Comparison of suture technique on patency of polytetrafluoroethylene-microarterial anastomoses

Modified anastomotic technique for 1 millimeter internal diameter polytetrafluoroethylene arterial grafts in the rat

Reported patency rates after standard end-to-end anastomoses for microvascular prosthetic grafts have been inconsistent and usually disappointing. A modified anastomotic technique is described in which the prosthetic graft is invaginated inside the arterial lumen. In this study of 6 cm lengths of 1 mm internal diameter polytetrafluoroethylene femoro-femoral bypass grafts in the rat, 6 (40%) of 15 grafts with standard anastomoses were patent at 6 months compared to 28 (90%) of 31 grafts using the modified anastomotic technique (P < 0.001). With invagination of the prosthetic graft inside the arterial lumen, reliable high patency rates can be achieved with microvascular prostheses long enough for potential clinical applications.

Achieving better patency rates and neoendothelialization in 1-millimeter polytetrafluoroethylene grafts by varying fibril length and wall thickness

This study evaluates the effects of different fibril lengths and wall thicknesses on patency and neoendothelialization in 1 mm inner diameter polytetrafluoroethylene (PTFE; Gore-Tex) grafts and highlights the importance of longer fibril lengths and matching wall thicknesses. Fibril lengths tested were 30, 60, and 90 microns. The grafts had a wall thickness ranging from 0.18 to 0.34 mm. Ninety-six grafts were implanted in the infrarenal aorta of Wistar rats. Grafts were harvested at various intervals and examined macroscopically, by light microscopy, and by scanning electron microscopy. Both the highest patency rates and the best grades of neoendothelialization were observed in the 90 microns fibril length grafts, while the lowest of both were seen in the 30 microns fibril length grafts. From this study we conclude that 90 microns fibril length PTFE can be considered a valid micrograft for bridging arterial defects in microvascular reconstructive procedures.

Polytetrafluoroethylene interposition grafts in vertebral to carotid artery transposition. A long-term follow-up study

Eight patients undergoing an end-to-side vertebral artery (VA) to common carotid artery transposition between August, 1979, and July, 1982, had a polytetrafluoroethylene (PTFE) interposition graft placed when a direct anastomosis was believed not to be satisfactory. Five of these patients are living; clinical and radiographic follow-up studies over periods ranging between 54 and 82 months show that their transpositions are patent. Two patients died perioperatively, one from an acute anterior myocardial infarction and the other from acute VA occlusion with a propagating thrombus. A third patient died of myocardial infarction 20 months after graft placement; the anastomosis had been found patent at 12 months. This report gives the clinical and radiographic follow-up results in a previously reported group of patients with PTFE interposition grafts. Some of these patients have been followed for over 6 years after surgery: the average radiographic follow-up period in the five survivors is 60 months, and all grafts are patent without evidence of progressive stenosis. Expanded PTFE appears to be an acceptable material for short interposition grafts in operations involving the VA; however, direct artery-to-artery anastomosis is preferred. The results of longer PTFE grafts in reconstructive cerebrovascular surgery have not been adequately studied.

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.

Microvascular polytetrafluoroethylene (Gore-Tex) grafts in the infrarenal rat aorta

To evaluate the use of microvascular prosthetic grafts, the infrarenal aorta in 33 male Sprague-Dawley rats was replaced by an interposition graft of PTFE (polytetrafluoroethylene, Gore-Tex). Three groups of experimental animals were studied: Group A consisted of rats with 7-mm-long grafts, group B consisted of rats with 20-mm-long grafts, and group C consisted of rats with 20-mm-long grafts and ligatures of one patent after varying observation periods (6-92 days, median value 28 days, mean value 49 days). In group B all grafts but one (13/14) were patent (0-201 days, median value 198 days, mean value 118 days). In group C two grafts occluded immediately postoperatively, whereas the remaining six were patent (0-24 days, median and mean values 9 days). Twelve of 13 grafts observed for 3 months or more remained patent. There were no signs of infection. Angiography did not reveal any stenosis in the anastomoses of patent grafts. Light microscopy demonstrated a good adaptation between the grafts and the aorta in all animals. In the short grafts observed for 3 months and in the long grafts observed for 6 months, the luminal surfaces were completely covered by endothelial-like cells. In the occluded graft in group B, a stenosis was demonstrated in one of the anastomoses. This was not found in any other specimen. The results of this study document the possibility of using PTFE grafts of 1 mm diameter in experimental microvascular position.

Microvascular silicon replamineform grafts of 2- and 5-cm lengths: experimental studies

Replamineform silicone microvascular grafts 1 mm in diameter were cut to clinically useful lengths (2 and 5 cm) and used to reconstruct segments of the femoral artery in the rabbit. Despite initial patency and flow rates comparable to flow seen in vein graft repairs and primary repair, no long-term patency was observed. The theoretical biomechanical advantages of this kind of graft material have not solved the problem of long microvascular grafting.

Rat epigastric pedicle model: a clinically relevant evaluation of 1-mm PTFE grafts

Twenty-eight Sprague-Dawley rats had 1.0-mm polytetrafluoroethylene (PTFE) interposition grafts placed in their femoral artery that supplied a 3.0 X 3.0 cm epigastric pedicle flap. The model is the first to evaluate 1.0-mm PTFE under rigorous, clinically simulating conditions. Anastomoses employed a new, continuous telescoping suture technique. Grafts were selected for histological and electron microscopic evaluation, which confirmed the development of a cellular neointimal lining. Viability of the flap model had a 90% correlation with graft patency. Overall graft patency was 50%. Patency was documented in some specimens harvested at 200 days. The flap model is a good indicator of graft patency. PTFE grafts of 1.0-mm internal diameter are not yet equivalent to autologous veins. Future refinements, particularly aseptic technique, are expected to result in even higher patency rates.