US20070038056A1 - System and methods for locating and ablating arrhythomogenic tissues - Google Patents

Abstract

A catheter for sensing electrical events about a selected annulus region of the heart and for treating tissue in the selected annulus region has a handle assembly, a shaft having a proximal end coupled to the handle assembly, a first expandable member provided at the distal end of the shaft, and a second expandable member positioned adjacent to, but spaced apart from, the first expandable member. The second expandable member has an ablation element that emits energy to a radially surrounding area to ablate tissue.

Description

RELATED CASES
• This is a continuation-in-part of co-pending Ser. No. 10/897,887, entitled “System and Method for Mapping and Ablating Body Tissue of the Interior Region of the Heart”, filed Jul. 22, 2004, now pending, which is in turn a continuation-in-part of co-pending Ser. No. 10/744,354, entitled “System and Method for Mapping and Ablating Body Tissue of the Interior Region of the Heart”, filed Dec. 22, 2003, which is in turn a continuation of Ser. No. 09/975,269, filed Oct. 11, 2001, now U.S. Pat. No. 6,671,533, whose disclosures are incorporated by this reference as though fully set forth herein.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention is directed to systems and methods for mapping and ablating body tissue of the interior regions of the heart for treating cardiac arrrhythmias.
• 2. Description of the Prior Art
• Atrial fibrillation (AF) is a common cardiac arrhythmia associated with significant morbidity and mortality. A number of clinical conditions may arise from irregular cardiac functions and the resulting hemodynamic abnormalities associated with AF, including stroke, heart failure and other thromboembolic events. AF is a significant cause of cerebral stroke, wherein the fibrillating motion in the left atrium induces the formation of thrombus. A thromboembolism is subsequently dislodged into the left ventricle and enters the cerebral circulation where stroke may result.
• For many years, the only curative treatment for AF has been surgical, with extensive atrial incisions used to compartmentalize the atrial mass below that critical for perpetuating AF. Recently, transcatheter linear radiofrequency ablation in the right or left atrium has been used to replicate surgical procedures in patients with paroxysmal or chronic AF. Such ablation is carried out by a catheter system that performs both mapping and ablation. With current techniques, there is still uncertainty regarding the number of lesions, the optimum ablation site, and the need for continuous lines. As a result, focal ablation has been proposed as an alternative approach, due to the belief that ectopic beats originating within or at the ostium of the pulmonary veins (PV) may be the source of paroxysmal and even persistent AF. Although successful, the technical feasibility of this technique is restricted by the difficulty in mapping the focus if the patient is in AF or has no consistent firing, the frequent existence of multiple foci causing high recurrence rates, and a high incidence of PV stenosis.
• There are a number of drawbacks associated with the catheter-based mapping and ablation systems that are currently known in the art. One serious drawback lies in the unstable positioning of the catheter inside the atrium of the heart. When a catheter is not properly stabilized, the mapping becomes difficult and inaccurate.
• Another drawback is associated with certain catheter-based systems that utilize an expandable balloon that is inflated to conform to the pulmonary vein ostium. After the balloon is inflated and the catheter positioned, it becomes difficult to map or record the distal PV potentials without removing this catheter and placing another mapping catheter inside the PV. Moreover, inflation of the balloon to conform to the pulmonary vein ostium blocks blood flow to the left atrium, and such prolonged blockage can have adverse effects to the patient. Blockage of blood flow from the PV deprives the patient from receiving oxygenated blood. In addition, the blockage may be a potential source for stenosis.
• Thus, there still remains a need for a catheter-based system and method that can effectively map and ablate potentials (also known as spikes) inside PVs which can induce paroxysmal AF, while avoiding the drawbacks set forth above.
SUMMARY OF THE DISCLOSURE
• It is an objective of the present invention to provide a system and method that effectively maps or records distal PV potentials and ablates the PV ostium.
• It is another objective of the present invention to provide a system and method that effectively maps and ablates potentials without blocking blood flow.
• In order to accomplish the objects of the present invention, there is provided a catheter for sensing electrical events about a selected annulus region of the heart and for treating tissue in the selected annulus region. The catheter has a handle assembly, a shaft having a proximal end coupled to the handle assembly, a first expandable member provided at the distal end of the shaft, and a second expandable member positioned adjacent to, but spaced apart from, the first expandable member. The second expandable member has an ablation element that emits energy to a radially surrounding area to ablate tissue.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 illustrates a mapping and ablation system according to one embodiment of the present invention.
• FIG. 2 is a perspective view of the catheter of the system ofFIG. 1.
