Intraoperative flow predicts the development of stenosis in infrainguinal vein grafts

Objective: There are data to suggest that the development of myointimial hy perplasia is affected by long-term alterations in blood flow. However, the clinical relevance of these findings has not been demonstrated. Methods: In this retrospective clinical study, intraoperative volume flow m easurement with transit time flowmeter was performed in 257 infrainguinal v ein grafts carried out in 241 patients. The patients were enrolled in an in tensive duplex scanning-based surveillance program. The relationship betwee n the intraoperative graft flow and subsequent occlusion or development of stenosis was evaluated and controlled for other pertinent risk factors. Results: The median follow-up time was 13.6 months. A graft stenosis was fo und in 58 grafts. The mean graft flow for event-free grafts was 98 mL/min, which was significantly higher compared with 78 mL/min for stenosed or 69 m L/min for occluded grafts. The patients were divided into four groups accor ding to quartiles of the sample distribution of graft flow measurements. Th e respective 2-year primary and assisted primary patency rates in the lowes t to the highest graft flow groups were 39%, 49%, 47%, and 72% (P=.003) and 55%, 67%, 71%, and 84% (P=.01). Analogous significant differences were obs erved for maximal flow capacity measurements. Female sex (P=.009) and low g raft flow in maximal flow capacity measurements (P=.003) were independent p redictors of stenosis development in the multiple regression model. Conclusion: Intraoperative graft volume flow is a predictor of bypass occlu sion after infrainguinal bypass. In addition, this study verifies an associ ation between the development of clinically evident graft stenoses and low graft flow.