WO2010018569A1

WO2010018569A1 - Method and apparatus for intra-atrial ablation

Info

Publication number: WO2010018569A1
Application number: PCT/IL2009/000776
Authority: WO
Inventors: Uri Stein
Original assignee: Cardionova Ltd.; Shafrir, Roey
Priority date: 2008-08-11
Filing date: 2009-08-10
Publication date: 2010-02-18

Abstract

An intra-atrial apparatus is disclosed. The apparatus comprises a catheter having an intra-atrial section positionable in the atrium, a plurality of balloons arranged along the intra-atrial section, and an inflation lumen being in fluid communication with the balloons. One or more of the balloons is configured for anchoring the intra-atrial section in position within the atrium.

Description

METHOD AND APPARATUS FOR INTRA-ATRIAL ABLATION

RELATED APPLICATION

This application claims the benefit of priority from U.S. Patent Application No. 61/087,741, filed on August 11, 2008, the contents of which are hereby incorporated by reference as if fully set forth herein.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to intra-atrial therapy and, more particularly, but not exclusively, to a medical apparatus and a method for performing intra-atrial ablation therapy.

An objective of intra-atrial ablation therapy is to isolate a defined portion of an atrium from an electrical signal. During pursuit of this objective, disruption of blood flow in a heart chamber can be a problem. US 5,575,810 discloses an inelastic balloon with an attached inelastic ablation element for use in a heart chamber. The described balloon provides an inner flow channel for blood. The disclosure of this patent is fully incorporated herein by reference. WO 04/105807 describes an expanding "clover" shaped balloon to bring a circular ablation element into contact with an inner surface of a pulmonary vein. The described clover configuration leaves channels for blood flow between the balloon and an inner surface of the pulmonary vein so that flowing blood can contact the inner surface of the pulmonary vein. The disclosure of this application is fully incorporated herein by reference.

US 6,237,605 and US 6,997,925 each describe a continuous electrically insulated boundary encircling the pulmonary veins as a means to electrically isolate the pulmonary veins from the myocardium. Both of these patents describe epicardial ablation procedures. The disclosures of each of these patents are fully incorporated herein by reference.

US 5,769,846 describes a balloon that fills an atrium of a heart. The disclosure of this patent is fully incorporated herein by reference. SUMMARY OF THE INVENTION

According to an aspect of some embodiments of the present invention there is provided an intra-atrial apparatus. The apparatus comprises a catheter having an intra- atrial section positionable in the atrium, one or more balloons arranged along the intra- atrial section, and an inflation lumen being in fluid communication with the balloon(s). When there is more than one balloon, at least one of the balloons can be configured for anchoring the intra-atrial section in position within the atrium.

According to some embodiments of the invention the balloons are arranged asymmetrically about the intra-atrial section. According to some embodiments of the invention the balloons are disposed non- uniformly along the intra-atrial section.

According to some embodiments of the invention at least one of the balloons comprises a peripheral chamber between an outer layer of the balloon and an inner layer of the balloon. According to some embodiments of the present invention the peripheral chamber is vacuum sealed.

According to some embodiments of the present invention the apparatus comprises an expandable ablation element. According to some embodiments of the invention the ablation element is mounted on or embedded in a wall of at least one of the balloons. According to some embodiments of the present invention the apparatus comprises a plurality of independently operative ablation elements, each being mounted on or embedded in a wall of a separate balloon.

According to some embodiments of the present invention when the balloon is inflated the ablation element moves towards an ablation location in the atrium.

According to some embodiments of the present invention the inflation of the balloon causes the ablation element to expand. According to some embodiments of the invention the ablation element is placed in the peripheral chamber.

According to some embodiments of the present invention the catheter has a tip which is positionable in the pulmonary vein.

According to some embodiments of the present invention the apparatus comprises a plurality of inflation lumens devoid of fluid communication thereamongst, wherein each of the balloons is in inflatable by a separate inflation lumen. According to some embodiments of the invention the apparatus further comprises an inflation controller adapted to independently inflate each of balloons. The ablation controller is configured to independently activate and deactivate each of the ablation elements. According to some embodiments of the present invention the catheter and/or the balloon(s) is marked with a radio-opaque or contrast marker.

According to an aspect of some embodiments of the present invention there is provided a method of intra-atrial ablation. The method comprises: inserting into the atrium an intra-atrial ablation apparatus such as the intra-atrial apparatus described above; alternately inflating and deflating at least some of the balloons; and alternately activating and deactivating the ablation elements. According to some embodiments of the present invention the activation and deactivation of the ablation elements is synchronized with the inflation and deflation of the balloons.

According to some embodiments of the present invention the insertion of the ablation apparatus comprises positioning a tip of the catheter in the pulmonary vein.

According to some embodiments of the present invention the method further comprises maintaining at least one balloon in inflated state while performing the alternate inflation and deflation of other balloons so as to anchor an intra-atrial section of the catheter in position within the atrium. According to some embodiments of the present invention the activation of the ablation element comprises generating a flow of cold fluid through the ablation element, and the method further comprises applying vacuum so as to prevent leakage of the cold fluid into the atrium.

According to some embodiments of the present invention the method further comprises imaging the ablation apparatus and the atrium.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting. BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

In the drawings: FIG. 1 is a schematic illustration of a an intra-atrial apparatus deployed in a left atrium of a heart, according to exemplary embodiments of the present invention;

FIGs. 2A-B are side and front views respectively of an exemplary balloon and ablation catheter according to an exemplary embodiment of the invention;

FIGs. 2C-D are cross sections of an atrium with an exemplary balloon and ablation catheter according to Figures 2A and 2B positioned in proximity to pulmonary veins in un-inflated and inflated states respectively;

FIGs. 3A-B are side and front views respectively of an exemplary balloon and ablation catheter according to another exemplary embodiment of the invention;

FIGs. 3C-D are cross sections of an atrium showing exemplary positioning of an ablation element by a balloon according to exemplary embodiments of the invention;

FIG. 4 is a simplified flowchart diagram illustrating a method according to exemplary embodiments of the invention;

FIG. 5 is a simplified flowchart diagram illustrating selected procedural phases of the method according to exemplary embodiments of the invention; FIG. 6 is a schematic flowchart diagram illustrating selected procedural phases of the method in embodiments in which alternate inflation of the balloons is employed;

FIGs. 7A-I are schematic illustrations of some of the procedural phases depicted in Figure 6;

FIGs. 8A-F are fragmentary schematically illustrations showing several relations between an exemplary ablation element and an exemplary balloon, according to various exemplary embodiments of the present invention; FIGs. 9A-K are schematic illustrations of a balloon according to various exemplary embodiments of the present invention;

FIGs. 10A-B are cross sectional views of a balloon according to an exemplary embodiment of the invention within an atrium, in inflated and deflated states respectively;

FIG. 11 is a front view of a balloon catheter adapted to eject dye or contrast agent according to an exemplary embodiment of the invention;

FIGs. 12A-E and 13A-D are fragmentary schematic illustrations showing an ablation element, according to various exemplary embodiments of the present invention; FIGs. 14A-B illustrate an exemplary slideable connection between an ablation element and a balloon according to some embodiments of the invention;

FIGs. 15 A-I are schematic illustrations of an expandable ablation element, according to various exemplary embodiments of the present invention;

FIGs. 16A-I are schematic illustrations showing several configurations which allow heat exchange between an ablation element and tissue, according to various exemplary embodiments of the present invention;

FIGs. 17A-E are schematic illustrations of connection types between the ablation element and the balloon, according to various exemplary embodiments of the present invention; FIGs. 18A-D are schematic illustrations of embodiments in which the ablation element and the balloon are initially disengaged, and the deployment of the ablation element is executed subsequently to the inflation of the balloon in the atrium; and

FIGs. 19A-C are schematic illustrations of a radial cross-section of a catheter according to various exemplary embodiments of the present invention. FIG. 20 is a schematic illustration of a system, including a controller, operably coupled to an intra-atrial ablation apparatus according to an exemplary embodiment of the invention;

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION The present invention, in some embodiments thereof, relates to intra-atrial therapy and, more particularly, but not exclusively, to a medical apparatus and a method for performing intra-atrial ablation therapy. Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the following description and/or illustrated in the drawings and/or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

Exemplary Intra-Atrial Apparatus

Referring now to the drawings, Figure 1 is a schematic illustration of a an intra- atrial apparatus 10 deployed in a left atrium 280 of a heart 20. Apparatus 10 comprises a catheter 210 having an intra-atrial section 12 which is adapted for being deployed in atrium 280. In some embodiments of the present invention catheter 210 is deployed such that at least its distal tip 22 engages one of the four pulmonary veins 284. It these embodiments, catheter 210 is supported by septum 18 on one side and the pulmonary veins on the other side. In the representative illustration of Figure 1, tip 22 is positioned in the left pulmonary vein ostium, but this need not necessarily be the case, since, for some applications, tip 22 can be positioned in another pulmonary vein, such as the right, inferior or superior pulmonary veins. Further, in some embodiments of the present invention tip 22 is not positioned in any of the pulmonary veins, as further detailed hereinunder and illustrated in some of the drawings.

