Vascular Graft Failure Of Leg Arterial Bypasses - A Review

A major problem facing the vascular surgeon is graft failure. Patients are often more symptomatic after graft failure than they were before the bypass procedure [1]. Vein graft failure can be divided into three phases, depending on the timing of failure: early (<30 days), intermediate (30 days?2 years) and late (>2 years) [1, 2]. Acute graft failures (within 48 hrs.) are usually secondary to technical errors such as poor anastomosis, poor inflow or outflow or a retained unlysed valve cusps [1, 2]. Graft failure occurring between 2 days and 12 weeks after surgery is usually secondary to increased graft thromboreactivity [1, 3, 4]. All grafts or reconstructions involve thromboreactivity but it varies in intensity and duration and is governed by both host factors (coagulability and blood flow), and by graft factors (surface thrombogenicity and compliance) [3]. The thrombotic threshold velocity is required to maintain graft patency and thrombosis and closure of the graft occur for velocities below a given level for any graft material [3]. The cause of intermediate vein graft failure is intimal hyperplasia [1, 5]. Anastomotic intimal hyperplasia is commonly greater at the downstream or at the outflow anastomosis [6]. Late vein graft failure is generally caused by dyslipidemia and the progression of atherosclerosis, compromising either inflow or outflow vessels [1, 5].