Percutaneous arterial to venous anastomosis clip application catheter system and methods

This application claims the benefit under 35 U.S.C. 119(e) of the filing date of Provisional U.S. Application Ser. No. 61/861,238, entitled Percutaneous Arterial to Venous Anastomosis Clip Application Catheter System and Methods, filed on Aug. 1, 2013, which application is expressly incorporated herein by reference, in its entirety.

In the body, various fluids are transported through conduits throughout the organism to perform various essential functions. Blood vessels, arteries, veins, and capillaries carry blood throughout the body, carrying nutrients and waste products to different organs and tissues for processing. Bile ducts carry bile from the liver to the duodenum. Ureters carry urine from the kidneys to the bladder. The intestines carry nutrients and waste products from the mouth to the anus.

In medical practice, there is often a need to connect conduits to one another or to a replacement conduit to treat disease or dysfunction of the existing conduits. The connection created between conduits is called an anastomosis.

In blood vessels, anastomoses are made between veins and arteries, arteries and arteries, or veins and veins. The purpose of these connections is to create either a high flow connection, or fistula, between an artery and a vein, or to carry blood around an obstruction in a replacement conduit, or bypass. The conduit for a bypass is a vein, artery, or prosthetic graft.

An arterio-venous fistula (AVF) is created by connecting an artery to a vein, and to create a leak-free blood flow path between them. This type of connection is used for hemodialysis, to increase exercise tolerance, to keep an artery or vein open, or to provide reliable access for chemotherapy. This is typically done by suturing the vein to the artery in an open surgical procedure. The vein and artery are either attached by an end-to-end anastomosis, end-to-side anastomosis, or a side-to-side anastomosis. The procedure is time consuming, tedious, clinician dependent (open to surgical error), and often results in strictures or clotting of the vein or artery.

It is well know that heat, whether it is Radio Frequency (RF), resistance or laser will attach and weld tissue or vessels upon direct pressure and contact over the targeted weld area. This is often done with jaw-type, compression heat delivery devices. It is also well known that radially expandable devices such as balloons, metal cages and baskets are often coupled with energy in the form of RF, or in the case of balloons, heated saline and used intraluminally to ablate tissue, stop bleeding or create a stricture.

Several catheter-based devices are disclosed herein that are advanced from one vessel into an adjacent vessel (i.e. vein into artery), mechanically couple two vessels together, and then sealing and cutting the anastomosis through the application of heat.

The present invention eliminates the open procedure described above, reduces operating time, and allows for a consistent and repeatable fistula creation.

More particularly, there is provided an intraluminal anastomotic device which comprises a proximal base having a distal tapered end surface and a distal tip connected to the proximal base and movable relative to the proximal base. The distal tip has a proximal tapered end surface. The distal tapered end surface and the proximal tapered end surface are adapted to contact opposing sides of a tissue portion to create an intraluminal anastomosis. Additionally, a clip housing is disposed on the proximal base.

A plurality of clip applicator guides, comprising clip storage bays, are disposed in spaced relation on the distal tapered end surface of the proximal base. The plurality of clip applicator guides are spaced radially about a circumference of the distal tapered end surface of the proximal base. The clip housing contains a plurality of clips. The device further comprises a clip deployment ring which is movable distally to push a clip through tissue captured between the proximal base and the distal tip.

The clip storage bays are provided for retaining the clips in a predetermined orientation as they are deployed.

In another aspect of the invention, there is disclosed a method of creating an anastomosis, which comprises steps of advancing a distal tip of a catheter device through a first blood vessel and into a second adjacent blood vessel, while simultaneously advancing a proximal base of the device into the first blood vessel, and contacting a wall of the first vessel with a distal blunt surface on the proximal base. A further step is to retract the distal tip so that a proximal blunt base of the distal tip contacts a wall of the second vessel, thereby capturing the two vessel walls between the blunt surfaces of the proximal base and the distal tip. A controlled pressure is applied between the two blunt surfaces to compress and stabilize the captured tissue and approximate the two vessel walls. A clip is then deployed through the captured tissue. The anastomosis is created by applying cutting energy to the captured tissue.

The deploying step includes a step of holding the clip in a clip storage bay to maintain a desired orientation of the clip when it is deployed, and also comprises advancing a clip deployment ring on which the clip is disposed to push the clip into the captured tissue.

The deploying step further includes deploying a plurality of clips into the captured tissue. The plurality of clips may be deployed in stages by first advancing a clip deployment mechanism a first distance into the first vessel and deploying at least one clip into the tissue comprising the first vessel, and then further advancing the clip deployment mechanism a second distance into the second vessel and deploying at least one clip into the tissue comprising the second vessel.

