Systems and methods for creating arteriovenous (AV) fistulas

1. A method of creating an AV fistula between adjacent first and second blood vessels, comprising:

puncturing the first blood vessel using a first needle;

inserting the first needle into the first blood vessel;

inserting a first guidewire through a lumen in the first needle;

withdrawing the first needle from the first blood vessel, leaving the first guidewire within the first blood vessel;

advancing a vessel access catheter into the first blood vessel over the first guidewire, and advancing the vessel access catheter to a desired procedural site;

extending a second needle from the vessel access catheter

using the second needle to cut a hole through the adjacent walls of the first and second blood vessels;

inserting a welding catheter into the first vessel, and through the hole into the second vessel, so that a distal end of the welding catheter is disposed within the second vessel;

expanding a first portion of wall defining the welding catheter radially outwardly;

pulling the expanded first wall portion proximally to engage the wall of the second blood vessel and to pull it toward the wall of the first blood vessel;

expanding a second portion of wall proximal to the expanded first wall portion and disposed in the first blood vessel radially outwardly, capturing the walls of each of the second and first blood vessels between the expanded first and second wall portions; and

energizing cutting elements on said expanded first and second wall portions to create a tissue welded elongate aperture between the first and second blood vessels.

2. The method as recited in claim 1 , and further comprising a step of collapsing said expanded first and second wall portions and withdrawing the welding catheter from the blood vessels.

3. The method as recited in claim 1 , wherein the energizing step comprises energizing electrodes with RF energy.

4. The method as recited in claim 1 , wherein the hole cutting step is performed by inserting the second needle into said first blood vessel, extending an obturator through a lumen in said second needle until a tip thereof contacts the wall of the first blood vessel, and energizing a cutting tip of said obturator to cut the hole.

5. The method as recited in claim 1 , wherein an outer sheath is disposed over an elongate tube comprising said welding catheter, the method further comprising a step of withdrawing the outer sheath proximally to expose the first wall portion prior to the first expanding step.

6. The method as recited in claim 5 , and further comprising a step of further withdrawing the outer sheath proximally to expose the second wall portion prior to the second expanding step.

7. The method as recited in claim 1 , wherein the first and second blood vessels comprise a vein and an artery.

8. The method as recited in claim 7 , wherein the vein and the artery are disposed in a patient's hand.

9. The method as recited in claim 1 , and further comprising a step of inserting a second guidewire through the lumen of the second needle after the puncturing step.

10. The method as recited in claim 9 , and further comprising a step of withdrawing the second needle.

11. The method as recited in claim 1 , wherein the first wall portion comprises a plurality of circumferentially spaced slots disposed thereon, and the first wall portion expanding step comprises actuating the first wall portion to a collapsed orientation, wherein the plurality of circumferentially spaced slots and surrounding wall material are expanded radially outwardly.

12. The method as recited in claim 11 , wherein the second wall portion comprises a second plurality of circumferentially spaced slots disposed thereon, and the second wall portion expanding step comprises actuating the second wall portion to a collapsed orientation, wherein the second plurality of circumferentially spaced slots and surrounding wall material are expanded radially outwardly.