US20070203479A1 - Transseptal closure of a patent foramen ovale and other cardiac defects - Google Patents

Abstract

The present invention provides for therapeutic treatment methods, devices, and systems for the partial or complete closure or occlusion of a patent foramen ovale (“PFO”). In particular, various methods, devices, and systems for joining or welding tissues, in order to therapeutically close a PFO are described. In yet another aspect of the invention, various methods, devices, and systems for the penetration of the interatrial septum enabling left atrial access are also provided.

Description

COPYRIGHT NOTICE
• A portion of this patent document contains material that is subject to copyright protection. The copyright owner does not object to the facsimile reproduction of the patent document as it appears in the U.S. Patent and Trademark Office patent file or records but otherwise reserves all copyright rights whatsoever.
FIELD OF THE INVENTION
• The present invention relates generally to the field of cardiology, and in particular to methods, devices, and systems to close or occlude a patent foramen ovale or “PFO.”
BACKGROUND OF THE INVENTION
• A closed foramen ovale is formed after birth when two fetal structures, the septum secundum (“secundum”) and septum primum (“primum”), become fused and fibrose together. Usually, the fusion of these two anatomical structures occurs within the first two years of life ensuring the formation of a normal functioning heart. However, in about 25-27% of the general population, the secundum and the primum either do not fuse or the fusion is incomplete. As a result, a long tunnel-like opening will exist in the interatrial septum (“septum”) which allows communication between the right and left atrial chambers of the heart. This tunnel-like opening is a cardiac defect known as a PFO.
• Normally, a PFO will be found near the fossa ovalis, an area of indentation on the right atrial side of the interatrial septum as illustrated inFIGS. 1A and 1B. In most circumstances, a PFO will remain functionally closed or “competent” and blood flow through the PFO will not occur due to the higher atrial pressures in the left atrium that serve to secure the flap-like primum against the secundum and interatrial septum, thereby closing the PFO. SeeFIGS. 1A and 1B. Nevertheless, in instances of physical exertion or when pressures are greater in the right atrium, inappropriate right-to-left shunting of blood can occur introducing venous blood and elements, such as clots or gas bubbles within the blood, into the left atrium and the systemic atrial system, posing serious health risks including: hemodynamic problems; cryptogenic strokes; venous-to-atrial gas embolism; migraines; and in some cases even death.
• Traditionally, open chest surgery was required to suture or ligate closed a PFO. However, these procedures carry high attendant risks such as postoperative infection, long patient recovery, and significant patient discomfort and trauma. Less invasive, or minimally invasive, treatments are preferred and are currently being developed.
• To date, most of these non-invasive, or minimally invasive, procedures involve the transcatheter implantation of various mechanical devices to close or occlude a PFO. SeeFIGS. 2A and 2B. That they are not well suited or designed for the long tunnel-like anatomical shape of a PFO, is a significant drawback of many PFO devices currently on the market including: the Cardia® PFO Closure Device, Amplatzer® PFO Occluder, and CardioSEAL® Septal Occlusion Device, just to name a few. As a result, device deformation and distortion is not uncommon and instances of mechanical failure, migration or even device dislodgement have been reported. Further, these devices can irritate the cardiac tissues at, or near, the implantation site, which in turn can potentially cause thromboembolic events, palpitations, and arrhythmias. Other reported complications include weakening, erosion, and tearing of the cardiac tissues around the implanted devices.
• Yet another disadvantage of these mechanical devices is that the occlusion of the PFO is not instantaneous or complete immediately following implantation. Instead, occlusion and complete PFO closure requires subsequent endothelization of these devices. This endothelization process can be very gradual and can take several months or more to occur. Thus, “occlusion” of the PFO is not immediate but can be a rather slow and extended process.
• Finally, the procedure to implant these devices can be technically complicated and cumbersome, requiring multiple attempts before the device can be appropriately and sufficiently delivered to the PFO. Accordingly, use of these devices may require long procedure times during which the patient must be kept under conscious sedation posing further risks to patients.
• In light of these potentially serious drawbacks, new and improved non-invasive and/or minimally invasive methods, devices, and systems for the treatment of PFO, which either do not require the use of implantable devices or overcome some of the current shortcomings discussed above, are needed. The present invention meets these, as well as other, needs.
SUMMARY OF THE INVENTION
• The present invention is directed to methods, devices, and systems for applying energy to join tissues, and in particular for joining the two flap-like tissues, the secundum and primum, that comprise a PFO. Tissues and blood in the human body demonstrate several unique properties when heated; accordingly heat can be used as an effective means for inducing the joining of tissues. Typically, when biological tissues and blood are heated, denaturation, melting, and/or coagulation of tissue and blood proteins, including collagen, takes place, along with the disruption of the cells and cellular walls, allowing intra-and-intercellular fluids and proteins to mix and form a type of “biological glue” which can be used to join tissues together. Yet another response to heat includes the activation of the body's healing mechanisms, which includes the activation of platelets, thrombin, fibrin, etc., and the formation of new scar tissue connections, which serve to join tissues.
