Intra-operative and post-operative flow in the in-situ saphenous vein bypass

We have attempted to further define the hemodynamic properties of the arterialized in-situ saphenous vein. The natural taper of the vein and the presence of arteriovenous fistulas are two unique factors associated with this conduit. Utilizing intra-operative electromagnetic flowmeter (EF) measurements and post-operative duplex ultrasound scanning (DUS), we have studied the natural history of these conduits from the time of their arterialization. The EF mean arterial blood flow in 71 in-situ bypasses was 100.8 cc/ml, range 25-200. No significant correlation was found between these measurements and angiographic runoff, vein diameter, pre- or post-operative Ankle/Brachial Index (ABI) and site of distal anastomosis. Three immediate failures requiring revisions were not predicted by EF flow measurements. Using the unique combination of Doppler ultrasound measurement and real time imaging, afforded by the DUS, fistula flow was determined. These studies showed that terminal bypass segment blood flow is not significantly affected by cutaneous fistula interruption. We found that duplex ultrasound scanning is a useful tool ideally suited to the study of the arterialized saphenous vein in-situ. One of its main advantages is the ability to accurately localize the site and hemodynamic significance of any arteriovenous fistulas.