HK1094145B

HK1094145B - Apparatus for the ligation of tissue

Info

Publication number: HK1094145B
Application number: HK07100745.1A
Authority: HK
Inventors: John R. Liddicoat; William E. Cohn; Roger Laham
Original assignee: Atricure, Inc.
Priority date: 2003-10-09
Filing date: 2004-10-11
Publication date: 2020-01-03

Description

Field Of The Invention

This invention relates to apparatus for ligating tissue, and more particularly to ligating cardiac tissue, and even more particularly to ligating tissue of the left atrium.

Background Of The Invention

Atrial fibrillation is a common problem that afflicts millions of patients. Unfortunately, atrial fibrillation often results in the formation of a thrombus, or clot, in the appendage of the left atrium. This presents a problem, inasmuch as the thrombus can dislodge and embolize to distant organs, resulting in adverse events such as a stroke. For this reason, most patients with atrial fibrillation are treated with a blood thinner so as to help prevent the formation of a thrombus in the left atrial appendage. Unfortunately, blood thinners pose a substantial health risk in their own right, particularly in the elderly.

An alternative treatment for atrial fibrillation is the ligation of the atrial appendage at its base. tissue of the left atrium. In one preferred form of the present invention, ligation of the left atrial appendage is effected using a novel apparatus and method.

Background Of The Invention

An alternative treatment for atrial fibrillation is the ligation of the atrial appendage at its base. This procedure occludes the space in which the thrombus can form, thereby substantially eliminating the risk of forming a clot in the left atrial appendage and/or preventing a clot in the appendage from embolizing. Surgeons have been ligating atrial appendages for years during open surgical procedures. Though effective, this approach requires general anesthesia and surgically opening the chest, which presents additional serious health risks to the patient. Therefore, such open-chest ligation of the atrial appendage is normally restricted to situations where the chest is already being surgically opened for other reasons, or where the patient is at a particularly high risk of embolizing.

Recently, catheter-based techniques have been developed for occluding the left atrial appendage space by placing mechanical devices inside the left atrial appendage. This is done under fluoroscopic and/or echocardiographic guidance without the need for a major chest incision or general anesthesia. Unfortunately, however, these techniques require the implantation of mechanical intracardiac devices which, over time, may result in clot formation, incomplete occluding of the appendage space, infection, etc.

In US 2002/0107531 there is described a method and system to stabilize and repair tissue. At least two opposing devices are used, with the two devices cooperatively engaging the tissue interposed therebetween. Stabilization may be accomplished by opposing force, vacuum force, or mechanical devices disposed at the distal portion of one or both devices. After the tissue has been stabilized, fasteners may be deployed into the tissue. Fasteners include sutures, clips, and staples. Also disclosed is a minimally invasive method of accessing tissue located within a body and conducting a repair of the area using the system.

In US 6,152,936 a surgical loop delivery device is disclosed. This device permits tissue targets larger than the device to be ligated while also maintaining a clear sight path between the surgeon and the target. The surgical loop is also described as stable during the procedure.

Summary Of The Invention

According to the present invention there is provided a system for ligating the left atrial appendage having the features set out in claim 1.

The catheter-based system ligates the left atrial appendage (LAA) on the outside of the heart, using a combination of catheters e.g., a guide catheter positioned inside the left atrial appendage which may assist in locating the left atrial appendage and/or assist in the optimal placement of a ligature on the outside of the appendage, and a ligating catheter outside the heart in the pericardial space to set a ligating element at the neck of the left atrial appendage. As a result, this novel approach provides the advantages of both the open surgical approach (i.e., successful ligation of the atrial appendage on the outside of the heart, while avoiding implantation of a mechanical intracardiac device within the heart), and the catheter-based approach (i.e., providing rapid and reliable access to the left atrial appendage without the need for a major chest incision or general anesthesia).

The apparatus described herein are primarily intended to ligate the left atrial appendage, however, the apparatus may also be used in the same or similar constructions to stabilize, suture, and/or ligate any other tissue in the body. By way of example but not limitation, using the apparatus and method described herein, other tissues of the heart (such as the left ventricle) may be manipulated so as to alter the conformational geometry of the heart into a more favorable shape.