• A first aspect of the invention provides for methods, devices, and systems for joining tissue structures, and in particular, for joining the secundum and the primum to close or occlude a PFO. In accordance with this aspect of the invention, one method involves coapting the secundum and primum between one or more members and delivering therapeutic amounts of energy in order to join the two tissue structures together. As used herein, “coapt” means the drawing together of separated tissues or other structures. Energy sufficient to raise the native tissue temperatures of the coapted tissues to about 50°-100° C. is applied to the secundum and the primum. In accordance with this first aspect of the invention, various catheters for coapting and joining the primum and secundum are provided and further described herein.
• In a second and related aspect of the invention, the primum and secundum are joined at one or more tissue contact sites, or alternatively are joined along a seam. Depending on the technique employed, complete or partial PFO closure can be selectively achieved. Described herein are possible implementations and configurations of heat generating members for creating: (1) a single tissue contact site; (2) a pattern of contact sites forming a seam; or (3) continuous seams having different shapes, for example, circular, curvilinear or straight seams.
• A third aspect of the invention provides different methods, devices, and systems for ensuring tight joining of the tissues involving a welding technique. As used herein, “welding” refers to the use of heat in conjunction with pressure (as opposed to heat only) to join tissues together. Energy sufficient to raise the native tissue temperatures to about 50°-100° C. is applied in order to affect tissue welding of the secundum and the primum. Preferably, compressive force is used to not only coapt the primum and the secundum, but also to ensure the efficient and secure tissue welding during heating or energy delivery. To efficiently weld the primum and secundum, the two tissues should be encased between two opposed members that are provided as means to compress the tissues in question. Describe herein are methods and devices including various inflation members and other like devices for encasing, coapting, and compressing the tissue to be welded. As will be better understood in reference to the description provided below, one method for encasing the primum and the secundum between two opposed members is to transseptally deploy and position the two opposed members. As used herein “transseptal” means across or to the other side of the interatrial septum of the heart.
• A fourth aspect involves various methods, devices, and systems for transseptally deploying various heating members, compressive members, or other like structures. In accordance with this aspect of the invention, one method involves puncturing the interatrial septum and a creating a passage therethrough so that one or more compressive members, heating members, or any combination thereof, which located at a distal working end of a PFO treatment catheter or catheter assembly, can be passed from one atrium of the heart to the other, preferably from the right to the left atrium.
• A fifth aspect of the invention involves various medical kits comprising one or more catheters, puncturing means, guidewires, and/or other related components for therapeutically joining tissues or welding tissues in order to close or occlude a PFO in accordance with the present invention.
• A sixth aspect of the invention involves various medical kits comprising one or more catheters, tissue penetrating devices, and other like means for transseptal penetration of the interatrial septum, thus allowing left atrial access. These devices and catheters embody various techniques and other aspects for easily identifying, positioning, and penetrating the septum at a pre-determined location.
• A seventh aspect involves methods, devices, and systems for the deployment and implantation of various mechanical devices that represent an improvement over PFO occlusion devices and techniques currently known to those skilled in the art. In a related embodiment, these various devices and implants can be heated fixed or secured inside the patient.
• A further aspect of the invention involves the various forms of energy that can be used to affect joining or welding of tissues, including, but not limited to: high intensity focused or unfocused ultrasound; direct heat; radiofrequency (RF); chemically induced heat (as in exothermic reactions), and other types of electromagnetic energy of differing frequencies, such as light (coherent and incoherent), laser, and microwaves can also be used. As described below, tissue heating in accordance with the present invention is char-free and controlled to prevent unintended thermal injury to the surrounding and adjacent cardiac tissues. One or more monitoring methods, devices (such as thermosensors), and systems are provided to ensure controlled and selective tissue heating.
• Further understanding of the nature and advantages of the invention may be realized by reference to the remaining portions of the specification and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIGS. 1A-1D illustrate a heart comprising a PFO, wherein:
• FIG. 1A is a cross sectional view of a human heart;