• FIG. 3 is an enlarged view of the distal tip section of the catheter ofFIGS. 1 and 2.
• FIG. 4 is a cross-sectional view of the distal tip section ofFIG. 3 taken along lines A-A thereof.
• FIG. 5 is a cross-sectional view of the distal tip section ofFIG. 3 taken along lines B-B thereof.
• FIG. 6 illustrates how the catheter ofFIGS. 1 and 2 is deployed for use inside the heart of a patient.
• FIG. 7 is a cross-sectional view illustrating the catheter ofFIGS. 1 and 2 in use in a pulmonary vein during the mapping and ablation steps.
• FIG. 8 illustrates the steering mechanism of the catheter ofFIGS. 1 and 2.
• FIG. 9 illustrates a mapping and ablation system according to another embodiment of the present invention.
• FIG. 10 is a perspective view of the catheter of the system ofFIG. 9.
• FIG. 11 is an enlarged view of the distal tip section of the catheter ofFIGS. 9 and 10.
• FIG. 12 is a cross-sectional view of the distal tip section ofFIG. 11 taken along lines A-A thereof.
• FIG. 13 is a cross-sectional view of the distal tip section ofFIG. 11 taken along lines B-B thereof.
• FIG. 14 is an enlarged persepective view of the distal tip section of the catheter ofFIGS. 9 and 10.
• FIG. 15 illustrates a mapping and ablation system according to another embodiment of the present invention.
• FIG. 16 is an enlarged persepective view of the distal tip section of the catheter ofFIG. 15.
• FIG. 17 illustrates an ablation system according to yet another embodiment of the present invention.
• FIG. 18 is a perspective view of the catheter of the system ofFIG. 17.
• FIG. 19 is an enlarged view of the distal tip section of the catheter ofFIGS. 17 and 18.
• FIG. 20 is a cross-sectional view of the distal tip section ofFIG. 19 taken along lines A-A thereof.
• FIG. 21 is a cross-sectional view of the distal tip section ofFIG. 19 taken along lines B-B thereof.
• FIG. 22 illustrates how the catheter ofFIGS. 17 and 18 is deployed for use inside the heart of a patient.
• FIG. 23 is a cross-sectional view illustrating the catheter ofFIGS. 17 and 18 in use in a pulmonary vein.
• FIG. 24 illustrates the steering mechanism of the catheter ofFIGS. 17 and 18.
• FIG. 25 illustrates an ablation system according to yet a further embodiment of the present invention.
• FIG. 26 is a perspective view of the catheter of the system ofFIG. 25.
• FIG. 27 is an enlarged view of the distal tip section of the catheter ofFIGS. 25 and 26.
• FIG. 28 is a cross-sectional view of the distal tip section ofFIG. 27 taken along lines A-A thereof.
• FIG. 29 is a cross-sectional view of the distal tip section ofFIG. 27 taken along lines B-B thereof.
• FIG. 30 is an enlarged persepective view of the distal tip section of the catheter ofFIGS. 25 and 26.
• FIG. 31 illustrates a mapping and ablation system according to yet another embodiment of the present invention.
• FIG. 32 is an enlarged persepective view of the distal tip section of the catheter ofFIG. 31.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims. In certain instances, detailed descriptions of well-known devices, compositions, components, mechanisms and methods are omitted so as to not obscure the description of the present invention with unnecessary detail.
• The present invention provides a catheter system that has two separate elements for performing the mapping and ablation operations. A first element that includes ring electrodes is provided along a distal ring and functions to map the region of the heart that is to be treated. After the mapping has been completed, a second element that includes a transducer mounted inside a balloon is positioned at the location where ablation is to be performed, and is used to ablate the selected tissue. During the ablation, the distal ring functions to anchor the position of the balloon, while the balloon is inflated to a maximum diameter that is less than the diameter of the distal ring and the annulus where the treatment is taking place. As a result, blood can still flow unimpeded through the annulus.
• Even though the present invention will be described hereinafter in connection with treating AF, it is understood that the principles of the present invention are not so limited, but can be used in other applications (e.g., treatment of accessory pathways, atrial flutter, ventricular tachycardia), and in other body pathways (e.g., right atrium, superior vena cava, right ventricle, left ventricle).
• FIGS. 1-8 illustrate acatheter system20 according to one embodiment of the present invention. Thecatheter system20 has atubular shaft22 having adistal tip section24, adistal end26, aproximal end28, and at least onelumen30 extending through theshaft22. Ahandle assembly32 is attached to theproximal end28 of theshaft22 using techniques that are well-known in the catheter art.
• Thedistal tip section24 includes anexpandable balloon38 and adistal ring80 that makes up the distal-most end of theshaft22. A transducer60 (e.g., piezoelectric or ultrasound) is housed inside theballoon38. Theballoon38 can be made from any conventional material (such as but not limited to silicone, polyurethane, latex, polyamide and polyethylene), and heat bonded or otherwise attached to theshaft22 using techniques that are well-known in the catheter art.
