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

Incision for carotid endarterectomy

A

Alternative incision for carotid

endarterectomy

B

FIGURE 84–2

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2. DISSECTION

After the incision is created, the platysma muscle is divided with electrocautery parallel to the skin incision. If the cervical skin crease incision is used, flaps must be created deep

to the platysma muscle and extended superiorly toward the mandible and inferiorly toward the clavicle. This can be accomplished using a combination of electrocautery and blunt dissection, which enlarges the operative field to allow the dissection to be continued in standard fashion.

The dissection is deepened along the medial border of the sternocleidomastoid muscle until the carotid sheath is identified (Figure 84-3). Small arteries and veins, which extend across the dissection line to supply the sternocleidomastoid muscle, are cauterized. The

carotid sheath is opened using sharp dissection. (I prefer 7-inch Potts-Smith scissors, but either Metzenbaum or tenotomy scissors can also be used.)

Once the sheath is opened, the dissection of the carotid arteries is completed using scissors (Figure 84-4). The common carotid artery is dissected first, followed by the external carotid artery and the superior thyroid artery. It is generally not necessary to continue the

dissection of the external carotid artery beyond the second branch, which may be the lingual artery or a combined trunk of the lingual and facial arteries. Once this dissection is completed, anticoagulants are administered to the patient systemically, usually with unfractionated heparin at a dose of 100 units/kg body weight. The dissection of the internal carotid artery is completed while the heparin is circulating, which provides some measure of protection from embolization of plaque from the internal carotid artery during the dissection. When the dissection is completed, the arteries are controlled with vessel loops, sutures, or Rumel tourniquets.

3. DETERMINING THE NEED FOR INSERTION OF A SHUNT

The dissected vessels are clamped so that the need for shunting can be determined. Except in the case of back-pressure monitoring, the internal carotid artery beyond the area of plaque is clamped first to prevent embolization into the intracranial circulation. I prefer a Gregory bulldog for clamping of the internal carotid artery; other choices include a Yasargil aneurysm clip or a small vascular clamp such as a Karchner. The common and external carotid arteries are also clamped with small vascular clamps; branches of the external carotid artery can be controlled with Yasargil clips, hemoclips, or Pott’s knots.

If back-pressure monitoring is used to determine the need for shunting, the internal carotid artery is not clamped. A 19-gauge butterfly needle or a small angiocatheter connected to pressure tubing is inserted into the artery distal to the plaque. It is imperative that this tubing be flushed thoroughly with heparinized saline before insertion to prevent introduction of air into the carotid, and hence intracranial, circulation. The back-pressure is then measured; I use a cutoff of 40 mm Hg mean arterial pressure to determine the need for insertion of a shunt.

Shunt

Clamp

A

Internal carotid artery

Shunt

Plaque

Common carotid artery

Shunt

B C

FIGURE 84–6

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4. ENDARTERECTOMY

The endarterectomy is performed using a Freer elevator (Figure 84-7). This is inserted into the plane between the circular muscle fibers and the adventitia, beginning in the common carotid artery. The adventitia is pushed away from the muscle fibers extending distally. When the end of the plaque is reached, gentle pressure on the plaque pulling inferiorly and toward the contralateral side will usually separate it from the normal distal artery. Alternatively, a Beaver blade can be used to divide the plaque from the normal artery. The plaque can then be peeled off transversely. The remainder of the plaque is removed from the internal and common carotid arteries in a similar fashion.

The plaque is removed from the external carotid artery using an eversion technique. The adventitia of the artery is everted by the surgical assistant, while the plaque and circular muscle fibers are dissected away circumferentially by the surgeon using the Freer elevator. The plaque is avulsed at its natural end.

Once the specimen is removed, any remaining debris or circular smooth muscle fibers can be removed by scraping transversely with the Freer elevator or a Kittner sponge. If the edge of the distal endpoint has been lifted up, it should be tacked down with 7-0 Prolene as shown in Figure 84-8. The proximal endpoint does not need to be tacked because it will be pushed into the adventitia of the artery by the blood flow.

