Experimental evaluation of bleeding complications, thrombogenicity and neointimal characteristics of prosthetic patch materials used for carotid angioplasty

Experiments were designed to compare perioperative blood loss, early thrombogenicity and morphologic and functional characteristics of the neointima of three types of prosthetic materials used for carotid artery patch angioplasty. Bilateral carotid patch angioplasties were performed in 20 dogs, using 20 gelatin-impregnated fluoropassivated Dacron (GIF), 10 untreated knitted Dacron and 10 expanded polytetrafluoroethylene (PTFE) patches (5 cm²). Intraoperative blood loss, platelet deposition at 24 h and neointimal morphology at 6 weeks after the operation were assessed. Bioassay of the neointima was performed at 6 weeks in 16 patches. Mean (s.e.m.) blood loss was significantly less in GIF patches (14.7 (2.7) ml) compared with either PTFE (75.6 (24) ml) or untreated Dacron (64. 3 (9.5)) (P < 0.005). Mean (s.e.m.) platelet deposition in GIF patches (1380 (328) platelets/cm²) was approximately 50% less at 24 h than in untreated Dacron (2562 (1035) platelets/cm²) or PTFE (2140 (998) platelets/cm²) patches (P < 0.05). Neointimal coverage was greater in PTFE (94 (1.3%)) compared with GIF (79 (2.7%)) or untreated Dacron (86(2.4%)) patches (P < 0.05). The thickness of the neointimal layer of PTFE (0.5 (0.01) mm) patches was greater than other patch types; GIF (0.2 (0.01) mm) or untreated Dacron (0.3 (0.01) mm) (P < 0.05). Under bioassay conditions, acetylcholine caused release of vasoactive relaxing factor(s) from all patches. However, relaxations from baseline were less with GIF patches (−37.9 (11.7)% versus −54.5 (9.6) for untreated Dacron; −50.2 (15.2)% for PTFE) (P = n.s.). Endothelin-1 release occurred from all patches and was increased with the extent of neointimal coverage. These data demonstrate that GIF patches caused the least perioperative bleeding, were the least thrombogenic at 24 h and developed the thinnest neointima at 6 weeks. All patch materials developed a functioning neointima.