• Thedistal ring80 can be preformed into a generally curved or circular shape, resembling an open loop. The shape of thedistal ring80 corresponds to the circumferential geometry of a selected annulus (e.g., the PV) in the heart. In fact, the preformed shape of thedistal ring80 can be provided in a variety of curved geometries to overlie the anatomical geometry of the selected annulus. Thedistal ring80 includes atransition section82 that extends distally at an angle from the longitudinal axis of theshaft22, and has a generally open-loopedcircular section84 that extends from thetransition section82. As best seen fromFIG. 3, thecircular section84 is oriented at an approximately perpendicular orientation from the longitudinal orientation of theshaft22. Thedistal ring80 can be made from the same material as theshaft22. Such a material can be an electrically nonconductive, biocompatible, resilient plastic material which retains its shape and which does not soften significantly at human body temperature (e.g., Pebax™, polyethylene or polyester). As a non-limiting example, the geometry of thedistal ring80 can be created by thermoforming it into the desired shape.
• A plurality ofthermocouple wires54 can have their distal tips secured to the interior surface of the balloon38 (seeFIG. 3), and are used to detect the temperature at the treatment site.
• A plurality ofring electrodes58 are provided in spaced-apart manner about thecircular section84 of thedistal ring80. Thering electrodes58 can be made of a solid, electrically conducting material, like platinum or gold, that is attached about thecircular section84. Alternatively, thering electrodes58 can be formed by coating the exterior surface of thecircular section84 with an electrically conducting material, such as platinum or gold. The coating can be applied by sputtering, ion beam deposition or similar known techniques. The number ofring electrodes58 can vary depending on the particular geometry of the region of use and the functionality desired.
• As will be explained in greater detail below, thering electrodes58 function to map the region of the heart that is to be treated. After the mapping has been completed, theballoon38 is positioned at the location where ablation is to be performed, and thedistal ring80 functions to anchor the position of theballoon38. Theballoon38 is expanded, but even the greatest expanded diameter of theballoon38 will be provided to be less than the diameter of thedistal ring80 when thedistal ring80 is fully deployed (seeFIGS. 2, 3 and7). The ablation is then carried out by energy that is emitted from theultrasound transducer60 through the inflation media (e.g., fluid, saline, contrast media or mixture) inside theballoon38, and theballoon38 itself.
• A standard Luer fitting34 is connected to theproximal end36 of thehandle assembly32 using techniques that are well-known in the catheter art. The Luer fitting34 provides a fluid line for inflation media to be introduced to inflate theballoon38 at thedistal tip section24 of theshaft22. The inflation media is delivered via aninflation lumen76 that extends from the handle assembly32 (and coupled to theline78 of the Luer fitting34), and terminates at theballoon38.
• Aconnector assembly40 is also connected to theproximal end36 of thehandle assembly32 using techniques that are well-known in the catheter art. Theconnector assembly40 has aproximal connector42 that couples thehandle assembly32 to theconnector44 of acontrol line46 that leads to anultrasound generator52. An EKG monitor50 is coupled to theultrasound generator52 via anotherline48. The EKG monitor50 can be a conventional EKG monitor which receives (via the ultrasound generator52) electrical signals detected by thering electrodes58 at thedistal tip section24, and processes and displays these electrical signals to assist the physician in locating the site of potentials in a PV. Theultrasound generator52 can be a conventional ultrasound generator that creates and transmits ablating energy to theultrasound transducer60 that is positioned inside theballoon38. Theultrasound transducer60 will emit the energy to ablate the tissue that extends radially from the position of theballoon38.
• Electrical wires (not shown) extend from theultrasound generator52 along thelines46 and48, andconductor wires62 andultrasound wires63 extend through theconnector assembly40, thehandle assembly32 and thelumen30 of theshaft22 to thedistal tip section24 of theshaft22 to couple thering electrodes58 and thetransducer60, respectively. In addition, thethermocouple wires54 can extend from theballoon38 through thelumen30 of theshaft22 and thehandle assembly32 to theproximal connector42, where they can be electrically coupled by the wires in theline46 to theultrasound generator52 where the temperature can be displayed.
• Thehandle assembly32 also includes asteering mechanism70 that functions to deflect thedistal tip section24 of theshaft22 for maneuvering and positioning thedistal tip section24 at the desired location in the heart. Referring toFIGS. 1, 5 and8, thesteering mechanism70 includes asteering wire72 that extends in themain lumen30 of theshaft22 from its proximal end at thehandle assembly32 to its distal end which terminates in thedistal tip section24 before the location of theballoon38. The proximal end of thesteering wire72 is wound around or secured to ananchor77 that is fixedly positioned inside thehandle assembly32. Thesteering mechanism70 also includes aflat wire75 that extends in thelumen30 from theanchor77 to its distal end at a location slightly proximal to the balloon38 (as shown inFIG. 5). Theflat wire75 is attached to thesteering wire72 at the distal ends of theflat wire75 and thesteering wire72 so as to be controlled by thesteering wire72. Specifically, by pushing thesteering mechanism70 forward in a distal direction, thesteering mechanism70 will pull thesteering wire72 in a proximal direction, causing thedistal tip section24 to deflect to one direction (see in phantom inFIG. 8). By pulling back thesteering mechanism70 in a proximal direction, thesteering wire72 is deactivated and thedistal tip section24 returns to its neutral position or deflects to the opposite direction.
