The Hemodynamics of Vein Grafts: Measurement and Meaning

Christopher L. Skelly, MD, Shari L. Meyerson, MD, Michael A. Curi, MD, Francis Loth, PhD, and Lewis B. Schwartz, MD, Chicago, Illinois
INTRODUCTION

The first successful experimental venous bypass grafts were created by Nobelist Alexis Carrel in 1906 in the Hull Physiologic Laboratory (now Culver Hall) at the University of Chicago.1 Over the ensuing century, infrainguinal autologous bypass has become increasingly applied, and approximately 100,000 grafts are now created annually in the United States. The safety and efficacy of the procedure have improved markedly in recent years. In large series, the mortality from infrainguinal by- pass approaches 2%, with major morbidity including myocardial infarction, cerebrovascular accident, and renal failure estimated at about 7%.2 The risk of immediate graft failure and limb loss also remains at about 7%. Thus, the vast majority of patients enjoy a favorable immediate operative result and revascularization. However, the lifespan of the graft is highly variable and, despite the initial technical success, grafts fail in subsequent years at an alarming rate. For all grafts in all patients, the reported 5 year primary patency, secondary patency, and limb salvage rates are about 60, 75, and 85%, respectively.2 These patency rates continue to slowly decline over the next 5 years to 40, 45, and 50%. This incessant attrition of functioning vein grafts remains the most important and frustrating limitation of the procedure.

Considerable attention has been devoted to improving the long-term results of peripheral vein grafting, with special emphasis on proper patient selection and refinement of surgical technique. Although certain clinical factors, such as renal fail- ure3,4 and diabetes,4-6 have implications for perioperative morbidity and long-term survival, none have predictive value for graft patency. The only remotely reliable predictors of graft patency are de- rived from the anatomic and hemodynamic aspects of the reconstruction itself, such as the quality and origin of the conduit and its outflow bed. The purpose of this review is to discuss the available techniques for the characterization of the hemodynamic environment of infrainguinal autologous bypass grafts, and the potential dependence of graft pa- tency on its hemodynamic environment.