• FIG. 1B is a partial, cross-sectional view of an interatrial septum comprising a closed PFO;
• FIG. 1C is a partial, cut-away, orthogonal view of the fossa ovalis and the PFO wherein the PFO is shown in phantom; and
• FIG. 1D is a partial, cross-sectional view of the interatrial septum comprising an open PFO.
• FIG. 2 illustrates the deployment of prior art mechanical occlusive devices inside the tunnel-like opening of a PFO, i.e. “PFO tunnel.”
• FIG. 3 is a flow chart illustrating a general treatment method in accordance with the present invention.
• FIGS. 4A-4B illustrate a PFO treatment catheter in accordance with the present invention wherein:
• FIG. 4A is a perspective view; and
• FIG. 4B is a cross-sectional view of one possible implementation of the distal working end of the PFO treatment catheter shown inFIG. 4A
• FIG. 5A-5B are cross-sectional view of a interatrial septum comprising a PFO, wherein:
• FIG. 5A is a partial, cross-sectional view of the interatrial septum illustrating the preferred region of penetration at a location where the secundum and primum overlap; and
• FIG. 5B is a partial, cross-sectional view of the interatrial septum illustrating the transseptal deployment of two opposed members.
• FIG. 6A-6B illustrates one embodiment of a PFO treatment catheter in accordance with the present invention wherein:
• FIG. 6A illustrates a PFO treatment catheter wherein the two opposed member comprise two inflation members comprising one or more RF electrodes; and
• FIG. 6B illustrates yet another embodiment of the PFO treatment catheter shown inFIG. 6A.
• FIGS. 7A-7B illustrate yet another embodiment of the present invention wherein PFO treatment catheter comprises a deployable wire assembly.
• FIG. 8 illustrates yet another embodiment of a PFO treatment catheter in accordance with the present invention.
• FIG. 9 is a perspective view of a PFO treatment catheter assembly comprising a guide catheter and an inflation catheter disposed within the guide catheter.
• FIG. 10 illustrates yet another embodiment of a PFO treatment catheter comprises a high intensity ultrasound transducer.
• FIGS. 11-12 illustrate various biocompatible, atraumatic, implantable mechanical devices for the transseptal occlusion or closure of a PFO.
• FIGS. 13A-13E illustrate a hook-and-twist mechanical device for occluding or closing a PFO in accordance with this aspect of the invention, where:
• FIG. 13A is a cross-sectional view illustrating the deployment of the hook-and-twist device within the PFO tunnel; and
• FIGS. 13B-13E are top views illustrating a method of implanting the hook-and-twist device inside the PFO tunnel.
• FIG. 14 generally illustrate yet another aspect of the present invention wherein the various PFO treatment catheters and device can be adapted with a location member designed to facilitate detection and location of a PFO, puncture location, as well as maintains the position of the PFO treatment catheter during the treatment process.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
• Referring now to the drawings, the flow chart ofFIG. 3 describes a method of therapeutically closing or occluding aPFO1. Generally, the treatment method involves insertingPFO treatment catheter21 configured to transseptally deliver energy to thesecundum5 and theprimum7 to affect joining or welding of these tissues.
• PFO treatment catheter21, in accordance with the present invention is illustrated inFIG. 4A.PFO treatment catheter21 should be long enough to extend from an insertion site tointeratrial septum3. Typical lengths forcatheter21 include, but are not limited to, a range of about 50°-200 cm and preferably sized between about 2-15 French. Suitable materials forPFO treatment catheter21 include, but are not limited to, various polyethylenes, polyurethanes, polysilicones, other biocompatible polymers and materials well known to those skilled in the catheter arts. The interior22 ofcatheter21 is adapted to allow passage of one or more other catheters and components (such asguidewires31, imaging devices, etc) therethrough. SeeFIG. 4B.PFO treatment catheter21 can be further configured to comprise one ormore lumens22 extending its entire length or only a portion thereof. The one ormore lumens22 ofcatheter21 can be used as paths for cables, other catheters, guidewire31, pull wires, insulated wires, fluids, gases, optical fibers, vacuum channels, and any combination thereof.
• PFO treatment catheter21 can be used in conjunction withguidewire31 so that it can be readily introduced and percutaneously advanced from the insertion site (such as a femoral vein, femoral artery, or other vascular access location) until distal workingend29 is appropriately seated within the patient's heart, at or near,PFO1. In one possible implementation, guidewire31 can be inserted into the femoral vein, advanced up the inferior or superior vena cava, into the right atrium and to theinteratrial septum3, near thefossa ovalis10, andPFO1.
• Penetration of theinteratrial septum3 at a pre-determined location can be accomplished, with or without image guidance. Imagine guidance methods include but are by no means limited to: fluoroscopic; ultrasound (IVUS); intracardiac echo (ICE) ultrasound; magnetic resonance imaging (MRI); and echocardiographic guidance including transesophageal echocardiography (TEE). To penetrate and pass throughinteratrial septum3, guidewire31 can be removed and tissue penetrating device41 advanced. In one embodiment of the present invention, tissue penetrating device41 may be a puncturing needle such as conventionally available Brockenbrough needles or other like means. Another possible implementation involves the direct use ofguidewire31 to penetrateinteratrial septum3, eliminating the need to insert and advance separate tissue penetrating device or devices41. In addition, various other transseptal penetrating methods and devices as disclosed in U.S. provisional applications: Ser. No. 60/477,760, filed Feb. 13, 2003 and entitled “PFO and ASD Closure via Tissue Welding” and Ser. No. 60/474,055, filed May 28, 2003 and entitled “Atrial Transseptal Atrial Access Technology;” the entire contents of which are hereby incorporated by reference and commonly assigned, can also be used to affect penetration ofinteratrial septum3 to facilitate the transseptal passage of various devices, including the distal end ofPFO treatment catheter21, into the left atrium of the heart.