• Thedistal ring80 can be preformed to a fixed size (i.e., diameter) and shape that cannot be changed. Alternatively, the diameter of thedistal ring80 can be adjusted using techniques and incorporating mechanisms that are well-known in the catheter art.
• FIGS. 6 and 7 illustrate how thecatheter system20 is used. First, aguide sheath88 is provided to deliver theshaft22 anddistal ring80 to the desired location (e.g., the left atrium) in the heart. Theshaft22 is slid into the hollow lumen of theguide sheath88, and theguide sheath88 can slide forward and backward along the longitudinal axis of theshaft22. When theguide sheath88 is slid forwardly towards thedistal ring80, thedistal ring40 is progressively straightened out and drawn into the lumen of theguide sheath88. Thus, when confined with theguide sheath88, thedistal ring80 assumes the generally linear low profile shape of theguide sheath88, which allows a physician to employ conventional percutaneous access techniques to introduce thecatheter20 into a selected region of the heart through a vein or artery. When theguide sheath88 is slid rearwardly away from thedistal ring80, thedistal ring80 is uncovered and its resilient memory will cause thedistal ring80 to re-assume its preformed generally circular shape.
• To introduce and deploy thedistal tip section24 within the heart, the physician uses a conventional introducer to establish access to a selected artery or vein. With theguide sheath88 confining thedistal ring80, and with theballoon38 deflated, the physician introduces theshaft22 and theguide sheath88 through a conventional hemostatic valve on the introducer and progressively advances theguide sheath88 through the access vein or artery into the desired atrium, such as the left atrium as shown inFIG. 6. The physician observes the progress of theguide sheath88 using fluoroscopic or ultrasound imaging. Theguide sheath88 can include a radio-opaque compound, such as barium, for this purpose. Alternatively, radio-opaque markers can be placed at the distal end of theguide sheath88.
• Theshaft22 and theguide sheath88 can be maneuvered to the left atrium by thesteering mechanism70. Once located in the left atrium, the physician slides theguide sheath88 back to free thedistal ring80 which resiliently returns to its preformed shape. Thedistal ring80 is then maneuvered into contact with the selected annulus (e.g., the ostium) with the aid of fluoroscopy. Good contact is established when thering electrodes58 contact the selected annulus, and at this time, the physician operates a control located on theultrasound generator52 to effectuate the mapping of the selected annulus by thering electrodes58. The results of the mapping operation are processed and displayed at theEKG monitor50. A differential input amplifier (not shown) in the EKG monitor50 processes the electrical signals received from thering electrodes58 via thewires62, and converts them to graphic images that can be displayed. Thethermocouple wires54 can also function to monitor the temperature of the surrounding tissue, and provide temperature information to theultrasound generator52. Throughout this mapping operation, theballoon38 remains deflated.
• Once the mapping operation has been completed and the desired position of theballoon38 has been confirmed, the physician can then inflate theballoon38 using inflation media. Theballoon38 is preferably manufactured using known techniques to a predetermined diameter so that its diameter at its maximum expansion will be less than the diameter of thedistal ring80 and the annulus or vessel (e.g., the PV inFIG. 7) where the ablation is to take place. The physician then controls theultrasound generator52 to generate ultrasound energy that is propagated through thewires63 to theultrasound transducer60 that is positioned inside theballoon38. The energy radiates in a radial manner from thetransducer60, propagates through the inflation media (which acts as an energy transmitting medium) inside theballoon38, exits theballoon38 and then reaches the selected tissue (typically in a waveform) to ablate the tissue. See the arrows E inFIG. 7 which illustrate the radiation of the energy from thetransducer60.
• During the ablation, thedistal ring80 functions to anchor thedistal tip section24 inside the PV at the desired location so that the ablation can be performed accurately. In contrast to known catheter systems where the same element is used to anchor and ablate, by providing a separate element (i.e., the distal ring80) to anchor thedistal tip section24, the function of the ablation element (i.e., theballoon38 and transducer60) will not be affected by the anchoring device, thereby ensuring that the ablation is performed accurately and effectively. In addition, since the maximum diameter of theballoon38 is always smaller than the smallest diameter of thedistal ring80, blood will be able flow through thedistal ring80 and around the surfaces of theballoon38.
• When the ablation has been completed, theballoon38 is deflated and thedistal tip section24 withdrawn from the heart.
• FIGS. 9-14 illustrate modifications made to thecatheter system20 ofFIGS. 1-5 to allow contrast medium to be introduced while the catheter is located within the vessel ostium and while theballoon38 is inflated. Thecatheter system20a inFIGS. 9-14 essentially provides an additional tubing and lumen to facilitate the injection of the contrast medium. Thecatheter system20 inFIGS. 1-5 did not provide an additional lumen, so the contrast medium for vessel geometry and catheter location could not be readily verified. Hence, thecatheter system20amakes it easier to verify vessel geometry and catheter location since the blood flow from within the vessel will not wash out when the contrast medium is injected due to balloon inflation.
