Extraanatomic bypasses include femorofemoral, axillofemoral, and axillobifemoral bypasses. Freeman and Leeds performed the first extraanatomic bypass in 1952 using an endarterectomized superficial femoral artery tunneled subcutaneously to the contralateral femoral artery. Vetto reported the first femorofemoral bypass in 1962. The first axillofemoral bypasses for lower extremity ischemia were independently reported by Blaisdell and Louw in 1963. Sauvage and Wood reported the first axillobifemoral bypass for bilateral lower extremity ischemia in 1966. Although extraanatomic bypass has largely been regarded as a second-choice alternative to standard aortoiliac and aortofemoral reconstruction and has been replaced to a large degree by percutaneous endoluminal interventions in appropriate patients, it remains a reliable and durable option for lower extremity revascularization that should remain in the armamentarium of physicians performing vascular surgery.

Extraanatomic bypass has traditionally been reserved for the treatment of symptomatic aortoiliac occlusive disease in patients with severe systemic illness increasing operative risk and in patients with local factors increasing the risk or difficulty of standard aortofemoral reconstruction. Examples of such local factors include prior aortoiliac procedures, prior radiation, extensive intra-abdominal adhesions, severe aortic calcification, abdominal malignancy, intra-abdominal infection, aortic or aortic graft infection, colostomy or ileostomy, and enterocutaneous fistula. While infrequently used, endovascular aortouniiliac repair of abdominal aortic aneurysms has resulted in an additional indication for femorofemoral bypasses. While many, if not most, aortoiliac revascularizations are now performed with percutaneous endoluminal therapy, extraanatomic bypass remains a viable alternative in patients whose extent of disease is too great for percutaneous treatment. Femorofemoral or unilateral axillofemoral bypass is indicated for unilateral aortoiliac occlusive disease, with axillobifemoral bypass indicated for bilateral disease.

Patients with aortoiliac occlusive disease of sufficient severity to warrant extraanatomic bypass grafting typically have absent or weak femoral pulses. Noninvasive vascular examination of the lower extremities is helpful in documenting the severity of ischemia and level of distal disease. Computed tomography (CT), magnetic resonance (MR), or digital subtraction arteriography is routinely performed for elective cases but often is not essential in urgent or emergent cases. Unilateral iliac artery angioplasty and stenting can occasionally be performed to facilitate femorofemoral bypass.

The adequacy of axillary inflow can be determined noninvasively in most cases. Segmental pressure measurements and Doppler analog waveforms are obtained at the level of the radial, ulnar, and brachial arteries in both arms. A pressure difference greater than 15 mm Hg between arms indicates significant occlusive disease. Upper extremity arteriography is performed when abnormalities are detected by noninvasive testing. Subclavian artery angioplasty with or without stenting is performed when indicated to improve axillary artery inflow. The right axillary artery is preferred for the axillary anastomosis, since the left subclavian artery has a higher reported incidence of developing atherosclerotic occlusive disease.

Prophylactic antibiotics, usually a first-generation cephalosporin, are administered immediately prior to surgery and continued for 24 hours. Aspirin therapy (325 mg/d) is started preoperatively and continued indefinitely postoperatively. Patients with an identified hypercoagulable state or a history of multiple graft failures are treated with long-term warfarin anticoagulation.