• As illustrated inFIG. 5A,interatrial septum3 can be punctured at a number of different locations within region R; however, for the purposes described herein, preferably, penetration ofinteratrial septum3 is made at a location wheresecundum5 andprimum7 overlap so that both tissue structures are penetrated. Whenseptum3 is penetrated, an access pathway is created allowing both secundum and primum to be encased between opposed members51 and enabling access to the left atrium of the heart. As illustrated generally inFIG. 5B, opposed members51 should be transseptally positioned inside the patient's heart before energy is delivered to the tissues. Opposed members51 can be used as: (1) a means for coapting the tissues to be joined or welded; (2) a means for supplying compressive force to the tissues; and/or (3) a means for generating sufficient energy in order to heat the coapted tissues to a tissue temperature in a range between about 50°-100° C. One or more heat generating members53 (for example, RF electrodes53) can be disposed on opposed members51 in order to affect tissue heating and application of therapeutic amounts of energy to the encased tissues. As described herein, other configurations are possible.
• In the present invention, various energies, energy delivery sources and devices can be employed to increase the native tissue temperatures within a therapeutic range between about 50°-100° C. including: (i) a radiofrequency (RF) generating source coupled to one or more RF electrodes; (ii) a coherent or incoherent source of light coupled to an optical fiber; (iii) a heated fluid coupled to a catheter with a closed channel configured to receive the heated fluid; (iv) a resistive heating source and heating element; (v) a microwave source coupled to a microwave antenna; (vi) an ultrasound power source coupled to an ultrasonic emitter or from external ultrasound; or (vii) any combination of the above. Tissue heating by any of these methods should be tightly controlled to ensure no charring and prevent overheating of the surrounding cardiac tissues. Accordingly, various known temperature sensing means, tissue impedance monitoring techniques, feedback systems, and controls may be incorporated into the present invention and toPFO treatment catheter21 to allow monitoring of the heating process. Various cooling techniques can be employed (such as the seepage or circulation of various biocompatible liquids, saline, or blood during the heating process as a cooling mechanism). Moreover, such heating systems can be made to focus more energy on the right side of the septum, so that any emboli that are generated will not be allowed to enter the systemic circulation.
• For ease of discussion and illustration, and for the remainder of this invention, use of RF energy, in a range of about 100-1000 kHz, supplying power in a range of about 5-50 watts, for duty cycles in a range of about 0.5-20 seconds, will be discussed. The various heat generating members described below are either monopolar orbipolar RF electrodes53. However, all of the other energy sources and devices described above are equally applicable and may be incorporated into any of the embodiments provided below and used to affect the transseptal joining or welding of tissues to partially or completely, close or occlude, a PFO.
• Turning now toFIGS. 6-10 and11, various embodiments ofPFO treatment catheter21 andcatheter assemblies21, for practicing the joining or welding treatment techniques of the present invention are described.
• FIG. 6A illustrates one embodiment ofPFO treatment catheter21 in accordance with the present invention.PFO treatment catheter21 comprises an elongated shaft having a proximal portion, a distal portion, aproximal inflation member61, and adistal inflation member63. Said proximal anddistal inflation members61,63 are located at a distal workingend29 ofcatheter21. Disposed on proximal61 and distal63 inflation members may be one ormore RF electrodes53 for tissue heating.
• During use, guidewire31 can be used to advancePFO treatment catheter21 across and throughinteratrial septum3 afterinteratrial septum3 has been penetrated. Preferably,PFO treatment catheter21 is advanced overguidewire31 untildistal inflation member63 is located on the left atrial side of theinteratrial septum3 whileproximal inflation member61 is located on the right atrial side. To ensure this relative arrangement, theseballoon structures61,63 can be inflated with contrast fluid, or one or more radio-opaque markers may be disposed on, or adjacent to, the inflation members, so that the desired transseptal positioning of the inflation members can be visually verified, for example, under fluoroscopy. After transseptal positioning ofinflation members61,63 is visually verified, guidewire31 may be removed and the tissue coapted together betweenproximal inflation61 anddistal inflation member63. A simple method for coapting the tissues may be to expand theinflation members61,63 with a fluid (such as contrast solution); a gas (such as carbon dioxide), or any combination thereof. As shown inFIG. 6A, thesecundum5 andprimum7 should be transseptally encased betweeninflation members61,63.
