Direct revascularization procedures are applicable for patients with peripheral arterial insufficiency and obstructive lesions located anywhere from the aorta to the arteries of the calf, providing there is demonstrable patency of the arteries distal to the segment to be revascularized. Recent trials have shown that perioperative beta-blocker administration is mandatory for most patients to reduce cardiac morbidity.
Aorta, Iliac, and Femoral Interventions
Endovascular techniques have replaced operative intervention for many lesions involving the aorta and common iliac artery. When stenoses are relatively short and localized, PTA with placement of intraluminal stents is the treatment of choice, for patency rates of such “less invasive” procedures approach the results of operative treatment; moreover, if disease recurs, repeat interventions are possible. Newer devices have improved outcomes after PTA and stenting of the external iliac artery, but lesions of the common femoral artery, where greater degrees of flexion may occur, are treated with open procedures.
Open operations are required for aortoiliofemoral occlusive disease when there are multiple lesions. An inverted Y-shaped prosthesis is interposed between the infrarenal abdominal aorta and the femoral arteries. The goal of operation is restoration of blood flow to the common femoral artery. The clinical results of aortofemoral reconstruction are excellent, although the mortality and morbidity clearly are higher than for endovascular therapy. The operative death rate is 5%; early patency rate, 95%; and late patency rate (5–10 years postoperatively), about 80%. Late complications include graft-intestinal fistula formation, anastomotic aneurysm formation, renal failure, and erectile dysfunction.
Although the risks of aortoiliac reconstruction are acceptably low in the average patient, simpler procedures may be preferable in high-risk patients. If the clinically important lesions are confined to one side, a femorofemoral or iliofemoral bypass graft can be used. A graft from the axillary to the femoral artery (ie, axillofemoral graft) can be used with aortoiliac disease when an abdominal operation is to be avoided, as in patients with excessive adhesions, infected abdominal aortic Dacron grafts, or aortoenteric fistulas. These “extra-anatomic” methods of arterial reconstruction are more prone to late occlusion and infection than are direct reconstructions.
When disease affects both the aortoiliac and femoropopliteal segments of the arterial tree, aortofemoral bypass (with profundoplasty if indicated) is generally adequate. When disease is confined to the femoropopliteal segment, femoropopliteal bypass is used. The principal indication for these operations is limb salvage. In patients with claudication alone, the indications for femoropopliteal bypass are more difficult to define but must include substantial disability from claudication. For limited lesions of the SFA, angioplasty is often attempted.
The best graft for femoropopliteal bypass is an autologous greater saphenous vein. The saphenous vein may be left in situ or removed and reversed. In the former instance the vein is left in its normal position, the venous tributaries are ligated, and special instruments are used to render the valves incompetent. Expanded polytetrafluoroethylene (PTFE) may also be used as a conduit, particularly for bypass to the supragenicular popliteal artery. Below the knee PTFE conduits produce much lower patency rates than saphenous veins. Operative death rates are low (2%).
When profundaplasty alone is performed for limb salvage, the goal is improvement of flow through collaterals to the popliteal arteries. Limb salvage in patients undergoing profundaplasty is 80% when the suprageniculate popliteal artery is patent and 40–50% when the popliteal artery is occluded. Isolated profundaplasty is rarely helpful for treating claudication.
The use of flexible stents, cryo-balloons, and atherectomy devices has shown promise in this area.
Distal Arterial Reconstruction
Reconstruction of distal arteries (ie, bypass to the tibial, peroneal, or pedal vessels) is performed only for limb salvage. Endovascular techniques are not widely used in the tibial vessels, and bypass remains the primary mode of therapy for these patients. Autogenous saphenous vein is the best graft material, and either in situ or reversed technique may be used. If the greater saphenous vein is unavailable, a composite graft of lesser saphenous or arm veins is the next best choice. Prosthetic conduits have high failure rates. The operative death rate for these procedures is about 5%. Five years after operation, only approximately one-half of the grafts at risk are still functioning, but the limb salvage rate is substantially higher.
Successful revascularization results in lower costs than primary amputation and an infinite improvement in quality of life. Occasionally, primary amputation may be preferable to revascularization if the likelihood of successful bypass is low, extensive foot infection is present, or the architecture of the foot is compromised so that ambulation is unlikely.
Lumbar sympathectomy has been shown to be ineffective in the management of gangrene of the toes or foot and does not lower the required level for amputation or delay the requirement for amputation. At present, reflex sympathetic dystrophy (causalgia) is the principal indication for sympathectomy.
Fortunately, if intermittent claudication is the only symptom, amputation of the limb will be necessary in only 5% of patients within 5 years and 10% in 10 years. Amputation becomes more common if patients continue to smoke cigarettes. Patients with multiple risk factors for atherosclerosis and short-distance claudication are also at increased risk for eventual limb loss. Of patients who present with ischemic rest pain, however, about 5% require amputation as initial therapy, and most will require amputation within 5 years, if not revascularized.