Nd:YAG laser-welded canine arteriovenous anastomoses.

This preliminary report describes formation of femoral arterio-venous fistulas (n = 10) in six dogs using a 1.32-microns wavelength Nd:YAG laser welding technique. Stay sutures (6-0 polypropylene) were placed at 5-7 mm intervals along the anastomoses for vessel apposition. Delivery of laser energy through a 400-microns diameter fiber optic was controlled by a new computer-based software system. At 3 mm distance above the anastomosis, energy fluences of 110-260 J/mm2/cm length of anastomosis were used for laser welding. One or two additional hemostatic sutures were required in seven of the ten anastomoses. Flow was maintained for 1-2 hours prior to tissue harvesting. No thrombosis or delayed anastomotic failures were observed after initial welding and repair. Histologic examination revealed good apposition and adherence between wall layers and a fibrinous coagulum at the intimal junctions. Mild thermal injury of the wall was present at some anastomoses. This early investigation suggests that a 1.32 microns Nd:YAG laser welding technique can successfully create large vessel arteriovenous fistulas in the canine.