• Once coapted, the one ormore RF electrodes53 disposed on the surface ofinflation members61,63 can be energized to heat the encased tissues and increase native tissue temperatures to about 50°-100° C. In accordance with this aspect of the invention,RF electrodes53 should be disposed on the surface of theinflations member61,63 so that when inflated, theseRF electrodes53 are in direct contact with the tissues to affect efficient tissue heating.RF electrodes53 can be energized as many times as needed to affect sufficient tissue heating and subsequently heat induced joining of the tissues. As illustrated inFIG. 6B, singlemonopolar RF electrode53 can be disposed on theproximal inflation member61 or alternatively abipolar RF electrode53 configuration may be used, wherein in afirst electrode53 is disposed onproximal inflation member61 andsecond electrode53 is disposed ondistal inflation member63. As will be readily appreciated by those skilled in the art,PFO treatment catheter21 comprising a singlemonopolar electrode53 onproximal inflation member61 can be advantageous in that heating from the right atrial side of theseptum3 can potentially limit or eliminate the potential of any embolic material from being introduced into the systemic atrial circulation.RF electrodes53 of this embodiment can be energized as many times and for as long as necessary to affect joining of the tissues. To adapt this embodiment ofPFO treatment catheter21 for the welding of thesecundum5 andprimum7,PFO treatment catheter21 can be configured so that user applied force at the proximal end ofPFO treatment catheter21 is transmitted downelongated shaft23, which then translates as compressive force supplied to the encased tissues by the proximal61 and distal63 inflation members.
• RF electrodes53 can be disposed on the surface of proximal61 and/or distal63 inflation members using techniques including: ion implanting, electroplating, sputtering, electro-deposition and chemical and/or adhesive bonding methods; to disposedvarious RF electrodes53 on the surface of the proximal61 and distal63 inflation members.Electrodes53 may be formed from gold, platinum, silver, or other materials, preferably, these other materials should be malleable, suitable for in-vivo tissue contact, and thermally conductive.
• To verify that a satisfactory level of closure or occlusion has been achieved, contrast TEE, ICE or TCD bubble studies can be performed before catheter is withdrawn from the patient through the passage created during penetration ofinteratrial septum3. Preferably, the opening should be small enough so that the body's natural injury response mechanisms will serve to close this left atrial access pathway.PFO treatment catheter21 can be used in conjunction with a guide or introducer sheath or catheter to facilitate advancement ofcatheter21 into and through the tortuous vasculature.
• FIGS. 7A and 7B illustrate yet another embodiment of a PFO treatment catheter in accordance with the present invention. In this embodiment,secundum5 andprimum7 are encased between distal end ofPFO treatment catheter21 andwire assembly27.Wire assembly27 can be pre-loaded into the distal workingend29 ofcatheter21 and deployed by the user after puncture of theinteratrial septum3 in order to coapt the tissues.
• FIG. 8 illustrates another embodiment of the present invention whereinPFO treatment catheter21 comprised of twocoiled RF electrodes71,73 disposed at the distal workingend29 ofcatheter21. In this embodiment,coiled RF electrodes71,73 are pre-loaded insidePFO treatment catheter21 and advanced out of distal workingend29 ofcatheter21 by user applied pressure or force on a release element (not shown) located at the proximal end ofcatheter21. As illustrated inFIG. 8, RF coils71,73 are transseptally deployable. The tissues are coapted by encasing them between RF coils71,73 that may be tension loaded. Alternatively,coiled RF electrodes71,73 may be disposed, for example on a wire or other like means, so that the user applied pull-back force on the wire serves to coapt and/or compress the tissues. Preferably,coiled RF electrodes71,73 should be made from any biocompatible material, including but not limited to: any nickel-titantium (Nitinol) alloy and other shape metal alloys, stainless steel, platinum, noble metals, and other like materials. Appropriate positioning of the RF coils71,73 may be visualized under fluoroscopy, x-ray, ultrasound, TEE, ICE, or using other conventional imaging techniques.
• In this aspect of the invention, joining or welding of the tissues may be affected at a single tissue contact point; at multiple tissue contacts points; or alternatively along a seam in order to affect partial or complete closure of the PFO tunnel. To this end, RF coils71,73 may be configured with one or more selectively spacedRF electrodes71,73 disposed on the coiled surfaces of RF coils71,73 in order to create the desired tissue contact point, pattern or seam given a pre-selected size and shape.
• FIG. 9 illustrates yet another embodiment of present invention wherein a PFOtreatment catheter assembly21 is provided. As shown inFIG. 9, PFOtreatment catheter assembly21 is comprised of aguide catheter81 andinflation catheter91 disposed therein. As shown inFIG. 9, guidecatheter81 is comprised of anelongated shaft83 having proximal85 and distal87 portion, and one or more lumens extending completely and/or partially therethrough with at least one lumen adapted to allow insertion and advancement ofinflation catheter91.Inflation catheter91 is comprised of elongated inflation catheter shaft93 having a proximal inflation catheter portion95, a distal inflation catheter portion97, one or more lumens extending completely or partially therethrough, andinflation member99 located at a distalcatheter working end101.