Apparatus 10 comprises one or more balloons 220 which can be arranged along intra-atrial section 12. Balloons 220 can be made stretchable (e.g., elastic) or non- stretchable with a certain degree of characteristic strain {e.g., about 300 % or higher for stretchable balloon and 20 % or lower for non-stretchable). In any event, balloon 220 is inflatable.

The term "balloon" as used herein refers to a single balloon or an arrangement of balloons.

Balloon(s) 220 are in fluid communication with one or more inflation lumens 24, which is or are configured to convey inflation fluid (gas or liquid) to balloons 220. The inflation lumens can be devoid of fluid communication thereamongst such that at least two of the balloons can be inflated by a separate inflation lumen. Representative examples of lumen configurations are provided hereinunder with reference to Figures

19A-C.

The balloons can be arranged symmetrically or asymmetrically about section 12, and they can be disposed uniformly or non-uniformly along section 12. The advantage of having asymmetrical and/or non-uniform arrangement of balloons 220 is that it provides additional degrees of freedom during the deployment of apparatus 10 in atrium 280. Specifically, section 12 can be rotated about its axis and/or further advanced within the atrium so as to achieve better deployment. In an exemplary embodiment of the invention, balloons 220 are arranged and deployed so as not to prevent blood flow in atrium 284.

In various exemplary embodiments of the invention apparatus 10 comprises one or more ablation elements or tools 230. Elements 230 can be mounted on or embedded in a wall of one or more of the balloons, such that when the respective balloon is inflated the ablation element moves towards an ablation location in the atrium. Alternatively, the ablation element can be deployable from the distal end of the catheter to engage the balloon on site. Embodiments directed to the type of connections between element 230 and the balloons are described hereinafter.

Ablation element 230 can be, for example, a cryo-ablation or a heat ablation element. Ablation element 230 can be activated by generating a flow of cold fluid (e.g., a biocompatible cryogenic fluid such as, but not limited to, carbon dioxide, nitrous oxide, liquid nitrogen and fluorocarbon), or by electrical activation of ablation energy (e.g., resistive heat, ultrasound and radiofrequency). In some embodiments of the present invention, two or more of the ablation elements operate independently. When two or more cryo-ablation elements are employed, independent operation can be effected using several lumens which are devoid of fluid communication thereamongst, as further detailed hereinunder with reference to Figures 19A-C.

In an exemplary embodiment of the invention, ablation element is constructed primarily of a metal. Several configurations which allow heat exchange between ablation element 230 and the contacting tissue are described hereinunder with reference to Figures 12A-F.

In some embodiments of the present invention one or more of the balloons of apparatus 10 serve as ablation elements by themselves. In these embodiments, the balloon or parts thereof is made thermally conductive to allow heat transfer between the tissue contacting the balloon and the inflation fluid. The inflation fluid releases or absorbs a sufficiently amount of heart such the heat transfer causes tissue ablation. In one embodiment, the inflation fluid is a cryogenic fluid in which case ablation is facilitated by heat transfer from the tissue contacting the balloon to the cryogenic fluid.

In an alternative embodiment, the inflation fluid is a heated fluid in which case ablation is facilitated by heat transfer from the inflation fluid to the tissue contacting the balloon.

One or more balloons of apparatus 10 can be configured for anchoring intra- atrial section 12 in its position within the atrium. This embodiment can be utilized irrespectively whether or not tip 22 engages the pulmonary vein. When several balloons are employed, one or more of the balloon can serve as anchors while other balloons can serve for purposes other than anchoring. A configuration in which not all the balloons anchor the catheter in its place is advantageous because it reduces obstruction of blood flow from pulmonary veins 284 to mitral valve 286. For example, when apparatus 10 comprises one or more ablation elements, one balloon can anchor the intra-atrial section and the other balloons can serve as platforms for the ablation element(s), such that blood flow is maintained during the ablation.

Figure 1 illustrates an embodiment in which three balloons are employed, wherein the middle balloon anchors the intra-atrial section in its place and each of the two peripheral balloons carries one ablation element. However, it is not intended to limit the scope of the invention to three balloons and two ablation elements. Apparatus 10 can include any number of balloons, as further detailed hereinunder and illustrated in some of the drawings.

Figures 2A-D illustrate an exemplary intra-atrial ablation therapy apparatus 200, which comprises one balloon. In the depicted embodiment, apparatus 200 includes an elastic balloon 220 adapted for intra-atrial inflation and an ablation element 230 passing through a plurality of rings 222 attached, integrally formed with, or connected to a net stretched on a surface of balloon 220. In an exemplary embodiment of the invention ablation element 230 passes through rings 222 so that inflation of balloon 220 causes element 230 to expand.

Figure 2A is a side view of apparatus 200 showing a catheter 210 with balloon 220 protruding from distal end 214 thereof. In the depicted embodiment, rings 222 attached to balloon 220 engage ablation element 230. But this need not necessarily be the case as further detailed hereinunder. In the depicted embodiment a catheter lumen 212 contains an inflation lumen 224 for balloon 220 and additional material 232 for element 230. Figure 2B is front view of apparatus 200 of Figure 2A.

Figure 2C illustrates apparatus 200 when deployed in atrium 280 and positioned so that element 230 will surround pulmonary veins 284 and optionally also encompass at least a portion of mitral valve 286 when expanded to contact inner atrial wall 282.

Figure 2D illustrates apparatus 200 when deployed in atrium 280 so that a loop of ablation element 230 surrounds pulmonary veins 284 and optionally also encompass at least a portion of mitral valve 286.

In an exemplary embodiment of the invention, ablation element 230 is operated when it contacts inner wall 282 of atrium 280 so that it forms an ablation line surrounding pulmonary veins 284 and optionally mitral valve 286. In an exemplary embodiment of the invention, the ablation line formed on the inner wall of the atrium is a hemiatrial ablation line which bisects the atrium in a transverse plane through mitral valve 286 as depicted in Figure 3D described below. Optionally, the ablation lines leave 50, 60, 70 or 80% or intermediate or greater percentages of atrial tissue in electrical contact with signals emanating from a SA node after formation of the ablation line, i.e., the signals reach the tissue.

Referring now to Figures 3A, 3B and 3C which are schematic illustration of an exemplary flow-through apparatus 202. Apparatus 202 is a variant of apparatus 10 and 200, depicted in Figures 1 and 2A-D. Apparatus 202 comprises one or more balloons 220 and ablation elements 230 where ablation element(s) 230 can be mounted on, embedded in, disposed within, or disengaged from balloon 220 as further detailed hereinabove. Although apparatus 202 is shown as having a single balloon, this need not necessarily be the case, since, apparatus 202 can comprise two or more balloons.

In the embodiment illustrated in Figures 3A-C, apparatus 202 comprises a spacer 340 disposed between balloon 220 and ablation element 230, such that spacer 340 touches inner wall 282 of atrium 280 around openings of pulmonary veins 284 without blocking the openings. When apparatus 202 comprises more than one balloon, a single spacer can used for two or more (e.g., all) of the balloons. Also contemplated are embodiments in which apparatus 202 has more than one spacer.

Optionally, the spacer(s) provides an open path for a flow of blood from pulmonary veins 284 to mitral valve 286 when balloon 220 is inflated by assuring that a portion of balloon 220 within a loop of ablation element 230 does not contact pulmonary veins 284.

Figure 3A is a side view of flow through ablation apparatus 202 protruding from a distal end 214 of catheter 210. Balloon 220 is inflated so that ablation element 230 is expanded to its operative size (e.g. to form a loop). In this view it is clear that a thickness of spacer 340 is optionally much greater than that of ablation element 230.

Optionally, spacer 340 is an inflatable balloon or is constructed of compressible material with an elastic memory.

In an exemplary embodiment of the invention, spacer 340 functions as an insulation layer which protects main balloon 220 and/or circulating blood from undesired temperature changes which might result from contact with ablation element

230. In some embodiments of the present invention, ablation element 230 ablates tissue being in contact therewith by generating sufficient heat flow from the tissue to ablation element 230, or by generating sufficient heat flow from ablation element 230 to the tissue. For example, in some exemplary embodiments of the invention, ablation element 230 is a cryo-ablation element 230. In other exemplary embodiments of the invention, ablation element 230 is a heat ablation element 230. Several configurations which allow heat exchange between ablation element 230 and the contacting tissue are described hereinunder with reference to Figures 12A-F.

When a cryo-ablation element is employed, spacer 340 preferably prevents freezing of main balloon 220 and/or circulating blood. Freezing of main balloon 220 could compromise its structural integrity and/or make it difficult to remove balloon 220 after an ablation procedure.

When a heat ablation element is employed, spacer 340 preferably prevents melting or burning of main balloon 220 and/or blood denaturation. Melting or burning of main balloon 220 could compromise its structural integrity. Denaturing of blood can cause unwanted, optionally dangerous, blood clots. Heat ablation element 230 may employ a variety of energy sources to generate heat including, but not limited to, electric current, ultrasound and radio frequency energy.

Figure 3B depicts a front view of flow through apparatus 202 with pulmonary veins 284 and mitral valve 286 in the foreground. In this view, the atrial wall is not shown for clarity. This view clearly shows that the loop of ablation element 230 surrounds all four pulmonary veins 284 and, optionally, also mitral valve 286.

