Extraanatomical bypass procedures.

Abstract

AbstractThose extraanatomical bypass procedures which are useful for revascularization of the lower extremities include femorofemoral, axillofemoral, and iliofemoral transobturator bypass. All of these procedures became firmly established during the 1960's, and have added greatly to the armamentarium of the vascular surgeon.The absolute indication for extraanatomical bypass is infection, which precludes the placement of a graft in a conventional location in a patient who requires revascularization to save life or limb. Relative indications for extraanatomical bypass exist when the risk of standard operations is high because of associated disease or anticipated technical problems. The most common indication is to provide revascularization of ischemic extremities in patients who are high‐risk for conventional operations. Utilization of axillofemoral graft to bypass aortic aneurysms is a most controversial indication. Occasionally, there is an extremely high‐risk patient who has symptomatic abdominal aortic disease who may benefit from the potential for staging the operation. Axillofemoral bypass can be done as one procedure and proximal or distal ligation of the aneurysm can be carried out simultaneously or at a later date with less stress on the patient.Important technical requirements of axillofemoral graft which will ensure optimal results are: (a) to place the proximal anastomosis on the first portion of the axillary artery, (b) to tunnel the graft well laterally so that it lies in the plane of flexion of the body, (c) to use an externally supported graft, (d) to ensure optimal outflow by using a femorofemoral graft in conjunction with axillofemoral bypass.The technical problems with the femorofemoral graft are relatively few: (a) the anastomoses should be placed in such a direction so as to avoid kinking, (b) the graft may be placed in a subcutaneous or subfascial position depending on the degree of obesity of the patient and the presence of preexisting scars.Technical aspects necessary for obturator bypass involve using whatever is the most accessible proximal vessel—usually the common iliac. The graft should be carried through the obturator membrane at its anterior medial portion, avoiding injury to the obturator nerve. The distal anastomosis is carried out in the low thigh.The results of axillofemoral graft vary greatly in individual reports. The 1‐year patency for these grafts varies from a low of 50% to a high of 87%, with 5‐year patencies varying from a low of 25% to a high of 76%.Regarding femorofemoral grafts, the literature documents 1‐year patency rates as varying between 82% and 93%, with 5‐year patency rates at approximately 75%, varying from 56% to 86.4%. Results for obturator bypass are not available since no one center has more than a limited experience with these operations.