• During operation, guidecatheter81 should be disposed on the right atrial side while the distal working end ofinflation catheter101 is transseptally passed through untilinflation member99 is located on the left atrial side. Various tissue penetrating devices41, as well asguidewires31, can be used to facilitate the transseptal advancement of the distal working end ofinflation catheter101 into the left atrium (as well as insertion and advancement ofguide catheter81 to the interatrial septum3). Once appropriately advanced,inflation member99 can be inflated to coapt and encase thesecundum5 andprimum7 between distal end89 ofguide catheter81 andinflation member99. In one embodiment of the invention, one ormore RF electrodes53 can be disposed on distal end89 ofguide catheter81 and oninflation member99 located on the inflation catheter so that bipolar RF energy may be used to join or weld the tissues. In another embodiment, one or moremonopolar RF electrodes53 can be disposed on distal end89 of theguide catheter81 and energized. Once the energy delivery is completed,inflation member99 may be deflated, and withinflation catheter91 and guidecatheter81, withdrawn from the patient.
• FIG. 10 illustrates yet another embodiment of the present invention. In this embodiment, highintensity ultrasound catheter111 as described in U.S. Pat. No. 6,635,054, the entire contents of which are hereby incorporated by reference and modified to suit the aims of the present invention, is employed to affect joining or welding ofsecundum5 andprimum7 to close or occludePFO1.
• As illustrated, the highintensity ultrasound catheter111 is comprised ofcatheter shaft113,first balloon115, and gas-filledsecond balloon117 located at distal working end ofcatheter111. Comprised withinfirst balloon115 is gas filled inner “structural”balloon121 and liquid filled outer “reflector”balloon123, which is coaxially disposed around the inner structural balloon such that when both structural121 andreflector123 balloons are in a deflated configuration,reflector balloon123 closely overlies deflatedstructural balloon121. As shown inFIG. 10, disposed within the innerstructural balloon121 isultrasound transducer125 adapted to emit high intensity ultrasound energy.
• In use, a highintensity ultrasound catheter111 is positioned so thatfirst balloon115 is disposed within right atrium andsecond balloon117 is disposed within the left atrium. Once appropriately positioned, first115 and second117 balloons may be inflated and the tissues to be joined or welded, coapted between first115 and second117 balloon.Ultrasound transducer125 located withinfirst balloon115 is energized and acoustic energy projected forward into the tissues coapted between the two115,117 inflated balloons.
• Becausesecond balloon117 is gas filled (and because high intensity acoustic waves cannot and do not travel well in gases)second balloon117 functions to reflect any excess energy, preventing overheating in the left atrium and minimizing the risk of left side embolic events.
• Briefly, the forward projection of acoustic energy fromultrasound transducer125 into the coapted tissues is achieved by the configuration and shape of gas-filledstructural balloon121 and fluid filledreflector balloon123 withinfirst balloon115, as described in more detail in U.S. Pat. No. 6,635,054. As described therein, gas-filledstructural balloon121 is comprised ofactive wall127 which is formed from a flexible material and has a specific shape or configuration (parabolic or conical shape) when inflated. The shape ofactive wall127, in conjunction with air-filledreflector balloon123, functions to refract and project theacoustic waves128 generated by the ultrasound transducer distally forward as illustrated inFIG. 10. Once sufficient energy is applied, first115 (including structural121 andreflector123 balloons) and second117 balloons are deflated and withdrawn through the access pathway created wheninteratrial septum3 is penetrated.
• FIGS. 11-12 are diagrammatic representations of yet another aspect of the present invention whereindevices141 adapted for the efficient occlusion or closure of a PFO are shown. In accordance with the present invention, thesedevices141 include various clips, staples, T-bar, Z-part devices that can be transseptally deployed. Preferably,such devices141 should be formed from biocompatible materials such as various nickel-titanium and other shape memory alloys, stainless steel, platinum and other like materials. Preferably thesedevices141 should not require the subsequent device endothelization, but rather should result in immediate, partial or complete, closure or occlusion of a PFO by coapting secundum and primum.Devices141 can be delivered and deployed, however, a further implementation of this aspect of the invention, isdevices141 being heat secured after delivery. As will be readily appreciated by those skilled in the art, one fairly significant issue related to use of heat generating members (such as RF electrodes) is that heated tissue frequently adheres or sticks to the member. (For further discussion of this issue, please refer to U.S. Pat. No. 4,492,231, the entire contents of which are hereby incorporated by reference.) While this may pose technical difficulties in other circumstances, this embodiment of the invention utilizes this feature to ensure that the coapted tissues anddevices141 are securely heat fixed together and implanted in the patient to avoid or prevent device migration, dislodgement, etc. Accordingly,various devices141 can be configured to comprise one or more RF electrodes using monopolar or bipolar RF energy to affect heat attachment ofdevices141.