Figure 3C shows a flow through apparatus 202 deployed in atrium 280 in a transverse cross section through line A-A of Figure 3B. This view demonstrates how spacer 340 contacts inner wall 282 of atrium 280. Because spacer 340 surrounds all four pulmonary veins 284 (see Figure3B) and mitral valve 286 a flow of blood (indicated by arrows) from pulmonary veins 284 to mitral valve 286 continues even when main balloon 220 is fully inflated. In the transverse cross section, spacer 340 appears to "cover" pulmonary veins 284. However, spacer 340 is "in front of" veins 284 so that blood flow continues "behind" spacer 340, as can be understood by comparing Figures 3C and 3B.

Figure 3D shows an additional exemplary embodiment 204 of a flow through balloon inflated in atrium 280. In the depicted embodiment rings 222 hold the loop of element 230 to main balloon 220 as the balloon expands. Because ablation element 230 describes a hemi-atrial circle, a flow of blood (indicated by arrows) from pulmonary veins 284 to mitral valve 286 continues even when main balloon 220 is fully inflated. In the depicted embodiment, balloon 220 is characterized by a disc or wheel configuration as opposed to the spheroid configuration of the previous figures.

Inflation of the balloon(s) can be effected by any fluid (gas or liquid) suitable for inflation of catheter balloons. In an exemplary embodiment of the invention, inflation of the balloon(s) is via an inflation pump 600 (not shown, see Figure 20) which is in fluid communication with balloon 220 and operable to provide a flow of an inflation fluid to the balloon. Pump 600 is described in greater detail hereinbelow.

Exemplary Intra-Atrial Ablation Procedure Figure 4 is a simplified flowchart diagram illustrating an exemplary intra-atrial ablation procedure 100. Ablation procedure 100 employs balloons 220 and ablation elements 230 in various configurations as depicted in the other figures. It is to be understood that, unless otherwise defined, method steps or stages described hereinbelow can be executed either contemporaneously or sequentially in many combinations or orders of execution. Specifically, the ordering of the flowchart diagrams is not to be considered as limiting. For example, two or more method steps or stages, appearing in the following description or in the flowchart diagrams in a particular order, can be executed in a different order (e.g., a reverse order) or substantially contemporaneously. Additionally, several method steps or stages described below are optional and may not be executed.

Ablation procedure 100 begins at 101. At 102 a catheter 210 is inserted into the atrium 280 (see, for example, Figure 1) of a subject (not shown). Such procedure is well known to those skilled in the art of cardiac catheterization. By way of example, catheter 210 can be introduced into the femoral vein (not shown) and intravenously advanced into the right atrium 14 of heart 20 through the inferior vena cava orifice 16. Access to left atrium 280 can be achieved via a trans-septal approach whereby a piercing the septum 18 is pierced and allow penetration of catheter 210 into left atrium 280 through septum 18.

At 103 balloon 220 is inflated within atrium 280. When ablation element 230 is mounted on balloon 220, the inflation of the balloon results in deployment 104 of element 230 to engage an ablation location 285 (see Figure 2C) in atrium 280. When ablation element 230 is not mounted on balloon 220, deployment 104 is optionally by delivering (e.g., by a string or guidewire already in place) ablation element 230 to ablation location 285. At 104 ablation element 230 is activated to ablate the tissue at ablation location 285. Activation of ablation element 230 can be done either by generating a flow of cold fluid (e.g., a biocompatible cryogenic fluid such as, but not limited to, carbon dioxide, nitrous oxide, liquid nitrogen and fluorocarbon), or by electrical activation of ablation energy (e.g., resistive heat, ultrasound and radiofrequency).

Following the ablation, procedure 100 optionally proceeds to 106 in which balloon 220 is deflated and 107 in which catheter 210 is withdrawn. Procedure 100 ends at 108.

Selected procedural phases are described in more details hereinbelow with reference to Figure 5 which is a more detailed flowchart diagram of selected phases of procedure 100. At 110 catheter 210 carrying one or more balloons 220 and ablation element 230 is inserted into atrium 280. Optionally, insertion is via a trans-septal approach as delineated above and illustrated in Figures 1, 2C and 2D described above, and further in Figures 3C, 3D, 1OA and 1OB described below. At 112, balloon 220 is inflated. In an exemplary embodiment of the invention, inflation of balloon 220 brings ablation element 230 into proximity with a target on an inner wall 282 of atrium 280.

In an exemplary embodiment of the invention, element 230 is mounted on balloon 220 via an arrangement of rings 222 (best seen in Figures 14A, 14B, 17A and 17D) such that inflation 112 causes an increase 114 in a distance between rings 222 on a surface of balloon 220. Rings 222 are typically, but not obligatorily, adapted to engage ablation element 230 at an engagement point which is fixed with respect to balloon 220 and slideable with respect to ablation element 230. Optionally, the increase in distance 114 causes an increase 116 in an area of ablation element 230, for example by causing element 230 to expand to form a loop.

In some exemplary embodiments of the invention, a spacer 340 is provided 118) between ablation element 230 and balloon 220 (see Figures 3A, 3B, 3C and 3D). Rings 222 are not shown in Figures 3A, 3B, 3C and 3D for clarity although they are optionally present. In an exemplary embodiment of the invention, rings 222 on balloon 220 engage ablation element 230 and spacer 340. Rings 222 can either be connected directly to the balloon or they can be connected to a net stretched over the balloon (see, e.g., Figure 18C). In an exemplary embodiment of the invention, spacer 340 contributes to an increase in blood flow between inner wall 282 of atrium 280 and balloon 220. Optionally, spacer 340 insulates 120 at least a portion of ablation element 230. In an exemplary embodiment of the invention, loop 230 is a cryo-ablation element and insulation 120 contributes to a reduction in unwanted cooling of tissue (e.g. blood) outside the target. In an exemplary embodiment of the invention, loop 230 is a heat generating loop and insulation 120 contributes to a reduction in unwanted heating of tissue (e.g. blood) outside the target. In an exemplary embodiment of the invention, an orientation of expanded ablation element 230 with respect to the target is checked 122 after inflation 112. Optionally, orientation of a loop of ablation element 230 with respect to the target is adjusted 124. In an exemplary embodiment of the invention, checking 122 is by means of contrast material injection as described in detail hereinbelow with regard to Figure 11. Optionally, checking 122 is by means of a camera (not shown) mounted in balloon 220.

In an exemplary embodiment of the invention, the loop of element 230 contacts 126 an inner wall 282 of atrium 280 forming an ablation line as further detailed hereinabove. Optionally, the loop of element 230 adheres, sticks or otherwise remains in contact 130 to inner wall 282 of atrium 280 as a result of contact 126 during or before ablation.

In an exemplary embodiment of the invention, blood flows from pulmonary veins 284 to mitral valve 286 during ablation (see, for example Figs 3C, 3D and 8B).

Optionally, partial deflation 134 of balloon 220 contributes to an ability of blood to flow from pulmonary veins 284 to mitral valve 286 during ablation while ablation element

230 continues to adhere or otherwise remain in contact 130 with the atrial wall.

Optionally, channels in spacer 340 facilitate blood flow from pulmonary veins 284 to mitral valve 286 during ablation without partial deflation 134.

After the procedure is completed, balloon 220 is deflated and catheter 210 is withdrawn 136 together with balloon 220 and ablation element 230.

In an exemplary embodiment of the invention, procedure 100 produces an ablation line which surrounds all four pulmonary veins 284 and, optionally, mitral valve 286.

Figure 6 is a schematic flowchart diagram illustrating selected procedural phases of procedure 100 in embodiments in which alternate inflation of the balloons is employed. Figures 7A-I are schematic illustrations of some of the procedural phases.

The procedure begins at 151 and continues to. 152 at which an intra-atrial ablation apparatus is inserted into the atrium 280. The apparatus is typically similar to apparatus 10 and includes catheter 210, a plurality of balloons 220 and a plurality of ablation elements 230. The apparatus can be inserted via a trans-septal approach as further detailed hereinabove. The pierced septum 18 is illustrated in Figure 7A and the trans-septal insertion of apparatus 10 into atrium 280 is illustrated in Figure 7B. At 153, at least some of balloons 220 are alternately inflated and deflated within atrium 280. As used herein the term "alternate" and its various deflections refers to operations performed on a plurality of objects at any order of executions such that at least two of the objects do not experience the same operation simultaneously. For example, the balloons are "alternately inflated and deflated" in the sense that for at least two of the balloons, the operation of inflation and deflation is not performed simultaneously.

An exemplified alternating inflation and deflation process for the case of three balloons is schematically illustrated in the sequence of Figures 7C-6G. In Figure 7C one balloon, designated 220-1 is inflated. In the present example balloon 220-1 is the closest to septum 18, but this need not necessarily be the case, since, for some applications, it may be desired to begin the inflation with a balloon which is farther from septum 18. While balloon 220-1 is still in its inflated state, a second balloon, designated 220-2 is inflated (Figure 7D). While balloons 220-1 and 220-2 are in their inflated state, a third balloon, designated 220-3 is inflated (Figure 7E). In Figure 7F, third balloon 220-3 is deflated, leaving first 220-1 and second 220-2 balloons in their inflated state, and in Figure 7H first balloon 220-1 is deflated, leaving second balloon 220-2 in its inflated state.

