Prevention of Autogenous Vein Graft Failure in Peripheral Artery Bypass Procedures

Overview

The purpose of this study is to determine the efficacy of graft pretreatment with the E2F decoy, CGT003, as compared to placebo, on the occurrence of graft failure among patients who receive autogenous vein grafts to treat chronic critical limb ischemia; on the occurrence of clinically significant graft stenosis (more than or equal to 70%); and on the incidence of critical limb ischemia (e.g., gangrene, non-healing ischemic ulcers or ischemic rest pain).

Peripheral vascular disease manifested by narrowing of the peripheral arteries is one of the more common manifestations of atherosclerotic vascular disease. Complications such as claudication, rest pain, and impaired wound healing are frequent and may result in gangrene and amputation. Restoration of circulation to the lower extremities may be undertaken using a variety of techniques including angioplasty, stenting, and bypass grafting. Approximately 99,000 infra-inguinal bypass procedures were performed in the U.S. in 1998. It is estimated that approximately 22% of all infra-inguinal bypass grafts will fail by 12 months. Graft failure rates have been estimated to increase to 40% at 12 months for patients receiving composite, cephalic or lesser saphenous (high-risk) vein grafts (Vascular Surgery Registry, Brigham and Women's Hospital). These primary graft failures are typically due to stenoses that result from neointimal hyperplasia, a pathological adaptation process that occurs in veins exposed to the arterial circulation. The consequences of graft failure are as significant as those of primary atherosclerotic disease and include ischemia and poor wound healing that may result in amputation. Since the long-term patency of venous grafts can be improved with treatment prior to frank occlusion, considerable efforts have been focused on the methods for the detection of grafts at high-risk for failure. Duplex ultrasonography has been determined to be a sensitive screening test for the early detection of failing grafts. Peak systolic velocity (PSV), as measured by duplex ultrasound, has been shown to be a sensitive marker for low flow, and wave form analysis has permitted the identification of areas of stenosis in the vein under study. Management of patients who have undergone infra-inguinal bypass therefore includes routine surveillance with duplex ultrasound and the immediate correction of significant (more than or equal to 70%) graft stenoses.