium. Finally, the electrode is energized to ablate a continuous, closed lesion pattern about the vessel ostium to electrically isolate the vessel from the chamber. In one preferred embodiment, the method further includes visually confirming contact between the ablation section and the chamber wall prior to ablation.[0015]
• Yet another aspect of the present invention relates to a method of forming an ablation pattern to electrically isolate a vessel from a chamber, the vessel having an ostium formed at the chamber wall for treatment of cardiac arrhythmia. The method includes selecting a catheter assembly including a delivery catheter, an ablation catheter, and at least one electrode. The delivery catheter forms a lumen terminating at an opening and includes a distal locator extending distal the opening. The ablation catheter includes a proximal portion and a distal portion that selectively assumes a helical shape. The distal portion further includes an ablation section forming a loop. Finally, the electrode is associated with the ablation section. The distal locator is guided into the chamber. The vessel is located with the distal locator. The distal portion of the ablation catheter is deployed from the delivery catheter via the opening. The distal portion is advanced over the distal locator such that the ablation section contacts the chamber wall about the vessel ostium. The electrode is energized to ablate a continuous, closed lesion patterns about the vessel ostium to electrically isolate the vessel from the chamber. In one preferred embodiment, the catheter assembly further includes a sensing electrode located along the distal portion of the ablation catheter. With this alternative embodiment, the method further includes sensing tissue conductivity with the sensing electrode to evaluate an extent of ablation.[0016]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1A is a side-elevational view of a catheter assembly in accordance with the present invention;[0017]
• FIG. 1B is a perspective view of a portion of the catheter assembly of FIG. 1A;[0018]
• FIG. 1C is an end view of a portion of the catheter assembly of FIG. 1A;[0019]
• FIG. 1D is an end view of a portion of an alternative catheter assembly in accordance with the present invention;[0020]
• FIGS.[0021]2A-2D illustrates use of the catheter assembly of FIG. 1A within a heart;
• FIG. 3A is a side view of a portion of an alternative catheter assembly in accordance with the present invention;[0022]
• FIG. 3B is an end view of the catheter assembly of FIG. 3A;[0023]
• FIG. 3C is a side view of a portion of an alternative catheter assembly in accordance with the present invention;[0024]
• FIG. 3D is a simplified cross-sectional view of a portion of the heart and a portion of the catheter assembly of FIGS. 3A and 3B;[0025]
• FIG. 4A is a side view of a portion of an alternative catheter assembly in accordance with the present invention;[0026]
• FIG. 4B illustrates placement of the catheter assembly of FIG. 4A within the left atrium of a heart;[0027]
• FIG. 5A is a side view of a portion of an alternative catheter assembly in accordance with the present invention;[0028]
• FIG. 6 is a side view of a portion of an alternative catheter assembly in accordance with the present invention;[0029]
• FIG. 7 is a side view of a portion of an alternative catheter assembly in accordance with the present invention;[0030]
• FIG. 8 is a side view of a portion of an alternative catheter assembly in accordance with the present invention;[0031]
• FIG. 9A is a side view of a portion of an alternative catheter assembly in accordance with the present invention, in a deployed position;[0032]
• FIG. 9B is a side view of the catheter assembly of FIG. 9A in a retracted position;[0033]
• FIG. 10 is a side view of a portion of an alternative catheter assembly in accordance with the present invention;[0034]
• FIG. 11 is a side view of a portion of an alternative catheter assembly in accordance with the present invention;[0035]
• FIGS. 12A and 12B are side views of a portion of an alternative catheter assembly in accordance with the present invention;[0036]
• FIG. 13A is a side view of an alternative catheter assembly in accordance with the present invention;[0037]
• FIG. 13B is a cross section of a catheter assembly of FIG. 13A along the line B-B;[0038]
• FIG. 13C is a cross-sectional view of the catheter assembly of FIG. 13A along the line C-C;[0039]
• FIG. 13D is a cross-sectional view of the catheter assembly of FIG. 13A along the line D-D;[0040]
• FIG. 13E is a cross-sectional view of an alternative embodiment catheter assembly;[0041]
• FIG. 14A is a side view of a catheter body of the catheter assembly of FIG. 13A in uncoiled position;[0042]
• FIG. 14B is a side view of an alternative catheter body portion of the catheter assembly of FIG. 13A;[0043]
• FIG. 15A is a side view of a shaping wire of the catheter assembly of FIG. 13A in a straightened position;[0044]
• FIG. 15B is a side view of the shaping wire of FIG. 1SA in a helical position;[0045]
• FIG. 15C is a side view of an alternative shaping wire in a straightened position;[0046]
• FIGS. 16A and 16B are side views of an alternative catheter assembly in accordance with the present invention;[0047]
• FIGS.[0048]17A-17D illustrate use of the catheter assembly of FIG. 13A within a heart;
• FIG. 18A is an end view of the catheter assembly of FIG. 13A in an axially compressed position;[0049]
• FIG. 18B is a simplified view of an ablation pattern formed with the catheter assembly of FIG. 13A;[0050]
• FIG. 19 illustrates use of an alternative catheter assembly within a heart;[0051]
• FIG. 20A is a simplified, side-sectional view of a pulmonary vein and associated ostium;[0052]
• FIG. 20B is a simplified, side-view of a shaping wire in accordance with the present invention in an axially compressed position;[0053]
• FIG. 20C is a simplified, side view of the shaping wire of FIG. 20B applied to the pulmonary vein of FIG. 20A;[0054]
• FIG. 21A is a simplified, side-sectional view of a pulmonary vein and associated ostium;[0055]
• FIG. 21B is a simplified, side view of an alternative shaping wire in an axially compressed position;[0056]
• FIG. 21 C is a simplified, side view of the shaping wire of FIG. 21 B applied to the pulmonary vein of FIG. 21A;[0057]
• FIG. 22 is a simplified, perspective view of an alternative embodiment catheter assembly in accordance with the present invention;[0058]
• FIG. 23 is a side view of a delivery catheter portion of the catheter assembly of FIG. 22;[0059]
• FIG. 24A is a cross-sectional view of the delivery catheter of FIG. 23 along the[0060]line24A-24A;
• FIG. 24B is a cross-sectional view of the delivery catheter of FIG. 23 along the[0061]line24B-24B;
• FIG. 24C is an enlarged, side view of a portion of the delivery catheter of FIG. 23;[0062]
• FIG. 24D is a cross-sectional view of the delivery catheter of FIG. 23 along the line[0063]24D-24D; and
• FIG. 25 is an end view of the catheter assembly of FIG. 22.[0064]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
• One preferred embodiment of a[0065]catheter assembly20 in accordance with the present invention is shown in FIGS.1A-1C. Thecatheter assembly20 is comprised of acatheter body22, ahandle24 andelectrodes26. As described in greater detail below, thecatheter body22 extends from thehandle24, and theelectrodes26 are disposed along a portion of thecatheter body22.
• The[0066]catheter body22 is defined by aproximal portion28, anintermediate portion30 and adistal portion32, and includes a central lumen (not shown). Although not specifically shown, the catheter body may be configured for over-the-wire or rapid exchange applications. In one preferred embodiment, theproximal portion28, the intermediate30 and thedistal portion32 are integrally formed from a biocompatible material having requisite strength and flexibility for deployment within a heart. Appropriate materials are well known in the art and include polyamide.
• The[0067]intermediate portion30 extends from theproximal portion28. Theproximal portion28 and theintermediate portion30 are preferably flexible, so as to facilitate desired articulation during use. In general terms, however, theintermediate portion30 defines a longitudinal axis L1. It should be recognized that in one position (shown in FIG. 1A), the longitudinal axis L1 extends linearly through theintermediate portion30 and theproximal portion28. Upon deployment, it may be that theproximal portion28 and/or theintermediate portion30 is forced to a curved or curvilinear orientation. With this in mind, the longitudinal axis L1 is more specifically defined as a center of theintermediate portion30 adjacent a point of intersection between thedistal portion32 and theintermediate portion30, as best shown in FIG. 1C.
• The[0068]distal portion32 extends from theintermediate portion30 and forms aloop34. In one preferred embodiment, theloop34 is circular, formed in a plane transverse to the longitudinal axis L1. To this end, thedistal portion32 preferably includes alateral segment36. Thelateral segment36 extends in a generally lateral fashion from theintermediate portion30. Theloop34 extends from thelateral segment36 in an arcuate fashion, turning or revolving about a central loop axis C1 (shown best in FIG. 1B). While theloop34 is shown in FIG. 1A as forming a single revolution about the central loop axis C1, theloop34 may instead include a plurality of revolutions to define a spiral or coil. In the one preferred embodiment depicted in FIGS.1A-lC, the central loop axis C1 is aligned with the longitudinal axis L1. Alternatively, however, thelateral segment36 may be eliminated such that theloop34 extends directly from theintermediate portion30. Even further, thelateral segment36 may be configured such that the central loop axis C1 is offset from the longitudinal axis L1. Regardless of the exact construction, however, the central loop axis C1 is preferably substantially parallel to the longitudinal axis L1.
• As best shown in FIG. 1C, the[0069]loop34 preferably extends to form a circle in a frontal plane. Alternatively, a variety of other shapes may also be useful. For example, as shown in FIG. 1D, a square-shaped loop is depicted. Theloop34 may further assume a triangular, rectangular, octagonal, or other closed shape. Returning to FIGS.1A-1C, regardless of the exact shape, theloop34 is preferably substantially closed and can be defined by aproximal end40 and adistal end42. To effectuate the preferred “closed” configuration of theloop34, thedistal end42 is preferably adjacent theproximal end40. In fact, thedistal end42 may contact theproximal end40, although this relationship is not required. Alternatively, thedistal end42 may be longitudinally spaced from theproximal end40. With this configuration, thedistal portion32 is preferably sufficiently flexible such that upon contact with a tissue wall, thedistal end42 will deflect proximally to a position adjacent theproximal end40.
• Regardless of the exact shape, the[0070]loop34 preferably defines an enclosed area A greater than a size of an ostium (not shown) associated with a particular vessel to be isolated, as described in greater detail below. In one preferred embodiment, thecatheter assembly20 is configured to electrically isolate a pulmonary vein from the left atrium. With this one preferred application, where theloop34 is circular, theloop34 has a diameter in the range of approximately 10-20 mm, more preferably 15 mm, although other sizes, either greater or smaller, are acceptable.
• The[0071]loop34 may be formed in a variety of ways, such as by incorporating a preformed section of super elastic, shape memory material, such as Nitinol, with a loop configuration. To facilitate guiding of thedistal portion32 into a heart (not shown), thecatheter assembly20 may include a stylet (not shown) internally disposed within thecatheter body22. In an extended position, the stylet would extend through thedistal portion32, so as to render theloop34 straight. Upon retraction of the stylet, thedistal portion32 would form theloop34. Alternatively, thecatheter assembly20 may include a sheath (not shown) slidably receiving thecatheter body22. Prior to deployment, thedistal portion32 would be retracted within the sheath, rendering theloop34 straight. Upon deployment from the sheath, thedistal portion32 would form theloop34. Other similar approaches for providing theloop34 are similarly acceptable.
• The[0072]handle24 is preferably sized to be grasped by a user and includes anelectrical connector44. The electrical connector provides electrical connections to theelectrodes26 carried by thedistal portion32. To this end, wire(s) (not shown) may extend within the central lumen (not shown) from thedistal portion32 to thehandle24.
• The[0073]electrodes26 are preferably of a type known in the art and are preferably a series of separate band electrodes spaced along theloop34. Instead of, or in addition to, separate band electrodes, theelectrodes26 may include one or more spiral or coil electrodes, or one or more counter-electrodes. Additionally, theelectrodes26 are preferably non-thrombogenic, non-coagulum or char forming. Theelectrodes26 may be cooled by a separate source (not shown), such as a saline source. Theelectrodes26 may be electrically isolated from one another, or some or all of theelectrodes26 may be electrically connected to one another. Preferably, however, at least oneelectrode26 is provided. Theelectrodes26 are preferably shaped and positioned such that during an ablation procedure, a continuous, closed therapeutically-effective lesion pattern is created. Preferably, the length of each of theelectrodes26 is about 4-12 mm, more preferably about 7 mm. The spacing between each of theelectrodes26 is preferably about 1-3 mm, and more preferably about 2 mm. Finally, to effectuate a continuous, closed lesion pattern, preferably one of theelectrodes26 is disposed at theproximal end40 of theloop34, and another of theelectrodes26 is disposed at thedistal end42. As previously described, it is not necessary that the loop segment38 be formed such that theproximal end40 and thedistal end42 are integral. Instead, a slight spacing may exist. With this in mind, the spacing or gap between theelectrode26 at the proximal40 and theelectrode26 at thedistal end42 is preferably less than about 5 mm.
• FIGS. 2A and 2B illustrate use of the[0074]catheter assembly20 shown in FIGS.1A-IC within a heart50. As a point of reference, the heart50 includes a right atrium RA, a left atrium LA, a right ventricle RV and a left ventricle LV. An inferior vena cava IVC and a superior vena cava SVC lead into the right atrium RA. The right atrium RA is separated from the left atrium LA by an interarterial septum (not shown). Finally, four pulmonary veins PV extend from the left atrium LA. Each of the pulmonary veins PV forms an ostium PVO in the left atrium LA wall. As previously described, during formation of the heart50, it is possible that tissue of the left atrium LA may grow upwardly into one or more of the pulmonary veins PV. This left atrium LA tissue may spontaneously depolarize, resulting in atrial fibrillation. Notably, the heart50 may be formed such that a separate ostium PVO is not formed for each individual pulmonary vein PV. In other words, a single pulmonary vein ostium PVO may be formed for two pulmonary veins PV. For example, a single pulmonary vein ostium PVO may be formed for both the left inferior pulmonary vein PV and the left superior pulmonary vein PV, with the two pulmonary veins PV bifurcating from the single ostium PVO.
• As shown in FIG. 2A, electrical isolation of a pulmonary vein PV begins by directing the[0075]distal portion32 of thecatheter body22 through the inferior vena cava IVC, into the right atrium RA through a puncture in the interarterial septum (not shown) and into the left atrium LA. Alternatively, the introduction of thedistal portion32 of thecatheter body22 into the right atrium RA is also suggested by passage of thedistal portion32 into the right atrium RA through the superior vena cava SVC. Theloop34 is positioned slightly spaced from the ostium PVO associated with the pulmonary vein PV to be treated. More particularly, theloop34 is positioned such that the central loop axis C1 (FIG. 1B) is approximately aligned with a center of the pulmonary vein ostium PVO. Thecatheter body22 is then advanced distally such that theloop34 contacts the left atrium LA wall about the pulmonary vein ostium PVO in question, as shown in FIG. 2B. In other words, thecatheter body22 is advanced in a direction parallel with the central loop axis C1 such that theloop34 contacts the left atrium LA wall, surrounding the pulmonary vein ostium PVO. Importantly, because the central loop axis C1 is parallel to the longitudinal axis L1, thecatheter body22 longitudinally supports advancement of theloop34. In other words, the longitudinal axis L1 is effectively aligned with the pulmonary vein ostium PVO such that blood flow from the pulmonary vein PV acts along the longitudinal axis L1. Thus, thecatheter body22 limits deflection of theloop34 otherwise caused by blood flow from the pulmonary vein PV.
