Monitoring functional patency of in situ saphenous vein bypasses: the impact of a surveillance protocol and elective revision.

Implementation of a protocol that monitored in situ saphenous vein bypass hemodynamics for low-flow states provided insight into the pathophysiologic characteristics and time course of graft failure. From 1981 to 1988, 250 in situ bypasses to popliteal (n = 83) or tibial (n = 167) arteries were performed in 231 patients. Indications for operation included critical limb ischemia in 232 cases (93%), popliteal aneurysm in 11 cases (4%), and disabling claudication in seven cases (3%). Arterial pressure measurements, continuous-wave Doppler spectral analysis, and duplex ultrasonography were used to assess patency, detect hemodynamic changes indicative of graft stenosis, and localize anatomic hemodynamic changes indicative of graft stenosis. Seventy grafts with correctable anatomic lesions (retained venous valves, graft stenosis, arteriovenous fistula, native vessel atherosclerosis) that decreased graft blood flow or ankle arterial pressure or both were identified. Correction of vein conduit or anastomotic lesions comprised 73 (77%) of the 95 revisions performed. Vein-patch angioplasty of a stenosis was the most common secondary operation performed. Graft revision was highest in the perioperative period (10% at 30 days), decreased to 7% per 6-month interval until 18 months, and was 3% per year thereafter. The primary patency rate of grafts not identified to have a correctable lesion was 86% at 4 years, a level similar to the secondary patency of 81% for grafts requiring one or multiple revisions. The surveillance protocol identified grafts with correctable lesions before thrombosis thereby permitting elective revision of patent grafts. Hemodynamic studies confirmed that a frequent mechanism of late failure of grafts was the development of a low-flow state produced by lesions not amenable to revision.