• FIGS. 13A-13E illustrate yet another aspect of the present invention referred to herein as “hook-and-twist”device151. Hook-and-twist device151 shown inFIG. 12 is comprised of an elongated neck153 disposed betweenproximal hook155 anddistal hook157. As illustrated inFIG. 12 and unlike the other devices illustrated inFIG. 11, “hook-and-twist”device151 of this embodiment is advanced into and through the tunnel-like opening of thePFO1. The proximal anddistal hooks155,157 are designed to atraumatically engage and catchPFO1 from the right and left atrial sides of PFO from within the PFO tunnel or PFO opening. Toimplant device151, it is wound until the tissues engaged bydevice151 are squeezed together and become taunt; and the increased tautness in the tissues serves to decrease the likelihood ofPFO1 from opening. In this embodiment, afterdevice151 has been appropriately twisted,device151 would be disengaged from a delivery catheter and thus implanted. In a related but different embodiment, hook-and-twist device151 and the tissues encased in by hook-and-twist device151 can be configured to comprise one or more monopolar electrodes to affect welding of the encased tissues and heat attachment of implanteddevice151 inside the patient.
• As discussed above, sticking of heated tissues to thevarious heating elements53, RF coils71,73, etc. should be avoided in those non-implant embodiments of the present invention. To this end, several techniques can be employed. For instance, various non-adhesive biocompatible gels, hydrogels, liquids (such as saline) may be employed to facilitate the release of the heated tissues from variousPFO treatment catheters21 of the present invention. Preferably, such materials are bio-absorbable. Also, these materials should be electrically conductive when used in conjunction with RF energy based components creating a complete electrical circuit. These materials may be disposed on the external surface ofcatheter21 or extruded from one or more ports disposed at or near the distal ends of the various devices (coils71,73, balloons61,63) andcatheters21 of the present invention. In accordance with this aspect of the invention,inflation members61,63 may be formed of porous material in order to facilitate seepage of saline or other like liquids to the tissues being heated. This seepage facilitates char-fee heating, ready release of tissues from the heating elements, and/or completion of the electrical circuit to enhance and promote the energy delivery process. In addition, circulation of these materials (as well as blood and/or other biological fluids) can also be provided as a means to promote cooling and heat dissipation during the energy delivery process to prevent issues of overheating, tissue charring, etc.
• Detecting and locatingPFO1 is an important aspect of the invention and conventional techniques, including ultrasound, fluoroscopy, TEE, ICE, and ear oximetry techniques can be used for this purpose. In yet another embodiment, of the present invention thevarious catheters21 of the present invention can be adaptively shaped to identify and engage certain detectable anatomical structures (such as the annular structure surrounding the fossa ovalis10) as one means of locatingPFO1 as well as securely positioningPFO treatment catheters21 andcatheter assemblies21 for penetration ofinteratrial septum3 and the energy delivery process. In one embodiment, thevarious catheters21 may be configured to further comprise location means161 complementarily shaped to securely engage the antero-superior portion of theannular tissue structure162 that typically surrounds thefossa ovalis10 which is nearPFO1; or location means161 may alternatively be used to locate thefossa ovalis10. This aspect of the invention is illustrated inFIG. 14.
• In a further aspect of the present invention, the process of joining or welding of the tissues can be immediate leading toPFO1 closure or occlusion following energy delivery in accordance with the present invention. However, it is also contemplated that joining or welding of the tissues can occur over several days wherein the tissue joining process is mediated in part to the body's healing response to thermal injury. Nevertheless, whether the closure or occlusion of the PFO is immediate or gradual, complete or partial; preferably, the attachment of the primum and secundum to affectPFO1 closure or occlusion should be permanent.
• Finally, while several particular embodiments of the present invention have been illustrated and described, it will be apparent to one of ordinary skill in the art that various modifications can be made to the present invention, including one aspect of one embodiment combined with another aspect of one embodiment. Other obvious adaptations of the present invention include the use of the devices, methods, and systems during minimally invasive surgery.
• Also, as will be readily appreciated by those skilled in the art, the present invention described methods and devices that can be used to treat other types of cardiac defect. The general energy-based method for joining tissues is applicable as a therapeutic treatment method for closing other cardiac defects including, but not limited to patent ductus arteriosus, atrial septal defects, and other types of abnormal cardiac openings wherein an effective treatment is to join or weld tissue. Accordingly, the present invention and the claims are not limited merely for the therapeutic treatment of PFO but can be used for closure of occlusion of cardiac defects, body lumens, vessels, etc. Modifications and alterations can be made without departing from the scope and spirit of the present invention and accordingly, it is not intended that the invention be limited, except as by the appended claims.