Brief Description Of The Drawings

These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which are to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein:

Fig. 1 is a side view of a ligating catheter, with the catheter's ligation subassembly being disposed in a retracted position;
Fig. 2 is a view like that of Fig. 1, except that portions of the ligating catheter have been shown in phantom;
Fig. 3 is an end view of the ligating catheter shown in Fig. 1;
Fig. 4 is a view like that of Fig. 1, except that the catheter's ligation subassembly is shown in an extended position;
Fig. 5 is a view like that of Fig. 4, except that portions of the ligating catheter have been shown in phantom;
Fig. 6 is an end view of the ligating catheter shown in Fig. 4;
Fig. 7 is a view like that of Fig. 4, but with the ligating element being contracted;
Fig. 8 is an end view of the ligating catheter shown in Fig. 7;
Fig. 9 is a view like that of Fig. 7, but with the catheter's ligation subassembly fully retracted;
Fig. 10 is a view like that of Fig. 9, except that certain portions of the ligating catheter are shown in phantom;
Fig. 11 is a view like that of Fig. 10, except that the ligating element has been severed from the ligating catheter;
Fig. 12 is a side view showing the ligating catheter in combination with a guide catheter;
Fig. 13 is a side view of the distal tip of the guide catheter, with the catheter's expanding element being shown in a contracted position;
Fig. 14 is a view like that of Fig. 13, except that the catheter's expanding element is shown in an expanded position;
Fig. 15 is a view showing the distal tip of the guide catheter placed within the left atrial appendage, with the catheter's expanding element being shown in a contracted position;
Fig. 16 is a view like that of Fig. 15, except that the catheter's expanding element is shown in an expanded position;
Fig. 17 shows the guide catheter placed within the left atrial appendage, the guide catheter's expanding element placed in its expanded state, and the ligating catheter placed over the left atrial appendage;
Fig. 18 is a view like that of Fig. 17, except that the ligating catheter has had its ligating element contracted about the neck of the left atrial appendage;
Fig. 19 is a view like that of Fig. 18, except that the ligating catheter has been withdrawn from the surgical site;
Fig. 20 is a view like that of Fig. 19, except that the guide catheter's expanding element has been contracted;
Fig. 21 is a view like that of Fig. 20, except that the guide catheter has been withdrawn from the left atrial appendage;
Fig. 22 is a schematic view showing the distal end of the guide catheter;
Fig. 23 is a schematic view showing the guide catheter's balloon in an expanded condition;
Fig. 24 is a schematic view showing the ligating catheter and the guide catheter;
Fig. 25 is a schematic view showing the distal end of the ligating catheter;
Figs. 26 and 27 are schematic views showing the distal ends of the ligating catheter and the guide catheter orienting an end-to-end fashion through the use of magnets;
Fig. 28 is a schematic view showing a flared suction tube extending out of the ligating catheter's outer tube;
Fig. 29 is a schematic view showing details of the ligating subassembly;
Fig. 30 is a schematic view showing the ligating subassembly extending over the guide catheter's inflated balloon;
Fig. 31 is a schematic view showing the ligature being drawn taut on the outboard side of the guide catheter's balloon; and
Fig. 32 is a schematic view showing a single wire track passing from the interior of the left atrial appendage out through the pericardium, whereby a guide catheter and/or a ligating catheter may be advanced to the surgical site.

Detailed Description Of The Preferred Embodiments Ligating Catheter

Looking first at Fig. 1, there is shown a ligating catheter 2. Ligating catheter 2 comprises an elongated tube or cylinder 5, having a distal end 10 and a proximal end 15. Exiting from proximal end 15 are one or more advancement/retraction control elements 20, which are connected to the ligation subassembly (not shown in Fig. 1) disposed inside cylinder 5. In the construction shown in Fig. 1, advancement/retraction control elements 20 comprise cables or wires. One or more advancement/retraction control elements 20 are used to advance or withdraw the ligation subassembly (not shown in Fig. 1) disposed inside cylinder 5. In addition to the foregoing, one or more constriction control elements 25 also exit from the proximal end of cylinder 5. Constriction control elements 25 are also connected to the ligation subassembly (not shown in Fig. 1) disposed inside cylinder 5 and are used to tighten or loosen the ligating element (also not shown in Fig. 1) about a portion of the tissue or the like. In the construction shown in Fig. 1, constriction control elements 25 comprise cables or sutures.

