Intraoperative flow predicts the development of stenosis in infrainguinal vein grafts

Objective: There are data to suggest that the development of myointimial hyperplasia 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 measurement with transit time flowmeter was performed in 257 infrainguinal vein grafts carried out in 241 patients. The patients were enrolled in an intensive duplex scanning-based surveillance program. The relationship between 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 found 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 mL/min for occluded grafts. The patients were divided into four groups according to quartiles of the sample distribution of graft flow measurements. The respective 2-year primary and assisted primary patency rates in the lowest 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 observed for maximal flow capacity measurements. Female sex (P=.009) and low graft flow in maximal flow capacity measurements (P=.003) were independent predictors of stenosis development in the multiple regression model. Conclusion: Intraoperative graft volume flow is a predictor of bypass occlusion after infrainguinal bypass. In addition, this study verifies an association between the development of clinically evident graft stenoses and low graft flow.