• Since thecatheter system20amerely includes modifications to thecatheter system20, the descriptions relating to the same elements and their functions will not be repeated herein. Instead, the same numerals used to designate elements inFIGS. 1-5 will be used to designate the same elements inFIGS. 9-14, except that an “a” will be added to the designations inFIGS. 9-14.
• Thecatheter system20aprovides anadditional tubing100 that extends from thehandle assembly32a(seeFIGS. 9-10). Thistubing100 is connected to alumen102 that extends through theshaft22a, thetransducer60ainside theballoon38a, and exits at the distal-most end of theshaft22a. SeeFIGS. 11 and 14. The contrast medium can be injected via thetubing100 and thelumen102 by a syringe (not shown), and exits the catheter into the blood vessel at the location of thedistal ring80ato provide visibility of the location of thedistal ring80aand theballoon38a. A guidewire (not shown) can be inserted into thislumen102 to increase the mobility of theshaft22ainto branches of the main vessel.
• In addition, theflat wire75aextends in thelumen30afrom the distal section of theshaft22a(not shown inFIGS. 9-14).
• FIGS. 15-16 illustrate yet another modification that can be made to thesystem20 inFIGS. 1-5. Thecatheter system20binFIGS. 15-16 is comprised of two separate catheters, afirst catheter120 that carries theballoon38band the transducer60b, and asecond catheter122 that carries thedistal ring80b.
• Since thecatheter system20bmerely includes modifications to thecatheter system20a, the descriptions relating to the same elements and their functions will not be repeated herein. Instead, the same numerals used to designate elements inFIGS. 9-14 will be used to designate the same elements inFIGS. 15-16, except that a “b” or a “c” will be added to the designations inFIGS. 15-16. The only notable differences are (i) thecatheter120 has the same structure as thecatheter20awith the exception of thedistal ring80a, and (ii) thecatheter122 has the same structure as thecatheter120 except for theballoon38a, thetransducer60a, and the thermocouples.
• Thedistal ring80band theshaft22cof thecatheter122 can be inserted through thelumen102bof thecatheter120. In this regard, thedistal ring80bcan progressively straightened out and drawn into thelumen102bof thecatheter120. Thus, when confined within thecatheter120, thedistal ring80bassumes the generally linear low profile shape of thecatheter120. When thedistal ring80bexits thedistal-most end124 of the catheter120 (seeFIG. 16), thedistal ring80bis uncovered and its shape memory (e.g., Nitinol) will cause thedistal ring80bto re-assume its preformed generally circular shape.
• Thecatheter122 can also be steered so that the diameter of thedistal ring80bcan be varied. This can be accomplished by providing a pulling wire (not shown, but can be the same as72 or72a), and then pulling the pulling wire. Thecatheter120 can also be steered so that thedistal end124 can be deflected. The steering of thecatheters120,122 can be accomplished usingsteering mechanisms70b,70cthat can be the same as thesteering mechanism70 described inFIGS. 1-5.
• The main lumen30bof thecatheter120 can be used to accomodate a guidewire (not shown), and can also be used for delivering contrast medium. Therefore, thecatheter system20bdoes not require an additional tubing (such as100) or lumen (such as102) as in thecatheter system20a, although it is also possible to provide an additional tubing (such as100) or lumen (such as102) if such is desired.
• The following illustrates one example of a possible use of thecatheter system20b. A transseptal sheath (with a dilator in the sheath lumen) is typically inserted into the patient's femoral vein and placed into the right atrium. Using a transseptal (Brockenbrough) needle, a puncture is produced in the fossa ovalis in the septal wall to provide access from the right atrium to the left atrium. The sheath is then brought inside the left atrium, the needle removed, and a guidewire is inserted through the lumen of the dilator to the target pulmonary vein or its branches. The distal opening of the dilator inside the sheath follows the guidewire to the pulmonary vein. When thecatheter20ais used, the dilator and the guidewire are removed and the catheter is inserted into the transseptal sheath into the pulmonary vein. When thecatheter120 is used, only the dilator is removed and thelumen102bof the distal end of the catheter follows the path of the guidewire and into the target PV. Once thecatheter20aor120 is situated in the pulmonary vein ostium, theballoon38aor38bis inflated until it engages the ostial wall. Contrast media is injected in thelumen102 or102bto visually verify the location of thetransducer60awith respect to the pulmonary vein anatomy.
• For thecatheter20a, the location of thetransducer60acan be verified via contrast medium injection while thedistal ring80arecords the PV potentials. This has not been possible with the conventional systems.
• For thecatheter system20b, thecatheter122 is inserted through thetubing100band thedistal ring80bexits from thelumen102b. The diameter of thedistal ring80bcan be adjusted to fit the different sizes of the pulmonary vein. The electrodes58bare again used to pick up the PV potentials. Once the potentials (or intracardiac signals) are recorded, thecatheter122 can be removed, and if needed, contrast medium can be injected for locating the transducer. Energy can then be delivered to perform the ablation, as described above.