Deployment of the at least one clip into the tissue comprising the second vessel is performed by retracting the clip deployment mechanism. During retracting of the clip deployment mechanism, the method further comprises a step of applying continued pressure on the captured tissue in order to ensure that the vessels do not move apart during the anastomosis procedure.

The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawings.

FIG. 1 is an isometric view of one embodiment of the device of the present invention in an extended orientation;

FIG. 2 is a schematic side view of the device of FIG. 1 , after a first insertion to a procedural site;

FIG. 3 is a schematic side view, similar to FIG. 2 , of the distal end of the device shown in FIG. 2 ;

FIG. 4 is a view similar to FIG. 3 , wherein tissue is being captured and controlled while clips are deployed;

FIG. 5 is an isometric view of a clip constructed in accordance with the principles of the present invention;

FIG. 5 a is an isometric view of a modified clip having a barb;

FIG. 6 is a schematic view illustrating the clips capturing only the adventitia of the vessel;

FIG. 6 a is a view similar to FIG. 6 wherein the clips puncture through both the adventitia and the intima for greater clipping strength;

FIG. 6 b illustrates various curvatures of the inventive clips;

FIG. 7 is a schematic side view illustrating the device of the present invention wherein the clip housing is retracted from the procedural site, leaving the deployed clips behind;

FIG. 7 a is an exploded isometric view illustrating the various components of the proximal shaft 3 of the device 1 ;

FIG. 8 is a schematic side view wherein the device is being removed from the procedural site, illustrating that the heater profile matches that of the tip so that all material captured under the tip is cut and removed;

FIG. 9 is a schematic side view of a modified embodiment of the present invention, wherein an introducer sheath is utilized in conjunction with the present invention;

FIG. 10 is an isometric exploded view of the proximal portion of the device of FIG. 9 ; and

FIG. 11 is an isometric exploded view of the device of FIG. 9 .

Referring now more particularly to the drawings, there is shown in FIGS. 1-9 one embodiment of a catheter or intraluminal anastomotic device 1 constructed in accordance with the principles of the present invention. The catheter device 1 tracks over a guidewire which has been placed from one vessel into an adjacent vessel, or any other two anatomical structures.

Referring now to FIG. 1 , a distal tip 5 of the catheter device 1 has a smooth taper from a 0.014 inch guidewire lumen up to the full diameter, which allows the catheter to advance easily through the vessel walls. Proximal to the distal tip 5 , the catheter has a significant reduction in diameter, and then a blunt, oval-shaped tapered proximal surface 6 , which is formed on a proximal base 3 . The blunt oval-shaped surface 6 is made up of two separate components, namely, a proximal heater 12 and a clip housing 45 . The catheter 1 has a guidewire lumen 18 , which allows it to track over a guidewire 19 previously placed between a first lumen and a second lumen, as shown in FIG. 2 . Clip applicator guides, comprising clip storage bays 48 , are spaced radially around the circumference of the heater.

As the catheter is tracked over the guidewire 19 , the tapered distal tip 5 easily passes from a first vessel 20 into a second vessel 22 , so that the device is deployed across the vessels 20 , 22 ( FIG. 2 ). After the distal tip passes through the artery, the puncture site recoils down and won't allow the blunt proximal base to pass through the vein into the artery. As the catheter is further advanced, blunt tapered proximal surface 6 comes into contact with the wall of the first vessel 20 and encounters resistance, and cannot perforate through the wall into the second vessel 22 ( FIG. 3 ). The distal tip 5 , which has a matching blunt surface 14 on its proximal end 4 , is then retracted, capturing and approximating the walls of the two vessels 20 , 22 between the two blunt surfaces. A known, controlled pressure (approximately 100 mN/mm 2 -750 mN/mm 2 ) is applied between the two surfaces to compress and stabilize any tissue that may be between the vessels. The pressure can be controlled either internally in the catheter or by the handle attached to the proximal end of the catheter. There may also be a position monitoring feedback mechanism or sensor which can provide feedback of the amount of tissue captured between the blunt surfaces 6 , 14 of the device. The angle between the tip and proximal blunt surfaces creates an anastomosis substantially larger than the diameter of the device.