Claims (26)

1. A treatment method for closing a patent foramen ovale comprising two flap-like tissue structures and which is located on an interatrial septum separating a right and left atrium of a heart; said method comprising the steps of:

a) detecting and locating the patent foramen ovale;

b) encasing the two flap-like tissue structures between one or more heat generating members;

b) energizing the one or more heat generating means; and

c) applying a therapeutic amount of energy to join the two overlapping tissue structures at one or more positions of contact.

2. The method ofclaim 1, wherein the therapeutic amounts of energy is produced by a proximal heat generating member located in the right atrium of the heart.

3. The methodclaim 1, wherein the therapeutic amounts of energy is produced by a distal heat generating member located in the left atrium of the heart.

4. The method ofclaim 3, wherein the therapeutic amounts of energy are simultaneously produced by the proximal heat generating member located in the right atrium and the distal heat generating member located within the left atrium.

5. The method ofclaim 4, wherein the proximal and distal heat generating members are transseptally deployed.

6. The method ofclaim 3 or4, further comprising the step of: penetrating the interatrial septum of the heart and forming a left atrial access pathway.

7. The method ofclaim 1,2,3, or4, wherein the tissues are joined at the one or more points of contact.

8. The method ofclaim 1,2,3, or4, wherein the one the tissue are joined along a seam.

9. The method ofclaim 1,2,3, or4, wherein the PFO is partially closed.

10. The method ofclaim 1,2,3, or4, wherein the PFO is completely closed.

11. The method ofclaim 1,2,3, or4, wherein the two overlapping tissue structures are permanently joined.

12. The method ofclaim 1, further comprising the step of: applying a lubricating means to prevent sticking of the tissues to the one or more heat generating means.

13. The method ofclaim 12, wherein the lubricating means is electrically conductive.

14. The method ofclaim 13, further comprising the step of: providing a monitoring means to prevent overheating of cardiac tissues adjacent the encased tissues.

15. A treatment method for therapeutically closing a patent foramen ovale on an interatrial septum separating a right and left atrium of the heart, said treatment method comprising the steps of:

a) determining the location of the patent foramen ovale; and

b) applying therapeutic amounts of energy to the septum at or near the location determined in step (a) to induce.

16. The method ofclaim 15, wherein the therapeutic amount of energy is applied from the right atrium of the heart.

17. The method ofclaim 15, further comprising the step of:

a) puncturing the septum on or near the patent foramen ovale and creating an access pathway into the left atrium of the heart.

18. The method ofclaim 17, further comprising the steps of: introducing the first heat generating member into the right atrium; and introducing a second heat generating member into the left atrium of the heart.

19. The method ofclaim 18, further comprising the step of: energizing the first heat generating member.

20. The method ofclaim 18, wherein the first and second heating means are energized simultaneously.

21. The method ofclaim 18, wherein the first and second heating means are used in order to apply a compressive force to the septum encased between the first and second heating means.

22. The method ofclaim 18, further comprising the step of: introducing a lubricating means to prevent sticking of the septum to the first and second heating means.

23. The method ofclaim 22, wherein the lubricating means is also electrically conductive.

24. A catheter apparatus for closing a patent foramen ovale comprised of two overlapping tissue structures located on an interatrial septum which separates a right and left atrium of the heart, said apparatus comprising:

a) a means for locating and detecting the patent foramen ovale;

b) a means for puncturing the interatrial septum at, or adjacent, the patent foramen ovale; and

c) one or more means for transseptally delivering therapeutic amounts of energy one or more tissue locations in order to affect joining of the overlapping tissue structures.

25. The apparatus ofclaim 24, wherein the one or more means for applying compressive force to the interatrial septum.

26. The apparatus ofclaim 25, further comprising one or more radio-opaque means.

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