• FIGS. 17-24 illustrate acatheter system20daccording to yet another embodiment of the present invention. Thecatheter system20dis similar to thecatheter system20 inFIGS. 1-8, except that thecatheter system20dhas asecond balloon37dinstead of a distal ring. As a result, the descriptions relating to the same elements and their functions inFIGS. 1-8 andFIGS. 17-24 will not be repeated herein. Instead, the same numerals used to designate elements inFIGS. 1-8 will be used to designate the same elements inFIGS. 17-24, except that a “d” will be added to the designations inFIGS. 17-24.
• Thedistal tip section24dincludes a firstexpandable balloon38dthat can be the same as theballoon38, and a secondexpandable balloon37d. Theballoons37dand38dcan be positioned side-by-side next to each other. Atransducer60d(e.g., piezoelectric or ultrasound) is also housed inside thefirst balloon38d. Both balloons37dand38dcan be made from any conventional material (such as but not limited to silicone, polyurethane, latex, polyamide and polyethylene), and heat bonded or otherwise attached to theshaft22dusing techniques that are well-known in the catheter art. A plurality ofthermocouple wires54dcan have their distal ends secured to the interior surface of thefirst balloon38d(seeFIG. 19), and are used to detect the temperature at the treatment site.
• Standard Luer fittings34dand35dare connected to theproximal end36dof thehandle assembly32dusing techniques that are well-known in the catheter art. TheLuer fittings34dand35dprovide fluid lines for inflation media to be introduced to inflate theballoons37dand38dat thedistal tip section24dof theshaft22d. For example, the inflation media is delivered via aninflation lumen76d(seeFIG. 21) that extends from thehandle assembly32d(and coupled to theline78dof the Luer fitting34d), and terminates at theballoon38d. Similarly, the inflation media is delivered via aninflation lumen73dthat extends from thehandle assembly32d(and coupled to theline79dof the Luer fitting35d), and terminates at theballoon37d.
• Theconnector assembly40dand its connection to theultrasound generator52dcan be the same as described inFIGS. 1-8 above. In addition, thesteering mechanism70dcan also be the same as described inFIGS. 1-8 above, except that thesteering wire72dextends in themain lumen30dof theshaft22dfrom its proximal end at thehandle assembly32dto its distal end which terminates in thedistal tip section24dbefore the location of theballoon38d.
• FIGS. 22 and 23 illustrate how thecatheter system20dis used. The primary difference between the operation of thecatheter systems20 and20dis that mapping is not provided in thecatheter system20dbecause there is no distal ring, and therefore no ring electrodes. First, atransseptal sheath88dis provided to deliver theshaft22dand theballoon37dto the desired location (e.g., the left atrium) in the heart. Theshaft22dis slid into the hollow lumen of thesheath88d, and thesheath88dcan slide forward and backward along the longitudinal axis of theshaft22d.
• To introduce and deploy thedistal tip section24dwithin the heart, the physician uses a conventional introducer to establish access to a selected artery or vein. With theballoons37dand38ddeflated, the physician introduces theshaft22dand thetransseptal sheath88dand progressively advances thesheath88dthrough the access vein or artery into the desired atrium, such as the left atrium via standard transceptal as shown inFIG. 22. The physician observes the progress of thesheath88dusing fluoroscopic or ultrasound imaging. Thesheath88dcan include a radio-opaque compound, such as barium, for this purpose. Alternatively, radio-opaque markers can be placed at the distal end of thesheath88d.
• Theshaft22dand thesheath88dcan be maneuvered to the left atrium by thesteering mechanism70d. SeeFIG. 23. Once located in the left atrium, the physician slides thesheath88dback to expose theballoons37dand38d. Theballoon37dis then maneuvered and then expanded into contact with the selected annulus (e.g., the ostium) with the aid of fluoroscopy.
• Once the positioning operation has been completed and the desired position of theballoon38dhas been confirmed, the physician can then inflate theballoon38dusing inflation media. Theballoon38dcan be manufactured using known techniques to a predetermined diameter so that its diameter at its maximum expansion will be greater than the diameter of theother balloon37dand the annulus or vessel where the ablation is to take place. This allows the smaller-diameter balloon37dto snugly contact and anchor a smaller-diameter vessel (e.g., the ostium inFIG. 23) while ablation is being performed in a larger-diameter vessel. Thethermocouple wires54dcan also function to monitor the temperature of the surrounding tissue, and provide temperature information to theultrasound generator52d. The physician then controls theultrasound generator52dto generate ultrasound energy that is propagated through thewires63dto theultrasound transducer60dthat is positioned inside theballoon38d. The energy radiates in a radial manner from thetransducer60d, propagates through the inflation media (which acts as an energy transmitting medium) inside theballoon38d, exits theballoon38dand then reaches the selected tissue (typically in a waveform) to ablate the tissue. See the arrows E inFIG. 23 which illustrate the radiation of the energy from thetransducer60d.
