Atlas of General Surgical Techniques (Courtney M. Townsend Jr., B. Mark Evers)

C H A P T E R 85

FEMOROPOPLITEAL BYPASS (IN SITU)

Lori Cindrick Pounds

STEP 1: SURGICAL ANATOMY

A comprehensive understanding of the anatomy of the leg is essential to performing the procedure and avoiding future complications. This anatomy includes the femoral triangle and the popliteal space below the knee. The saphenous vein can have many variations in its course in the thigh. Identifying the main branch and avoiding a flap are key points

(Figures 85-1 through 85-3).

Femoral nerve

Inguinal ligament

Femoral artery

Femoral vein

Profunda artery

Superficial external pudendal vein

Femoral triangle

Superficial femoral artery

Medial accessory saphenous vein

Great

Anterior lateral accessory saphenous vein saphenous vein

Sartorius muscle

MC

FIGURE 85–1

919

Continuous incision

(solid lines)

True great saphenous vein

Posterior medial

or posterior arch vein

A

Skip/bridge incision

(dashed lines)

B

Medial accessory

saphenous vein

Great saphenous vein

True great saphenous vein

Posterior medial

or posterior arch vein

C

FIGURE 85–3

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STEP 2: PREOPERATIVE CONSIDERATIONS

The standard indication for reconstruction for occlusive disease is limb-threatening ischemia. This includes ischemic rest pain, ulceration, and gangrene. There are certain accepted indications for bypass in the setting of severe claudication that prohibit gainful employment or maintenance of the activities of daily living.

The femoropopliteal in situ bypass is one of many open reconstructive options available to the surgeon. In general, when the vein is to be used for limb salvage, it is customary to use the below-knee popliteal segment. The above-knee segment may seem like an appropriate target, but it is known to have a high rate of progression of disease. The in situ technique offers the advantage of allowing the larger part of the saphenous to be placed on the larger common femoral artery and the smaller section of vein to be placed on the smaller outflow artery. The alternatives to this include a femoropopliteal bypass with vein that is reversed and buried in an anatomic tunnel that follows the native superficial femoral and popliteal arteries. A prosthetic infrageniculate (below the knee) graft is reserved for the individual who has exhausted all autogenous (vein) options in the lower and upper extremities— including the great and small (also known as the lesser or short) saphenous, as well as the basilic and cephalic veins. Last, with the endovascular revolution, many catheter-based options are available, including a percutaneous bypass with covered stent grafts, an atherectomy, or laser treatment, to name a few.

Preoperative venous duplex (a grayscale B-mode ultrasound and doppler waveform analysis) of the superficial veins is very helpful to determine the quality of the vein and to help choose an operative plan. If the ultrasound can be arranged close to the bypass surgery date, it is helpful to have the technician mark the course of the vein. Many operative suites have an ultrasound available, and the vein can be marked before the leg is prepped. This may help reduce the risk of a flap formation.

STEP 3: OPERATIVE STEPS

The patient is placed in a supine position. For occlusive disease, it is a good rule to prepare more than is needed. In general, both lower extremities should be draped in case further vein is needed to complete a procedure. The first incision is typically placed in the groin at the level of the inguinal ligament. The great saphenous vein is identified first at the fossa ovalis, below Scarpa’s fascia. The femoral sheath is then opened longitudinally to identify the femoral vessels. The common femoral artery, superficial femoral artery (SFA), and profunda femoris artery (PFA) should be isolated. The saphenous vein can then be isolated either through a continuous incision that “unroofs” the entire vein or through a series of “skip” incisions, also known as bridge incisions. A continuous incision allows maximal visualization of all branches but can be associated with greater wound-healing and infection risks. The bridge technique can heal better but has limited viewing of the vein, which may result in either vein injury or inadequate ligation of all branches (see Figure 85-3). A third alternative is a hybrid between a traditional vein harvest and an in situ harvest—an endoscopic vein harvest. Some institutions may have a designated individual with extensive experience, such as a physician’s assistant who harvests for coronary artery bypass grafting. This technique offers many advantages. There is one incision in the lower thigh that can be used to harvest the vein to the saphenofemoral junction. The vein can then be placed in

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The below-knee popliteal incision on the medial calf typically extends from the tibial tuberosity to the midcalf. A general rule for this exposure is to have a bump placed well above the knee so that the gastrocnemius and soleus muscles hang freely. The fascia is entered, and an avascular plane is developed by retracting the gastrocnemius and soleus muscles downward. The popliteal space is then entered, and the vein (anterior to the artery) is dissected free from the popliteal artery. The popliteal vein is commonly duplicated and that branch is lying posterior to the artery. It can be injured when trying to dissect bluntly with a right angle. It is best to use sharp dissection in this tight space, because it is much easier to repair a cut than an avulsed branch (see Figure 85-2).

