- Critical limb ischemia is assessed by angiography to define the run-in and run-off vessels.
- The preferred choice of conduit for below knee bypass grafting is autologous long saphenous vein, which can be assessed clinically and by duplex scanning.
- The course of this vein is marked by indelible ink on the leg before the operation.
- A prosthetic graft can be used for distal bypass as a composite graft if no vein is long enough, but for above-knee bypass a synthetic graft carries good long-term patency rates.
The knee of the affected leg is flexed and slightly rotated externally with a support under the popliteal fossa.
Are longitudinal and placed as required.
- For a reversed saphenous vein graft, first, harvest the saphenous vein, if suitable, using interrupted longitudinal incisions. Tie off all tributaries away from the main trunk, to avoid any stenosis of the vein, and flush and distend the vein with heparinised saline.
- Expose the common femoral artery and its divisions along with the proposed site for the distal anastomosis. Encircle all these vessels by rubber slings.
- For an above-knee femoro-popliteal bypass, a tunnel is fashioned from the femoral triangle to the proximal popliteal space by blunt dissection in the sub-sartorial plane.
- The reversed saphenous vein or prosthetic graft is placed in this tunnel alongside the natural artery.
- For a below-knee femoro-popliteal bypass to either the distal popliteal or crural arteries, harvest a longer length of the long saphenous vein.
- The distal popliteal artery near the trifurcation is exposed, posterior to the medial border of the tibia, by opening the facial compartment between gastrocnemius and soleus muscles.
- For a femoro-distal bypass, the distal anastomisis is to be made to the best vessel, either the anterior tibial, posterior tibial or peroneal artery at the ankle or foot, and a separate incision is made over the appropriate vessel.
- Rubber slings or small vascular clamps are applied to get proximal and distal control.
- After making longitudinal arteriotomies over the proximal and distal anastomosis sites a Fogarty catheter (size 4 or 5) may be passed distally to ensure the patency of distal artery.
- The reversed saphenous is then anastomosed end to side, starting proximally.
- Alternatively an in-situ saphenous vein graft might be used. The proximal end of the long saphenous vein is transposed and anastomosed onto the common femoral artery and then clamped. It’s distal end is opened and flushed with heparinised saline to distend the vein. A valvulotome is introduced through distal end to cut the intact venous valves.
- At completion, the flow should be pulsatile down to its distal end, which is divided and spatulated for the distal anastomosis. Larger branches of the in situ vein are cut down to and ligated.
- At completion Doppler signals and on-table angiography are used to assess graft function and run off.
Closure and Drainage
Routine wound closure, after meticulous hemostasias and closed suction drains can be used.
Requires regular and careful monitoring of distal pulses by palpation and Doppler.
Main Postoperative Complications
Include graft thrombosis, haemorrhage and infection. Later on false aneurysms and graft occlusion.