Looking next at Fig. 2, outer cylinder 5 is shown in phantom. Fig. 2 shows the ligation subassembly 30 in an undeployed state, i.e., with ligation subassembly 30 retracted into cylinder 5. Inside cylinder 5, ligation subassembly 30 is shown having a ligating element 32 (e.g., a suture or string) that may be connected to supports or guides (such as felt pledgets or loops 35) which help to grip and protect the tissue which is being ligated. Ligation subassembly 30 also includes supporting structure 40 with struts 45. Felt pledgets 35 are disposed on the distal ends of struts 45. Struts 45 are configured to expand when ligation subassembly 30 is deployed from cylinder 5. In one preferred construction, struts 45 are expanded by connecting them to one another with springs 50, whereby to render struts 45 self-expandable when the struts are advanced out of the distal end of cylinder 5. Ligation subassembly 30 is connected to advancement/retraction control elements 20, whereby the ligation subassembly 30 can be advanced out of, or retracted into, cylinder 5. Furthermore, ligation subassembly 30 is connected to constriction control elements 25, whereby the ligating element 32 can be constricted about a piece of tissue or the like. Advancement/retraction control elements 20, and/or constriction control elements 25, may be connected to an appropriate handle (not shown) for manipulation by a practitioner.

Looking now at Fig. 3, there is shown the distal end 10 of cylinder 5, with the ligation subassembly 30 undeployed within outer cylinder 5, with felt pledgets 35.

Looking next at Fig. 4, a portion of the ligation subassembly 30 is shown advanced out the distal end of the cylinder 5. The ligation subassembly 30 expands as the struts 45 exit the constraining environment of tube 5 and expand away from one another. In the construction shown in Figs. 1-4, struts 45 expand under the influence of springs 50. Ligation subassembly 30 is connected to constriction control elements 25 which extend beyond proximal end 15 of tube 5 for actuation by the practitioner. Ligation subassembly 30 may be advanced out of the cylinder by pushing on advancement/retraction control elements 20.

Fig. 5 is similar to Fig. 4, except that the walls of cylinder 5 are shown in phantom, thereby exposing the inner workings of the device. Struts 45 are shown connected to supporting structure 40, e.g., an inner supporting ring 40.

Fig. 6 is a distal end view of the device, showing ligation subassembly 30 advanced out of cylinder 5. Ligation subassembly 30 is expanded radially, with the ligating element 32 following an expanded arcuate path about the distal ends of struts 45, with the proximal ends of ligating element 32 passing up through the center of cylinder 5 for actuation by constriction control elements 25. Thus, ligating element 32 is supported by struts 45 (or other means), struts 45 may be expanded by springs 50 (or by other means), and struts 45 may be supported by supporting structure 40.

Looking next at Fig. 7, ligating catheter 2 is shown with ligating element 32 contracted. Ligating element 32 may be contracted by pulling on the proximal ends of constriction control elements 25. This actuation causes radial contraction of the ligature loop.

Fig. 8 is a distal end view of the ligating catheter 2 with ligating element 32 contracted. There is radial compression of the ligature loop. Preferably, the inner supporting structure 40 remains unchanged in radial dimension, as does the distal end of the cylinder 5. Preferably, struts 45 and springs 50 collapse as the device is actuated by the practitioner.

Fig. 9 shows struts 45 and springs 50 retracted back into cylinder 5, i.e., by pulling on the advancement/retraction control elements 20. Ligating element 32 remains in place, applying radial compression to any captivated tissue.

Fig. 10 is similar to Fig. 9, except that ligating catheter 2 is shown with its cylinder 5 in phantom. Struts 45, springs 50, and supporting structure 40 are shown retracted into cylinder 5.

Fig. 11 shows the ligating element 32 severed from constriction control elements 25.

Guide Catheter

Fig. 12 shows the ligating catheter 2 equipped with an alignment element 90. Alignment element 90 is intended for use in aligning ligating catheter 2 with a left atrial appendage or other target structure. In one embodiment of the present invention, alignment element 90 comprises a radio-opaque material and the device is placed into the desired anatomical position by visualization, e.g., fluoroscopy.

Alignment element 90 is intended to work in conjunction with a guide catheter 100, wherein the guide catheter 100 is placed (e.g., endoluminally) within the interior of the left atrial appendage. In this construction, guide catheter 100 also comprises a radio-opaque material, and alignment element 90 and guide catheter 100 are placed in alignment by visualization.