In various exemplary embodiments of the invention at least one balloon in maintained in the inflated state while performing the alternate inflation and deflation of the other balloons. The balloon which is maintained in its inflated states can anchor the intra-atrial section of the catheter in position within the atrium. For example, in the illustration of Figures 7A-I, balloon 220-2 can serve as an anchor since once it is inflated it remains in its inflated state until the end of the alternating process.

Any of balloons 220-1, 220-2 and/or 220-3 can serve as an ablation element by itself, namely it is made, at least in part from a thermally conductive material and is inflated by an inflation fluid which releases or absorbs a sufficiently amount of heart to ensure tissue ablation as further detailed hereinabove. In an embodiment of the invention, balloons 220-1 and/or 220-3 are ablation elements, while balloon 220-2 is not a heat ablation element. For example, balloon 220-2 can be inflated by an inflation fluid at approximately body temperature or any temperature which does not ablate tissue. When a balloon serves as an ablation element by itself, it can be provided with or without additional ablation element thereon. If desired, the deflation level of one or more of the balloons can be modified during the process. For example, as shown in Figures 1C, 7D and 7G, first balloon 220- 1 is only partially inflated (Figure 7C) before the inflation of balloon 220-2 (Figure 7D) but further inflated once third balloon 220-3 is deflated (Figure 7G). The advantage of partially inflating first balloon 220-1 at the beginning of the procedure is that such partial inflation can prevent backward movement of the catheter into septum 18. Once such backward movement is prevented, the anchor balloon (second balloon 220-2 in the present embodiment) can be inflated to fix the device in its position.

In an exemplary embodiment of the invention, once a balloon having an ablation element 230 is inflated, an ablation line is formed on the inner wall of the atrium as further detailed hereinabove. At 154 the ablation elements are alternately activated and deactivated synchronously with the alternate inflation and deflation of the balloons. Typically, an ablation element is activated when the respective balloon is inflated. For example, suppose that ablation elements are mounted on balloons 220-1 and 220-3. These elements are designated by reference signs 230-1 and 230-3, respectively. The synchronous activation and deactivation of elements 230-1 and 230-3 can be such that element 230-1 is activated when balloon 220-1 is fully inflated (see Figure 7G) and element 230-3 is activated when balloon 220-3 is fully inflated (see Figure 7E). Tool 230-1 is deactivated prior to the deflation of balloon 220-1, and element 230-3 is deactivated prior to the deflation of balloon 220-3.

When a particular balloon serves as an ablation element by itself, it can be provided with or without additional ablation element thereon. When the balloon is not provided with an additional ablation element, the activation of ablation is facilitated by the inflation of the balloon. For this balloon, 154 can be skipped since the activation and deactivation occurs at 153. For example, suppose that balloons 220-1 and/or 220-3 are ablation elements which are not provided with additional ablation elements (namely elements 230-1 and 230-3 are not present). Suppose further that balloon 220-2 is not a heat ablation element and is also devoid of ablation element thereon. In this case, activation and deactivation of ablation is by inflation and deflation of balloons 220-1 and 220-3 and 154 is not executed at all.

Following the ablation and once all the balloons are deflated, procedure 100 optionally proceeds to 155 in which the apparatus is withdrawn. Procedure 100 ends at 156.

Exemplary Balloons with Ablation elements

In any of the above embodiments, ablation element 230 can be mounted on, embedded in, disposed within, or disengaged from balloon 220. Figures 8A-E are fragmentary schematically illustrations showing several relations between ablation element 230 and balloon 220. In Figure 8A, ablation element 230 is mounted on balloon 220, in Figure 8B ablation element 230 is embedded with the wall 221 of balloon 220, in Figure 8C ablation element 230 is disposed within the inner cavity 223 of balloon 220, and in Figure 8D ablation element 230 is disengaged from balloon 220 (e.g., ablation element 230 and balloon 220 are devoid of contact thereamongst).

Additional embodiments are illustrated in Figures 8E-F. In these embodiments, balloon 220 comprises a peripheral chamber 236 between an outer layer 238 and an inner layer 234 of balloon 220. Peripheral chamber 236 preferably surrounds an inner chamber 240 of balloon 220. In various exemplary embodiments of the invention chamber 236 is vacuum sealed. When balloon 220 is inflated, an inflation fluid is supplied to chamber 240 but not to peripheral chamber 236 which preferably remains vacuum sealed at all times.

Figure 8E illustrates an embodiment in which ablation element 230 is placed in chamber 236. This embodiment is particularly useful when tool 230 is a cryo-ablation element, in which case the vacuum conditions in peripheral chamber 236 prevent leakage of cold fluid out of element 230.

Figure 8F illustrates an alternative embodiment in which chamber 236 serves as an ablation element. In this embodiment cold fluid 244 can be introduced into chamber 236, for example, via a fluid channel 242 which optionally extends along the length of the catheter (not shown in Figure 8F, see, e.g., Figure 1, 2A-D and 3A-B).

For clarity of presentation, the configurations are shown in Figures 8A-F for a single balloon. Yet it is to be understood that more detailed reference to a single balloon is not to be interpreted as limiting the scope of the invention, when the ablation apparatus comprise two or more balloons, each of these configurations can be employed to any of the balloons. In some embodiments of the present invention different configurations are employed to different balloons of the apparatus. As stated, balloon(s) 220 can be made stretchable (e.g., elastic) or non- stretchable with a certain degree of characteristic strain. Catheter balloons with sufficiently low characteristic strains are oftentimes referred to in the literature as "non- compliant" balloons. The term "non-compliant" when made in reference to a catheter balloon refers to a body which does not substantially stretch when inflated with fluid. A "non-compliant" balloon has a particular characteristic distended profile and it does not inflate beyond the characteristic distended profile by more than about 20 %, more preferably 15 %. A non- compliant balloon remains at a preselected size and profile even when the internal pressure in the balloon is increased above that required to fully inflate the balloon.

The term "compliant" when in reference to a catheter balloon refers to a body which continually distends with increasing inflation pressure to a point below its burst pressure. Typically, but not necessarily, compliant balloons also have lower tensile strength compared to the tensile strength of a non-compliant balloon of the same dimensions.

The term "semi-compliant" as used herein in reference to a catheter balloon refers to a body which continually distends with increasing pressure to a point below its burst pressure and which has a tensile strength which is greater than the tensile strength of a compliant balloon of the same dimensions. Suitable non-compliant structural polymeric materials for a non-compliant balloon include, without limitation, modified polyesters, polyethylene terephthalate (PET), modified polybutylenes, polyvinyl chlorides, polyamides (e.g., Nylon), etc. Also contemplated are combinations of the structural polymeric materials listed above.

A compliant balloon can be made from relatively soft or flexible polymeric materials, including, without limitation, thermoplastic polymers, thermoplastic elastomers, polyethylene (high density, low density, intermediate density, linear low density), various copolymers and blends of polyethylene, ionomers, polyesters, polyurethanes, polycarbonates, polyamides, polyvinyl chloride, acrylonitrile-butadiene- styrene copolymers, polyether-polyester copolymers, and polyether-polyamide copolymers. A compliant balloon can be made from a silicone elastomer, such as medical grade silicone silicon. Semi-compliant balloons are exemplified by, but not limited to, balloons made of nylon and polyamines

In any of the embodiments of the present invention any of the balloons can be complaint, semi-compliant or non-compliant. The advantage of a compliant balloon over a non-compliant balloon is that fewer models of compliant balloons are required to fill a range of sizes. The advantage of a non-compliant balloon over a compliant balloon is that it is more easy to design the distended profile of a non-compliant balloon to perform a certain function. Another advantage of non-compliant balloons is that they are less likely to be punctures. The present embodiments contemplate configurations in which different balloons have different compliances. For example, an anchoring balloon can be made compliant or semi-compliant while other balloons can be non-compliant.

The present embodiments further contemplate configurations in which different parts of a particular balloon have different compliances. For example, when a balloon has more than one chamber, one or more of the chambers can be made compliant or semi-compliant while other chambers can be non-compliant. This embodiment is particularly useful when the balloon comprises a peripheral chamber 236 (see Figures 8E-F), in which case outer layer 238 can be made non-compliant and inner layer 234 can be made compliant or semi-compliant. Figures 9A-H are schematic illustrations of a balloon which can be employed by the method and apparatus of various exemplary embodiments of the present invention.

Figure 9A illustrates an embodiments in which balloon 220 is generally spherically symmetric. Figure 9B illustrates an embodiments in which balloon 220 is asymmetric with respect to catheter 210, where on one side of catheter 210 the balloon is inflated to a larger extent than on the other side thereof. Figure 9C illustrates an embodiment in which balloon 220 includes a lumen 218. In this embodiment, balloon 220 is preferably deployed in the atrium such that when balloon 220 is in its inflated state one end of lumen 218 approximately faces the pulmonary veins and the other end of lumen 218 approximately faces the the mitral valve. Thus, lumen 218 establishes fluid communication between the pulmonary veins and the mitral valve. Figure 9D illustrates an embodiment in which balloon 220 is elongated. Balloon 220 can be mounted at distal end 214 of the catheter (as shown, for example, in Figure 9A), or at a distance d from distal end 214 (as shown, for example, in Figures 9B and 9D).