• The electrodes[0076]26 (shown best in FIGS.1A-1C) are then energized to a sufficient level to ablate the contacted tissue, for example with an r.f. source. In one preferred embodiment, theelectrodes26 ablate the left atrium LA tissue for 30-120 seconds at a temperature in the range of approximately 60-70 degree C. As a result, a continuous, closed lesion pattern is formed around the pulmonary vein ostium PVO as shown in FIG. 2C. Pursuant to the above describedcatheter assembly20 configuration, the lesion pattern is formed in a plane substantially perpendicular to the longitudinal axis L1. Notably, while the lesion pattern is shown as being only slightly larger than the pulmonary vein ostium PVO, the loop34 (FIG. 1A) may be sized to produce an even larger ablation lesion pattern. To this end, where a single pulmonary vein ostium PVO is formed for two pulmonary veins PV, the resulting pulmonary vein ostium PVO may be elongated. As shown in FIG. 2D, then, the loop34 (FIG. 1A) is configured to form a continuous, closed lesion pattern about the elongated-shaped pulmonary vein ostium PVO.
• The continuous, closed lesion pattern electrically isolates the pulmonary vein PV from the left atrium LA. Any undesired electrical impulses generated in the pulmonary vein are effectively “stopped” at the lesion pattern, and will not propagate into the left atrium LA.[0077]
• An[0078]alternative catheter assembly60 is shown in FIGS. 3A and 3B. Thecatheter assembly60 includes acatheter body62, a handle (not shown) andelectrodes64. Thecatheter body62 includes a proximal portion (not shown), anintermediate portion66 and adistal portion68. For ease of illustration, the handle and the proximal portion of thecatheter body22 are not shown in FIGS. 3A and 3B, it being understood that these components are similar to thehandle24 and theproximal portion28 shown in FIG. 1A. Similar to thecatheter body22, theintermediate portion66 extends from the proximal portion and defines a longitudinal axis L2. Thedistal portion68 extends from theintermediate portion66 and forms a loop orcoil70 substantially transverse to the longitudinal axis L2 and includes a plurality of loop segments72A-72C. Thecoil70 is formed such that each of the loop segments72A-72C revolves about a central loop axis C2. In one preferred embodiment, the central loop axis C2 is aligned with the longitudinal axis L2 defined by theintermediate portion66. Alternatively, the central loop axis C2 may be offset from the longitudinal axis L2. Regardless, the central loop axis C2 is preferably substantially parallel with the longitudinal axis L2.
• Each of the loop segments[0079]72A-72C preferably defines a different diameter. For example, the first loop segment72A defines a diameter slightly larger than that of the second loop segment72B; whereas the second loop segment72B defines a diameter slightly greater than that of the third loop segment72C. In this regard, while each of the loop segments72A72C are depicted as being longitudinally spaced (such that theloop70 forms a multi-lane spiral or coil), the loop segments72A-72C may instead be formed in a single plane (such that theloop70 forms a unitary plane spiral or coil). While the loop segments72A-72C extend distal theintermediate portion66 so as to define a descending or decreasing diameter, an opposite configuration may also be employed. For example, FIG. 3C depicts acoil70′ having loop segments distally increasing in diameter.
• Returning to FIGS. 3A and 3B, the[0080]electrodes64 are similar to the electrodes26 (FIG. 1A) previously described, and preferably are band electrodes disposed along the loop segments72A-72C. In this regard, each of the loop segments72A-72C includes electrodes64A-64C, respectively. In one preferred embodiment, a power source (not shown) associated with theelectrodes64 is configured to individually energize theelectrodes64 to varying levels. Further, theelectrodes64 are preferably configured to provide feedback information indicative of tissue contact, such as by including a thermocouple.
• The[0081]catheter assembly60 is used in a fashion highly similar to the method previously described for the catheter assembly20 (as shown, for example, in FIGS.2A-2C). Thus, for example, thedistal portion68 of thecatheter body62 is directed within the left atrium LA (FIG. 2A) such that theloop70 is disposed about a pulmonary vein ostium PVO. It should be understood that one or more of the loop segments72A-72C may define a diameter (or area) that is less than a diameter (or area) of the pulmonary vein ostium PVO in question. For example, in the simplified cross-sectional view of FIG. 3D, the electrodes64C associated with the third loop segment72C (FIG. 3A) are not in contact with the left atrium LA wall, but instead are within the area defined by the pulmonary vein ostium PVO. Conversely, the electrodes64B associated with the second loop segment72B (FIG. 3A) and the electrodes64A associated with the first loop segment (FIG. 3A) are in contact with the left atrium LA wall. To avoid potential collateral damage caused by full energization of the electrodes64C not in contact with the left atrium LA wall, each of the electrodes64A-64C are selectively energized with a low energy supply. The energy level is not sufficient to ablate contacted tissue, but provides a low energy measurement, such as through a thermocouple or other sensing device associated with each of the electrodes64A-64C. If the sensing device detects a temperature rise, an indication is given that the particular energized electrode64A,64B or64C is in contact with tissue of the left atrium LA. Following the low energy measurement procedure, only those electrodes determined to be in contact with the left atrium LA (for example, electrodes64A and64B) are powered to ablate a continuous, closed lesion pattern about the pulmonary vein ostium PVO, as previously described.
• Another alternative embodiment of a[0082]catheter assembly80 is shown in FIG. 4A. Thecatheter assembly80 includes acatheter body82, anelectrode84 and a locatingdevice86. For ease of illustration, only a portion of thecatheter assembly80 is shown, andcatheter assembly80 may further include a handle similar to thehandle24 associated with the catheter assembly20 (FIG. 1 A) previously described.
• [0083]Catheter body82 is defined by a proximal portion (not shown), anintermediate portion88 and adistal portion90. Theintermediate portion88 extends from the proximal portion and is defined by aproximal segment92 and adistal segment94. In a preferred embodiment, thedistal segment94 is preferably more flexible than theproximal segment92. With this configuration, thedistal segment94 can more easily deflect relative to theproximal segment92, thereby facilitating desired positioning of thedistal portion90 during deployment. In this regard, an internal pull wire (not shown) may be provided to effectuate desired deflection of thedistal segment94. Even further, ananchor96 is preferably included for facilitating a more radical displacement of thedistal portion90 relative to theintermediate portion88.
• As with previous embodiments, the[0084]intermediate portion88 defines a longitudinal axis L3. Once again, where theintermediate portion88 is axially aligned with the proximal portion (not shown), the longitudinal axis L3 is linear along theintermediate portion88 and the proximal portion. However, because theintermediate portion88 is preferably bendable relative to the proximal portion, and further because thedistal segment94 may bend relative to theproximal segment92, the longitudinal axis L3 is more succinctly defined by theintermediate portion88 at the point of intersection between theintermediate portion88 and thedistal portion90.
• Similar to the catheter assembly[0085]20 (FIG. 1A) previously described, thedistal portion90 preferably forms aloop98. Theloop98 may include one or more loop segments (one is shown in FIG. 4A), with each loop segment revolving around a central loop axis C3. Theloop98 is formed substantially transverse to the longitudinal axis L3, with the central loop axis C3 preferably aligned with the longitudinal axis L3. Alternatively, the central loop axis C3 may be slightly offset from the longitudinal axis L3. Regardless, the central loop axis C3 is preferably parallel with the longitudinal axis L3.
• The[0086]electrode84 is shown in FIG. 4 as being a continuous coil electrode. Alternatively, a plurality of spaced, band electrodes or counter-electrodes may be used.
• Finally, the locating[0087]device86 includes atip100 configured to extend distal theloop98. In one preferred embodiment, the locatingdevice86 is integrally formed with thecatheter body82, extending from thedistal portion90. Alternatively, the locatingdevice86 may be a separate body. Regardless, thetip100 extends distal thedistal portion90, and is aligned with the central loop axis C3 defined by theloop98. Thetip100 preferably has a diameter less than a diameter of a pulmonary vein, and a length in the range of approximately 1-15 mm. Further, as shown in FIG. 4, thetip100 may include a series ofmapping electrodes102. Themapping electrodes102 are electrically connected to an external recording system (not shown) for providing information indicative of tissue polarization.
• As shown in FIG. 4B, during use, the[0088]catheter assembly80 is directed into the left atrium LA as previously described. The locatingdevice86, and in particular thetip100, is then used to locate the pulmonary vein ostium PVO. Once located, thetip100 is inserted into the pulmonary vein PV, effectively centering theloop98 around the pulmonary vein ostium PVO. Where thetip100 includes themapping electrodes102, a mapping procedure can be performed, whereby information indicative of tissue activity nearby themapping electrodes102 is provided. During this mapping procedure, a determination can be made as to whether the particular pulmonary vein PV is generating undesired electrical impulses. Where it is determined that, in fact, tissue in the pulmonary vein PV is spontaneously depolarizing, theelectrode84 is energized to form the continuous, closed lesion pattern about the pulmonary vein ostium PVO as previously described.
• Yet another alternative embodiment of a[0089]catheter assembly110 in accordance with the present invention is shown in FIG. 5. Thecatheter assembly110 is highly similar to the catheter assembly80 (FIG. 4A) and includes acatheter body112,electrodes114 and alocating device116. Thecatheter body112 includes a proximal portion (not shown) anintermediate portion88 defining a longitudinal axis L4 and adistal portion120. Thedistal portion120 extends from theintermediate portion118 and forms aloop122 substantially transverse to the longitudinal axis L4. In this regard, theloop122 revolves about a central loop axis C4. In one preferred embodiment, the central loop axis C4 is aligned with the longitudinal axis L4. Alternatively, the central loop axis C4 is offset from, but substantially parallel with, the longitudinal axis L4. The electrodes114 (shown as spaced band electrodes) are disposed along theloop122 for forming a continues, closed lesion pattern.
• The[0090]locating device116 includes atip124 that extends distal theloop122. In one preferred embodiment, the locatingdevice116 is integrally formed with thecatheter body112 and includesmapping electrodes126 connected to an external recording device (not shown). Alternatively, the locatingdevice116 may be a separate body. As shown in FIG. 5, thetip124 forms a descending diameter coil, generally aligned with the central loop axis C4. By providing a coil configuration for thetip124, thetip124 facilitates a more positive centering of theloop122 about a pulmonary vein ostium PVO (FIG. 4B). In one preferred embodiment, thetip124 defines a maximum diameter approximating a diameter of a pulmonary vein. When inserted within a pulmonary vein, then, thetip124 effectively lodges along the pulmonary vein wall. This, in turn, positions theloop122 in a more central fashion about the associated ostium. Further, by providing themapping electrodes126, the locatingdevice116 additionally serves as a mapping device for evaluating a particular pulmonary vein.
• It should be recognized that other devices can be provided to assist in centering the ablation loop about the pulmonary vein ostium. For example, yet another alternative embodiment of a[0091]catheter assembly130 is depicted in FIG. 6. The catheter assembly includes acatheter body132,electrodes134, aballoon136 and alocating device138. Thecatheter body132 is similar to those previously described, and includes a proximal portion (not shown) anintermediate portion140 defining a longitudinal axis L5 and adistal portion142. Thedistal portion142 extends from theintermediate portion140 and forms aloop144 substantially transverse to the longitudinal axis L5. Theloop144 revolves about a central loop axis C5, that, in one preferred embodiment, is aligned with the longitudinal axis L5. Theballoon136 is disposed along thedistal portion142 distal theloop144. In one preferred embodiment, theballoon136 is fluidly connected to a fluid source (not shown), such as a pressurized reservoir of saline, by a lumen (not shown) formed within thecatheter body132. Finally, the locatingdevice138 includes atip146 extending distal theloop144. In one preferred embodiment, as shown in FIG. 6, the locatingdevice138 is integrally formed with thecatheter body132, with thetip146 extending distal theballoon136. Alternatively, the locatingdevice138 may be a separate body, and thetip146 may be positioned between theloop144 and theballoon136. Regardless, thetip146 preferably includesmapping electrodes148.
• During use, the locating[0092]device138 is used to locate a pulmonary vein PV (FIG. 4B) via thetip146. Thetip146 axially inserted into the pulmonary vein PV. Themapping electrodes148 may then be used to ascertain whether tissue in the pulmonary vein PV is spontaneously generating unexpected electrical impulses. Upon determining that the pulmonary vein PV requires electrical isolation, thecatheter body132 is deployed such that theloop144 contacts the left atrium LA (FIG. 4B) wall (as previously described). Theballoon136 is inflated such that it engages the pulmonary vein PV wall. Once inflated, theballoon136 positively centers theloop144 about the pulmonary vein ostium PVO (FIG. 4B).
• Yet another alternative embodiment of a[0093]catheter assembly160 is shown in FIG. 7. Thecatheter assembly160 includes acatheter body162,electrodes164, awire basket166 and alocating device168. As with previous embodiments, thecatheter body162 includes a proximal portion (not shown), anintermediate portion170 defining a longitudinal axis L6 and a distal portion172. The distal portion172 extends from theintermediate portion170 and forms aloop174 transverse to the longitudinal axis L6. In this regard, theloop174 revolves around a central loop axis C6 that, in one preferred embodiment, is aligned with the longitudinal axis L6.
• The[0094]wire basket166 is maintained by the distal portion172 distal theloop174. Thewire basket166 may be radially extended and retracted via a pull wire or similar activation device extending through a lumen (not shown) formed within thecatheter body162.
• Finally, the locating[0095]device168 includes atip176 positioned distal theloop174. In one preferred embodiment, the locatingdevice168 is integrally formed with thecatheter body162 and includesmapping electrodes178. Alternatively, the locatingdevice168 may be a separate body, and thetip176 may be disposed between thewire basket166 and theloop174.
• During use, the[0096]catheter assembly160 functions in a fashion highly similar to the catheter assembly130 (FIG. 6) previously described. The locatingdevice168, and in particular thetip176, is used to locate and map a pulmonary vein PV (FIG. 4B). Theloop174 is maneuvered into contact with the left atrium LA (FIG. 4B) wall. Thewire basket166 is then radially deployed so as to engage the pulmonary vein PV wall. In this deployed position, thewire basket166 serves to positively center theloop174 about the pulmonary vein ostium PVO (FIG. 4B).