Even more preferably, ligating catheter 2 and guide catheter 100 are provided with physical means (e.g., magnets, male and female connectors, wires and snares, etc.) to facilitate alignment of ligating catheter 2 and guide catheter 100. Thus, in one preferred construction, ligating catheter 2 has its alignment element 90 equipped with a reference magnet 95 at its distal tip. Guide catheter 100 in turn comprises an alignment element 102 having a reference magnet 105 at its distal tip. More particularly, with this preferred construction, ligating catheter 2 has the alignment element 90 which can be extended from the distal end of cylinder 5. On the distal end of alignment element 90 is the reference magnet 95. Alignment element 90 is put into proximity with the guide catheter 100, which has the alignment element 102 with reference magnet 105 mounted on its distal end. When these two alignment elements 90 and 102 are brought into proximity with one another, magnets 95 and 105 cause the alignment elements 90 and 102 to automatically align with one another.

For example, during left atrial appendage ligation, guide catheter 100 is passed endoluminally into the left atrium appendage under visual guidance such as fluoroscopy or ultrasound. The ligating catheter 2 is passed into the pericardium. The alignment element 90 of the ligating catheter is then extended from cylinder 5. Once alignment element 90 is placed into proximity with alignment element 102, magnets 95, 105 cause the two catheters to automatically align with one another, thereby causing ligating catheter 2 to assume a desired position with respect to the left atrial appendage. Then, ligating catheter 2 is utilized as described above to ligate the left atrial appendage.

Looking next at Fig. 13, there is shown a guide catheter 100 which is provided with an expandable element 115. Expandable element 115 is adapted to expand inside the anatomy (e.g., the left atrial appendage) so as to facilitate ligation. As noted above, guide catheter 100 has a magnet 105 mounted to its distal end. It should be noted that expandable element 115 is shown in its non-expanded state in Fig. 13.

Looking next at Fig. 14, guide catheter 100 is shown with its expandable element 115 in its expanded state.

Fig. 15 shows guide catheter 100, with its expandable element 115 not expanded, and with guide catheter 100 disposed in the left atrial appendage 130.

Fig. 16 shows guide catheter 100, with its expandable element 115 expanded, and with guide catheter 100 shown in the left atrial appendage 130. In this respect it should be appreciated when expandable element 115 is in its expanded condition within left atrial appendage 130, expandable element 115 may or may not alter the shape of the recipient tissue, depending on the size of the tissue cavity, the size of the expanded expandable element 115, etc.

Ligating Catheter Used In Conjunction With Guide Catheter

Fig. 17 shows guide catheter 100 with its expandable element 115 expanded in the left atrial appendage 130, and with ligating catheter 2 expanded over the left atrial appendage 130. This aligned positioning is facilitated through the use of alignment element 90 on ligating catheter 2 and alignment element 102 on guide catheter 100. More particularly, guide catheter 100 is positioned in the left atrial appendage 130, expandable element 115 is expanded, ligating catheter 2 is positioned in the state depicted in Figs. 4, 5 and 6 and, using guide elements 90 and 102 to align the apparatus, ligating catheter 2 is slid over the left atrial appendage 130. Guide catheter 100 (inside the left atrial appendage) and ligating catheter 2 are aligned in this preferred construction using magnets 120 and 95, respectively. Significantly, by properly sizing the apparatus vis-à-vis the anatomy, ligating element 32 can be positioned at the neck of the left atrial appendage (and on the atrium side of expandable element 115) when alignment elements 90 and 102 function as described.

Looking next at Fig. 18, guide catheter 100 is shown in the left atrial appendage 130, with its expandable element 115 in its expanded condition, and ligating catheter 2 is shown actuated as described hereinabove with respect to Figs. 7 and 8. Due to the relative positioning of the expanded guide catheter 100 within the left atrial appendage 130 while ligating catheter 2 is being actuated, the constricting ligating element 32 is maintained at the neck of the left atrial appendage 130 by the presence of the expandable element 115, thereby helping to ensure proper positioning of the ligating element 32 relative to the anatomy. In other words, the presence of the expandable element 115 inside the left atrial appendage 130 guides ligature 32 into the desired position 135. In the example of ligating the left atrial appendage 130, the desired position 135 is where the left atrial appendage 130 meets the left atrium 140.

Looking next at Fig. 19, the apparatus is shown with guide catheter 100 still in the left atrial appendage 130, but with the ligating catheter 2 withdrawn, leaving the ligating element 32 deployed at the neck of the left atrial appendage 130.

In Fig. 20, guide catheter 100 has had its expandable element 115 returned to its unexpanded condition.

Looking next at Fig. 21, the left atrial appendage 130 is shown with guide catheter 100 removed from the interior of the left atrial appendage, leaving ligating element 32 at the location where the left atrial appendage 130 meets the left atrium 140, thereby effectively ligating the left atrial appendage from atrium 140.