In each of the embodiments of the present invention balloon 220 can include structural elements which facilitate blood flow between the wall of the atrium and the balloon's surface portion which contacts the wall.

For example, in some embodiments of the present invention the structural elements comprise a plurality of protrusions 227 extending from the surface balloon 220. The protrusions may be disposed regularly or irregularly about the body portion of balloon 220. Protrusions 227 serve for facilitating attachment of balloon 220 to the inner wall of the atrium while allowing blood flow. In use, balloon 220 is inflated until protrusions 227 contact or pressed against the inner wall of the atrium, such that a gap is formed between the atrium wall and regions on surface of balloon which are devoid of protrusions. Blood can then flow in the gap. The shape of the protrusions can be generally cylindrical, generally pyramidal, generally conical, generally frustoconical, and the like.

In some embodiments of the present invention the structural elements comprise slits formed on its surface so as to allow blood flow in the slits. This embodiment is illustrated in Figure 9E, showing balloon 220 with slits 217 formed on its surface. Slits 217 serve for facilitating attachment of balloon 220 to the inner wall of the atrium while allowing blood flow. In use, balloon 220 is inflated until its surface contacts or pressed against the inner wall of the atrium. Blood can then flow in slits 217. The profile of the slits can be of any shape including generally rectangle, generally hemicylinderical, and the like. Slits 217 can be arranged on the surface of balloon 220 in any arrangement. For example, In some embodiments of the present invention slits 217 are arranged in a helical or screw-like arrangement, as schematically illustrated in Figure 9F.

In embodiments in which the surface of the balloon comprises structural elements which facilitate blood flow between the balloon and the wall of the atrium, the balloon can have low characteristic strain (e.g., non-compliant). For example, when balloon 220 includes slits 217 is can be a non-compliant balloon. Balloon 220 can also comprises an arrangement of balloons as schematically illustrated in Figure 9G. In this embodiment, blood can flow in spaces 215 formed between adjacent balloons. Figures 9H, 9i and 9J illustrate an exemplary balloon 400 comprising at least two independently inflatable chambers 410 and 420 separated by a common wall 430.

In all three figures, ablation element 230 is mounted on chambers 410 and 420 of balloon 400 so that it is influenced by inflation of balloon 400. The same effect can be achieved when ablation element 230 is embedded in the wall of balloon 400. Thus, although the ablation element is shown as mounted on balloon 400 in Figures 9H-J, this need not necessarily be the case, since ablation element 230 can be embedded in the wall or internal cavity of balloon 400 as further detailed hereinabove. Balloon 400 is inflated by an inflation controller 600 (Figure 20) adapted to independently inflate each of chambers 410 and 420 of balloon 400. Controller 600 is described in greater detail hereinbelow in the context of Figure 20.

Figure 9H shows that when chambers 410 and 420 are equally inflated, ablation element 230 forms a loop which is bilaterally symmetric with respect to common wall

430. Figures 9i and 9J illustrate how a relative position of ablation element 230 with respect to an intra-atrial target is adjustable by regulating a degree of inflation of each of chambers 410 and 420 of the balloon.

In Figure 9i a degree of inflation of chamber 420 is greater than a degree of inflation 410. As a result, the ablation element 230 loop is shifted to the right. In Figure 9J a degree of inflation of chamber 410 is greater than a degree of inflation 420. As a result, the ablation element 230 loop is shifted to the left.

Figure 9K illustrates an exemplary multi chamber balloon 402 comprising four independently inflatable chambers 410, 420, 440 and 450. Each of the four chambers is separated from its neighbors by a common wall 430. In the pictured embodiment, each chamber 410, 420, 440 and 450 is in fluid communication with its own inflation lumen 412, 422, 442 and 452 respectively.

Optionally, the inflation lumens are routed through catheter 210.

There is a tradeoff between the increased control over a shape of a loop of ablation element 232 offered by an increasing number of chambers and the increased complexity of inflation patterns which must be implemented to realize the increased control. In an exemplary embodiment of the invention, the two compartment balloon 400 offers a sufficient degree of control over a shape of a loop of ablation element 232 with an inflation program that is sufficiently simple to implement.

Figures 1OA and 1OB illustrate an exemplary apparatus 700 adapted to perform intra-atrial ablation. A catheter 210 of apparatus 700 is inserted into atrium 280, optionally via a trans-septal route. A balloon 220 and ablation element 230 are deployed from a distal end of catheter 210. Balloon 220 is inflated so that a loop of element 230 contacts tissue surrounding a target. At this stage ablation element 230 is activated to form an ablation line around the target (e.g. all four pulmonary veins 284 or all four pulmonary veins 284 plus at least a portion of mitral valve 286). However, as seen in Figure 1OA, inflated balloon 220 blocks a flow of blood from pulmonary veins 284 to mitral valve 286.

Therefore, in an exemplary embodiment of the invention, balloon 220 is partially deflated after ablation element 230 adheres to tissue surrounding the target on inner wall 282 of atrium 280 as depicted in Figure 1OB. This partial deflation permits a flow of blood (depicted by arrows) from pulmonary veins 284 to mitral valve 286. In an exemplary embodiment of the invention, element 230 adheres to inner wall 282 of atrium 280 with sufficient force that contraction of balloon 220 does not cause it to disengage.

In an exemplary embodiment of the invention, ablation element 230 is a cryo- ablation element. Optionally, element 230 is activated by causing a flow of a cold fluid (e.g., cryogenic fluid) through the ablation element. In an exemplary embodiment of the invention, chilling of the ablation element causes the tissue to freeze and the ablation element 230 to adhere to the frozen tissue of the inner wall 282 of atrium 280.

In an exemplary embodiment of the invention, ablation element 230 is a heat ablation element. Optionally, element 230 is activated by causing an electric current to flow through the element so that it heats. In an exemplary embodiment of the invention, heating of the ablation element causes the tissue to be scorched and/or emit a sticky fluid which allows the ablation element 230 to adhere to inner wall 282 of atrium 280.

Alternatively, or additionally, element 230 adheres by using small anchors or hooks that attach to the tissue and/or glue. Exemplary Orientation Confirmation of the Ablation element

Figure 11 illustrates an exemplary apparatus 500 for verifying a placement of an ablation element. In the depicted embodiment, apparatus 500 comprises an expandable balloon 220 on which ablation element 230 and at least one contrast solution channel 510 including at least one contrast injection port 520 (five.are shown) are mounted.

In an exemplary embodiment of the invention, a contrast injector 670 (not shown, see Figure 20) is employed for to injecting contrast solution from the at least one contrast injection port 520 and an imaging module 680 (not shown, see Figure 20) is employed for imaging the contrast solution. In an exemplary embodiment of the invention, ablation element 230 is configured as a loop and the at least one contrast injection port 520 is positioned within the loop.

In an exemplary embodiment of the invention, imaging module 680 comprises a fluoroscopy device. In an exemplary embodiment of the invention, imaging module 680 is aimed to provide an image of pulmonary veins 284 and presence of contrast solution in the pulmonary veins indicates a correct placement of ablation element 230. Optionally, the contrast agent is injected from injection ports 520 with sufficient force to overcome a flow of blood from vessels 284 to valve 286 so that some of the contrast enters vessel 284. Alternatively, or additionally, a flow of blood from vessel 284 to valve 286 can be cyclic so that contrast agent can enter vessel 284 in a part of the cycle when flow is diminished or absent.

Another visualization technique may be to employ a radio-opaque marker or a radio-opacifying agent. Such markers or agents can be disposed along the catheter (e.g., along intra-atrial section 12 and/or tip 22) and/or the ablation element to facilitate viewing the location, shape and/or orientation thereof. The radio-opaque marker or agent typically functions by scattering X-rays. The areas of the catheter and/or ablation element that scatter the X-rays are detectable on a radiograph.

The radio-opaque marker can be, for example, a ring or soldering made of a biocompatible metal such as, but not limited to, platinum. Also contemplated are radio- opacifying agents such as, but not limited to, bismuth salt (e.g., bismuth subcarbonate), bismuth oxychloride, bismuth trioxide, barium sulfate, tungsten, and mixtures thereof. The radio-opaque marker or radio-opacifying agent can also be a radio-opaque polymer, such as, but not limited to, the radio-opaque materials disclosed in U.S. Patent No. 6,852,308 and U.S. Published Application No. 20040086462.

Exemplary Ablation element Figures 12A-E and 13A-D are fragmentary schematic illustrations showing several configurations for ablation element 230. Typically, ablation element is in the form of a curved tubular structure generally forming a loop. At least part of the loop (e.g., the part being in contact with the wall of the atrium) can be described geometrically as a toroidal shape 910. A toroidal shape is a solid generated by moving a closed curve 912 along generating line 914 (Figure 12A). Curve 912 does not intersect or contain line 914. A toroidal shape is typically described mathematically using a toroidal coordinate system (ξ, η, ψ) shown in Figure 12B.

For clarity of presentation the following conventions are used herein. A "longitudinal direction" refers to a direction tangential to a point on line 914. for example, when line 914 is a circle, the longitudinal direction can coincide with the first circumferential direction ξ of the toroidal coordinate system. A "circumferential direction" refers to a direction tangential to a point on closed curve 912. For example, when curve 912 is a circle, the circumferential direction can coincide with the second circumferential direction ψ of the toroidal coordinate system. For a given point on ablation element 230, the circumferential direction is orthogonal to the longitudinal direction. A "radial direction" refers to a direction which is orthogonal to both the circumferential and the longitudinal directions for every point on tool 230.