Referring now to FIG. 4 , with the artery and vein walls captured between the two surfaces a clip deployment ring 47 is advanced forward, which pushes a sharp pointed clip through the captured tissue 23 . This may be identified as the arterial clip deploy step. Clips 46 can be made of a superelastic material and heat set into an a-like shape. Although Nitinol is currently a preferred material for fabricating the clips 46 , other materials may include stainless steel, cobalt chrome, or polymer materials that are known to those skilled in the art. When loaded into the clip housing 45 , the clips 46 are held in a straight configuration, but as they are advanced forward, through the wall of the vessel, they begin to return to their a-like shape, clipping the tissue together. In order for the clips to remain in their desired orientation, the cross-section of the clip may be oval, as shown at 41 in FIG. 5 , or rectangular (not shown). The curvature of the clip ( 43 a and 43 b — FIG. 6 b ) may be adjusted to determine how much tissue is captured inside the clip ( FIG. 6 ). For instance, it may be desirable that the clip does not puncture through the intima 49 of the second vessel 22 . Therefore, the clip does not disturb the flow in the artery and minimizes the neointimal growth ( FIG. 6 ). In this case, the curvature 43 b of the clip has such a small radius that it does not penetrate through the adventitia of the adjacent artery before it starts curving back on itself. Contrarily, if strong clipping forces are desired, it is beneficial to pierce deeper into the lumen and capture a larger section of vessel wall, including the adventitia 50 , before curving back on itself ( FIG. 6 a ), in which case the curvature 43 a of the clip has a large radius primary curve. In one embodiment, the device is shown with four clips, but the number of clips may be modified depending upon the size anastomosis to be created and desired coupling strength.

The distal end of the clips 46 are sharpened with a lancet grind profile 40 in order for them to pierce easily through the tissue as they are advanced ( FIG. 5 ). The oval profile 41 of the shape memory clip 46 is such that their orientation is maintained in a clip storage bay 48 and as they are being deployed. It may also be desirable for the clips to have retention barbs 42 to prevent them from migrating once deployed, or as the clip storage bay is being retracted to release them in the first vessel 20 , as shown in FIG. 5 a.

After the clips have been advanced into the adjacent second vessel 22 , the clips are deployed in the vein by retracting the clip housing 45 ( FIG. 7 ). During retraction of the clip housing 45 , the proximal heater 12 on the proximal base 3 maintains pressure on the tissue that is captured between it and the tip. This pressure ensures that the vein cannot move away from the artery, and the clips capture and stabilize the vein to the artery.

Once the clips have been deployed, the anastomosis is created and sized by heating the proximal heater 12 . As the proximal heater is heated, the tissue captured between the distal tip 5 and the proximal heater 12 is desiccated and burned away. The tissue immediately surrounding the device is heated to a temperature that is sufficient to denature the proteins within the tissue and create a weld band surrounding the device. The weld band seals the anastomosis and increases its strength. The welding process applicable to this inventive system and method is similar to what has been disclosed in prior commonly assigned U.S. patent application Ser. Nos. 13/161,182, 13/161,356, and 13/763,501, which are herein each expressly incorporated by reference, in their entirety.

Referring now particularly to FIG. 8 , the outer profile of a distal heating element 9 aligns with the outer profile of the proximal heater 12 to allow the device to be easily removed once heat has been applied. All of the tissue that has been desiccated remains captured between the distal heating element 9 and the proximal heater 12 to prevent any embolus from being introduced into the vascular system.

FIGS. 9-11 illustrate an alternative embodiment of the invention, wherein an introducer sheath is utilized. In this embodiment, like elements are identified by like reference numerals. Introducer sheaths are typically used in surgical procedures where vascular access is needed for multiple different devices. They provide a conduit for devices to be introduced into the vasculature while providing hemostatis. The introducer shown herein also has the capability to dispense clips 46 to secure two anatomical structures together. This introducer sheath works in combination with the intraluminal anastomotic device 1 and procedures previously disclosed in FIGS. 1-8 . Once the intraluminal anastomotic device 1 has crossed into the artery and the tip is retracted, the introducer sheath is advanced over the intraluminal anastomotic device shaft until it comes into contact with the vein wall. The tip of the sheath is cut at an angle that matches the intraluminal anastomotic device and mates evenly with the venous wall. With slight forward pressure on the sheath to seat it on the venous wall, the clips are deployed using the same method previously disclosed. After the clips have been deployed, the intraluminal anastomotic device 1 is activated, creating the anastomosis. In the inset of FIG. 9 , which is an enlarged view of the distal end of the device, an introducer lumen 51 is disposed within the introducer 53 . A hemostasis hub 52 is fluidly connected to a stop cock 54 .

Accordingly, although an exemplary embodiment and method according to the invention have been shown and described, it is to be understood that all the terms used herein are descriptive rather than limiting, and that many changes, modifications, and substitutions may be made by one having ordinary skill in the art without departing from the spirit and scope of the invention.