Invited commentary

Abstract

Ever since the first subcutaneous veins were used as arterial substitutes in 1949, surgeons have been searching for new and better ways to procure venous conduits. Technical and biochemical methods have included “no touch” harvesting, gentle inflation with heparinized saline or lactate, infusion with smooth muscle cell dilators or cellular preservatives, endoscopic excision, and/or genetic modification through vector-based gene transfer. To date, no method had conclusively been found to be superior to the combination of an olive-tipped catheter, room temperature heparinized saline, and a good surgeon. Even with superlative technique, however, vein graft narrowing still occurs at an alarming rate, as 30% to 50% of all veins will respond to arterialization by pathologic thickening resulting in hemodynamically significant stenosis. Certainly, a major impetus for the development of vein graft neointimal hyperplasia is the abrupt increase in diameter and wall tension that accompanies exposure of thin, systemic veins to the intra-arterial environment. In their in vivo animal study of vein grafting presented herein, Salinas et al sought to limit vein graft dilatation by pre-emptively cross-linking venous collagen through the process of photochemical tissue passivation (PTP). Treated vein grafts were less dilated by exposure to intra-arterial pressure at the time of grafting and, after 4 weeks, had thickened significantly less than their untreated counterparts. Although the actual flow lumens of treated and untreated grafts appeared similar, PTP produced a thinner, more pliable graft, with profoundly attenuated cellular activation and proliferation. It remains to be seen whether PTP would be similarly effective in more muscular saphenous veins and whether limitation of their “natural” expansion might lead to increased rates of thrombosis and failure. Nonetheless, the authors provide another convincing experimental example of how vein grafts pathologically respond to arterialization and how modulation of that response might prove therapeutically useful. Prevention of vein graft intimal hyperplasia with photochemical tissue passivationJournal of Vascular SurgeryVol. 65Issue 1PreviewSaphenous vein is the conduit of choice for bypass grafting. Saphenous vein grafts have poor long-term patency rates because of intimal hyperplasia (IH) and subsequent accelerated atherosclerosis. One of the primary triggers of IH is endothelial injury resulting from excessive dilation of the vein after exposure to arterial pressures. Photochemical tissue passivation (PTP) is a technology that cross-links adventitial collagen by a light-activated process, which limits dilation by improving vessel compliance. Full-Text PDF Open Archive