The open proximal end of the saphenous vein is tailored to match the arteriotomy. The edges of the tip may be removed to create a more oval taper and the vein may be opened in a longitudinal direction posteriorly to create a larger opening if needed. The anastomosis is performed with a 6-0 monofilament polypropylene suture that is double-ended with a needle at each end. As shown in Figure 7A, the course of each stitch in this running suture begins by entering the vein from the outside to lumen and proceeds from lumen to outside on the artery. This avoids raising an intimal flap in the artery, since the point of the needle is always pressing the intima onto rather than off the arterial wall. The suture line is begun with a mattress-type suture at the “heel” end of the vein (Figure 7). The lateral or far side is run first and brought around the tip or “toe” end to join the medial or near-side suture in the midportion (Figure 8). The anastomosis is flushed with heparinized saline, and the sutures are tied.
The arterial vessel loops are released, and the proximal saphenous vein will dilate with a pulsatile arterial inflow that stops at the next venous valve about 4 to 6 cm downstream. A retrograde valvulotome is introduced into the saphenous vein via a venotomy in a small side branch (Figure 9). The blunt-tip valvulotome is positioned above (proximal to) each competent valve in the inflated proximal section and then rotated and withdrawn separately through each anterior and posterior valve. It is important that the valve be inflated and that the retrograde valvulotome be positioned to cut perpendicularly to the plane of the skin as the valve leaflet lies parallel to the skin surface (Figure 10). Several passes are often needed. When the valve is successfully cut, the proximal inflation will proceed distally to the next valve. The distal vein is marked longitudinally with ink to ensure against rotation.
When all the valves have been successfully cut, the valvulotome is removed via the side branch, which is doubly ligated and divided between 000 silk sutures. This technique is repeated sequentially down the saphenous vein to the level chosen for the distal anastomosis. A strong pulsatile arterial flow should eject from this distal end of the in situ saphenous vein. Care must be taken not to hook the valvulotome into a posterior branch orifice as a disastrous tear may result.
The choice of site for the distal bypass anastomosis is determined according to the preoperative studies. It is important that the vein have a clear path without angulation. Also, the vein must be of sufficient length for it to reach the anastomotic site without tension when the leg is straightened. An anastomosis to the posterior tibial artery is shown. The peroneal artery may be approached in a similar manner, whereas the anterior tibial artery is approached by tunneling through the interosseous membrane in its upper two-thirds or by tunneling around the anterior tibia in its lower one-third. The appropriate arterial segment has been previously dissected over a 3- to 4-cm zone and isolated with Bulldog vascular clamps (Figure 11). An advantage of the in situ vein bypass technique is now apparent as the sizes of the two vessels (distal artery and bypass vein) are nearly the same. Most surgeons use magnifying loops or glasses for the end-of-vein-to-side-of-artery anastomosis, which is performed in a manner similar to the proximal anastomosis.
The vein may be incised longitudinally and tapered to create a larger stoma. All vessels are occluded with the elastic loops or small Bulldog vascular clamps. The artery is opened longitudinally (Figure 12). A double-ended 6-0 or 7-0 monofilament vascular suture is placed through the vein and artery in a mattress-suture manner at the proximal angle with the knots and free ends on the outside. A continuous, running suture is placed such that it enters through the vein and exits through the artery. This prevents the raising of an intimal flap as the needle point is pressed from the lumen outward on the artery. The posterior suture line is run first and usually carried around the distal angle to the midportion of the anterior line. This allows better visualization in the placement of the completed anterior line suture. The artery and vein are flushed with heparinized solutions and the loops and clamps are transiently released to flush all segments clear of clot or air (Figure 13). The two suture ends are tied.
Pulsations within the in situ vein and artery are palpated or verified with a Doppler instrument. An intraoperative on-the-table angiogram should be performed. The leg is flexed and straightened to be certain that the vein does not kink. A careful search is made along the entire vein to reveal any arteriovenous fistulas in the venous branches that were not recognized and ligated. These fistulas may be visualized or may be palpated as a hum or thrill, which can be localized with a Doppler instrument. Simple division between 000 silk ligatures is sufficient.
The superficial fascia is approximated with interrupted absorbable 000 sutures, and the skin is closed in the routine manner.
The hemodynamic status of the patient is monitored carefully in the recovery or intensive care setting. Cardiac output and tissue perfusion are maximized, while pulmonary function is monitored with arterial blood gases. A record of distal pulses obtained by palpation or Doppler is made hourly for the first day and at sequentially regular intervals thereafter. The patient is usually not anticoagulated but is kept well hydrated.
Many surgeons use low-molecular-weight Dextran infusions of about 20 mL per hour for the first 24 hours, especially if a low anastomosis was performed. The patients begin ambulation on the day after surgery. Many can be discharged home within 4 days. Aspirin is given for its platelet effects. Distal lesions such as gangrenous toes or ischemic ulcers will need continued local care. Patients may experience dependent edema in the treated leg for several months. Patients are studied with duplex ultrasound scans at 6 weeks, 3 months, and 6 months to detect areas of stenosis, which predict graft failure. Early bypass occlusion usually results from a mechanical or technical defect in either anastomosis. This event may be signaled by loss of pulses or a cool, pale extremity with pain, paresthesia, or loss of motor function. Doppler studies followed by angiography are useful in preparation for urgent reoperation. Late occlusions occur less frequently when compared with synthetic grafts or reversed saphenous vein bypass grafts.