A "radial cross-section" refers to a section through toroidal shape 910 in a plane containing closed curve 912 (see Figure 12C). An "azimuthal angle" φ (0 < φ < 360°) is defined in a radial cross-section as an angle between two radius-vectors pointing from the center of the radial cross-section to points on closed curve 912. A "longitudinal section" of element 230 refers to a surface which is a portion of toroidal shape 910 between two radial cross-sections (see Figure 12D). A longitudinal section is characterized by a length along the longitudinal direction. A "circumferential section" of element 230 refers to a sectional surface of a longitudinal section which is on one side of a plane parallel to (but not necessarily containing) line 914 (see Figure 12E). A circumferential section is characterized by a length L along the longitudinal direction and an azimuth angle φ. Two or more circumferential sections are said to be

"complementary" if they complete a full circumference of ablation element 230 about generating line 914. Thus, the sum of azimuth angles of complementary circumferential sections is 2π or 360°. When tool 230 is a cryo-ablation element, its tubular shape allows flow of cryogenic fluid through its inner lumen. When tool 230 is a heat-ablation element, its tubular shape allows delivery of ablative radiation through its internal lumen.

Tool 230 can be a tube made of a flexible material, such as, but not limited to, silicon or the like (Figure 13A). Tool 230 can also be a reinforced tube having a reinforcing member 225 embedded in or mounted on the wall of element 230 (Figure 13B). Reinforcing member 225 can be, for example, a coiled pattern winding element 230 in the circumferential direction and extending over its length or part thereof. In some embodiments, element 230 is a made of a metallic foil (Figure 13C). In some embodiments, element 230 has a shape of a bellows (Figure 13D) which can be made, for example, of a metal.

In various exemplary embodiments of the invention the length of ablation element 230 is increasable to facilitate deployment thereof following the delivery to the atrium.

In some embodiments of the present invention ablation element 230 is a longitudinally compliant structure such its length is increased or decreased in congruity with the inflation or deflation of balloon 220. This embodiment is illustrated in Figures 14A and 14B which illustrate an exemplary intra-atrial ablation therapy apparatus 800.

In Figure 14A, balloon 220 of apparatus 800 is deflated so that distances between rings 222 are small. As described above, each of rings 222 engages ablation element 230. In the depicted embodiment, a portion 232 of element 230 is stored within catheter 210.

In Figure 14B, balloon 220 of apparatus 800 is inflated so that distances between rings 222 are increased relative to Figure 14A. Since each of rings 222 engages ablation element 230, a loop formed by element 230 is expanded and/or altered in shape. In an exemplary embodiment of the invention, at least some of portion 232 of element 230 pulled from within catheter 210 when balloon 220 expands. In an exemplary embodiment of the invention, each of rings 220 defines an engagement point which is fixed with respect to balloon 220 and dynamic with respect to ablation element 230.

Figures 15A-H illustrate additional embodiment which facilitate deployment of element 230.

Figures 15A-B show balloon 220 in its deflated (Figure 15A) and inflated (Figure 15B) state. As shown, when balloon 220 is in its deflated state ablation element 230 is in its collapsed state and when balloon 220 is in its inflated state ablation element 230 is in its stretched state. A longitudinally compliant structure can be realized in more than one way.

In some embodiments of the present invention tool 230 is made of a material which is compliant (e.g., elastic) along the longitudinal direction.

In some embodiments of the present invention the compliance along the longitudinal direction ablation element is realized by a bellows or telescopic structure which allows element 230 to be stretched or collapse in congruity with the inflation of balloon 220. Figures 15C-F schematically illustrate exemplary embodiments in which ablation element 230 is provided as a bellows (Figures 15C-D) and telescopic (Figures 15E-F) structure. Shown in Figures 15C-F are collapsed (Figures 15C and 15E) and stretched (Figures 15D and 15F) states of ablation element 230. Balloon 220 is not shown in Figures 15C-F (see, e.g., Figures 15 A-B).

In some embodiments of the present invention the ablation element is stored in a surplus compartment such that deployment of the ablation element is facilitated by pulling the tubular structure forming the ablation element out of the surplus compartment. This embodiment is illustrated in Figures 15G-i showing an exemplary surplus compartment 252 which stores surplus (not shown) of the tubular structure therein. When balloon 220 in its deflated state (Figure 15G) the part of element 230 which engages balloon 220 is short. Upon inflation of balloon 230 (Figure 15H) surplus of tubular structure is being pulled out of compartment 252 and the length of ablation element 230 is increased in congruity with the inflation of balloon 220. Compartment 252 can be mounted on or installed in the body of catheter 210, e.g., near distal end 214. A representative example for such configuration is illustrated in Figure 15i. Exemplary Heat Exchange Mechanisms

Figures 16A-F are fragmentary schematic illustrations showing several configurations which allow heat exchange between ablation element 230 and the contacting tissue. It is to be understood that although the embodiments described below and illustrated in Figures 16A-F are directed to a cryo-ablation element, this need not necessarily be the case, since ablation element 230 can, as stated, be also a heat ablation element.

Figure 16A schematically illustrates an embodiment in which a generally symmetric heat flow is employed. Shown in Figure 16A is a cross-sectional view of a lumen 235 of cryo-ablation element 230 contacting inner wall 282 of atrium 280. A cryogenic fluid 237 flows in lumen 235 in a direction perpendicular to the plane of Figure 16A, and generate a heat flow from wall 280 to lumen 235. In this embodiment, at least part of the wall 241 of element 230 is thermally conductive. Lumen 235 can be concentric or nonconcentric with the external surface of element 230. Figure 16A illustrates a concentric configuration in which the thickness of wall 241 is generally radially symmetric hence allow a heat flow which is generally radially symmetric. Nonconcentric embodiments of the present invention are described hereinunder (see Figures 16E and 16F). The heat flow is represented in Figure 16A as block arrows. For clarity of presentation, the heat flow is not shown in Figures 16B-F. In various exemplary embodiments of the invention ablation element 230 conducts heat in an asymmetric manner. In these embodiments the amount of heat being conducted through one side of element 230 is suppressed relative to the amount heat being conducted through the side thereof. From the standpoint of thermal conductivity, a longitudinal section of element 230 is typically characterized in that the thermal conductivity of one circumferential section is higher than the thermal conductivity of the complementary circumferential section. For example, one circumferential section of element 230 can be thermally conductive while the complementary circumferential section can be thermally isolating.

Figure 16B schematically illustrates an embodiment in which heat is conveyed via a plurality of heat conducting channels within ablation element 230. In this embodiment, ablation element 230 comprises a heat conducting surface 239 which is brought into contact with inner wall 282 of atrium 280. The wall 241 of ablation element 230 further comprises a plurality of openings 243 disposed along surface 239 to establish a continuous thermal path between surface 239 and cryogenic fluid 237. In this embodiment, wall 241 can be made thermally isolating such that heat flows through surface 239 and openings 243 is allowed and heat flow through other sections of wall 241 is prevented or at least reduced. Thus, the circumferential section which comprises surface 239 is thermally conductive while the complementary circumferential section is thermally isolating. Figure 16C schematically illustrates an embodiment in which wall 241 of ablation element 230 is made of a thermally isolating material 245 on one circumferential section and a thermally conducting material 247 on the complementary circumferential section. Thermally conducting material 247 is brought into contact with inner wall 282 of atrium 280, and thermally isolating material 245 can be in contact with the blood or balloon 220 (not shown). Cryogenic fluid 237 flows in lumen 235 in a direction perpendicular to the plane of Figure 16C, and generate a heat flow through material 247 to lumen 235. Heat flow through material 245 is prevented or at least reduced.

Figure 16D schematically illustrates an embodiment in which heat is conveyed via a plurality of heat conducting elements 249 disposed in wall 241 of element 230. The principles and operations of this embodiment are similar to the principles and operations of the embodiment shown in Figure 16B described above, except that heat flows through elements 249. Thus, elements 249 are brought into contact with inner wall 282 of atrium 280, to establish a continuous thermal path between wall 282 and cryogenic fluid 237. Similar to the embodiment shown in Figure 16B, wall 241 can be made thermally isolating such that heat flow through elements 249 is allowed and heat flow through other sections of wall 241 is prevented or at least reduced. Figure 16E schematically illustrates an embodiment in which a nonconcentric configuration is employed. Shown in Figure 16E is a cross-sectional view of lumen 235 of cryo-ablation element 230 contacting inner wall 282 of atrium 280. As shown the thickness of wall 241 of element 230 is not radially symmetric such that lumen 235 is nonconcentric with the external surface of element 231. Cryogenic fluid 237 flows in lumen 235 in a direction perpendicular to the plane of Figure 16E, and generate a heat flow from wall 280 to lumen 235. The thinner side of wall 241 is brought into contact with inner wall 282 of atrium 280, and the thicker side of wall 241 can be in contact with the blood or balloon 220 (not shown). Since lumen 235 is nonconcentric with the external surface of element 231 more heat flows through the thinner side of wall 241 than through the thicker side thereof.

