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

C H A P T E R 86

FEMOROTIBIAL AND

PERONEAL BYPASS

Lori Cindrick Pounds

STEP 1: SURGICAL ANATOMY

A review of the proximal femoral and saphenous vein anatomy has been discussed at length in Chapter 85. The popliteal artery branches are commonly called the “trifurcation,” denoting its division into three distinct arteries—(1) the anterior tibial artery (ATA), which crosses the interosseus membrane and runs in the anterior compartment until the ankle mortise; at that point it is called the dorsalis pedis artery (DPA). It has a large branch that also may be suitable to receive the bypass is the lateral tarsal artery; (2) the posterior tibial artery (PTA); and (3) the peroneal artery—which have a common trunk (tibioperoneal trunk) that courses in the deep posterior compartment. The PTA continues its course on to the foot at the medial malleous, where it divides into the medial and lateral plantar arteries. The peroneal artery does not cross the ankle joint, but gives out two consistent branches that collateralize to the DPA and PTA.

STEP 2: PREOPERATIVE CONSIDERATIONS

The same standard indications for reconstruction are true for tibial bypass as are true for femoropopliteal reconstructions (see Chapter 85). They include limb-threatening ischemia (ischemic rest pain, ulceration, and gangrene). Typically the lower in the leg you have to go to find a suitable target, the greater the burden of disease. There are three basic sections of the arterial tree below the renal arteries: aortoiliac, femoropopliteal, and tibial (infrageniculate). When the disease is confined to one segment, then usually the patient will either be asymptomatic or have claudication. If two or more segments are involved, then the ischemia is more profound and the limb can be threatened. So if you are planning a femorotibial bypass, the occlusive lesions would be in two sections, the femoropopliteal and tibial distribution. It is generally a statement to the overall status of the patient as well, because these patients tend to have a heavier burden of atherosclerotic disease in other beds also (coronary and extracranial carotid arteries).

Autogenous vein is clearly the best option for reconstruction below the knee. Similar considerations for vein assessment and procurement exist as for the femoropopliteal, but a longer section of quality vein is needed. At times, this can be hard to secure, and sections of different veins can be anastomosed to create a conduit. Always remember that the small saphenous, cephalic, and basilic veins are wonderful options. They can also be mapped with ultrasound before the surgery. Again, having to do this raises the degree of complexity and the possibility for adverse events.

929

9 3 0 S E C T I O N X I I • VA S C U L A R

The decision to leave the vein in situ or bury it anatomically next to the native vessels is the choice of the surgeon. Each has been shown to be appropriate. A consideration would be the thin leg of a diabetic patient that has minimal subcutaneous tissue and is at risk for a wound dehiscence. This would leave the graft easily exposed and at risk for rupture.

STEP 3: OPERATIVE STEPS

The patient is placed supine. 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 a series of “skip” incisions, also known as bridge incisions, or if available, endoscopic vein harvesting (please see Chapter 85 for more detail; see Figure 85-3).

The target vessel has usually been identified on either a preoperative or intraoperative arteriogram. It is helpful to use a radiopaque ruler on the skin to show where the tibial vessel is good, otherwise you can reference a bony landmark (i.e., medial malleolus) and measure backward. The tibial arteries can be more difficult to isolate and work with than the popliteal artery. They are found deep in the muscular compartments of the leg and are generally smaller to sew to.

THE POSTERIOR TIBIAL ARTERY

The PTA is approached through a medial calf incision (Figure 86-1, A) and is generally combined with the saphenous harvest incision (please see Chapter 85 for more details on a saphenous vein harvest). When the target is more proximal in the calf, say just past the tibioperoneal trunk, it can be easier to identify the popliteal artery and then divide more of the soleus muscle off the tibia. Immediately below will be the origin of the ATA and the tibioperoneal trunk. There is typically an extensive network of interconnected veins that will need to be ligated to allow full exposures. The origin of the PTA is approximately 2 to 3 cm below the ATA, if that is to be the target.

In the mid to distal leg above the ankle, the PTA remains in the deep posterior compartment, and a thorough knowledge of the anatomy is helpful. The soleus is again removed from its tibial attachments and retracted toward the OR table (Figure 86-1, B). A plane can then be developed between the flexor digitorum longus and the soleus muscles. The artery will be surrounded again with a complex plexus of veins that need to be divided. In large muscular legs it can be helpful to use a Doppler pencil to guide the exposure.

At the ankle, the PTA becomes much more superficial, allowing an easier dissection, but also raising the chances of wound complications. A reverse J-shaped incision is made at the ankle, and the flexor retinaculum is divided. The neurovascular bundle will be nestled in a groove between the tendons of the flexor hallucis longus and flexor digitorum longus muscles (Figure 86-1, C).

9 3 2 S E C T I O N X I I • VA S C U L A R

THE ANTERIOR TIBIAL ARTERY

The ATA is isolated through an incision on the lateral calf between the tibia and fibula (Figure 86-2, A). Sometimes in thin legs, you can appreciate the division between the anterior and lateral compartments of the leg and guide your incision more toward the anterior compartment. In the proximal leg, a plane can be developed between the tibialis anterior and extensor digitorum longus muscles (Figure 86-2, B). The artery, vein, and nerve (deep peroneal) will be just anterior to the interosseus membrane. Once again there will be a rich network of surrounding veins.

