Intravascular arterial to venous anastomosis and tissue welding catheter
A catheter-based device tracks over a guidewire which has been placed from a first blood vessel into a second blood vessel. The distal tip of the catheter is advanced into the second vessel while a proximal member remains in the first vessel. Matching blunt tapered surfaces on each of the distal tip and the proximal member are clamped together, with adjacent walls of each vessel between them, after which a known, controlled pressure is applied between the two surfaces. Heat energy is then applied to the blunt surfaces for approximately 1-30 seconds to weld the walls of the two vessels together. After coaptation of the vessel walls, the heat is increased to then cut through the vessel walls to create a fistula of the desired size.
1. A method of creating an AV fistula between adjacent first and second vessels, comprising:
inserting a guidewire from the first vessel into the second vessel;
inserting a catheter comprising a proximal elongate member and a distal member over the guidewire, so that a tapered distal tip of the distal member comes into contact with a selected anastomosis site;
advancing the distal member into the second vessel, until a blunt tapered distal face of the elongate member contacts a tissue wall of the first vessel, so that the elongate member remains in the first vessel, thereby enlarging an aperture between the two vessels;
moving the distal member and the elongate member together to clamp tissue surrounding the aperture between the blunt tapered distal face of the elongate member and a corresponding blunt tapered proximal face on the distal member;
applying energy to a heating member on one of the distal member and the elongate member to cut and form the aperture, and to weld the edges thereof in order to create a desired fistula between the two vessels; and
retaining cut tissue using a plurality of physically separate protruding elements extending from at least one of the blunt tapered faces and surrounding the heating member.
2. The method as recited in claim 1 , and further comprising maintaining a temperature of 150-300° C. at the location where the aperture is being cut, during the applying energy step.
3. The method as recited in claim 2 , wherein the applying energy step is sustained for about 1-30 seconds to weld the walls of the two vessels together.
4. The method as recited in claim 1 , wherein the moving and clamping step further comprises applying a known, controlled pressure between the blunt tapered distal face on the elongate member and a corresponding blunt tapered proximal face on the distal member, wherein the known, controlled pressure is within a range of approximately 100 mN/mm 2 to 400 mN/mm 2 .
5. The method as recited in claim 1 , and further comprising a step of rotating the distal member during the advancing step, for a purpose of reducing frictional resistance to the distal member.
6. The method as recited in claim 1 , wherein the plurality of physically separate protruding members are disposed circumferentially around a periphery of the heating member.
7. The method as recited in claim 6 , and further comprising a step of promoting heat transfer through a coapted tissue interface from the heating member to a second passive heating member disposed on the other of the distal member and the elongate member.
8. The method as recited in claim 6 , wherein the heating member is disposed on the blunt tapered distal face of the elongate member and the second passive heating member is disposed on the blunt tapered proximal face of the distal member.
9. The method as recited in claim 1 , and further comprising a cavity disposed within the heating member, wherein the step of retaining cut tissue includes receiving the cut tissue within the cavity.