One Preferred Form Of Use

In one preferred form of use, not according to the present invention, guide catheter 100 is passed endoluminally across the atrial septum and into the left atrium. Guide catheter 100 (Fig. 22) has one or more magnets 105 at its tip. Magnets 105 are preferably so-called "rare earth" magnets composed of, for example, Neodymium-Iron-Boron, Cobalt-Samarium or other powerful fixed magnet elements. Just behind the magnets, preferably integral with and axi-symmetric to the body of the guide catheter, is inflatable balloon 115 (Fig. 23) which, when inflated, is spherical, conical, elliptical or of other configuration, and which preferably conforms roughly to the size and shape of the left atrial appendage 130. The entire guide catheter 100, inclusive of balloon 115 and magnets 105, is of a size consistent with passage through a commercially-available sheath (not shown), the likes of which may be readily passed across the atrial septum under fluoroscopic guidance using currently available tools and techniques.

In one preferred use of this system, the practitioner gains percutaneous access to the femoral vein using the Seldinger or other standard technique, and the aforementioned sheath (not shown) is introduced under fluoroscopic guidance across the atrial septum. The magnetic tip 105 of the guide catheter is then advanced out of the aforementioned sheath and into the left atrial appendage, in the manner previously discussed.

The second instrument used with this iteration (i.e., the ligating catheter 2, as shown in Fig. 24) is introduced into the pericardial space, between the heart and the pericardium. Pericardial access may be obtained, for example, by either a small incision below the zyphoid process of the sternum, or by percutaneous access using needles or dedicated systems designed for such purposes. Under fluoroscopic guidance, a wire is introduced into the pericardial space, between the heart and the pericardial sack. Similarly, pericardial access can be obtained by way of a mini-thoracotomy or by a "Chamberlain"-type incision over the 2nd costal cartilage. Percutaneous access using dedicated systems designed for such purposes is generally preferred as it can be done under local anesthesia. An incision over the 2nd costal cartilage, or a small incision below the zyphoid, is generally preferred to approaches that require violation of the left pleural space.

Once pericardial access is obtained, the second instrument (i.e., the ligating catheter 2, as shown in Fig. 25) is introduced to the surgical site. In a preferred procedure, the second instrument is preceded by a series of dilators and sheaths that are introduced over wires. The dilators are of a progressively increasing size culminating in the placement of a large thin-walled tube or cylinder 5, approximately 8mm in outside diameter (24 French) or smaller, positioned such that its distal end is in the region of the left atrial appendage. This thin-walled tube 5 then acts as a delivery cannula for advancing the ligating subassembly 30 to the surgical site. In one iteration, the distal end 10 of the thin-walled tube 5 is deflectable by an asymmetric element that can be placed under tension. Alternatively, the thin-walled tube may have a permanent angulation or curve at its tip.

Once the thin-walled tube 5 is in position, the intrapericardial tool (i.e., the ligating subassembly 30) is advanced down the thin-walled tube 5. In a preferred embodiment, the ligating catheter 2 comprises a central intrapericardial catheter or alignment element 90 at the end of which is one or more rare-earth magnets 95, as described previously. These magnets 95 are poled to attract the ligating catheter 2 to the guide catheter 100 (previously placed in the left atrial appendage) in an end-to-end orientation. The ligating catheter 2 may be flexible or, in another embodiment, is stiff with a malleable, deflectable tip.

Coaxial to this alignment element 90, and constructed in such a manner that it can be advanced or withdrawn relative to either the alignment element 90 or the thin-walled tube 5, is a tube 150 that ends in a funnel-like or trumpet-bell flare 160. The internal diameter of this flared tube 150 is significantly larger than the external diameter of the intrapericardial magnet-tipped alignment element 90 (over which the flared tube 150 slides) so as to allow vacuum to be conveyed from the back of the flared tube 150 to the distal flare 160. This flared end 160 acts as a suction cup to grasp the tip of the left atrial appendage 130 from outside the heart.

In a preferred procedure, not according to the present invention, the ligating catheter's alignment element 90 is advanced (Fig. 26) under fluoroscopic guidance until it engages, and couples with, the guide catheter 100 (Fig. 27), which was previously placed across the atrial septum and into the inside of the left atrial appendage. Once such alignment has been achieved, and magnetic coupling confirmed by fluoroscopy, the flared tube 150 is advanced (Fig. 28) until it comes into contact with the outside of the left atrial appendage. Suction is then applied to the back of the flared tube 150, such that the left atrial appendage is fixed to the tip of the flared tube by vacuum.