Figure 16F schematically illustrates another embodiment in which element 230 has a thermally conductive side and a thermally isolating side. In the exemplified embodiment illustrated in Figure 16F, wall 241 is embedded with an internal thermally isolating layer 251. In this embodiment, the thickness of wall 241 can be either radially symmetric or radially asymmetric. In the non-limiting example illustrated in Figure 16F the thickness of wall 241 is radially asymmetric such that lumen 235 is nonconcentric with the external surface of element 231, but a symmetric thickness (such as the configuration illustrated in Figure 16A) is also contemplated. Thermally isolating layer 251 is embedded in wall 241 such as to prevent or at least reduce heat flow from one side of element 231. Thermally isolating layer 251 can be shaped, e.g., as a part of a cylinder (for example, a hemicylinder) and is preferably embedded in wall 241 so as to partially enclose lumen 235 while maintaining at least one continuous thermally conductive path 253 between lumen 235 and the external surface of wall 241. Thus, element 230 has a thermally isolating side and a thermally conductive side. Tool 230 can be positioned such that the conductive path 235 contacts inner wall 282. Cryogenic fluid 237 flows in lumen 235 in a direction perpendicular to the plane of Figure 16F, and generate a heat flow from wall 280 to lumen 235, through path 253. The thermally isolating side of wall 241 can be in contact with the blood or balloon 220 (not shown), such that layer 251 prevents or at least reduces heat flow from the balloon or the blood.

Figures 16G-H schematically illustrate embodiments in which two lumens are employed. Shown in Figures 16G-H is a cross-sectional view of an inner lumen 235 and an outer lumen 266 of cryo-ablation element 230. Inner lumen 235 has a wall 265 which separates inner lumen 235 from outer lumen 266. Wall 241 of outer lumen 266 contacts inner wall 282 of atrium 280.

A cryogenic fluid 237 flows in lumen 235 in a direction perpendicular to the plane of Figure 16G-H. In the embodiment illustrated in Figure 16G, lumens 235 and 266 are concentric, and there are vacuum conditions within lumen 266. The advantage of this embodiment is that it prevents leakage of fluid 237 into the atrium. In the embodiment illustrated in Figure 16H, lumens 235 and 266 non concentric, such that walls 241 and 265 contact along a section of element 230. Lumen 266 is filled with thermally isolating medium 267, which can be gas or liquid. Heat flow is established in the contact area between walls 241 and 265. In other regions heat flow into lumen 235 is substantially prevented by means of medium 267.

Figure 16i schematically illustrates an embodiment in which three lumens are employed. This embodiment is similar to the embodiment illustrated in Figure 16H with the addition of an external lumen 268 having vacuum conditions therein. Lumen 268 surrounds wall 241 of lumen 266. The wall 270 of lumen 268 contacts wall 282 or atrium 282. The vacuum serves for preventing leakage of fluid 237 to the atrium, as further detailed hereinabove.

Various combinations of the above embodiments are also contemplated, and one of ordinary skill in the art would know how to construct element 230 by combining features described above. For example, the embodiment illustrated in Figure 16E and/or 12F can be combined with any of the other embodiments by manufacturing element 230 such that lumen 235 and wall 241 are non-concentric and/or by incorporating internal thermally isolating layer 251 in wall 241; the embodiment illustrated in Figure 16D can be combined with the embodiment illustrated in Figure 16B by replacing openings 243 with heat conducting elements 249; the embodiment illustrated in Figure 16C can be combined with any of the other embodiments by manufacturing wall 241 such that it is made of thermally isolating material 245 on one circumferential section and thermally conducting material 247 on the complementary circumferential section; ant so on.

Exemplary Ablation element Connections

Figures 17A-E are schematic illustrations of connection types between tool 230 and balloon 220 according to various exemplary embodiments of the present invention.

Figure 17A illustrates an embodiment in which element 230 is connected to balloon 220 by a plurality of rings 222; Figure 17B illustrates an embodiment in which element 230 is connected to balloon 220 via an adhesive layer 226; Figure 17C illustrates an embodiment in which element 230 is connected to balloon 220 by a string 228 which is fixed to balloon 220 via an arrangement of rings or loops 229.

In some embodiments of the present invention, the connection between ablation element 230 and the balloon is sufficiently weak so as to allow disengagement of ablation element 230 from balloon 220 once balloon is in its inflate state. This can be done in more than one way. For example, in embodiments in which adhesive layer 226 is employed, the adhesive can be selected sufficiently weak such that tension forces resulting from the inflation of the balloon are stronger than the adhesion strength of layer 226. Adhesive layer 226 can also be made from a biodegradable material. In embodiments in which rings 222 are employed, rings 222 can be loosely closed or be made elastic such that in the deflated state of balloon 220 rings 222 are closed (see Figure 17D), but once balloon 220 is inflated rings 222 are opened and element 230 is released therefrom (see Figure 17E). Figures 18A-D are schematic illustrations of embodiments in which the ablation element and balloon 220 are initially disengaged, and the deployment of ablation element at the ablation location is executed subsequently to the inflation of the balloon in the atrium. For clarity of presentation the atrium is not shown in Figures 18A-D.

Figures 18A-B are schematic illustrations of an embodiment in which balloon 220 includes a plurality of rings 222 connected thereto. A string or guidewire 272 engages rings 222 and is connected on one of its ends 274 to ablation element 230 which is initially disengaged from balloon 220. Deployment of ablation element 230 in the atrium is by pulling the other end 276 of guidewire 272. Rings 222 can be arranged to receive element 230. In this embodiment guidewire 272 is pulled at least until it passes through one or more of the rings, for example, to assume the configuration shown in Figures 17A. Alternatively, rings 222 can be arranged such that once element 230 is not received thereby. In this embodiment, the pulling of guidewire 272 is stopped before element 230 engages the first ring. The deployment of element 230 in this embodiment is illustrated in Figure 18B. Figures 18C is a schematic illustration of an embodiment which is similar to the embodiment illustrated in Figures 18A-B with exception that a net 278 is stretched over balloon 220. Rings 222 can then be connected to net 278 rather than directly to balloon 220.

Figure 18D is a schematic illustration of an embodiment in which rings 222 are mounted on catheter 210 instead of balloon 220. Deployment of ablation element 230 in the atrium is by pulling end 276 of guidewire 272 until element 230 is appropriately deployed at the ablation location of the atrium. Exemplary Catheter

Figures 19A-C are schematic illustrations of a radial cross-section of catheter 210 according to various exemplary embodiments of the present invention.

Figure 19A schematically illustrates an embodiment in which catheter 210 comprises three generally concentric flow lumens, 330, 332 and 334. Lumen 330 is the innermost lumen and it can be used for providing inflow of cryogenic fluid to ablation element 230 (not shown). Lumen 332 is the intermediate lumen and it can be used for guiding outflow of cryogenic fluid from ablation element 230. Lumen 334 is the outermost lumen and it can be used for delivering balloon inflating fluid to balloon 220 (not shown). In various exemplary embodiments of the invention lumens 330, 332 and 334 are in fluid communication with a pump, e.g., pump 630 (not shown).

Figure 19B schematically illustrates an embodiment in which the radial cross section of catheter 210 is divided non-concentrically. In the representative illustration of Figure 19B, catheter 210 comprises a main flow lumen 336 and two additional flow lumens 338 and 342 disposed in main lumen 336. Although Figure 19B shows a triangular radial cross-section for lumens 338 and 342, this need not necessarily be the case, since the radial cross-section lumens 338 and 342 can have any other shape. Lumen 336 can be used for delivering balloon inflating fluid to the balloon, and lumens 338 and 342 can be used for providing inflow and outflow of cryogenic fluid to and from the ablation element. In various exemplary embodiments of the invention lumens 336, 338 and 342 are in fluid communication with a pump.

Figure 19C schematically illustrates another embodiment in which catheter 210 comprises a plurality of non-concentric lumens. In the representative illustration of Figure 19C, catheter 210 comprises six lumens designated 350-1, 350-2, 350-3, 350-4, 350-5 and 350-6. This configuration is suitable for an intra-atrial apparatus with a plurality of balloons. For example, lumens 350-1 and 350-2 can be used for independently delivering balloon inflating fluid to two separate balloons, lumens 350-3 and 350-4 can be used for independently providing inflow cryogenic fluid to two separate ablation elements, and lumens 350-5 and 350-6 can be used for generating outflow of cryogenic fluid from the two separate ablation elements.. Any number of lumens can be employed, depending on the number of balloons and ablation elements which operate independently. In some embodiments of the present invention the same lumen can be utilized to provide inflow of cryogenic fluid to more than one ablation element.

In various exemplary embodiments of the invention catheter 210 has a peripheral thermal isolation layer 344 surrounding the flow region of catheter 210. Layer 344 can be made of a material having sufficiently low thermal conductivity, such as, but not limited to, a ceramic material. Layer 344 can also be embedded with objects or particles, such as glass beads, which reduce thermal conductivity. Layer 344 can also be made of foam material having closed or open cells. In some embodiment layer 344 is filled with gas. Alternatively layer 344 can be a vacuum layer. Exemplary System with Controller

Figure 20 is a schematic representation of a system 600 including a controller 610 operably coupled to an intra-atrial apparatus according to an exemplary embodiment.