• Thus, during the ablation, theballoon37dfunctions to anchor thedistal tip section24dinside the PV at the desired location so that the ablation can be performed accurately. In contrast to known catheter systems where the same element is used to anchor and ablate, by providing a separate element (i.e., theballoon37d) to anchor thedistal tip section24d, the function of the ablation element (i.e., theballoon38dandtransducer60d) will not be affected by the anchoring device, thereby ensuring that the ablation is performed accurately and effectively.
• When the ablation has been completed, theballoon38dis deflated and thedistal tip section24dwithdrawn from the heart.
• FIGS. 25-30 illustrate modifications made to thecatheter system20dofFIGS. 17-24 to allow contrast medium to be introduced while the catheter is located within the vessel ostium and theballoon38dinflated. Thecatheter system20einFIGS. 25-30 essentially provides an additional tubing and lumen to facilitate the injection of the contrast medium. Thecatheter system20dinFIGS. 17-24 did not provide an additional lumen, so the contrast medium for vessel geometry and catheter location could not be readily verified. Hence, thecatheter system20emakes it easier to verify vessel geometry and catheter location since the blood flow from within the vessel will not wash out when the contrast medium is injected due to balloon inflation.
• Since thecatheter system20emerely includes modifications to thecatheter system20d, the descriptions relating to the same elements and their functions will not be repeated herein. Instead, the same numerals used to designate elements inFIGS. 17-24 will be used to designate the same elements inFIGS. 25-30, except that an “e” will be added to the designations inFIGS. 25-30.
• Thecatheter system20eprovides anadditional tubing100ethat extends from thehandle assembly32e(seeFIGS. 25-26). Thistubing100eis connected to alumen102ethat extends through theshaft22e, thetransducer60einside thesecond balloon38e, and exits at the distal-most end of theshaft22e. SeeFIGS. 27 and 30. The contrast medium can be injected via thetubing100eand thelumen102eby a syringe (not shown), and exits the catheter into the blood vessel at the location of theballoon37eto provide visibility of the location of theballoons37eand38e. A guidewire (not shown) can be inserted into thislumen102eto increase the mobility of theshaft22einto branches of the main vessel.
• In addition, theflat wire75eextends in thelumen30efrom the distal section of theshaft22e(not shown inFIGS. 25-30).
• FIGS. 31-32 illustrate yet another modification that can be made to thesystem20dinFIGS. 17-24. Thecatheter system20finFIGS. 31-32 is comprised of two separate catheters, afirst catheter20ethat is identical to thecatheter20einFIGS. 25-30 above, and asecond catheter122 that is identical to thecatheter122 inFIGS. 15 and 16.
• Thedistal ring80band theshaft22cof thecatheter122 can be inserted through thelumen102eof thecatheter20e. In this regard, thedistal ring80bcan be progressively straightened out and drawn into thelumen102eof thecatheter20e. Thus, when confined with thecatheter20e, thedistal ring80bassumes the generally linear low profile shape of thecatheter20e. When thedistal ring80bexits thedistal-most end124eof thecatheter20e(seeFIG. 32), thedistal ring80bis uncovered and its shape memory (e.g., Nitinol) will cause thedistal ring80bto re-assume its preformed generally circular shape.
• Thecatheter122 can also be steered so that the diameter of thedistal ring80bcan be varied. This can be accomplished by providing a pulling wire (not shown, but can be the same as72 or72a), and then pulling the pulling wire. Thecatheter20ecan also be steered so that thedistal end124ecan be deflected.
• The following illustrates one example of a possible use of thecatheter system20f. A transseptal sheath (with a dilator in the sheath lumen) is typically inserted into the patient's femoral vein and placed into the right atrium. Using a transseptal (Brockenbrough) needle, a puncture is produced in the fossa ovalis in the septal wall to provide access from the right atrium to the left atrium. The sheath is then brought inside the left atrium, the needle removed, and a guidewire is inserted through the lumen of the dilator to the target pulmonary vein or its branches. The distal opening of the dilator inside the sheath follows the guidewire to the pulmonary vein. When thecatheter20eis used, only the dilator is removed and thelumen102eof the distal end of the catheter follows the path of the guidewire and into the target PV. Once thecatheter20eis situated in the pulmonary vein ostium, theballoon38eis inflated until it engages the ostial wall. Contrast media is injected in thelumen102eto visually verify the location of thetransducer60ewith respect to the pulmonary vein anatomy.
• For thecatheter20e, the location of thetransducer60ecan be verified via contrast medium injection while the distal ring80erecords the PV potentials. This has not been possible with the conventional systems.
• For thecatheter system20f, thecatheter122 is inserted through thetubing100eand thedistal ring80bexits from thelumen102e. The diameter of thedistal ring80bcan be adjusted to fit the different sizes of the pulmonary vein. The electrodes58bare again used to pick up the PV potentials. Once the potentials (or intracardiac signals) are recorded, thecatheter122 can be removed, and if needed, contrast medium can be injected for locating the transducer. Energy can then be delivered to perform the ablation, as described above.
• While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.

