Early patency of in situ saphenous vein bypasses as determined by intraoperative velocity waveform analysis

Intraoperative velocity waveform analysis following in situ saphenous vein bypass grafting can identify abnormal hemodynamic conditions that correlate with the presence of a technical error or likelihood of perioperative thrombosis. Pulsed Doppler spectral analysis was used at operation to measure peak systolic blood flow velocity in the distal graft segment of 83 in situ saphenous vein bypasses to the popliteal (n = 35) or tibial (n = 48) arteries. Blood flow velocities were measured in the smallest diameter graft segment below the knee. Peak systolic blood flow velocity was greater than 40 cm/sec in 77 (93%) of grafts, and no early graft failures occurred. Low blood flow velocity (peak systolic blood flow velocity less than 40 cm/sec) was measured in six bypasses (7%) and was attributed to large (greater than 5 mm) vein diameter, residual hemodynamically significant lesions (intact valve leaflet, proximal arteriovenous fistula), or sclerosed vein segments. With the correction of these abnormalities, the 30 day patency for the entire series was 100%. The measurement of low blood flow velocity in the distal segment of an in situ saphenous vein bypass is an uncommon occurrence and mandates a thorough evaluation of the arterial reconstruction for correctable lesions.