• Yet another alternative embodiment of a[0097]catheter assembly190 is shown in FIG. 8. Thecatheter assembly190 includes a catheter body192 (shown partially in FIG. 8),electrodes194, a locatingdevice196 and a guide catheter orsheath198. As described in greater detail below, thesheath198 coaxially maintains thecatheter body192 and the locatingdevice196 such that each of thecatheter body192 and the locatingdevice196 are slidable between a retracted position and a deployed position (shown in FIG. 8).
• The[0098]catheter body192 is virtually identical to the catheter body62 (FIG. 3A) previously described and includes a proximal portion (not shown), anintermediate portion200 defining a longitudinal axis L7 and adistal portion202. Thedistal portion202 extends from theintermediate portion200 and forms a coil or plurality ofloops204 substantially transverse to the longitudinal axis L7. Alternatively, thecoil204 may form a single loop. Thecoil204 revolves around a central loop axis C7, that, in one preferred embodiment, is aligned with the longitudinal axis L7. Thedistal portion202, and in particular thecoil204, is preferably sufficiently flexible so as to assume a relatively straight configuration when retracted within thesheath198. Further, thedistal portion202 includes a shape memory characteristic such that when deployed from thesheath198, thedistal portion202 forms thecoil204 as shown in FIG. 8.
• The[0099]electrodes194 are identical to those previously described and preferably comprise band electrodes disposed along thecoil204. Alternatively, a continuous coil electrode or counter-electrode may be provided.
• The[0100]locating device196 is relatively rigid and includes ashaft206 defining atip208 that preferably maintainsmapping electrodes210. Theshaft206 is sized to be slidably received within a lumen (not shown) in thesheath198. As shown in FIG. 8, thetip208 preferably assumes a coil shape with decreasing diameter. Alternatively, thetip208 may be substantially straight. Preferably, however, thetip208 is sufficiently flexible such that upon retraction into thesheath198, thetip208 assumes a relatively straight form. Additionally, thetip208 has a shape memory characteristic such that upon deployment from thesheath198, thetip208 assumes the coiled shape shown in FIG. 8. For example, thetip208 may include stainless steel or Nitinol core wires. Further, thetip208 may be formed from a shape memory alloy of Nitinol that forms the coil shape when heated above a certain temperature. The heat may be achieved through resistive heating of the wire directly, or by surrounding the wire with a tubular heater.
• The[0101]sheath198 includes a proximal end (not shown) and adistal end212, and forms at least one central lumen (not shown) sized to maintain thecatheter body192 and the locatingdevice196. Alternatively, a separate lumen may be provided for each of thecatheter body192 and the locatingdevice196. Regardless, thesheath198 is configured to slidably maintain each of thecatheter body192 and the locatingdevice196 in a relatively close relationship. In one preferred embodiment, thesheath198 is formed of a relatively soft material such as 35D or 40D Pebex.
• As described above, each of the[0102]catheter body192 and the locatingdevice196 are slidable relative to thesheath198. In a deployed position (depicted in FIG. 8), thedistal portion202 of thecatheter body192 and thetip208 of the locatingdevice196 extend distally from thesheath198. More particularly, the locatingdevice196 is positioned such that thetip208 is distal thecoil204. In this extended position, thetip208 is essentially aligned with the central loop axis L7.
• During use, the[0103]catheter body192 and the locatingdevice196 are retracted within thesheath198. Thesheath198 is then guided to the left atrium LA (FIG. 4B). Thecatheter body192 and the locatingdevice196 are deployed from thesheath198. More particularly, thedistal portion202 of thecatheter body192 and thetip208 of the locatingdevice196 are extended from thedistal end212 of the sheath198 (as shown in FIG. 8). A locking device (not shown) is preferably provided to secure thecatheter assembly190 in the deployed position. As previously described, upon deployment, thedistal portion202 forms thecoil204, whereas thetip208 preferably assumes a coil shape. Thetip208 locates and is directed axially into a pulmonary vein PV as previously described. Themapping electrodes210 sample electrical activity of the pulmonary vein tissue. If the mapping procedure determines that the pulmonary vein PV requires electrical isolation, thesheath198 is guided in a direction along the central loop axis C7 until thecoil204 contacts the left atrium LA (FIG. 4B) wall about the pulmonary vein ostium PVO (FIG. 4B). Because thecatheter body192 and the locatingdevice196 are directly connected by thesheath198, thetip208 effectively positively centers theloop204 about the pulmonary vein ostium PVO. Theelectrodes194 may be selectively energized with a low energy supply to determine which of theelectrodes194 are in contact with tissue of the left atrium LA. Some or all of theelectrodes194 are then energized to ablate a continuous, closed lesion pattern about the pulmonary vein ostium PVO, thereby electrically isolating the pulmonary vein PV from the left atrium LA.
• While the[0104]catheter assembly190 has been described as including thesheath198 to maintain thecatheter body192 and the locatingdevice196, thesheath198 may be eliminated for example, thecatheter body192 may alternatively be configured to include lumen (not shown) sized to slidably receive thelocating device192. In this regard, the locatingdevice192 may serve as a guide wire, with thecatheter body192 riding over the locatingdevice192 much like an over-the-wire catheter configuration commonly known in the art. Even further, thecatheter body192 may include a rapid exchange design characteristic for quick mounting to removal from the locatingdevice190.
• Yet another alternative embodiment of a[0105]catheter assembly220 is shown in FIGS. 9A and 9B. Thecatheter assembly220 includes a catheter body222 (shown partially in FIGS. 9A and 9B),electrodes224,stylets226 and alocating device228. Theelectrodes224 are disposed along a portion of thecatheter body222. Thestylets226 are slidably maintained within thecatheter body222. Finally, the locatingdevice228 is slidably maintained by thecatheter body222.
• The[0106]catheter body222 is similar to those previously described and includes a proximal portion (not shown), anintermediate portion230, defining a longitudinal axis L8, and adistal portion232. Thedistal portion232 forms aloop234 substantially transverse to the longitudinal axis L8. Theloop234 revolves around a central loop axis C8 which, in one preferred embodiment, is aligned with the longitudinal axis L8. Thedistal portion232 is preferably sufficiently flexible so as to be relatively straight in a retracted position (FIG. 9B). Further, thedistal portion232 has a shape memory characteristic such that thedistal portion232 forms theloop234 in a deployed position (FIG. 9A). For example, thecatheter body222 may be formed of a super elastic, shape memory Nitinol alloy.
• Each of the[0107]stylets226 are relatively rigid shafts sized to be slidably received within lumens (not shown) formed by thecatheter body222. To this end, as shown in FIG. 9A, in a deployed position, thestylets226 are proximal thedistal portion232 such that thedistal portion232 is allowed to form theloop234. Conversely, in a retracted position (FIG. 9B) thestylets226 extend into thedistal portion232, thereby rendering thedistal portion232 substantially straight.
• The[0108]electrodes224 are identical to those previously described and preferably comprise band electrodes disposed along theloop234. Alternatively, a continuous coil electrode or counter electrode may be provided.
• The[0109]locating device228 includes ashaft236 having atip238. Similar to previous embodiments, thetip238 is preferably coil shaped, and includesmapping electrodes240. In this regard, thetip238 is preferably sufficiently flexible such that in the retracted position (FIG. 9B), thetip238 is rendered relatively straight by thecatheter body222. Conversely, in the deployed position (FIG. 9A), thetip238 assumes the coiled shape. Alternatively, thetip238 may be substantially straight in the deployed position.
• The[0110]catheter assembly220 is used in a manner highly similar to that previously described. Thecatheter assembly220 is initially placed in the retracted position (FIG. 9B), whereby thestylets226 are maneuvered distally to straighten thedistal portion232. Further, the locatingdevice228 is retracted within thecatheter body222 such thattip238 is proximal thedistal portion232 and is rendered relatively straight. In this retracted position, thecatheter assembly222 can more easily be directed into the left atrium LA (FIG. 4B) as previously described. Once in the left atrium LA, thecatheter assembly220 is maneuvered to the deployed position (FIG. 9A), whereby the stylets are moved proximally such that thedistal portion232 forms theloop234. Further, the locatingdevice228 is maneuvered distally relative to thecatheter body222 such that thetip238 extends distal theloop234. In the deployed position, the locatingdevice228 is maneuvered in a generally axial fashion to locate and extend into a pulmonary vein PV. Themapping electrodes240 map the pulmonary vein tissue (FIG. 4B). Where the mapping procedure indicates that the pulmonary vein PV requires electrical isolation, thecatheter assembly220 is advanced such that theloop234 surrounds the pulmonary vein ostium PVO (FIG. 4B). More particularly, thecatheter assembly220 is advanced in the direction of the central loop axis C8. Once again, the unique configuration of thecatheter assembly220 facilitates movement in an axial direction (relative to the pulmonary vein ostium PVO) as opposed to a radial, sliding direction required by previous ablation catheter designs. Notably, because thelocating device228 is directly connected to thecatheter body222, the locatingdevice228 facilitates positive centering of theloop234 about the pulmonary vein ostium PVO. Theelectrodes224 are then energized to ablate a continuous, closed lesion pattern about the pulmonary vein ostium PVO, thereby electrically isolating the pulmonary vein PV.
• Yet another alternative embodiment of the[0111]catheter assembly250 in accordance with the present invention is shown in FIG. 10. Thecatheter assembly250 includes a catheter body252 (shown partially in FIG. 10),electrodes254, a locatingdevice256 and a guide catheter orsheath258. As described in greater detail below, thesheath258 coaxially maintains thecatheter body252 and the locatingdevice256 such that each of thecatheter body252 and the locatingdevice256 are slidable between a retracted position and a deployed position (shown in FIG. 10).
• The[0112]catheter body252 is virtually identical to the catheter body62 (FIG. 3A) previously described and includes a proximal portion (not shown), anintermediate portion260 defining a longitudinal axis L9 and adistal portion262. Thedistal portion262 extends from theintermediate portion260 and forms a coil orloops264 substantially transverse to the longitudinal axis L9. Alternatively, thecoil264 may form a single loop. Thecoil264 revolves around a central loop axis C9, that, in one preferred embodiment, is aligned with the longitudinal axis L9. Thedistal portion262, and in particular thecoil264, is preferably sufficiently flexible so as to assume a relatively straight configuration when retracted within thesheath258. Further, thedistal portion262 includes a shape memory characteristic such that when deployed from thesheath258, thedistal portion262 forms thecoil264 as shown in FIG. 10.
• The[0113]electrodes254 are identical to those previously described and preferably comprise band electrodes disposed along thecoil264. Alternatively, a continuous coil electrode or counter-electrode may be provided.
• The[0114]locating device256 includes a shaft266 and aballoon268. The shaft266 includes adistal portion270 and atip272. Thedistal portion270 preferably forms anexpansion joint274. Thetip272 is distal theexpansion joint274 and preferably maintainsmapping electrodes276. Theballoon268 is sealed to thedistal portion270 of the shaft266 about theexpansion joint274. In this regard, theexpansion joint274 is configured to be manipulated between a contracted position (FIG. 10) and an expanded position. In the expanded position, theexpansion joint274 extends axially so as to collapse theballoon268. When collapsed, theballoon268 can more easily be retracted within thesheath258.
• The[0115]sheath258 includes a proximal end (not shown) and a distal end278, and forms at least one central lumen (not shown) sized to maintain thecatheter body252 and the locatingdevice256. Alternatively, a separate lumen may be provided for each of thecatheter body252 and the locatingdevice256. Regardless, thesheath258 is configured to slidably maintain each of thecatheter body252 and the locatingdevice256 in relatively close relationship. In one preferred embodiment, thesheath258 is formed of a relatively soft material such as 35D or 40D Pebex.
• As described above, each of the[0116]catheter body252 and the locatingdevice256 are slidable relative to thesheath258. In a deployed position (depicted in FIG. 10), thedistal portion262 of thecatheter body252 and thedistal portion270 of the locatingdevice256 extend distally from thesheath258. More particularly, thecoil264 is positioned distal the distal end278 of thesheath258. Further, thedistal portion270, including theballoon268, of the locatingdevice256 is positioned distal thecoil264. In this position, thedistal portion270 is essentially aligned with the central loop axis L9.
• Prior to use, the[0117]catheter body252 and the locatingdevice256 are retracted within thesheath258. Thesheath258 is then guided to the left atrium LA (FIG. 4B). Thecatheter body252 and the locatingdevice256 are deployed from thesheath258. More particularly, thedistal portion262 of thecatheter body252 and thedistal portion270 of the locatingdevice256 are extended from the distal end278 of the sheath258 (as shown in FIG. 10). A locking device (not shown) is preferably provided to secure thecatheter assembly250 in the deployed position. As previously described, upon deployment, thedistal portion262 of thecatheter body252 forms thecoil264. Thedistal portion270 of the locatingdevice256, including theballoon268, is positioned distal thecoil264. Thetip272 locates and is directed axially into a pulmonary vein PV (FIG. 4B) as previously described. Themapping electrodes276 sample electrical activity of the pulmonary vein tissue. If the mapping procedure determines that the pulmonary vein PV requires electrical isolation, thesheath258 is guided in a direction along the central loop axis C9 until thecoil264 contacts the left atrium LA wall about the pulmonary vein ostium PVO (FIG. 4B). Theexpansion joint274 is contracted and theballoon268 inflated. Once inflated, theballoon268 engages the pulmonary vein PV. Because thecatheter body252 and the locatingdevice256 are directly connected by thesheath258, theballoon268 effectively positively centers thecoil264 about the pulmonary vein ostium PVO. Theelectrodes254 may be selectively energized with a low-energy supply to determine which of theelectrodes254 are in contact with the tissue of the left atrium LA. Some or all of theelectrodes254 are then energized to ablate a continuous, closed lesion pattern about the pulmonary vein ostium PVO, thereby electrically isolating the pulmonary vein PV from the left atrium LA.
• Yet another alternative embodiment of a[0118]catheter assembly290 is shown in FIG. 11. Thecatheter assembly290 is highly similar to the catheter assembly250 (FIG. 10) previously described, and includes acatheter body292,electrodes294, a locatingdevice296 and a guide catheter orsheath298. Thesheath298 coaxially maintains thecatheter body292 and the locatingdevice296 such that each of thecatheter body292 and the locatingdevice296 are slidable between a retracted position and a deployed position (shown in FIG. 11).
• The[0119]catheter body292 includes a proximal portion (not shown), anintermediate portion300 defining a longitudinal axis L10 and adistal portion302. Thedistal portion302 extends from theintermediate portion300 and forms a coil or plurality ofloops304 substantially transverse to the longitudinal axis L10. Alternatively, thecoil304 may form a single loop. Thecoil304 revolves around a central loop axis C10, that, in one preferred embodiment, is aligned with the longitudinal axis L10. Thedistal portion302, and in particular thecoil304, is preferably sufficiently flexible so as to assume a relatively straight configuration when retracted within thesheath298. Further, thedistal portion302 includes a shape memory characteristic such that when deployed from thesheath298, thedistal portion302 forms thecoil304 as shown in FIG. 11.
