Remodeling of extracellular matrix patch used for carotid artery repair

Background: We evaluated the in vitro strength and in vivo arterial-wall response to an extracellular-matrix-based patch material in a sheep model of carotid artery repair.

Materials and methods: A six-ply sheet of acellular, porcine extracellular matrix (ECM) was subjected to in vitro material strength testing and implanted in 15 sheep for 30, 90, and 180 d. Bovine pericardium was used as a control in some animals. In vivo graft patency was assessed by angiography. Explanted grafts were evaluated by histopathology and burst-strength testing.

Results: Mean (SD) in vitro suture retention force of the ECM sheet was 14.5 (3.06) N; tensile strength was 29.7 (6.11) N; and probe burst strength was 185 (22.6) N. In vivo, mild stenosis was observed at 30 d for all patches; stenosis was absent at 90 d in the ECM-repaired arteries but not bovine pericardium controls. Pseudoaneurysm was not observed in any animal. Histopathology showed progressive graft degradation, collagen deposition, formation of neocapillaries and fibrocellular neointima, and endothelialization, but no calcification. Mean (SD) burst pressure for unrepaired arteries was 2608 (858) mmHg and 1473 (694) mmHg for ECM-repaired vessels. Mean change in diameter from unloaded state to burst pressure was 29% (9.7) for unrepaired vessels and 24% (13.4) for ECM-repaired vessels.

Conclusions: The six-ply ECM sheet can withstand the forces encountered after carotid artery repair. In sheep, it shows evidence of progressive, constructive remodeling as early as 30 d post-implantation with rapid deposition of endothelium. ECM shows promise as a patch material for CEA repair.