In the depicted embodiment the intra-atrial apparatus comprises one or more balloons 220 and one or more ablation elements 230 protruding from a distal end 214 of catheter 210 as described above. Optionally, contrast channel 510 and contrast injection ports 520 are provided as described above.

Controller 610 controls the inflation and deflation of the balloon(s) and the activation and deactivation of the ablation elements. In various exemplary embodiments of the invention controller 610 independently inflate and deflate at least two of the balloons. The inflation and dilatation performed by controller 610 are independent in the sense that controller 610 can inflate or deflate one balloon without changing the sate of inflation of the other balloon. Yet, in some embodiments of the present invention controller 610 is configured to simultaneously inflate or deflate two or more of the balloons.

In various exemplary embodiments of the invention controller 610 independently activate and deactivate at least two of the ablation elements. Thus, controller 610 can activate or deactivate one ablation element while keeping the other element active or while keeping the other element inactive. Yet, in some embodiments of the present invention controller 610 is configured to simultaneously activate or deactivate two or more of the ablation elements. In some embodiments of the present invention controller 610 is configured to alternately inflate and deflate the balloons, and to alternately activate and deactivate the ablation elements synchronously with the alternate inflation and deflation of the balloons. In some embodiments of the present invention controller 610 is configured to maintaining at least one balloon in inflated state while alternately inflating and deflating the other balloons as further detailed hereinabove.

In an exemplary embodiment of the invention, controller 610 includes a pump interface 630. Optionally, pump interface 630 provides instructions to one or more pumps 650 (one is pictured). Pump interface 630 can control inflation of balloon(s) 220 and/or a flow of cooling fluid in ablation element(s) 230. In those exemplary embodiments of the invention in which balloon 220 is divided into compartments, pump interface 630 controls inflation of each compartment separately. In those exemplary embodiments of the invention in which a plurality of balloons are employed pump interface 630 can control the inflation of each balloon separately. Optionally, Pump interface 630 also implements deflation of the balloons or compartments thereof. In those exemplary embodiments of the invention in which a plurality cryo-ablation elements are employed pump interface 630 can control flow of cooling fluid for each cryo-ablation element separately. In some embodiments of the present invention pump interface 630 provides instructions to pump(s) 650 for applying vacuum so as to prevent leakage of the cold fluid into the atrium.

In some exemplary embodiments of the invention, ablation element is provided as an electro-ablation element. Optionally, controller 610 includes a voltage controller 640. Voltage control module 640 operates a power source 660 which sends an electric current through ablation element 230 when the voltage controller is operated. In those exemplary embodiments of the invention in which a plurality of electro-ablation elements are employed controller 610 can control each electro-ablation element separately. In those exemplary embodiments of the invention which include contrast channel

510 and contrast injection ports 520, system 600 includes a contrast injector 670. Contrast injector 670 is pictured as a separate unit, although it can optionally be integrated into a housing of controller 610 and/or be subject to control of controller 610.

Optionally, injector 670 is a manually operated device, such as a syringe.

In an exemplary embodiment of the invention, controller 610 includes a timing module 620. In various exemplary embodiments of the invention, timing module 620 exercises temporal control over one or more of pump interface 630, voltage control module 640, and injector 670. In an exemplary embodiment of the invention, temporal control insures that ablation element 230 is activated after balloon 220 is inflated and/or after a position of element 230 has been deemed satisfactory. Alternatively, or additionally, timing module 620 governs how long ablation element 230 remains active so that ablation occurs only to a desired degree.

System 600 includes an imaging module 680, optionally including a fluoroscopy unit.

In an exemplary embodiment of the invention, imaging module 680 provides an output to controller 610. Optionally, analytic circuitry in controller 610 analyzes the output to determine if ablation element 230 is correctly oriented. Alternatively, or additionally, a human user of system 600 assesses a degree of orientation correctness based on a plurality of views.

In an exemplary embodiment of the invention, controller 610 inflates balloon

220 and/or activates ablation element 230 based upon the analysis. In an exemplary embodiment of the invention, tuning module 620 coordinates these activities according to a treatment plan.

It is expected that during the life of a patent maturing from this application many relevant catheter balloons and ablation elements will be developed and the scope of the terms "balloon" and "ablation element" is intended to include all such new technologies a priori.

A variety of numerical indicators have been utilized to describe various components of the apparatus and/or relationships between the apparatus and a heart chamber (e.g. atrium). It should be understood that these numerical indicators could vary even further based upon a variety of engineering principles, materials, intended use and designs incorporated into the invention.

As used herein the term "about" refers to + 10 %. The terms "comprises", "comprising", "includes", "including", "having" and their conjugates mean "including but not limited to".

The term "consisting of means "including and limited to". The term "consisting essentially of" means that the composition, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting.

Claims

WHAT IS CLAIMED IS:

1. An intra-atrial apparatus, comprising: a catheter having an intra-atrial section positionable in the atrium; and a plurality of balloons arranged along said intra-atrial section, wherein at least one balloon is configured for anchoring said intra-atrial section in position within the atrium; and an inflation lumen being in fluid communication with each balloon of said plurality of balloons.

2. The apparatus according to claim 1, wherein said balloons are arranged asymmetrically about said intra-atrial section.

3. The apparatus according to any of claims 1 and 2, wherein said balloons are disposed non-uniformly along said intra-atrial section.

4. The apparatus according to any of claims 1-3, wherein at least one of said plurality of balloons comprises peripheral vacuum sealed chamber between an outer layer of said balloon and an inner layer of said balloon.

5. The apparatus according to any of claims 1-4, wherein at least one of said plurality of balloons is configured as an ablation element.

6. The apparatus according to any of claims 1-5, further comprising an expandable ablation element.

7. The apparatus according to claim 6, wherein said ablation element is mounted on or embedded in a wall of at least one of said balloons such that when said balloon is inflated said ablation element moves towards an ablation location in the atrium.

8. The apparatus according to claim 6, wherein at least one of said plurality of balloons comprises peripheral vacuum sealed chamber between an outer layer of said balloon and an inner layer of said balloon, and wherein said ablation element is placed in said chamber.

9. The apparatus according to any of claims 1-8, wherein said catheter has a tip positionable in the pulmonary vein.

10. The apparatus according to any of claims 1-9, wherein said ablation element comprises a cryo-ablation element.

11. The apparatus according to any of claims 1-9, wherein said ablation element comprises an ablation element which ablates by heating.

12. The apparatus according to any of claims 1-11, wherein inflation of said balloon causes said ablation element to expand and move towards an ablation location.

13. The apparatus according to any of claims 1-12, further comprising a plurality of inflation lumens devoid of fluid communication thereamongst, wherein each of said balloons is in inflatable by a separate inflation lumen.

14. The apparatus of claim 13, further comprising an inflation controller adapted to independently inflate each of balloons.

15. The apparatus according to any of claims 1-14, further comprising a plurality of independently operative ablation elements, each being mounted on or embedded in a wall of a separate balloon.

16. The apparatus of claim 15, further comprising an ablation controller adapted to independently operate each of said ablation elements.

17. The apparatus according to any of claims 1-14, wherein at least one of said catheter and said balloons is marked with a radio-opaque or contrast marker.

18. A method of intra-atrial ablation, comprising: inserting an intra-atrial ablation apparatus into the atrium, said ablation apparatus having a plurality of balloons and a plurality of ablation elements; alternately inflating and deflating at least some of said balloons; and alternately activating and deactivating said plurality of ablation elements; wherein said alternate activation and deactivation is synchronized with said alternate inflation and deflation.

19. The method according to claim 18, wherein said ablation elements are mounted on or embedded in walls of said balloons such that when a balloon is inflated a respective ablation element moves towards an ablation location in the atrium.

20. The method according to claim 18 or 19, wherein at least one of said balloons is configured as an ablation element.

21. A method of intra-atrial ablation, comprising: inserting an intra-atrial ablation apparatus into the atrium, said ablation apparatus having a plurality of balloons, wherein at least one of said balloons is configured as an ablation element; and alternately inflating and deflating at least some of said balloons so as to alternately activate and deactivate tissue ablation.

22. The method according to any of claims 18-20, wherein at least one of said plurality of balloons comprises peripheral vacuum sealed chamber between an outer layer of said balloon and an inner layer of said balloon, and wherein a respective ablation element is placed in said chamber.

23. The method according to any of claims 18-22, wherein said insertion of said ablation apparatus comprises positioning a tip of said catheter in the pulmonary vein.

24. The method according to any of claims 18-23, wherein said ablation element comprises a cryo-ablation element.

25. The method according to any of claims 18-23, wherein said ablation element comprises an ablation element which ablates by heating.

26. The method according to any of claims 18-23, further comprising maintaining at least one balloon in inflated state while performing said alternate inflation and deflation of other balloons so as to anchor an intra-atrial section of said catheter in position within the atrium.

27. The method according to any of claims 18-26, further comprising imaging said ablation apparatus and the atrium.

28. The method according to any of claims 18-27, wherein said activation of said ablation comprises generating a flow of cold fluid through said ablation element, and the method further comprising applying vacuum so as to prevent leakage of said cold fluid into the atrium.