• The[0120]electrodes294 are identical to those previously described and preferably comprise band electrodes disposed along thecoil304. Alternatively, a continuous coil electrode or counter-electrode may be provided.
• The[0121]locating device296 includes ashaft306 and awire basket308. Theshaft306 includes adistal portion310 and atip312. Thedistal portion310 forms anexpansion joint314. Thetip312 preferably maintainsmapping electrodes316. Thewire basket308 is secured to thedistal portion310 about theexpansion joint314. With this configuration, theexpansion joint314 can be manipulated between an expanded position in which thewire basket308 is relatively flat and a contracted position (FIG. 11) in which thewire basket308 expands radially.
• The[0122]sheath298 is highly similar to previous embodiments and includes a proximal end (not shown) and adistal end318, and forms at least one central lumen (not shown) sized to maintain thecatheter body292 and the locatingdevice296. Alternatively, a separate lumen may be provided for each of thecatheter body292 and the locatingdevice296. Regardless, thesheath298 is configured to slidably maintain each of thecatheter body292 and the locatingdevice296 in a relatively close relationship.
• As described above, each of the[0123]catheter body292 and the locatingdevice296 are slidable relative to thesheath298. In a deployed position (depicted in FIG. 11), thedistal portion302 of thecatheter body292 and thedistal portion310 of the locatingdevice296 extend distally from thesheath298. More particularly, thecatheter body292 is positioned such that thecoil304 is distal thedistal end318. Further, thedistal portion310 of the locatingdevice296 is distal thecoil304.
• During use, the[0124]catheter assembly290 functions in a manner highly similar to the catheter assembly250 (FIG. 10) previously described. However, thewire basket308 is used to positively center thecoil304 about a pulmonary vein ostium PVO instead of the balloon268 (FIG. 10) previously described.
• Yet another alternative embodiment of the[0125]catheter assembly330 is shown in FIGS. 12A and 12B. Thecatheter assembly330 includes a catheter body332 (shown partially in FIGS. 12A and 12B), awire basket334, a locatingdevice336 and a stylet orguide wire338. Thewire basket334 is secured to thecatheter body332. The locatingdevice336 is preferably integrally formed with thecatheter body332 and includes aballoon340. Finally, theguide wire338 is slidably disposed within a central lumen (not shown) in thecatheter body332 and the locatingdevice336.
• The[0126]catheter body332 includes a proximal portion (not shown), an intermediate342 defining a longitudinal axis L11 and a distal portion344. The distal portion344 maintains aproximal collar346 and adistal collar348. In a preferred embodiment, theproximal collar346 is slidable relative to thedistal collar348.
• The[0127]wire basket334 is secured to the distal portion344 by theproximal collar346 and thedistal collar348. Further, thewire basket334 includes a plurality of individual wire struts350 each maintaining anelectrode352. In a preferred embodiment, the wire struts350 are preferably tubular and are fluidly connected to a cooling source. Theelectrodes352 are preferably disposed along the wire struts350, respectively, slightly distal of a central position. With this configuration, thewire basket334 can be maneuvered between a retracted position (FIG. 12A) and an expanded position (FIG. 12B) with movement of theproximal collar346 relative to thedistal collar348. Notably, in the expanded position of FIG. 12B, thewire basket334 positions theelectrodes352 so as to form a loop transverse to the longitudinal axis L11. More particularly, the loop formed in the expanded position revolves around a central loop axis C11, that, in one preferred embodiment, is aligned with the longitudinal axis L11.
• The[0128]electrodes352 are identical to those previously described and preferably comprise band electrodes disposed along thewire basket334.
• The[0129]locating device336 extends distal thedistal collar348, and maintains theballoon340 andmapping electrodes354. Theballoon340 is fluidly connected to an inflation source (not shown) by a lumen (not shown) formed within thecatheter body332. As shown in FIGS. 12A and 12B, theballoon340 is preferably positioned distal thewire basket334. Further, themapping electrode354 is positioned distal theballoon340.
• Prior to use, the[0130]catheter assembly330 is positioned in the retracted position shown in FIG. 12A. Theguide wire338 is guided to the left atrium LA (FIG. 4B) and into a pulmonary vein PV (FIG. 4B). Thecatheter body332, including thelocating device336, are guided over theguide wire338 to a point adjacent the pulmonary vein. Thecatheter body332 is then advanced such that the locatingdevice336 enters the pulmonary- vein PV. Themapping electrodes354 sample electrical activity of the pulmonary vein tissue. If the mapping procedure determines that the pulmonary vein PV requires electrical isolation, thecatheter assembly330 is maneuvered to the expanded position shown in FIG. 12B, whereby thewire basket334 expands radially. Thecatheter body332 is then advanced axially toward the pulmonary vein such that thewire basket334 contacts the left atrium LA about the pulmonary vein ostium PVO (FIG. 4B). Theballoon340 is then inflated so as to engage the pulmonary vein PV. Once inflated, theballoon340 effectively centers thewire basket334, and thus theelectrodes352, about the pulmonary vein ostium PVO. Theelectrodes352 are then energized to ablate a continuous, closed lesion pattern about the pulmonary vein ostium PVO, thereby electrically isolating the pulmonary vein PV from the left atrium LA. If necessary, the individual wire struts350 are cooled, such as by forcing a cooling liquid through the wire struts350. Theballoon340 is deflated and thewire basket334 maneuvered to the contracted position (FIG. 12A). Theentire catheter assembly330 may then be removed from the patient. Alternatively, thecatheter body332 may be retracted from the patient along theguide wire338 and replaced with a separate catheter device (not shown). To this end, thecatheter body332 may be configured to provide a rapid exchange feature, as would be apparent to one of ordinary skill.
• Yet another alternative embodiment of a[0131]catheter assembly400 is shown in FIGS.13A-13E. With reference to FIG. 13A, thecatheter assembly400 includes acatheter body402, afluid source404, a shaping wire406 (hidden in FIG. 13A), aguide wire408 and first and second sensing electrode pairs410aand410b. Thefluid source404 is fluidly connected to a lumen formed by thecatheter body402. Theshaping wire406 and theguide wire408 are coaxially and slidably maintained by thecatheter body402 such that each of theshaping wire406 and theguide wire408 are slidable between a retracted position and a deployed position (shown in FIG. 13A). Finally, the sensing electrodes410a,410bare secured to a portion of thecatheter body402.
• The[0132]fluid source404 is shown schematically in FIG. 13A, and can assume a wide variety of forms. Thefluid source404 maintains an appropriate volume of a conductive liquid or ionic fluid, such as a hypertonic saline solution, and includes a pump (not shown). The pump is controllable to provide a desired flow rate of the liquid to thecatheter body402.
• The[0133]catheter body402 includes aproximal portion416, anintermediate portion418, and adistal portion420. Construction of thecatheter body402 is described in greater detail below. In general terms, and as shown in FIG. 13A, thedistal portion420 extends from theintermediate portion418 and forms, or is formed to, a coil or helix (e.g., conical or cylindrical). Further, thedistal portion420 defines anablation section422. Theablation section422 forms, or is formed to, a loop of at least one revolution. As with previous embodiments, the loop formed at or by theablation section422 revolves around a central loop axis C12, that is substantially parallel with, preferably aligned with, a longitudinal axis L12 defined by theintermediate portion418. Alternatively stated, the loop formed at or by theablation section422 extends transversely relative to the longitudinal axis L12.
• With additional reference to FIG. 13B, the[0134]catheter body402 preferably defines afirst lumen428 and asecond lumen430. Thefirst lumen428 extends from theproximal portion416 through thedistal portion420, including theablation section422, and is preferably closed or terminates at adistal end432 of thecatheter body402. As described in greater detail below, thefirst lumen428 is sized to slidably receive theshaping wire406 as depicted in FIG. 13B, and preferably has a diameter slightly greater than that of theshaping wire406 and any other elements carried by theshaping wire406, such as a coil electrode. With this configuration, thefirst lumen428 provides sufficient spacing about theshaping wire406 to allow passage of the conductive liquid or ionic fluid (not shown) from thefluid source404. Thus, thefirst lumen428 is fluidly connected to thefluid source404 and directs liquid from thefluid source404 to at least theablation section422. By closing thefirst lumen428 at thedistal end432, a back pressure can be generated within thefirst lumen428 to promote fluid irrigation through theablation section422 as described below.
• The[0135]second lumen430 extends from theproximal portion416 to thedistal portion420, preferably terminating at anopening434 located proximal theablation section422. This relationship is illustrated in FIG. 13C. Thesecond lumen430 is sized to slidably maintain theguide wire408. In this regard, thecatheter body402 is preferably configured such that in the deployed position of FIG. 13A, theguide wire408 extends from theopening434 in a substantially concentric fashion relative to the helix formed in or by thedistal portion420.
• The[0136]catheter body402 is described in greater detail with reference to FIG. 14A. For ease of illustration, only a portion of thecatheter body402 is provided in FIG. 14A, including theintermediate portion418 and thedistal portion420. Further, thedistal portion420 is shown in a straightened or uncoiled state, as compared to the helical configuration of FIG. 13A. As previously described, thecatheter body402 includes theablation section422 formed along thedistal portion420. In one preferred embodiment, theablation section422 is formed of a material different from a remainder of thecatheter body402, including thedistal portion420. More particularly, theablation section422 is tubular, formed of a flexible, microporous, surgically-safe material, whereas a remainder of thecatheter body402, and in particular thedistal portion420, is formed of a flexible, fluid impermeable material. In one preferred embodiment, theablation section422 is a microporous polymer, preferably microporous, high density, expanded polytetrafluoroethylene (PTFE), whereas a remainder of thedistal portion420 is a fluid impermeable polymer, such as polyethylene, polyurethane or PEBAX™ material (polyurethane and nylon). A remainder of thecatheter body402 is similarly formed from a fluid impermeable, polymeric, electrically nonconductive material but can be more rigid than thedistal portion420. Alternatively, other known materials useful in catheter applications are equally acceptable.
• Use of a porous material for the[0137]ablation section422 establishes a plurality ofpores440 extending from aninterior surface442 to anexterior surface444. As shown in FIG. 13D, thepores440 are in fluid communication with thefirst lumen428. It should be noted that a size of thepores440 has been greatly exaggerated in FIG. 13D for purposes of illustration. Further, thepores440 need not be continuous from theexterior surface444 to theinterior surface442. Instead, a plurality of interconnected interstitial spaces can be formed by theablation section422 so as to establish fluid communication between theinterior surface442 and theexterior surface444. As a point of reference, a porosity of theablation section422 is preferably in the range of approximately 5-25 microns. Regardless of the exact construction, theablation section422 formed with microporous material irrigates liquid (and contained ions) from thefirst lumen428 to theexterior surface444 in a uniform fashion along an entirety of theexterior surface444, or at least along an entire length of the ablation section422 (and thus into contact with targeted tissue (not shown)). With this construction, then, where the conductive fluid has been energized (such as by an electrode), a continuous electrode is effectively established along an entire length of theablation section422, in direct contrast to “compartmentalized” ablation electrodes typically employed. By way of example, use of a high density, expanded PTFE material for theablation section422 having a straightened length of approximately 3.2 inches (81.3 mm) and wall thickness of approximately 0.010 inch (0.25 mm) exhibited virtually uniform liquid distribution of a preferably isotonic, alternatively hypertonic, saline solution along theexterior surface444 at flow rates as low as 1 ml/min.
• While the[0138]ablation section422 has been preferably described as being formed of a microporous polymer, other constructions are equally acceptable. For example, as shown in FIG. 14B, analternative ablation section450 is initially formed as a non-porous sleeve. During manufacture, a series ofsmall passages452 are created in the sleeve, such as with a laser, to facilitate generally uniform irrigation of a conductive liquid for an interior to an exterior of the sleeve. Once again, thepassages452 are minute, preferably having a diameter in the range of 5-100 microns. A wide variety of materials are useful for the sleeve, including polyethylene (high or low density), nylon, polyamide block co-polymer, PTFE, polyurethane, fluoropolymers, etc.
• Regardless of exact construction, in a preferred embodiment the[0139]distal portion420, including theablation section422, is preferably compliant, and can readily be manipulated to a desired shape. To this end, theshaping wire406 is preferably employed to selectively direct thedistal portion420 to the helical or coiled configuration of FIG. 13A. Thus, in one preferred embodiment, thedistal portion420, including theablation section422, defines thefirst lumen428 for receiving theshaping wire406 along with an electrode (not shown) for applying an ablation energy to fluid irrigated through theablation section422. This relationship is depicted in FIG. 13D. Alternatively, and with reference to FIG. 13E, an additional lumen, such as athird lumen460, can be formed in the distal portion420 (and extending to the proximal portion418). With this configuration, thefirst lumen428 is available to direct fluid to theablation section422, while thethird lumen460 is available to maintain theshaping wire406 and/or an electrode for applying an ablation energy. Even further, the material selected for thedistal portion420 can have an elasticity or shape memory characteristic such that the helix configuration is independently achieved by thedistal portion420 without requiring theseparate shaping wire406.
• Returning to FIG. 14A, regardless of the exact construction, the[0140]ablation section422 is preferably sized so as to provide a relatively large ablation area when formed as a loop (as otherwise depicted in FIG. 13A). In one preferred embodiment, theablation section422 has a straightened length in the range of approximately 2-8 inches (51-203 mm), more preferably approximately 5 inches (127 mm). Alternatively, other dimensions are equally acceptable.
• The[0141]shaping wire406 is shown in greater detail in FIGS. 15A and 15B. Theshaping wire406 includes a proximal segment (not shown), anintermediate segment464 and a distal segment466. In addition, ametal wire470 is preferably provided and secured to theshaping wire406 as described below. As a point of reference, the distal segment466 is shown in a straightened or uncoiled state in FIG. 15A, whereas FIG. 15B depicts a helical (or coiled) state.