Claims (20)

1. A catheter for sensing electrical events about a selected annulus region of the heart and for treating tissue in the selected annulus region, comprising:

a handle assembly;

a shaft having a proximal end coupled to the handle assembly, and a distal end, the shaft extending along an axis;

a first expandable member provided at the distal end;

a second expandable member positioned adjacent to, but spaced apart from, the first expandable member, the second expandable member having an ablation element; and

means for providing ablation energy to the ablation element.

2. The catheter ofclaim 1, wherein the ablation element emits energy to a radially surrounding area.

3. The catheter ofclaim 1, wherein the second expandable member covers the ablation element.

4. The catheter ofclaim 3, wherein the second expandable member defines an interior space that is filled with a fluid.

5. The catheter ofclaim 2, wherein the shaft has a main lumen, and further including a plurality of wires that are coupled to the ablation element and extending through the main lumen.

6. The catheter ofclaim 1, wherein the shaft has a main lumen, and the catheter further includes a steering mechanism that includes a steering wire extending through the main lumen to the distal end.

7. The catheter ofclaim 1, wherein the shaft has a main lumen, and further including a plurality of thermocouple wires that are coupled to the distal end and extending through the main lumen.

8. The catheter ofclaim 1, wherein the expandable members are positioned side-by-side next to each other.

9. The catheter ofclaim 1, further including an energy source coupled to the ablation element.

10. The catheter ofclaim 1, further including means for introducing contrast medium to the distal end of the shaft.

11. The catheter ofclaim 1, further including:

a contrast media tubing coupled to the handle assembly; and

a contrast media lumen extending through the shaft and out the distal end of the shaft, the contrast media lumen coupled to the contrast media tubing.

12. The catheter ofclaim 1, wherein the maximum diameter of the second expandable member is greater than the maximum diameter of the first expandable member.

13. A method of ablating tissue in a body cavity, comprising:

providing a catheter having a shaft having a proximal end and a distal end, with the distal end of the shaft having an anchoring element and an ablation element that is separate from the mapping element;

positioning the anchoring element at the desired treatment location in the body cavity, including injecting contrast medium to the distal end of the catheter; and

actuating the ablation element to ablate the desired treatment location.

14. The method ofclaim 13, wherein the step of providing a catheter includes:

providing the anchoring element in the form of a first expandable member; and

providing the ablation element in the form of a transducer housed inside a different second expandable member.

15. The method ofclaim 14, further including:

providing the second expandable member with a maximum diameter that is greater than the maximum diameter of the first expandable member.

16. The method ofclaim 13, wherein the step of ablating the desired treatment location includes emitting energy to the desired treatment location.

17. A system for sensing electrical events about a selected annulus region of the heart and for treating tissue in the selected annulus region, comprising:

(a) a first catheter having:

a handle assembly;

a shaft having a proximal end coupled to the handle assembly, and a distal end, the shaft extending along an axis;

an ablation element provided adjacent the distal end of the shaft; and

an expandable member provided next to the ablation element;

(b) a second catheter having:

a handle assembly;

a shaft having a proximal end coupled to the handle assembly of the second catheter, and a distal end, the shaft of the second catheter extending along an axis; and

a distal ring provided at the distal end of the shaft of the second catheter and oriented perpendicular to the axis of the shaft of the second catheter, the distal ring having a plurality of electrodes positioned in spaced-apart manner about the distal ring of the second catheter;

(c) an energy source coupled to the ablation element; and

(d) means coupled to the plurality of electrodes for processing electrical signals received from the plurality of electrodes.

18. The system ofclaim 17, wherein:

the expandable member is a first expandable member; and

the ablation element is a transducer housed inside a different second expandable member that is positioned proximal of the first expandable element.

19. A catheter for sensing electrical events about a selected annulus region of the heart and for treating tissue in the selected annulus region, comprising:

a handle assembly;

a shaft having a proximal end coupled to the handle assembly, and a distal end, the shaft extending along an axis;

a first expandable member provided at the distal end;

a second expandable member positioned adjacent to, but spaced apart from, the first expandable member, the second expandable member having an ablation element; and

means for introducing a guidewire to the distal end.

20. The catheter ofclaim 19, further including:

means for providing ablation energy to the ablation element.

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