Graft thrombosis in small diameter vascular prosthesis: A laboratory model

Abstract

There are strong demands for innovative anti-thrombogenic materials, such as carbon, because of their necessity in fabricating artificial organs and progressive surgical vascular prostheses. Serial platelet deposition, surface topography, and patency were evaluated in control standard (N 45) and carbon-lined (N 45), small diameter (4 mm inner diameter) polytetrafluoroethylene grafts implanted in the abdominal aortic replacement in rabbits. A pilot study of 80 animals—40 carbon-lined (CL) and 40 standard (ST) grafts were used to develop microsurgical techniques. The 2-hour graft patency (Doppler and angiographic studies) showed better patency rate in the CL group (93% vs 80%). In 10 animals (5 ST and 5 CL grafts) the platelet deposition on each prostheses was quantitated by means of Indium 111 labeled platelets in a dual, isotope-platelet imaging technique. Platelet deposition on ST grafts 2 hours after insertion was significantly higher than on the CL grafts (6.60 ± 1.98 × 10³ platelets/mm² vs 0.82 ± 0.25 × 10³ platelets/mm²; p < 0.05). Light microscopy evaluation of explanted ST midgrafts sections, including both anastomoses, indicated platelet-fibrin deposition (PFD) in nearly all prostheses, whereas only 13% of the CL grafts exhibited PFD (chi-square: 61.117; p < 0.001). Gammacamera imaging allowed scintiphotos of the grafts and cinetic acquisition. We conclude that carbon-lining decreases platelet accumulation and improves patency in small-diameter PTFE grafts in the acute phase.