• The[0142]shaping wire406, and in particular the distal segment466, is preferably formed of a thin material having a super elasticity or shape memory characteristic. For example, in one preferred embodiment, theshaping wire406 is formed from spring-like material such as super elastic or pseudo-elastic nickel titanium (commercially available as Nitinol material), having a diameter in the range of approximately 0.010-0.020 inch (0.25-0.5 mm). With this or other resilient material (such as stainless steel or resilient plastic), the desired helical configuration of the distal segment466 is imparted during formation of theshaping wire406. As a result, the distal segment466 has a highly resilient, spring-like attribute whereby the distal segment466 can be “forced” to the straightened state of FIG. 15A, but will readily revert to the helical configuration of FIG. 15B (it being understood that the super elastic Nitinol or other material has a phase transition temperature well below normal human body temperature).
• The[0143]metal wire470 is wound about a portion of the distal segment466 to form acoil electrode474 and is secured to theshaping wire406, such as by aweld472. Further, themetal wire470 extends to the proximal segment (not shown) where it is electrically connected to a power source (not shown), for example a source of radio frequency (RF) energy. The location and length of thecoil electrode474 relative to theshaping wire406 corresponds with a location and length of the ablation section422 (FIG. 14A) relative to the catheter body402 (FIG. 14A). Thus, upon final assembly and activation of the power source, thecoil electrode474 serves to provide an ablation energy to theablation section422, and in particular, the conductive fluid (not shown) otherwise supplied to theablation section422. Notably, a winding density and thickness of thecoil electrode474 does not impede the ability of the distal segment466 to revert to the helical state of FIG. 15B. In the straightened state of FIG. 15A, thecoil electrode474 preferably has a length slightly greater than a length of theablation section422, in the range of approximately 2.5-8.5 inches (63-216 mm). In one preferred embodiment, with theablation section422 length of approximately 5 inches (127 mm), thecoil electrode474 has a length of approximately 5.5 inches (140 mm). A wide variety of known, electrically conductive materials are available for use as themetal wire470. Preferably, however, themetal wire470 is comprised of platinum, copper, copper-silver alloy, nickel-cobalt alloy, etc.
• While the[0144]shaping wire406 has been described as carrying asingle metal wire470, and thus asingle coil electrode474, multiple wires/coil electrodes can be provided. For example, in a more preferred embodiment, depicted in FIG. 15C, sixmetal wires470a-470fforming sixcoil electrodes474a-474fare each secured to the distal segment466 (depicted in a straightened state for ease of illustration) as previously described. Thecoil electrodes474a-474fare preferably longitudinally spaced by approximately1 -2 mm. For ease of illustration, only one of themetal wires470ais shown as extending proximally, it being understood that all of themetal wires470a-470fextend proximally, and are connected to a power source and/or control box (not shown). Thecoil electrodes474a-474fare sized such that when theshaping wire406 assumes the helical shape, (e.g., FIG. 15B) each of thecoil electrodes474a-474fhave a length less a full revolution defined by the distal segment466. While thecoil electrodes474a-474fmay have varying lengths, thecoil electrodes474a-474fare sized such that a combined length is slightly greater than one revolution (or of a length of the ablation section422 (FIG. 13A)). With this configuration, a user can selectively ablate quadrants or portions of a complete circle (or other closed shape) by selectively energizing less than all of thecoil electrodes474a-474f. For example, a user may wish to ablate only muscle tissue (determined by electrogram analysis). By providing multiple, relativelyshort coil electrodes474a-474f, this desired procedure is available. Once again, however, only a single coil electrode is necessary.
• Returning to FIG. 13A, the[0145]guide wire408 is of a type known in the art, and is preferably constructed of a rigid metal material. In this regard, theguide wire408 includes a proximal section480 and adistal section482. Further, theguide wire408 is sized to be slidably received within thesecond lumen430 of thecatheter body402. With this relationship, theguide wire408 is selectively moveable from a retracted position in which thedistal section482 is proximal thedistal portion420, and a deployed position in which thedistal section482 is distal the distal portion420 (as shown in FIG. 13A). Finally, thedistal section482 can be formed to include a J-shaped or floppy tip to facilitate placement within a vein. As described below with reference to an alternative embodiment, theguide wire408 is not a necessary element, and can be replaced with an alternative locating device.
• Finally, the sensing electrode pairs[0146]410a,410bare preferably band electrodes capable of providing feed back information indicative of electrical activity. As described below, the sensing electrode pairs410a,410bare useful for evaluating the “completeness” of an ablation pattern formed by thecatheter assembly400. To this end, the sensing electrode pairs410a,410bare strategically located along thedistal portion420 relative to theablation section422. It will be noted that thedistal portion420 is preferably helically-shaped, having a decreased diameter proximal theablation section422, and an increased diameter distal theablation section422. With this in mind, the first sensing electrode pair410ais preferably located proximal theablation section422 for evaluating electrical activity “within” the loop pattern defined by theablation section422. Conversely, the second sensing electrode pair410bis distal theablation section422 for evaluating electrical activity “outside” the loop. With alternative embodiments, one or both of the sensing electrode pairs410a,410bcan be eliminated; or additional sensing electrodes provided. Even further, additional sensors, such as a thermocouple, can be included along thedistal portion420.
• The[0147]catheter assembly400 of FIG. 13A is deployed to a desired area of a heart as described below, preferably in a straightened or uncoiled state. To facilitate this arrangement, and in a more preferred embodiment, thecatheter assembly400 further includes a guide catheter orsheath486 as shown in FIGS. 16A and 16B. For ease of illustration, only a distal region of thecatheter assembly400 is shown in FIGS. 16A and 16B. Theguide catheter486 forms alumen488 sized to slidably maintain the catheter body402 (including theshaping wire406 and the guide wire408), and terminates at anopen tip490. With this configuration, thecatheter assembly400 is selectively maneuverable between the retracted position of FIG. 16A in which entireties of thecatheter body402, theshaping wire406, and theguide wire408 are proximal thetip490, and the deployed position of FIG. 16B in which portions of thevarious components402,406,408 are distal thetip490. As described in greater detail below, then, thecatheter assembly400 is initially directed to a desired area in the retracted position. Subsequently, thecatheter body402, theshaping wire406 and theguide wire408 are directed to the deployed position of FIG. 16B.
• FIG. 17A-[0148]17D illustrate use of thecatheter assembly400 within the heart50, and in particular the left atrium (LA). Prior to deployment of thecatheter assembly400, the left atrium LA anatomy is preferably evaluated using an available 3-D imaging device, such as a fluoroscope, CT scanner, MRI or ultrasound, to determine the geometry and orientation of the various pulmonary veins (PV). The fluid source404 (FIG. 13A) is activated to provide a continuous flow of conductive liquid, (e.g., isotonic saline solution) to the first lumen428 (FIG. 13A), and in particular the ablation section422 (FIG. 13A). For example, a continuous flow rate in the range of 1-4 ml/min is established to purge air from thefirst lumen428.
• Following the preparatory steps, and with reference to FIG. 17A, electrical isolation of a left pulmonary vein (LPV) begins by directing the[0149]catheter assembly400 of FIG. 16A in a retracted position through the inferior vena cava (IVC), into the right atrium (RA) through a puncture in the interatrial septum (not shown) and into the left atrium LA. Alternatively, the introduction of thecatheter assembly400 into the right atrium RA is also suggested by passage of thecatheter body402 into the right atrium RA through the superior vena cava (SVC). Thetip490 of theguide catheter486 is positioned slightly spaced from the pulmonary vein ostium PVO associated with the left pulmonary vein (LPV) to be isolated. Thecatheter body402 is then deployed as shown in FIG. 17B. More particularly, thedistal portion420 is extended distal thetip490 of theguide catheter486. In this regard, the distal segment466 (FIG. 13A) of the shaping wire406 (FIG. 13A) is within thedistal portion420 of thecatheter body402 such that thedistal portion420 forms the helical shape shown in FIG. 17B.
• Following deployment of the[0150]catheter body402, theguide wire408 is then deployed as illustrated in FIG. 17C. By preferably performing deployment of thecatheter assembly400 in this order, the opportunity for damage to thecatheter body402 is minimized. Once deployed, thedistal section482 of theguide wire408 is substantially concentric with, and extends distally beyond, the helix formed at thedistal portion420.
• Once deployed, the[0151]guide wire408 is utilized to locate the left pulmonary vein LPV to be treated. In this regard, a fluoroscope is preferably employed to provide visual confirmation that theguide wire408 is positioned within the left pulmonary vein LPV to be isolated.
• The[0152]catheter body402 is advanced over theguide wire408 and into contact with the left atrium LA tissue wall/material surrounding the pulmonary vein ostium PVO as shown in FIG. 17D. In particular, thedistal portion420 is pressed against the tissue wall such that the helix formed in or by thedistal portion420 compresses onto itself and the loop formed by theablation section422 is in complete contact with the chamber wall about the pulmonary vein ostium PVO. To this end, fluoroscopic visualization is preferably utilized to confirm relatively continuous contact between theablation section422 and the chamber wall. In addition, bipolar electrograms can be recorded from the electrode pairs410a,410bto assess LA endocardial wall contact.
• The fluid flow rate from the fluid source (not shown) to the[0153]ablation section422 is then increased to approximately 4-10 ml/min. After waiting for a short period to ensure increased fluid flow to, and irrigation through, theablation section422, the coil electrode472 (FIG. 16A) is energized, for example with RF energy. This energy is transferred via the fluid irrigated along theablation section422 to the tissue contacted by theablation section422. The conductive fluid establishes a conductive path from thecoil electrode472 to the contacted tissue, thereby ablating the targeted tissue. As previously described, a porosity associated with theablation section422 is such that the conductive fluid irrigates or “weeps” or “sweats” to the exterior surface444 (FIG. 13D) of theablation section422. This weeping attribute serves to cool thecoil electrode472 and, because the fluid contacts the targeted tissue, minimizes the opportunity for thrombosis formation. In one preferred embodiment, thecoil electrode472 is energized for two minutes at 40-50 watts, although other ablation energies and times are equally acceptable. The endpoint of energy delivery can be determined by the reduction in electrogram amplitude at the discretion of the physician.
• Following application of the ablation energy, the[0154]catheter assembly400 is preferably operated to determine whether a closed, electrically isolating ablation pattern has been established in the chamber wall, about or outside of the ostium PVO. More particularly, and as shown in FIGS. 18A and 18B, the sensing electrode pairs410a,410bare simultaneously interrogated to evaluated isolation of the PV ostium PVO from the left atrium LA wall. As a point of reference, FIG. 18A provides an end view of thedistal portion420 compressed against a chamber wall (not shown), including theablation section422 and the sensing electrode pairs410a,410b. Conversely, FIG. 18B depicts an ablation pattern494 formed on a tissue wall496, as well as locations of the sensing electrode pairs410a,410brelative to the ablation pattern494 when the distal portion420 (not shown in FIG. 18B) is compressed against the tissue wall496. With these orientations in mind, the first sensing electrode pair410ais located within the ablation pattern494, whereas the second sensing electrode pair410bis located outside of the ablation pattern494. This configuration is further exemplified by reference to FIG. 18A in which the first sensing electrode pair410ais located within loop defined by theablation section422, whereas the second sensing electrode pair410bis outside of the loop. Following application of the ablation energy, the sensing electrode pairs410a,410bare operated to observe and sense electrical activity inside and outside of the ablation pattern494. If it is determined that electrical activity continues to traverse the ablation pattern494, an ablation energy can again be applied to the coil electrode472 (FIG. 13A) to further ablate the tissue wall about the pulmonary vein ostium PVO. Once sufficient ablation has been achieved, thecatheter body402 and theguide wire408 are retracted from the pulmonary vein ostium PVO. Subsequently, additional ablation patterns can be formed about other ones or all of the pulmonary vein ostia PVOs.
• As should be evident from the views of FIG. 17A-[0155]17D, proper positioning of thecatheter assembly400 relative to the left pulmonary veins LPVs is straightforward in that thecatheter assembly400 is essentially axially aligned with the left pulmonary veins LPVs upon passage into the left atrium LA. However, the right pulmonary veins RPVs are normally obliquely orientated relative to thecatheter assembly400 upon guidance into the left atrium LA. Thus, in one preferred embodiment, and as shown in FIG. 19, thecatheter assembly400 is preferably provided with a steering capability so that the right pulmonary veins RPVs are more easily accessed. For example, theguide catheter486 can be configured such that thetip490 is deflectable relative to remainder of theguide catheter486, and therefore maneuverable by a user to the position shown in FIG. 19. Controls and structures useful in providing this steering capability are well-known in the art, and can include a stiffening wire or pulling wire extending along theguide catheter486. Alternatively and/or in addition, thecatheter body402 may be provided with a steering device to facilitate selective deflection of thedistal portion420 relative to a remainder of thecatheter body402.
• The preferred implementation of the shaping wire[0156]406 (FIG. 16A) to dictate the axially compressible, helical shape of thedistal portion420 of thecatheter body402 provides several advantages. First, because thedistal portion420, and in particular theablation section422, need not have a rigid characteristic necessary to maintain the helical shape, a compliant, microporous material can be used for theablation section422, such as high density, expanded PTFE. The microporous material facilitates uniform perfusion of conductive fluid that cools theablation section422, thereby minimizing the opportunity for thrombus formation. In addition, a wide variety of differently shaped andsized shaping wires406 can be made available to a user, who can then select the size and shape most appropriate for achieving desired ablation. In other words, upon evaluating the pulmonary vein and associated ostium, the user can select an appropriate shaping wire that in turn dictates an optimal size and shape of thedistal portion420 and theablation section422. In this regard, not only can an overall size of the ostium (e.g., larger or smaller) be properly accounted for, but also the associated shape. For example, as shown in FIG. 20A, a simplified, side-sectional view of a pulmonary vein PV is shown, including the chamber wall tissue T surrounding and forming the pulmonary vein ostium PVO. As is evident from the illustration, the chamber wall tissue T is relatively planar adjacent the pulmonary vein ostium PVO. As such, the selected shaping wire500 of FIG. 20B includes a coil segment502 that axially compresses to a relatively planar loop or series of loops. During use, then, and as shown in FIG. 20C, the relatively planar, axially compressed configuration of the shaping wire500 readily conforms with the relatively planar configuration of the chamber wall tissue T, so that an optimal ablation pattern is formed on the chamber wall tissue T outside of the pulmonary vein ostium PVO.