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It is the current standard of care to close the arteriotomy with a patch, as shown in Figure 84-9. Prosthetic patches are used most commonly, either Dacron or expanded polytetrafluoroethylene (ePTFE). Before the final closure, flushing should be performed

with care taken to ensure that the internal carotid artery is flushed last. If a shunt has been used, this should be removed before flushing. Once flushing is completed, the inner surface of the endarterectomized vessel is irrigated copiously with heparinized saline, and the closure is completed. The internal carotid artery is then back-bled into the common carotid artery and gently clamped across its origin. (I use DeBakey pickups.) Flow is then restored through the common carotid artery into the external carotid artery, providing an additional means for flushing any remaining debris or air, or both, into the external carotid artery rather than the intracranial circulation. After 10 seconds, flow is restored through the internal carotid artery.

It is possible to perform an intraoperative duplex ultrasound or angiogram to check the operative result, although this has not been my practice.

FIGURE 84–9

5. CLOSING

The heparin can be reversed using protamine, if necessary. The platysma is closed with running 3-0 Vicryl. The skin is closed with 4-0 Monocryl and surgical glue. In some cases, I place a drain in the surgical site, bringing it out through a lateral skin stab incision. If a drain is used, it should be removed on the morning of the first postoperative day.

STEP 4: POSTOPERATIVE CARE

Aspirin or clopidogrel, or both, should be continued daily throughout the postoperative period. Most surgeons would continue at least one of these medications for life.

Drains should be removed on the first postoperative day.

Hematoma in the neck can cause respiratory compromise. If a rapidly expanding hematoma or any evidence of respiratory compromise exists, the patient should be return emergently to the operating room for evacuation and control of the hemorrhage.

Cranial nerves, which can be injured during the surgery, include the vagus, recurrent laryngeal, external branch of the superior laryngeal, hypoglossal, and marginal mandibular branch of the facial. Vagal and recurrent laryngeal injuries result in hoarseness secondary to vocal cord paresis or paralysis in the midline. A patient who is hoarse after carotid surgery should have a vocal cord assessment, in particular if contralateral carotid surgery is contemplated. Bilateral vocal cord paralysis requires emergent intubation or tracheostomy, or both. Injury to the external branch of the superior laryngeal nerve results in loss of the resonance and high tones in the voice. Hypoglossal nerve injury results in deviation of the tongue to the side of the injury; this can result in reduced ability to move food around in the mouth and drooling. Injury to the marginal mandibular nerve results in pulling of the inferior aspect of the mouth in a direction away from the injury. In general, hypoglossal and marginal mandibular nerve injuries are temporary.

Patients, particularly those who undergo carotid endarterectomy under general anesthesia, can experience blood pressure instability after surgery. Most commonly, this is manifested as hypertension, which can be treated with intravenous medication such as nitroprusside. Hypotension, which is less common, can be treated with medication such as phenylephrine.

The most feared complication after carotid endarterectomy is stroke, which can occur intraoperatively or postoperatively. Intraoperative strokes are usually treated with anticoagulant or antiplatelet therapy postoperatively. Postoperative strokes (in other words, the patient’s neurologic examination is normal immediately after surgery, but changes within the first

12 to 24 hours) should be treated by emergent return to the operating room because of the possibility of carotid thrombosis. This can be treated with thrombectomy and possibly thrombolytic therapy.

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STEP 5: PEARLS AND PITFALLS

Injury to the marginal mandibular nerve can be avoided by not retracting the mandible too strongly.

Division of an unusually large ansa cervicalis crossing anterior to the carotid bifurcation will usually result in hoarseness. Avoid cutting it if possible.

Because of the risk of infection and carotid rupture, a tracheostomy adjacent to a fresh carotid endarterectomy is a disaster and should be avoided at all costs.

SELECTED REFERENCES

1. North American Symptomatic Carotid Endarterectomy Trial Collaborators: Benefit of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med 1991;325:445-453.

2. North American Symptomatic Carotid Endarterectomy Trial Collaborators: Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. N Engl J Med 1998;339:1415-1425.

3. Executive committee for Asymptomatic Carotid Atherosclerosis Study: Endarterectomy for asymptomatic carotid artery stenosis. JAMA 1995;273:1421-1428.

4. Ricotta JJ Jr, Malgor RD: A review of the trials comparing endarterectomy and carotid angioplasty and stenting. Perspect Vasc Surg Endovasc Ther 2008;20:299-308.