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

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Aortic anastomosis

The diameter of the aorta just below the left renal vein is assessed, and the size of the bifurcated prosthetic graft is chosen. The typical location of the proximal anastomosis is approximately 1 to 2 inches below the renal arteries. The aorta can be partially clamped or cross-clamped below the renal arteries.

The aortic limb of the aortic bifurcation graft is trimmed so that after the aortic anastomosis, the two limbs lie in a natural position through the tunnels in the pelvis and exit into the groin anterior to the femoral arteries. If the common trunk is too long, there is a risk of kinking of the two limbs, compromising flow.

The proximal aortic anastomosis can be performed in an end-to-end or end-to-side fashion. The end-to-end technique is used for patients who will not suffer circulatory compromise from interruption of prograde flow in the abdominal aorta. The end-to-side technique is used for patients who require prograde flow to perfuse an important hypogastric or inferior mesenteric artery.

For an end-to-side anastomosis, an arteriotomy is made on the aorta just below the renal vein, and the anastomosis is sutured with a running technique using a 3-0 nonabsorbable monofilament suture (Figure 83-6). The suture can be tightened with a nerve hook.

For an end-to-end anastomosis, the aorta is divided sharply and the distal segment is oversewn with a heavy suture (3-0 nonabsorbable monofilament) using mattress stitches, followed by a second row using a running stitch over the cut edge. The graft is then anastomosed to the proximal aortic segment (Figure 83-7).

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After the aortic anastomosis is completed, the clamp is released for several beats to flush clots, debris, and air. The limb to be used first is then flushed with heparinized saline. An aortic clamp is placed through the tunnel from the groin, and the limb is pulled out of the abdominal cavity (Figure 83-8).

A plaque-free area in the distal common femoral artery is selected, and the artery is opened on the anterior surface. The length of the limb is trimmed, and the end of the graft is beveled. The anastomosis is performed with a 5-0 nonabsorbable monofilament suture, starting at the heel (Figure 83-9).

Before the anastomosis is completed, the limb is flushed by removing the clamp from the limb, and the aortic clamp is released. The anastomosis is completed, and the flow is restored first to the common femoral artery and allowed to retrogradely fill the iliac artery in the pelvis so that debris is swept into this vessel rather than toward the feet. The superficial and deep femoral arteries are then reopened to restore flow to the lower extremity.

The procedure is repeated for the other limb.

3.CLOSING

The retroperitoneal tissue is closed over the graft to separate it from the viscera to prevent future adhesion or erosion of bowel. If this tissue is insufficient, the omentum can be used by bringing it around the left side of the colon and tacking it down on top of the graft. The bowel is returned to the abdominal cavity, and the nasogastric tube location is reconfirmed in the mid-portion of the stomach. The abdominal wall is closed using standard technique.

The groin wound is closed in multiple layers with interrupted and/or running adsorbable 2-0 and/or 3-0 sutures using standard technique.

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STEP 4: POSTOPERATIVE CARE

Patients are monitored in the intensive care unit immediately after surgery for several days and then transferred to the floor unit. Most patients are discharged on their seventh or eighth postoperative day.

The nasogastric tube is removed with return of bowel function, usually on the third or fourth postoperative day.

Patients are assisted by physical therapists for early mobilization with ambulation. Aggressive use of incentive spirometry is encouraged. Deep vein thrombosis prophylaxis is used.

Patients are discharged when they have good pain control, exhibit return of bowel function, and are ambulatory.

Surveillance of the bypass graft patency uses clinical cues, such as pulse examination, and objective criteria such as ankle-brachial indices (ABIs). Distal perfusion to the feet is verified in the operating room before closure of the wounds. Any unexpected findings require imaging and possible embolectomy. ABIs are followed in the postoperative period, at the first postdischarge clinic visit, and then at 6-month intervals.

Initial graft patency rates are nearly 100%. The 5-year patency rates range from 80% to 90%. Long-term patency rate at 10 years is approximately 75%.

Complications include pelvic ischemia caused by interruption of pelvic blood flow. Patients may develop colon ischemia, neurologic deficit from lumbar ischemia, and infarction of the pelvic musculature and skin.

Embolization of large atheromatous debris may cause occlusion of major named vessels. Microscopic debris may cause injury ranging from minor focal toe ischemia to extensive tissue loss involving the major muscle groups of the buttocks, thigh, and leg.

Other complications include lower extremity ischemia, male sexual dysfunction, and wound infection. Long-term complications include anastomotic pseudoaneurysms or stenoses. The most serious complication is aortic graft infection with development of aortoenteric fistula. Patients with this complication may present with acute gastrointestinal bleeding or chronic anemia.

STEP 5: PEARLS AND PITFALLS

The lateral femoral circumflex vein is located between the origins of the superficial femoral and deep femoral arteries. Injury to this vein should be avoided during dissection of the deep femoral artery. When the vein is identified, it may be ligated to provide direct access to the deep femoral artery.

The inferior epigastric and deep circumflex iliac arteries and veins can be found on the anterior surface of distal external iliac or proximal common femoral arteries beneath the inguinal ligament. Injury to these branches should be avoided during proximal dissection of the common femoral artery. Tunneling from the groin wound should be performed under direct visualization.

In men, distal dissection should avoid the fibroareolar tissue on the anterior surface of the left common iliac artery. This tissue contains the autonomic nerves that control sexual function. Extended dissection can lead to nervous disruption and resultant retrograde ejaculation.