• Alternatively, as shown in FIG. 21A, the pulmonary vein ostium PVO and associated chamber wall tissue T can have a non-planar shape. More particularly, pulmonary vein ostia are often formed to have a “saddle” shape. When so identified, a user will select a correspondingly-shaped shaping wire, such as the[0157]shaping wire504 depicted in FIG. 21B. Theshaping wire504 includes acoiled segment506 that, when axially compressed, assumes a non-planar shape. During use, and when axially compressed against the chamber wall tissue T, thecoiled segment506 assumes a “saddle” shape corresponding generally with the chamber wall tissue outside of (or surrounding) the pulmonary vein ostium PVO, as depicted in FIG. 21C. In practice, by providing a number of interchangeable, but uniquely sized and shaped shaping wires, a user can quickly ablate and electrically isolate all of the pulmonary vein ostia PVOs without removing thecatheter body402 from the left atrium LA.
• Another alternative, more preferred embodiment of a[0158]catheter assembly550 is shown in FIG. 22. For ease of illustration, only a distal region of thecatheter assembly550 is depicted. Thecatheter assembly550 is similar to the catheter assembly400 (FIGS.13A13E) previously described, and includes adelivery catheter552 and anablation catheter554. Thedelivery catheter552 includes adistal locator556 and forms a delivery lumen558 (shown partially in FIG. 22) terminating at anopening560 proximal thedelivery locator556. Theablation catheter552 is slidably disposed within thedelivery lumen558 such that theablation catheter552 is selectively deployable and retractable relative to thedelivery catheter552 via theopening560.
• The[0159]delivery catheter552 is shown in greater detail in FIG. 23. For ease of illustration, the ablation catheter554 (FIG. 22) has been omitted from the view of FIG. 23. Thedelivery catheter552 includes aproximal region570, anintermediate region572, and thedistal locator556. Theintermediate region572 extends from theproximal region570 and terminates in theopening560. Thedistal locator556, in turn, extends from theintermediate region572 distal theopening560. As described in greater detail below, thedelivery catheter552 is preferably steerable both proximal and distal theopening560.
• In light of the preferred steerable attribute of the[0160]delivery catheter552, theproximal region570 includes a Y-connector574 coupled to ahandpiece576 and a guide piece578. Thehandpiece576 is of a type known in the art and providescontrol devices580, the operation of which effectuates desired bending of thedelivery catheter552 via pull wires (not shown) described in greater detail below. The guide piece578 is fluidly connected to the delivery lumen558 (FIG. 22) and preferably is a hemostatic valve forming afirst port582 and asecond port584. Thefirst port582 is available for receiving and directing a separate body, such as the ablation catheter554 (FIG. 22) or a dilator (not shown), to thedelivery lumen558. Further, thesecond port584 is also fluidly connected to thedelivery lumen558, and is available for directing fluid thereto. For example, thesecond port584 can be fluidly connected to a stop cock valve (not shown) that in turn facilitates flushing of a liquid, such as saline, through thedelivery lumen558 while preventing back flow of other liquids, such as blood.
• With further reference to FIG. 24A, the[0161]proximal region570 forms thedelivery lumen558 within which the ablation catheter554 (FIG. 22) is slidably disposed. In addition, theproximal region570 forms a passage588 surrounding thedelivery lumen558 and maintaining, as depicted in FIG. 24A, afirst pull wire590, asecond pull wire592, and a cluster ofelectrode wires594. In one preferred embodiment, thedelivery lumen558 is defined by atube596 disposed within the passage588. Alternatively, theproximal region570 can be configured to integrally form thedelivery lumen558. Thefirst pull wire590 extends from thehandpiece576 to theintermediate region572 for effectuating steering or bending of thedelivery catheter552 proximal the opening560 (FIG. 23). Thesecond pull wire592 extends from thehandpiece576 to thedistal locator556 for effectuating steering or bending of thedelivery catheter552 distal theopening560. Finally, the cluster ofelectrode wires594 are electrically connected to an auxiliary energy source (not shown) for energizing various electrodes associated with thedelivery catheter552.
• The[0162]proximal region570 is preferably formed of a reinforced, braided material such as a tubular shaft constructed of “Ultem,” polyamide, or other high temperature polymer covered with a reinforcing braid wire or high strength filament and jacketed by a flexible polymer such as nylon, polyurethane or “PEBAX”™. With this preferred material, theproximal region570 exhibits enhanced torqueability, such that a user can more easily steer or guide thedelivery catheter552 to a target site.
• The[0163]intermediate region572 forms theopening560 and preferably maintains anelectrode600. With additional reference to FIG. 24B, theintermediate region572 defines first, second, and third lumens602-606, in addition to thedelivery lumen558. Once again, thedelivery lumen558 is preferably defined by thetube596 otherwise carried within theintermediate region572. Alternatively, thedelivery lumen558 can be integrally formed by theintermediate region572. Thedelivery lumen558 is available to slidably maintain the ablation catheter554 (FIG. 22) or other body, and terminates at theopening560. Thefirst pull wire590 extends through thefirst lumen602 and is secured to theintermediate region572 adjacent theopening560. Thesecond pull wire592 extends through thesecond lumen604. Finally, the cluster ofelectrode wires594 are maintained within thethird lumen606.
• The[0164]electrode600 is preferably a band electrode electrically connected to one or more of the cluster ofelectrode wires594. With this configuration, theelectrode600 serves as a mapping electrode. Notably, however, theelectrode600 is not a necessary element for use of thedelivery catheter552.
• The[0165]intermediate region572 is preferably formed of a material different from that of theproximal region570. More particularly, unlike the preferably reinforced, torqueable composition of theproximal region570, theintermediate region572 is preferably comprised of a softer material such as nylon, polyurethane or “PEBAX”™. With this configuration, theintermediate region572 is highly amenable to bending via tensioning of thefirst pull wire590. To this end, a length of the intermediate region572 (i.e., longitudinal distance proximal the opening560) dictates the focal point at which bending of theintermediate region572 occurs, as well as an available bend radius. In a preferred embodiment, theintermediate region572 has a longitudinal length in the range of 5-25 cm, more preferably 15 cm.
• The[0166]opening560 is shown more clearly in FIG. 24C, and preferably includes rounded or curved edges608. This preferred configuration minimizes possible tissue damage as thedelivery catheter552 is passed through bodily lumens, for example veins. Alternatively, however, theopening560 may assume a wide variety of other forms. As described below, a rounded-tip dilator (not shown) is preferably extended into and/or through theopening560 to further minimize the opportunity for tissue damage during delivery through bodily lumens.
• The[0167]distal locator556 extends distally beyond theopening560 and preferably includes electrode pairs610aand610b. Further, thedistal locator556 preferably terminates at atip612 that, in one preferred embodiment, incorporates a thermocouple and serves as an electrode pair with an electrode614. With additional reference to FIG. 24D, thedistal locator556 defines thesecond lumen604, maintaining thesecond pull wire592, and thethird lumen606, maintaining the cluster ofelectrode wires594. Thesecond pull wire592 is attached to thedistal locator556 adjacent thetip612. The cluster ofelectrode wires594 are connected to the pairs of electrodes610aand610b, as well as thetip612 and the electrode614. With this configuration, the electrode pairs610aand610b, as well as thetip612 and the electrode614, are available for mapping and/or ablation functions.
• The[0168]distal locator556 is preferably formed from a soft material similar to theintermediate region572, preferably nylon, polyurethane or “PEBAX”™. With this configuration, thedistal locator556 is bendable or steerable via tensioning of thesecond pull wire592. In a preferred embodiment, thedistal locator556 has a length in the range of 5-20 cm, more preferably 15 cm; and a diameter in the range of 5-7 French, more preferably6 French.
• Returning to FIG. 22, the[0169]ablation catheter554 includes adistal portion620 forming anablation section622. In one preferred embodiment, theablation catheter554 is highly similar to the catheter body402 (FIGS.13A-13C) previously described, such that theablation section622 is formed from a microporous material that is fluidly connected to a fluid source (not shown) by a lumen (not shown). Further a shaping wire (not shown) similar to that previously described is slidably disposed within theablation catheter554 for selectively forming thedistal portion620, and in particular theablation section622, to the helical or loop configuration, and an electrode(s) is associated with theablation section622. Alternatively, theablation catheter554 can be formed in accordance with any other of the embodiments disclosed herein.
• To facilitate deployment of the[0170]ablation catheter554, adistal end624 of thedistal portion620 extends radially outwardly relative to a curvature defined by theablation section622. This relationship is shown most clearly in FIG. 25. The angle of deflection defined by thedistal end624 relative to theablation section622 is preferably in the range of approximately 5-45°, more preferably 10°. As described in greater detail below, as thedistal portion620 is initially deployed relative to the distal locator556 (FIG. 23) of the delivery catheter552 (FIG. 23), the offset or deflected orientation of thedistal end624 assists in guiding thedistal portion620 about thedistal locator556.
• Returning to FIG. 22, in a preferred embodiment the[0171]ablation catheter554 further includesmapping electrodes626,628, proximal and distal theablation section622, respectively. As with previous embodiments, theelectrodes626,628 are available to assist a user in evaluating a target site prior to and following ablation.
• The[0172]delivery catheter552 can further include an additional anchoring device (not shown), such as the balloon136 (FIG. 6) or the wire cage166 (FIG. 7) previously described.
• During use, the[0173]delivery catheter552 is first directed toward the target site (e.g., pulmonary vein ostium). In one preferred embodiment, prior to placement in the patient, theablation catheter554 is replaced with a rounded-tip dilator (not shown) known in the art that extends through thedelivery lumen558 and partially out of theopening560. By providing the dilator, thedelivery catheter552 can be fed through bodily lumens, such as veins, without damaging the tissue walls at theopening560. Once theintermediate region572 and thedistal locator556 of thedelivery catheter552 have been guided to the general area of interest (e.g., the left atrium LA), the rounded-tip dilator is removed from thedelivery lumen558, and theablation catheter554 inserted therein. Thedistal portion620 of theablation catheter554 is then deployed through theopening560. In particular, as thedistal portion620 is directed distally through theopening560, theablation catheter554 is rotated such that thedistal end624 passes around thedistal locator556. The preferred deflected or tangential orientation of thedistal end624 relative to a curvature of a remainder of thedistal portion620 facilitates guiding of thedistal end624 around thedistal locator556. Continued rotation of theablation catheter554 positions thedistal locator556 within the circle or spiral defined by thedistal portion620.
• With the[0174]ablation catheter554 deployed to the position depicted in FIG. 22, thedistal locator556 is then maneuvered to locate the orifice in question, for example one of the pulmonary vein ostia. In this regard, a user can steer thedelivery catheter552 both proximal and distal theopening560. For example, the first pull wire590 (FIG. 25A) can be manipulated or tensioned to bend thedelivery catheter552 at the intermediate region572 (proximal the opening560). This first bend serves to “aim” or direct thedistal locator556 generally toward the orifice (or ostium) of interest. As thedistal locator556 is then maneuvered or directed toward the ostium, thedistal locator556 itself can steered via tensioning of the second pull wire592 (FIG. 24A) so as to facilitate exact, desired positioning of thedistal locator556 within the ostium.
• Once the[0175]distal locator556 has been positioned within the ostium in question, theablation catheter554 is advanced, with thedistal locator556 effectively “guiding” thedistal portion620, and in particular theablation section622, to the target site. In other words, thedistal portion620 “rides” along thedistal locator556 and is thereby properly positioned about the pulmonary vein ostium. Once positioned, theablation catheter554 is available to form a continuous ablation pattern on the chamber wall outside of/around the pulmonary vein ostium as previously described. If other of the pulmonary vein ostia require electrical isolation, thedistal locator556 can readily be aligned with the desired ostium by steering or bending of thedelivery catheter552 both proximal and distal theopening560 as previously described.
• The catheter assembly of the present invention provides a highly viable tool for electrically isolating a vessel, such as a pulmonary vein or coronary sinus, from a chamber, such as the left atrium. With respect to one preferred embodiment in which an irrigation ablation section material is provided in conjunction with a separate shaping wire, an optimally shaped ablation pattern about the pulmonary vein ostium can consistently be achieved. Further, by providing a number of differently shaped and sized shaping wires, virtually any tissue configuration can be accommodated. Further, implementation of a distal locator or guide wire in conjunction with a helical-shaped catheter body, along with fluoroscopic or other 3-D visualization techniques, facilitates proper deployment and positioning of the catheter assembly.[0176]
• Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. For example, the preferred embodiment has described electrical isolation of a pulmonary vein from the left atrium for treatment of atrial fibrillation. Alternatively, the method and apparatus of the present invention may be utilized in the treatment of other cardiac arrhythmias, such as isolating the coronary sinus from the right atrium, the superior vena cava, or isolating the outflow tract (or pulmonary valve) from the right ventricle. Further, a number of the described embodiments have included a catheter body forming a single loop. Alternatively, a multi-plane helix or spiral may be formed. The helix or spiral may increase or decrease in diameter (conical) as it extends distally, or may have a uniform diameter (cylindrical), or a combination of both shapes. Additionally, while the loop has been described as preferably being circular, a variety of other substantially closed shapes, including triangular, square, octagonal, etc., are equally acceptable. Also, several of the described embodiments have included a locating device for centering the loop about a pulmonary vein ostium and for mapping a pulmonary vein. In this regard, the locating device may be configured to serve only as a centering device or only as a mapping device, or both. With respect to the preferred embodiments described with reference to FIG. 13A-FIG. 13D and FIG. 22, certain features can be altered or eliminated while still providing a viable device. For example, the shaping wire can be employed to dictate a helical shape of a number of differently configured catheter bodies that form an ablation section of something other than a microporous, fluid irrigation material. Conversely, the microporous material ablation section technique can be applied to a catheter body that does not require a separate shaping wire to form the desired helical shape. Finally, other features may be incorporated into the catheter assembly. For example, the catheter assembly may include a rapid exchange feature for quick placement over, and removal from, the guide wire.[0177]