Over the outside of this flared tube 150, but inside the lumen of the 8mm diameter (24 French) thin-walled tube 5, is a Nitinol stent-like structure or ligation subassembly 30 that can be advanced down the thin-walled tube 5 toward the tissue by way of a stiff catheter or other structure (i.e., the advancement/retraction control element 20) attached to its back end. This Nitinol structure 30 is designed to expand (once released from the constraints of the thin-walled outer tube 5) into a bell shaped crown (Fig. 29), the tips of which attach (circumferentially) the loop of a snare (i.e., the ligating element 32). In a preferred embodiment, the ligating element or snare 32 is composed of polypropylene or PTFE suture. The snare loop 32 is secured to the tips of the crown 30 in a reversible, easy-to-release fashion.

Once the left atrial appendage is secured with suction, the Nitinol structure 30, and its attached snare 32, is advanced over the flared tube 150 toward the left atrial appendage. The flared tube 150 extends 2 or 3 centimeters beyond the end of the thin-walled outer tube 5. As such, the Nitinol structure 30 begins to expand into a bell-shape which facilitates its advancement over the flared suction catheter 150, and over the left atrial appendage.

Once the Nitinol structure 30 has been advanced to the point where it is near the base of the left atrial appendage, the balloon 115 on the guide catheter 100 inside the appendage is inflated, preferably with a contrast material. The Nitinol structure is advanced under fluoroscopic guidance so that the tips of its bell-shaped crown 30 (and the suture snare 32) are beyond the inter-atrial balloon (Fig. 30). The snare 32 is then tightened by pulling on a strand of the suture that runs down the lumen of the stiff catheter 20 which is used to advance the Nitinol structure 30 (Fig. 31). With the suture snared, the guide catheter's balloon is deflated and the trans-septal left atrial catheter 100 is removed. The suture snare 32 is then preferably tightened again to account for the space previously occupied by the inter-atrial catheter 100. The Nitinol structure 30 releases away from the suture snare 32 when the snare is tightened. The ligating catheter 2 is then removed and the suture is cut at the skin.

Additional Constructions

In one particular procedure, not according to the present invention, and looking now at Fig. 32, a wire 155 is passed through the left atrial appendage 130, through the wall of the left atrial appendage 130 and advanced through the pericardial space, whereby tip 165 of the left atrial appendage is perforated. Wire 155 can then be grasped by a catheter or snare in the pericardial space and pulled all the way through the pericardium and then out of the body, thereby creating a single wire track on which guide catheter 100, ligating catheter 2, and/or other devices can be passed along from either end of wire 155.

Additionally, if desired one or more of the magnets 95 and/or 105 may comprise an electromagnet. Such a construction permits the magnetic field to be selectively turned on and off, thus facilitating separation of the devices at the end of the procedure.

Furthermore, in the foregoing description, struts 45 are described as being preferably expanded by connecting them to one another with springs 50, whereby to render the struts self-expandable when they are advanced out of the distal end of cylinder 5. Alternatively, struts 45 may be expanded by other means, e.g., an expansion mechanism mounted to struts 45, or by making struts 45 out of a spring material (e.g., a superelastic material such as Nitinol), etc.

And in another arrangement not according to the present invention, the apparatus may be used to ligate the left atrial appendage as follows. Access to the pericardial space is acquired using standard techniques such as the Seldinger over-the-wire technique. For example, such device, which preferably comprises an elongated device such as a cylinder containing an expandable element, a ligature, and an alignment mechanism, is placed into the pericardium over a guidewire. For example, the elongated device can be a large catheter in which there is an expandable element, a ligature, and an alignment mechanism.

