Plate 162

Surgical bypass of the femoropopliteal segment is reserved for patients with severe claudication and impending limb loss manifested by ischemic rest pain or tissue necrosis. Typically, such patients have generalized atherosclerosis and a high incidence of significant coronary artery or extracranial carotid artery occlusive disease. Multiple risk factors—including cigarette smoking, hypertension, diabetes mellitus, and hyperlipoproteinemia—can be identified in the majority. Careful selection of candidates for operation is of utmost importance, weighing the expected benefit against the potential risk.

Aortography with full evaluation of the distal runoff is mandatory to identify and exclude more proximal occlusive disease and to ensure adequate graft runoff. Noninvasive vascular laboratory studies—including duplex ultrasound scanning, segmental limb pressures and segmental limb plethysmography—aid accurate physiologic assessment and serve as a baseline for estimation of the response to therapy.

Careful assessment of cardiopulmonary function is most important. An electrocardiogram and chest x-ray are obtained and further investigations may be prompted by the history or physical examination. Cardiac evaluation with an ultrasonic echo or radionuclide imaging stress test may be prudent, as may be pulmonary function studies. Further investigation may be prompted by history, physical examination, or these initial studies. Immediately preceding operation, catheters are placed for monitoring the central venous pressure, arterial pressure, and urinary output. Prophylactic antibiotic therapy is begun before operation and continued for 24 to 48 hours. The entire abdomen and both lower extremities are shaved from the nipples to toes bilaterally early on the day of operation.

General anesthesia or occasionally spinal anesthesia is employed with careful attention given to maintaining satisfactory hemodynamic parameters.

The patient is placed supine on the operating table.

The lower abdomen and appropriate limb are prepared in the usual manner to allow full mobility and exposure of the extremity. The foot is placed in a clear plastic Lahey bag, after which a clear plastic drape may be applied to the skin with special care anteromedially over the areas of planned incision. If the contralateral greater saphenous vein is to be used as the graft, the opposite extremity must be prepared in a similar fashion. If there is any question concerning the adequacy of inflow from the aortoiliac segment, the entire abdomen must be prepared for possible aortofemoral bypass grafting unless inflow has been secured with an iliac stent.

The initial incision, which follows the course of the greater saphenous vein (Figure 1), is made vertically across the inguinal crease, and early identification is made of the greater saphenous vein at the fossa ovalis. Dissection is continued distally in a progressive fashion to expose the entire length of vein required for the bypass. Alternatively, multiple incisions with intervening skin bridges may be elected. The creation of large skin flaps must be avoided to prevent skin necrosis and serious wound problems. After exposure of a suitable length of saphenous vein (Figure 2), the venous tributaries are doubly ligated proximally and distally with 0000 silk suture, or proximally with 0000 silk suture and distally with a medium silver clip, and divided (Figure 3). Flow is maintained with both ends intact as tributaries are ligated. Precautions are taken not to gather venous adventitia by ligating these tributaries excessively close to the vein wall, which will result in stenosis of the bypass graft (Figure 4). The vein should be kept in situ with flow maintained until just before the bypass graft is to be performed. After the saphenous vein is removed, a ball-tipped needle is inserted into the distal lumen (Figure 5) to permit flushing and distention during graft preparation (Figure 6). The proximal vein is then clamped gently with a bulldog clamp, and the vein is distended gently with cold autologous heparinized blood. This maneuver reveals leaks resulting from division of unidentified tributaries and stenotic areas that may require attention. Overdistention by forceful irrigation is avoided, as this may irreversibly damage the vein graft. At the completion of vein distention, an ink line is drawn down the graft to help avoid twisting the segment as it is brought through the tunnel later in the procedure (Figure 7). The femoral arterial exposure is performed as for aortofemoral bypass grafting with tapes passed around the common femoral artery proximally, the profunda femoris artery, and the superficial femoral artery (Figure 8). Care is taken to ligate the overlying lymphatic tissue to prevent formation of a lymphocele or lymph fistula.

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