Microvascular synthetic grafts

Long-term histological changes in 1 millimeter polytetrafluoroethylene (Gore-Tex) prosthetic arterial grafts

Vein grafts are used extensively to repair blood vessels. However, when suitable vein segments are unavailable, alternative graft materials must be used. This study tested the suitability of 1 mm diameter polytetrafluoroethylene (PTFE) grafts for small-calibre arterial replacements. Grafts of 4 mm length were inserted microsurgically into the iliac arteries of 26 rats. The grafts were removed between 3 and 22 months postoperatively and examined with light microscopy and scanning and transmission electron microscopy (SEM:TEM). Anastomotic intimal hyperplasia was minimal, consisting of a few smooth muscle cells extending 100-200 microns onto the graft. The rest of the PTFE was covered with endothelium. In a few isolated areas, there was a subendothelial layer of smooth muscle, 2-10 cells thick. The short segments used in this study were highly successful, with an overall long-term patency rate of 80%. These grafts showed no evidence of excessive neo-intimal hyperplasia.

Evaluation of patency of synthetic and autogenous venous and arterial micrografts in rats

Long-term patency rates of synthetic and autogenous venous and arterial microvascular grafts in rats were compared. The grafts were interposed between the carotid arteries. The geometry of the anastomoses was designed in a manner intended to be comparable to the situation commonly encountered in cerebral revascularization procedures in man. Patency rates were 37.5% for synthetic grafts, 90% for venous grafts, and 60% for arterial grafts. Venous grafts are the best currently available microvascular prostheses.

Comparison of suture technique on patency of polytetrafluoroethylene-microarterial anastomoses

Polytetrafluoroethylene (PTFE) grafts, 1 mm in internal diameter, were interpositioned in the infrarenal aortas of 20 adult Sprague-Dawley rats with either continuous or interrupted sutures. The interrupted-suture (I-S) technique was used in ten rats, the continuous-suture (C-S) technique in the other ten. After followup of 90 days, the overall patency rate for the 20 rats was 95% (19/20); all grafts in the C-S group were patent; one graft in the I-S group had occluded on the day of operation. Since excellent patency rates were obtainable with these minute PTFE grafts placed in the rat aorta by either technique, the speed with which the C-S technique can be accomplished appears to make it preferable.