Claims (65)

What is claimed:

1. A catheter assembly for treatment of cardiac arrhythmia comprising:

a catheter body including:

a proximal portion,

an intermediate portion extending from the proximal portion and defining a longitudinal axis,

a distal portion extending from the intermediate portion and forming a helix,

a first lumen extending from the proximal portion to the distal portion,

an ablation section formed along the coil and defining a loop transverse to the longitudinal axis, the ablation section being formed of a microporous material in fluid communication with the first lumen to irrigate fluid from the first lumen to an exterior surface of the ablation section;

at least one electrode associated with the ablation section; and

a fluid source for supplying a liquid to the first lumen;

wherein upon activation, the electrode supplies an ablation energy to fluid irrigated to the exterior surface of the ablation section for ablating a continuous, closed lesion pattern.

2. The catheter assembly of

claim 1

, wherein the ablation section is formed of a microporous polymer.

3. The catheter assembly of

claim 2

, wherein the microporous polymer is high density, expanded PTFE.

4. The catheter assembly of

claim 1

, wherein the ablation section has a straightened length in the range of 2-8 inches.

5. The catheter assembly of

claim 1

, wherein the at least one electrode is disposed within the first lumen at the ablation section.

6. The catheter assembly of

claim 5

, wherein the at least one electrode includes a coil electrode.

7. The catheter assembly of

claim 5

, wherein the at least one electrode includes a plurality of coiled electrodes.

8. The catheter assembly of

claim 5

, wherein the at least one electrode has a length approximating a length of the ablation section.

9. The catheter assembly of

claim 5

, wherein the at least one electrode has a length slightly greater than a length of the ablation section.

10. The catheter assembly of

claim 1

, wherein the loop defines a loop axis, the loop axis and the longitudinal axis being substantially parallel.

11. The catheter assembly of

claim 1

, further comprising:

a shaping wire coaxially maintained by the catheter body, the shaping wire including a proximal segment and a distal segment, the distal segment formed of a shape memory material configured to revert to helical shape;

wherein the distal segment selectively shapes the distal portion as a helix.

12. The catheter assembly of

claim 11

, wherein the shaping wire is slidably disposed within the first lumen.

13. The catheter assembly of

claim 11

, wherein the catheter body further includes a second lumen extending from the proximal portion to the distal portion, and further wherein the shaping wire is slidably disposed within the second lumen.

14. The catheter assembly of

claim 11

, further comprising:

a guide catheter forming a lumen sized to slidably receive the catheter body and terminating at an opening, the catheter body being moveable between a retracted position in which the distal portion is proximal the opening and a deployed position in which the distal portion is distal the opening.

15. The catheter assembly of

claim 1

, further comprising:

a guide wire coaxially maintained by the catheter body, the guide wire being selectively moveable relative to the catheter body and including a proximal section and a distal section;

wherein in a deployed position, the distal section of the guide wire is substantially concentric with, and extends distally beyond, the helix formed at the distal portion of the catheter body.

16. The catheter assembly of

claim 1

, further comprising:

a sensing electrode positioned along the helix distal the ablation section for sensing tissue conductivity.

17. The catheter assembly of

claim 1

, further comprising:

a sensing electrode positioned along the helix proximal the ablation section for sensing tissue conductivity.

18. The catheter assembly of

claim 1

, wherein the loop is axially compressible to an axially compressed position following contact with a tissue wall, and further wherein the loop is configured to be substantially planar in the axially compressed position.

19. The catheter assembly of

claim 1

, wherein the loop is axially compressible to an axially compressed position following contact with a tissue wall, and further wherein the loop is configured to be non-planar in the axially compressed position.

20. The catheter assembly of

claim 19

, wherein the loop is configured to have a saddle shape in the axially compressed position.

