Patients with chronic arterial occlusive disease of the femoropopliteal and infrapopliteal vessels present with varying degrees of ischemia of the lower limb, clinically manifesting as calf claudication, ischemic rest pain, or loss of tissue in the foot. The classic indications for surgical revascularization are disabling claudication and limb salvage in patients with critical limb ischemia (defined as ischemic rest pain, ulceration, and gangrene). Less common indications for infrainguinal arterial bypass surgery include trauma (e.g., popliteal artery occlusion from posterior knee dislocation), popliteal artery entrapment syndrome, and femoropopliteal arterial aneurysm with thrombo-embolism.

Infrainguinal arterial reconstruction should not be performed for nondisabling claudication, in severely debilitated patients with prohibitive comorbidities, or in patients who are bedridden or who have severe joint contractures. In patients who do not ambulate but require the use of their limb for balance in a wheelchair and bed transfers (e.g., paraplegic patients due to spinal cord injury), infrainguinal bypass surgery for arterial occlusive disease may be considered for limb salvage.

The clinical diagnosis of significant lower-limb ischemia should be confirmed by noninvasive arterial testing using segmental pressures, ankle-brachial indices (ABI), and pulse-volume recordings (PVR). These studies can often identify the level of disease in the lower limb (e.g., iliofemoral, femoropopliteal, and tibial) and indicate the severity of the ischemia. Furthermore, this pre-operative baseline study will aid in the follow up of patients after surgical revascularization has been performed.

When the indications for surgery have been met, the exact procedure required depends on the pathologic arterial anatomy. Classically, this has been defined by a diagnostic aortogram with lower-extremity runoff using intra-arterial contrast and digital subtraction imaging. Although the information obtained from such a study is usually excellent, the disadvantages of this procedure include its invasive nature and the risk of contrast-induced nephrotoxicity and allergic reaction. In patients with diabetes mellitus (DM) and chronic renal insufficiency (CRI), the risk of contrast-induced renal failure is significant. Preprocedural intravenous hydration, oral acetyl-cysteine, and the use of newer generation isoosmolar, non-ionic contrast medium (e.g., VisipaqueTM) may minimize this risk but do not eradicate it. Carbon dioxide and gadolinium have been used as alternative contrast agents, but the image resolution of the arterial anatomy is suboptimal and gaseous bubbling may induce artifacts that mimic stenotic lesions.

Recently, magnetic resonance angiography (MRA) using time-of-flight sequences and gadolinium enhancement has emerged as an alternative study of choice for preoperative planning. This noninvasive study offers good imaging of the arterial anatomy and does not impose any risks of renal toxicity or radiation exposure. With current technology, the quality of the images is usually limited only by the experience of the imaging technician and has improved with the adoption of standardized protocols and increasing experience with these studies. Other authors have relied solely on duplex ultrasonography of the tibial arteries for preoperative planning. This is a time-consuming and technically demanding diagnostic procedure, which is not practical in most high-volume vascular laboratories.

Once the anatomy has been clearly defined and the magnitude of the planned vascular reconstruction determined, it is important to evaluate the patient’s fitness for surgery. Myocardial infarction (MI) is the major cause of peri-operative morbidity and mortality. The incidence of coronary artery disease (CAD) in patients presenting with significant lower-limb ischemia is as high as
50%. Objective cardiac risk stratification often necessitates some form of provocative cardiac stress testing, because these patients have poor exercise tolerance (e.g., persantine-sestamibi myocardial scan or dobutamine stress echocardiogram). Any suggestion of significant myocardium that may be at potential risk for infarction should be selectively evaluated with coronary angiography. In general, coronary arterial disease is treated on its own merits, and this is performed before infrainguinal arterial bypass surgery. Routine medical measures include control of blood pressure and heart rate with beta-blockade, antiplatelet therapy with aspirin, lipid-lowering with statin therapy and normalization of blood glucose levels in diabetics. Patients are advised to stop smoking at least 2 weeks before surgery.

Pre-operative vein mapping with duplex ultrasonography is useful for guiding the selection of alternative autogenous conduits in patients in whom both greater saphenous veins (GSV) are absent or suspected of being diseased (e.g., thrombosis, sclerosis, or varicosities). Ideally, this study should be performed with the superficial veins in a distended state by placing a tourniquet in the proximal arm or leg and with the extremity in a dependent position. In the absence of usable GSV, the cephalic vein (CV), basilic vein (BV), and lesser saphenous vein (LSV) should be studied.

The first prerequisite for the successful performance of infrainguinal arterial bypass grafting is to ensure that there is adequate inflow into the artery from which the bypass graft is originating. If the inflow artery is inadequate, preliminary procedures such as iliac angioplasty/stent or a surgical inflow procedure will need to be performed prior to construction of the infrainguinal arterial bypass graft. The most acceptable distal inflow vessel is chosen for origination of the bypass graft.

Secondly, the target vessel chosen as the outflow vessel should be the least diseased vessel that is the dominant blood supply to the foot. In the presence of tissue necrosis, restoration of pulsatile flow to the foot is preferred to maximize the chances for wound healing. We have not found the site of the distal anastomosis per se (i.e., popliteal vs. tibial/pedal) to influence the long-term patency of the bypass graft. Bypass grafts performed to distal tibial/pedal target vessels may not relieve calf claudication if this is the primary indication for surgery.

Thirdly, the preferred conduit for arterial reconstruction is the GSV, even for reconstructions to the above-knee popliteal artery. In elderly patients with significant medical comorbidities where long-term graft patency may not be as relevant, it is reasonable to use a prosthetic graft, e.g., polytetrafluoroethylene (PTFE) or Dacron, for bypass to the popliteal artery. In the absence of ipsilateral GSV, the contralateral GSV is the next conduit of choice unless the contralateral lower limb is also severely ischemic and in need of bypass surgery. When both GSVs are unavailable, alternative vein conduits (CV, BV, and LSV), including autogenous composite vein (ACV) grafts, are used. Due to the poor performance of prosthetic grafts for infrageniculate arterial reconstruction, all autogenous options are exhausted before such grafts are considered for infrapopliteal bypasses.

The GSV is harvested starting below the groin crease and proceeding distally. There are several configurations in which the GSV can be used:

Equivalent long-term results have been reported with all three configurations. The in situ technique emphasizes leaving the GSV in its vein bed with ligation of the tributaries and lysis of valves. Theoretical advantages of this approach include minimal “disruption” of the nutrient supply to the vein wall and optimization of the sizematch between the vein graft and the native vessels. Our preference, however, is to use the GSV in the nonreversed, transposed configuration, as this achieves the above advantage of size optimization between the vein graft and the native vessels; in addition, it offers the flexibility of being able to move the vein graft to more distal inflow sites. In our practice, vein grafts are used in a reversed orientation only if the caliber of the graft is uniform throughout. Ideally, vein segments should have a minimum diameter of 3.5 mm, distend easily with irrigation, and have no evidence of significant wall thickening and sclerosis/thrombosis. Vein segments that do not meet these criteria are excised, and composite vein grafting is performed. The vein graft is preferably placed in a subcutaneous location to facilitate postoperative graft surveillance using duplex ultrasound and graft revision if necessary. Finally, a completion study (contrast angiogram and/or duplex ultrasonography) should be performed to assess the technical adequacy of the bypass procedure.