The left renal vein anterior to the aorta can be divided to facilitate aortic exposure.

A large pulsatile artery next to the inferior mesenteric artery on the left side of the aorta is likely a meandering mesenteric artery. This artery provides collateral circulation in the presence of mesenteric occlusive disease of the celiac or superior mesenteric artery, or both, and should not be divided.

Interruption of pelvic blood flow should be avoided. The use of end-to-end or end-to-side aortic anastomosis is determined by preoperative arteriography of the abdominal aorta and bilateral iliac arteries. The end-to-end technique is used for patients who are not dependent on prograde flow in the abdominal aorta. The end-to-side technique is used for patients who require prograde flow to perfuse an important hypogastric or inferior mesenteric artery.

The deep femoral artery can serve as the only outflow despite complete occlusion of the superficial femoral artery from atherosclerotic disease. The deep femoral artery is a lowresistance vessel that is usually free of atherosclerotic disease beyond its secondary branches.

The common trunk of the bifurcated graft should be short, approximately 3 or 4 cm. This facilitates coverage of the graft with retroperitoneal tissue to separate the anastomosis from the overlying viscera. This also reduces the chance of kinking the graft limbs by decreasing the angle at the bifurcation.

Proximal anastomosis on the aorta is performed just distal to the origins of the renal arteries. The infrarenal aorta can be affected by disease progression from atherosclerosis and later compromise graft patency.

SELECTED REFERENCES

1. Zarins C, Gewertz B: Atlas of Vascular Surgery, 2nd ed. Philadelphia, Churchill Livingstone, 2005. 2. Valentine RJ, Wind GG: Anatomic Exposures in Vascular Surgery, 2nd ed. Philadelphia, Lippincott

Williams & Wilkins, 2003.

3. Moore WS: Vascular and Endovascular Surgery: A Comprehensive Review, 7th ed. Saint Louis, Saunders, 2006.

4. Zelenock GB, et al: Mastery of Vascular and Endovascular Surgery, 4th ed. Philadelphia, Lippincott Williams & Wilkins, 2005.

C H A P T E R 84

CAROTID ENDARTERECTOMY

Lois A. Killewich

STEP 1: SURGICAL ANATOMY

The carotid sheath and its contents—including the extracranial carotid artery, the internal jugular vein, and the vagus nerve—are located in the anterior triangle of the neck, which is bounded by the mandible, the midline, and the strap muscles. Successful carotid endarterectomy requires a thorough understanding of the anatomy of the anterior triangle, in particular because a number of cranial nerves are located in the area and are easily injured if care is not taken to identify and preserve them.

Figure 84-1 demonstrates the structures found in the anterior triangle of the neck. The venous anatomy is variable. In the most commonly found situation, the anterior facial tributary crosses anterior to the carotid arteries at the level of the common carotid bifurcation and joins the internal jugular vein.

The common carotid artery in the cervical region has no branches other than the external and internal carotid arteries. The internal carotid artery in this region also has no branches, except in rare situations. The persistent hypoglossal artery, a fetal structure that normally regresses before birth, is found in less than 0.1% of cases. The external carotid artery most commonly has three branches in the immediate region of the carotid bifurcation—the superior thyroid, lingual, and facial—although this anatomy can also be highly variable (see Figure 84-1, A and B).

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STEP 2: PREOPERATIVE CONSIDERATIONS

Standard indications for carotid endarterectomy include a stenosis of 50% or higher in a patient with a transient ischemic attack or stroke thought to originate from internal carotid artery plaque and 60% to 80% stenosis in an asymptomatic patient. Recurrent stenosis, stenosis secondary to radiation therapy, and high-risk patients with severe coronary artery or pulmonary disease are often treated with carotid stenting.

Carotid endarterectomy can be safely performed with the patient under general, regional, or local anesthesia. Whichever technique is selected, a method must be used to ensure that the patient has adequate intracranial blood flow while flow through the operated internal carotid artery is interrupted. When local or regional anesthesia is used, the patient’s neurologic status can be monitored by assessing contralateral motor function and, in some cases, speech. Many surgeons use a squeeze toy in the contralateral hand and instruct the patient to squeeze the toy to demonstrate that neurologic function is maintained when the carotid arteries are clamped. If general anesthesia is used, neurologic function can be monitored by measuring carotid back-pressure (the internal carotid artery pressure with the common and external carotid arteries; a mean arterial pressure of 25 to 40 mm Hg is sufficient), by using electroencephalographic or evoked potential monitoring, or by using routine carotid shunting.

Patients should be administered 325 mg of aspirin by mouth daily, starting before the surgical procedure. In selected instances, clopidogrel (75 mg by mouth daily) may be used in addition to or in place of aspirin.

STEP 3: OPERATIVE STEPS

1.INCISION

The head should be positioned with the neck hyperextended and rotated to the contralateral side. This can be facilitated by placement of a rolled sheet between the shoulder blades. The standard incision is placed along the medial border of the sternocleidomastoid muscle. The superior aspect should be extended posteriorly to the ear to ensure against division of the greater auricular nerve (Figure 84-2, A).

For a more cosmetically pleasing result, the incision can be created in a mid-cervical skin crease, with an extension superiorly toward the ear (Figure 84-2, B).