There are multiple methods for destruction of the valves. A hand-held valvulotome or scissors can be inserted through large side branches. There are also disposable products available (Figure 85-5). The proximal anastomosis should be created in a standard fashion (see Figure 85-4). The most proximal first and second valves are removed under direct vision before this anastomosis is started. It is important to remove the thin valve cusp flush with the vein wall. This will ensure that the cusp remnants do not become involved in the anastomosis, which would severely stenose or occlude the flow. Flow should then be established in the vein graft to identify whether any other valves are intact. There will be a decrease in pulsatility and flow detected by Doppler ultrasound where the valve is still intact.

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Once adequate flow has been established in the vein, the distal anastomosis can be created in a similar fashion (Figure 85-6). If the outflow artery is calcified, a tourniquet can be used to occlude the flow and avoid placing a clamp on the artery. Before the anastomosis is completed, it should be appropriately irrigated and flushed free of any potential debris or clot. A completion arteriogram can then be performed, ideally through a large preserved side branch with a radiopaque marking tape. This is essential if the entire vein had not been mobilized or if bridge incisions were used so that large branches can be ligated.

STEP 4: POSTOPERATIVE CARE

Most patients undergoing surgery for peripheral arterial disease have multiple comorbidities including coronary artery disease. They can be monitored in an intensive care unit, stepdown unit, or specialized floor bed depending on the protocols of the institution. Minimum requirements should include telemetry, and vital signs should be taken every 2 hours, including monitoring patency of the graft with Doppler ultrasonography. It is important to educate staff on the importance of using a quantitative measure such as a Doppler signal and not relying on an individual’s experience at feeling pedal pulses.

If medically stable, the patient should be moved to a floor bed as soon as possible. Rehabilitation therapy should begin immediately, even if it is as simple as sitting in a chair. Realistic expectations should be discussed with the family and staff about discharge planning. Many patients will need transition care either in a rehabilitation facility or by a skilled nurse facility (SNF) before they are independent and can go home by themselves or with a caregiver.

Postoperatively, many surgeons prescribe a nonadjusted unfractionated heparin intravenous drip for 12 to 24 hours. It is common for the patient to take either an anticoagulant (warfarin) or a platelet inhibitor (aspirin or clopidrogel) after that. The decision on which to use needs to be individualized based on certain factors. In general, these include quality of the inflow, which should be adequate before attempting an infrainguinal procedure. The outflow artery may not always be ideal, and a substandard conduit such as ePTFE or a bad vein may convince the surgeon to use a stronger agent.

After discharge, the patient should be seen in clinic and understand that he or she will have a relationship with the surgeon for the life of that graft. Routine graft surveillance with duplex scanning and ankle-brachial indices (ABIs) has been demonstrated to increase the primary patency of grafts (assisted primary patency). Protocols include a postprocedure baseline level and close follow-up (every 3 months for a year, then biannually). A drop in the ABI or a velocity elevation is suggestive of a stenosis in the graft and warrants an arteriogram and possible intervention.

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STEP 5: PEARLS AND PITFALLS

The in situ bypass technique has been shown to be an excellent choice for infrainguinal reconstruction for occlusive disease. The location of the graft in the subcutaneous tissues makes it quite easy to feel and evaluate with duplex ultrasound. There are certain groups of patients with whom I am very cautious. The diabetic, end-stage renal patient is the classic individual to have a wound-healing issue. Because the graft is directly under the skin, any wound dehiscence will result in exposure of the adventitia and graft rupture if it is not dealt with expediently. One may consider leaving large skin bridges, or I find it preferable to place the graft in a more anatomic location adjacent to the artery and vein. Thus, when there are wound-healing issues, it is just a simple superficial or deep tissue infection and not an organ space (i.e., the graft) that is involved.

SELECTED REFERENCES

1. Ouriel K, Rutherford R (eds): Atlas of Vascular Surgery: Operative Procedures. Philadelphia, Saunders, 1998.

2. Norgren L, Hiatt WR, Dormandy JA, et al: Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II). J Vasc Surg 2007;45:S5-S6.

3. Valentine RJ, Wind GG: Anatomic Exposures in Vascular Surgery, 2nd ed. Philadelphia, Lippincott Williams & Wilkins, 2003.

4. Rutherford RB: Atlas of Vascular Surgery: Basic Techniques and Exposures. Philadelphia, Saunders, 1993.