By the mid-portion of the leg, the extensor hallucis longus muscle originates and becomes more prominent, and the plane will be between it and the anterior tibialis muscle.

In the distal third of the leg, the ATA courses much more anteriorly and is found between the tendon of the tibialis anterior muscle and the extensor hallucis longus muscles.

The challenge with the ATA, however, is how to tunnel the vein graft. The two most popular options include an anatomic location with it going through the interosseus membrane in the popliteal space and then laterally in the anterior compartment. The other is to have the vein in a modified in situ position that courses from a medial to lateral position just below the skin. If the origin of the bypass is the femoral artery and it courses along the lateral knee, great care must be taken to account for the knee bending. If the origin of the bypass is the popliteal, then the options include laying it on top of the tibia or removing a section of the bone to allow it to sit better. Either way, if this approach is used, extra length of vein, which may not be available, is required.

9 3 4 S E C T I O N X I I • VA S C U L A R

THE PERONEAL ARTERY

The peroneal artery is the most difficult tibial artery to work with. It is always much deeper than expected. In a thin calf, the peroneal artery is generally approached medially. The same general dissection is used as for the PTA, but you must go deeper for the peroneal artery. The soleus is again divided and retracted posteriorly toward the OR table (Figure 86-3). The PTA is left in its loose areolar tissue with the soleus muscle. The peroneal artery will be located on the anterior surface of the flexor hallucis longus. This makes sewing the distal anastomosis more challenging because seeing and sewing in a small deep space is more difficult.

Medial Approach Peroneal Artery

Tibialis posterior muscle

Deep peroneal nerve,

anterior tibial artery and vein Tibialis anterior muscle

Tibia

Extensor digitorum longus muscle

Peroneus longus muscle

Fibula

Soleus

Flexor hallucis muscle longus muscle

Posterior tibial artery and vein, tibial nerve

FIGURE 86–3

9 3 6 S E C T I O N X I I • VA S C U L A R

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, step-down 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 a skilled nurse facility (SNF) before they are independent and can go home by themselves or with a caregiver.

The need for postoperative modulation of the coagulation cascade is greater the longer the bypass is. Postoperatively, many surgeons prescribe a nonadjusted unfractionated heparin intravenous drip for 12 to 24 hours. It is common to prescribe either an anticoagulant (warfarin) or a platelet inhibitor (aspirin or clopidrogel) after that. The decision on which one 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, or a bad vein may convince the surgeon to use a stronger agent. Most surgeons try to avoid prosthetic conduits (ePTFE) below the knee, but if it is used, warfarin is generally used.

After discharge, the patient should be seen in the 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.

STEP 5: PEARLS AND PITFALLS

Femorotibial reconstruction is an excellent option for patients with advanced occlusive disease, most of which present with critical limb ischemia (rest pain or tissue loss). These individuals have a larger burden of disease and tend to have other serious comorbidities, such as cardiac disease and long-standing diabetes. They are more likely to have an adverse clinical event in the perioperative period. Great care must be taken to limit the risk of this, and such treatment as perioperative beta blockade is essential for this group.

Just as in the in situ femoropopliteal reconstruction, the tibial bypass is also at risk for wound complication issues. Great care with tissue handling, keeping the graft as deep as possible, and avoiding a flap creation are essential to promote good wound healing.

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.

C H A P T E R 87

FASCIOTOMY—FOREARM AND LEG

William J. Mileski

STEP 1: SURGICAL ANATOMY FOR FOREARM

The forearm is divided into multiple fascial compartments, each containing several muscles that are additionally enclosed within individual epimysial envelopes. Three forearm compartments are usually described: the volar, dorsal, and lateral (mobile wad) compartments.

The interosseous membrane separates the volar and dorsal compartments from each other, and the posteriorly and radially located lateral compartment is demarcated by a connective tissue septum from the antebrachial fascia. In most cases of compartment syndrome, the volar muscles are the most severely affected, followed in severity by the muscles of the dorsal compartment and of the lateral compartment. Some communication exists among the three main compartments, and release of the volar compartment often relieves elevated tissue pressure in the dorsal compartment. Intraoperative pressure measurements and clinical findings may preclude the need for a separate dorsal fasciotomy to relieve this extensor compartment. The lateral compartment musculature is superficial and easily decompressed.

Within the volar compartment, additional distinction can be made between the superficial and deep muscles. The superficial muscles include the pronator teres, palmaris longus, flexor digitorum superficialis, flexor carpi radialis, and flexor carpi ulnaris. The deep muscles include the flexor digitorum profundus, flexor pollicis longus, and pronator quadratus. The flexor digitorum profundus and flexor pollicis longus are particularly vulnerable in compartment syndrome, because they may be compressed against rigid bone and the unyielding interosseous membrane. Anatomic and clinical reports demonstrate that release of the superficial volar compartments may not be adequate to relieve deep pressures in these muscles.

The dorsal compartment is also divided into superficial and deep muscles. The extensor digitorum, extensor carpi ulnaris, and extensor digiti minimi are the superficial group, which lie in a plane above the deeper abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis, and supinator (Figure 87-1, A).

938