And in another arrangement not according to the present invention, a guide catheter is placed into the left atrium using standard techniques, such as transseptally, through the veins or retrograde across the mitral valve, etc. The guide catheter in the left atrium is then placed into the left atrial appendage under fluoroscopic guidance. At this point, the guide catheter is in the left atrial appendage and the ligating mechanism is disposed in connection with a deployment catheter in the pericardial space. The guide catheter in the left atrium and the deployment catheter in the pericardial space are then aligned with one another. This can be done using a variety of techniques. For example, one or both of the devices can be magnetized, thus allowing them to be aligned relative to one another using magnetic force. Alternatively, the guide catheter and deployment catheter can be "steered" into proximity using visual or ultrasonic guidance. Or the guide catheter in the left atrium can penetrate the left atrial appendage and be "snared" by the deployment catheter in the pericardium. At this point, the device in the pericardium is advanced into proximity with the left atrial appendage. A ligating apparatus is then deployed from the deployment catheter and advanced over the left atrial appendage. Preferably, the guide catheter inside the left atrium includes an expandable element such as a balloon. This expandable element is then expanded inside the left atrial appendage. In so doing, this expansion helps prevent the ligature from slipping or migrating off of the left atrial appendage as the ligature is tightened around the left atrial appendage. The ligature is then tightened around the left atrial appendage. The expandable element inside the left atrium is then contracted. The guide catheter inside the left atrial appendage is then backed out of the left atrial appendage. The procedure can be repeated as necessary. The guide catheter and deployment catheter are then removed from the body cavity.

Alternatively, the guide catheter inside the left atrial appendage may be removed after the ligature has been mostly placed, but before the final tightening of the ligature. This will allow the base of the left atrial appendage to be completely occluded after the guide catheter is withdrawn from the left atrial appendage.

The following text further illustrates a preferred manner not according to the present invention for ligating the left atrial appendage. A trans-septal left atrial guide catheter that has (integral to its construction) a rare-earth magnet, or other alignment means, and an inflatable balloon, is of great utility in effectively occluding the left atrial appendage with a snare or ligature. The left atrial appendage is typically roughly conical in shape, with a slight neck or narrowing in the plane of the orifice where it joins the left atrium proper. To effectively exclude the left atrial appendage from the outside with a ligature or snare, the snare must be tightened precisely in this plane. Ideally, with the ligature tightened, the resultant left atrial geometry should be essentially spherical, with only a slight dimple visible from the endocardial or luminal aspect at the site of the obliterated orifice. If the snare is tightened above the plane of the orifice (toward the left atrial appendage tip), incomplete exclusion of the left atrial appendage may result in a persistent diverticulum of left atrial appendage, which may provide a site of stasis and thrombus formation in the fibrillating atrium. Conversely, if the snare is tightened below the plane of the orifice, there is a risk of injury to the circumflex coronary artery, which runs in the atrio-ventricular grove.

Snaring the left atrial appendage precisely and accurately in the optimal plane presents several technical challenges. In some individuals, the geometry of the left atrium and left atrial appendage may be such that the neck or narrowing between them is poorly defined, especially from the epicardial or outer aspect. Furthermore, because the left atrial appendage wall is thin and flexible, and the wall tension low (left atrial pressure is generally low, e.g., <2.67 kPa (<20mm Hg)), the external geometry of the left atrial appendage-left atrial junction may be of little help in constraining the snare to the correct plane during tightening. This challenge is compounded by the fact that the anatomy is moving vigorously, even in the fibrillating atrium, due to translational motion from ventricular systole. A trans-septal left atrial guide catheter equipped with a magnetic tip and a large inflatable balloon such as described above enables snaring the left atrial appendage in the proper plane. More particularly, it is believed that identifying and capturing the tip of the left atrial appendage using just an intra-pericardial instrument under fluoroscopic or echocardiographic guidance may prove prohibitively challenging. At the same time, passing a catheter across the atrial septum into the left atrium, and subsequently positioning it in the apex of the left atrial appendage, is readily accomplished by those skilled in the art with catheters that are commercially available. Thus, positioning a guide catheter with a rare-earth magnet (or other alignment mechanism) at the tip thereof in the left atrial appendage is readily achievable and thereby allows fluoroscopic guidance as to the position of the left atrial appendage apex, as well as enabling precise capturing of the apex with an intra-pericardial tool.

A balloon near the tip of the trans-septal left atrial guide catheter greatly facilitates positioning and tightening of the snare or ligature in the proper plane of the orifice between the left atrial appendage and left atrium. Preferably, the balloon is designed to inflate to approximately the size of the left atrial appendage. As the balloon is inflated, it is confined to the left atrial appendage by the neck or narrowing at the orifice between left atrial appendage and left atrium. This may be readily confirmed by echocardiographic examination, or fluoroscopy, especially if the balloon is inflated with a contrast agent. Separate ports in the guide catheter allow the contrast agent to be injected into the left atrial appendage and/or the left atrium proper to provide further confirmation of correct position of the inflated balloon.