21. The catheter assembly of

claim 1

, further comprising:

a delivery catheter having a distal locator and forming a catheter body lumen terminating at an opening proximal the distal locator;

wherein the catheter body is slidably disposed within the catheter body lumen such that the catheter body is selectively deployable and retractable relative to the distal locator via the opening.

22. The catheter assembly of

claim 21

, wherein the delivery catheter is configured to be selectively bendable distal the opening.

23. The catheter assembly of

claim 21

, wherein the delivery catheter includes a steering device for selectively bending the distal locator.

24. A catheter assembly for treatment of cardiac arrhythmia comprising:

a catheter body including:

a proximal portion,

a distal portion comprised of a flexible material,

an ablation section defined along the distal portion,

a first lumen extending from the proximal portion to the distal portion;

at least one electrode associated with the ablation section; and

a shaping wire moveably disposed within the first lumen, the shaping wire including a proximal segment and a distal segment, wherein the distal segment is formed of a shape memory material configured to revert to a helical shape;

wherein upon advancement of the distal segment within the distal portion, the distal portion assumes the helical shape of the distal segment and the ablation section forms a loop.

25. The catheter assembly of

claim 24

, wherein the shaping wire further includes an intermediate segment between the proximal and distal segments, the intermediate segment defining a longitudinal axis, and further wherein the helical shape extends transversely relative to the longitudinal axis.

26. The catheter assembly of

claim 24

, wherein the catheter body further includes an intermediate portion between the proximal and distal portions, the intermediate portion defining a longitudinal axis, and further wherein upon advancement of the shaping wire within the catheter body, the loop defines a loop axis, the loop axis and the longitudinal axis being substantially parallel.

27. The catheter assembly of

claim 24

, wherein the at least one electrode includes a coil electrode wound about at least a portion of the distal segment of the shaping wire.

28. The catheter assembly of

claim 24

, wherein the loop is axially compressible to an axially compressed position following contact with a tissue wall, and further wherein the shaping wire is configured such that the loop is substantially planar in the axially compressed position.

29. The catheter assembly of

claim 24

, wherein the loop is axially compressible to an axially compressed position following contact with a tissue wall, and further wherein the shaping wire is configured such that the loop is non-planar in the axially compressed position.

30. The catheter assembly of

claim 29

, wherein the loop is configured to have a saddle shape in the axially compressed position.

31. The catheter assembly of

claim 24

, further comprising:

a plurality of shaping wires each independently moveable within the first lumen and defining a proximal segment and a distal segment;

wherein a shape of the respective distal segments is different.

32. The catheter assembly of

claim 31

, wherein the respective distal segments are configured to define varying sized loops.

33. The catheter assembly of

claim 31

, wherein each of the distal segments are axially compressible to an axially compressed position, and further wherein a first one of the respective distal segments defines a substantially planar loop in the axially compressed position and a second one of the respective distal segments defines a non-planar loop in the axially compressed position.

34. The catheter assembly of

claim 24

, wherein the ablation section is formed of a microporous material in fluid communication with the first lumen to irrigate liquid from the first lumen to an exterior surface of the ablation section.

35. The catheter assembly of

claim 24

, further comprising:

a guide catheter having a lumen sized to slidably receive the catheter body and terminating at an opening, the catheter body being moveable between a retracted position in which the distal portion is proximal the opening and a deployed position in which the distal portion is distal the opening.

36. The catheter assembly of

claim 24

, further comprising:

a guide wire coaxially maintained by the catheter body, the guide wire being selectively moveable relative to the catheter body and including a proximal section and a distal section;

wherein in a deployed position, the distal section of the guide wire is substantially concentric with, and extends distally beyond, the helix formed in the distal portion.

37. The catheter assembly of

claim 24

, further comprising:

a sensing electrode positioned along the helix distal the ablation section for sensing tissue conductivity.

38. The catheter assembly of

claim 24

, further comprising:

a sensing electrode positioned along the helix proximal the ablation section for sensing tissue conductivity.

39. The catheter assembly of

claim 24

, further comprising:

a delivery catheter having a distal locator and forming a catheter body lumen terminating at an opening proximal the distal locator;

wherein the catheter body is slidably disposed within the catheter body lumen such that the catheter body is selectively deployable and retractable relative to the distal locator via the opening.

40. A catheter assembly for treatment of cardiac arrhythmia comprising:

a catheter body including:

a proximal portion,

an intermediate portion extending from the proximal portion and defining a longitudinal axis,

a distal portion extending from the intermediate portion and comprised of a flexible material,

a first lumen extending from the proximal portion to the distal portion,

an ablation section formed along the distal portion and formed of a microporous material in fluid communication with the first lumen to irrigate fluid from the first lumen to an exterior surface of the ablation section;

at least one electrode associated with the ablation section;

a fluid source for supplying a fluid to the first lumen; and

a shaping wire slidably disposed within the catheter body, the shaping wire including a proximal segment and a distal segment, wherein the distal segment is formed of a shape memory material configured to revert to a helical shape such that upon advancement of the distal segment within the distal portion, the distal portion assumes the helical shape of the distal segment and the ablation section forms a loop transverse to the longitudinal axis;

wherein upon activation, the electrode supplies an ablation energy to fluid irrigated to the exterior surface of the ablation section for ablating a continuous, closed lesion pattern.

41. A method for forming an ablation pattern to electrically isolate a vessel from a chamber, the vessel having an ostium formed at a chamber wall, for treatment of cardiac arrhythmia, the method comprising:

selecting a catheter assembly including a catheter body, a first shaping wire, and at least one electrode, the catheter body including a proximal portion, a distal portion, and a first lumen extending from the proximal portion through the distal portion, the distal portion including an ablation section, wherein the first shaping wire is selectively disposed within the first lumen and includes a proximal segment and a distal segment formed to selectively assume a first helical shape, and further wherein the at least one electrode is associated with the ablation section;

guiding the distal portion into the chamber;

forming the distal portion to a helical configuration with the distal segment of the shaping wire such that the ablation section forms a loop;

directing the distal portion such that the ablation section contacts the chamber wall about the vessel ostium; and

energizing the electrode to ablate a continuous, closed lesion pattern about the vessel ostium to electrically isolate the vessel from the chamber.

42. The method of

claim 41

, wherein selecting a catheter assembly includes:

providing a second shaping wire having a distal segment formed to selectively assume a second helical shape different from the first helical shape;

evaluating a shape of the vessel ostium; and

selecting one of the shaping wires based upon the evaluation of the vessel ostium.

43. The method of

claim 42

, wherein the second helical shape is saddle-shaped and evaluating a shape of the vessel ostium includes determining that the vessel ostium is saddleshaped, and further wherein selecting one of the shaping wires includes selecting the second shaping wire.

44. The method of

claim 42

, wherein the first shaping wire is selected for use in ablating

a pattern to electrically isolate a first pulmonary vein, the method further comprising:

retracting the first shaping wire from the catheter body;

inserting the second shaping wire into the first lumen;

directing the ablation section into contact with the tissue wall about an ostium of a second pulmonary vein; and

energizing the at least one electrode to ablate a continuous, closed lesion pattern about the ostium of the second pulmonary vein to electrically isolate the second pulmonary vein from the chamber.

45. The method of

claim 41

, wherein the catheter assembly further includes a guide catheter having a lumen terminating at an opening, the guide catheter coaxially maintaining the catheter body such that the catheter body is slidable between a retracted position in which the distal portion is proximal the opening and a deployed position in which in the distal portion is distal the opening, and further wherein forming the distal portion to a helical configuration includes sliding the catheter body to the deployed position.

46. The method of

claim 41

, wherein the catheter body further includes a second lumen extending from the proximal portion to the distal portion and a guide wire slidably disposed within the second lumen, the guide wire including a proximal section and a distal section, the method further comprising:

extending the distal section of the guide wire distal the distal portion of the catheter body after forming the distal portion to the helical configuration; and

locating the vessel with the distal section of the guide wire.

47. The method of

claim 41

, wherein the ablation section is formed of a microporous material in fluid communication with a fluid source for irrigating liquid from the fluid source to an exterior surface of the ablation section, the method further comprising:

activating fluid flow from the fluid source to the ablation section prior to guiding the distal portion into the chamber.

48. The method of

claim 47

, wherein energizing the electrode includes applying an ablation energy to the fluid irrigated to the exterior surface of the ablation section.

49. The method of

claim 41

, further comprising:

viewing the chamber with a fluoroscope prior to energizing the electrode to confirm sufficient contact between the ablation section and the chamber wall.

50. The method of

claim 41

, wherein the catheter assembly further includes a first sensing electrode located along the distal portion, the first sensing electrode being positioned such that upon compression of the distal portion against the chamber wall, the first sensing electrode is within an area defined by the loop, the method further comprising:

sensing tissue conductivity with the first sensing electrode to evaluate an extent of ablation.

51. The method of

claim 50

, wherein the catheter assembly further includes a second sensing electrode located along the distal portion, the second sensing electrode being positioned such that upon compression of the distal portion against the chamber wall, the second sensing electrode is outside an area defined by the loop, the method further comprising:

sensing tissue conductivity with the second sensing electrode to evaluate an extent of ablation.

52. The method of

claim 41

, further comprising:

deflecting the distal portion relative to the proximal portion such that the loop is aligned with a right pulmonary vein ostium.

53. The method of

claim 41

, wherein the catheter assembly further includes a delivery catheter having a distal locator and forming a catheter body lumen terminating at an opening proximal the distal locator, the catheter body being slidably disposed within the catheter body lumen such that the catheter body is deployable and retractable through the opening, the method further comprising:

locating the vessel with the distal locator.

54. The method of

claim 53

, further comprising:

deploying the distal portion of the catheter body after locating the vessel.

55. The method of

claim 53

, wherein the delivery catheter is configured to be deflectable

proximal and distal the opening, and further wherein locating the vessel includes:

bending the delivery catheter proximal the opening; and

bending the delivery catheter distal the opening.

56. A method for forming an ablation pattern to electrically isolate a vessel from a chamber, the vessel having ostium formed at a chamber wall, for treatment of cardiac arrhythmia, the method comprising:

selecting a catheter assembly including a delivery catheter, an ablation catheter and at least one electrode, wherein the delivery catheter includes a lumen terminating at an opening and a distal locator extending distal the opening, and further wherein the ablation catheter includes a proximal portion and a distal portion that selectively assumes a helical shape and includes an ablation section forming a loop, and further wherein the at least one electrode is associated with the ablation section;

guiding the distal locator into the chamber;

locating the vessel with the distal locator;

deploying the distal portion from the opening;

advancing the distal portion over the distal locator such that the ablation section contacts the chamber wall about the vessel ostium; and

energizing the electrode to ablate a continuous, closed lesion pattern about the vessel ostium to electrically isolate the vessel from the chamber.

57. The method of

claim 56

, wherein extending the distal portion over the distal locator includes concentrically positioning the distal locator within the loop.

58. The method of

claim 56

, wherein the ablation catheter further includes a lumen slidably maintaining a shaping wire having a proximal segment and a distal segment, the distal segment formed to selectively assume a helical shape and to direct the distal portion to a corresponding helical shape upon final assembly, wherein deploying the distal portion includes:

forming the distal portion to the helical shape with the distal segment.

59. The method of

claim 58

, wherein selecting a catheter assembly further includes:

providing a plurality of shaping wires each having differently shaped distal segments;

evaluating a shape of the vessel ostium;

selecting one of the plurality of shaping wires based upon the evaluation of the vessel ostium; and

inserting the selected one of the plurality of shaping wires into the lumen.

60. The method of

claim 56

, wherein the ablation section is formed of a microporous material in fluid communication with a fluid source for irrigating fluid from the fluid source to an exterior surface of the ablation section, the method further comprising:

activating fluid flow from the fluid source to the ablation section prior to guiding the distal portion into the chamber.

61. The method of

claim 60

, wherein energizing the electrode includes applying an ablation energy to the fluid irrigated to the exterior surface of the ablation section.

62. The method of

claim 60

, further comprising:

viewing the chamber with a fluoroscope prior to energizing the electrode to confirm sufficient contact between the ablation section and the chamber wall.

63. The method of

claim 56

, wherein the ablation catheter further includes a first sensing electrode located along the distal portion, the first sensing electrode being positioned such that upon compression of the distal portion against the chamber wall, the first sensing electrode is within an area defined by the loop, the method further comprising:

sensing tissue conductivity with the first sensing electrode to evaluate an extent of ablation.

64. The method of

claim 63

, wherein the ablation catheter further comprises a second sensing electrode located along the distal portion, the second sensing electrode being positioned such that upon compression of the distal portion against the chamber wall, the second sensing electrode is outside an area defined by the loop, the method further comprising:

sensing tissue conductivity with the second sensing electrode to evaluate an extent of ablation.

65. The method of

claim 56

, further comprising:

deflecting the distal locator such that the loop is aligned with a right pulmonary vein ostium.

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