The inflated balloon accentuates external geometric features at the left atrial appendage-left atrial junction. When the spherical balloon is inflated, the flexible left atrial appendage is distended and its shape changed (e.g., to spherical) to facilitate ligation. The junction between the left atrial appendage and left atrium becomes better defined, like a waist of a snowman. This constrains the snare or ligature to the proper plane during tightening. The balloon, and consequently the left atrial appendage, is inflated to a pressure significantly higher than that of the left atrium proper. As such, there is a significant differential in wall tension between the left atrial appendage and the left atrium. As the balloon is spherical, an attempt at snaring above the plane will result in the snare slipping off of the tense spherical surface toward the low tension, flexible neck. Radio-opaque contrast agent in the balloon, the ability to selectively inject contrast in the left atrial appendage and/or left atrium proper, and a radio-opaque snare or ligature greatly facilitate performing these procedures under fluoroscopic guidance. Once the left atrial appendage-left atrial junction is snared, the balloon is deflated and removed and the snare tightened completely.

In general, it should be appreciated that, among other things, the described system comprises the alignment of two devices, one within and one outside of a lumen, cardiac chamber, etc. Thus, the present system could be used in the stomach to help with an endoscopic fundiplication.

The foregoing description is intended to illustrate preferred embodiments of the present invention. However, numerous changes may be made to the preferred embodiments without departing from the scope of the present invention, which is defined by the appended claims.

Claims

A system for ligating the left atrial appendage comprising:
a guide catheter (100) comprising:
a shaft having a distal end;

an alignment element (102) disposed on the distal end of the shaft; and

an expandable element (115) provided on the shaft, wherein the expandable element (115) is adapted to expand inside the left atrial appendage; and

a ligating catheter (2) for ligating the left atrial appendage, comprising:
a hollow shaft (5) having a distal end (10);

a ligating subassembly (30) comprising a plurality of expandable arms (45) arranged in an arcuate configuration and releasably supporting a ligating element (32) thereon, the ligating subassembly (30) being slidably received within the hollow shaft (5) and adapted to move between (i) a retracted position wherein the expandable arms (45) are received within the hollow shaft (5), and (ii) an extended position wherein the expandable arms (45) project from the distal end (10) of the hollow shaft (5), with the expandable arms (45) holding the ligating element (32) radially outboard of the shaft (5) when the ligating subassembly (30) is in its second position; and

a counterpart alignment element (90) mounted to the shaft (5),

wherein the alignment element (102) on the guide catheter (100) is adapted to couple from inside the left atrial appendage with the counterpart alignment element (90) on the ligating catheter (2) placed outside the left atrial appendage so as to facilitate alignment of the ligating catheter (2) with the guide catheter (100).
A system according to claim 1 wherein the alignment element (102) of the guide catheter (100) comprises a magnet (105).
A system according to claim 2 wherein the counterpart alignment element (90) of the ligating catheter (2) comprises a magnet (95).
A system according to any preceding claim wherein one or both of the alignment elements (102,90) comprise an electromagnet.
A system according to claim 1 wherein the alignment element (102) of the guide catheter (100) comprises a mechanical mechanism for coupling with a counterpart mechanical mechanism on the ligating catheter (2).
A system according to claim 5 wherein the alignment element (102) of the guide catheter (100) is chosen from the group consisting of a male mechanical mechanism and a female mechanical mechanism.
A system according to claim 1 wherein the expandable element (115) of the guide catheter (100) comprises a balloon.
A system according to claim 1 wherein the counterpart alignment element (90) of the ligating catheter (2) is slidably mounted to the shaft (5).
A system according to claim 8 wherein the counterpart alignment element (90) is slidably received within the hollow shaft (5) and is adapted to move between (i) a retracted position wherein the alignment element (90) is received within the hollow shaft (5), and (ii) an extended position wherein the alignment element (90) projects from the distal end (10) of the hollow shaft (5).
A system according to claim 1 wherein the ligating catheter (2) further comprises gripping apparatus for gripping tissue.
A system according to claim 10 wherein the gripping apparatus comprises a suction tube (150) mounted to the hollow shaft (5).
A system according to claim 11 wherein the suction tube (150) is slidably received by the hollow shaft (5).
A system according to claim 1 wherein the expandable arms (45) comprise arms connected by a spring (50).
A system according to claim 1 wherein the expandable arms (45) comprise arms connected by an expansion mechanism.
A system according to claim 1 wherein the expandable arms (45) comprise a spring material.