Carotid stenosis is caused by plaque formation that can lead to (1) narrowing of both carotid arteries; and (2) emboli, both of which can result in transient ischemic attacks and stroke. Carotid endarterectomy (CEA) is a prophylactic procedure used to decrease the risk of stroke in patients with significant atherosclerotic occlusive disease of the carotid arteries. In asymptomatic patients, the risk of stroke is 5% per year, but in symptomatic patients with a history of a TIA, the risk is doubled at 10% per year.
The primary perioperative risks associated with CEA are stroke and myocardial infarction. Perioperative mortality secondary to cardiac complications is 1%–4%, and perioperative morbidity secondary to neurological events is 4%–10%. Given that this is a preventative procedure, the benefits must outweigh the risks. Surgical intervention is indicated in patients who are medically optimized with symptomatic severe carotid stenosis of greater than 70%, as shown in the NASCET study, and may be considered for symptomatic patients with greater than 50% stenosis. The Asymptomatic Carotid Surgery Trial showed asymptomatic patients with greater than 60% stenosis may also benefit from combined medical and surgical therapy, but this remains controversial.
During this procedure, the common and internal carotid arteries are dissected to expose and remove the atherosclerotic plaque. In order to achieve this, the carotid arteries are cross-clamped, both proximally and distally, for a period of time. This can lead to cerebral ischemia in patients with inadequate collateral blood flow. In these patients, cerebral perfusion can be maintained using a carotid shunt; however, the shunt itself can lead to cerebral emboli and arterial dissection.
The primary goals of an anesthesiologist is to maintain cerebral blood flow and avoid cerebral and coronary ischemia during this procedure; additional goals include blunting the surgical stress response, managing hemodynamics, and rapid emergence from anesthesia in order to perform an early neurological assessment.
Patients presenting for carotid endarterectomy are commonly elderly with multiple co-morbidities. Special attention should be given to the cardiac evaluation, as these patients typically have significant coronary artery disease. Preexisting neurologic deficits should be noted. Independent risk factors for poor outcome (i.e., stroke, MI, or death) at 30 days postoperative include age over 80 years, major cardiac disease, and chronic obstructive pulmonary disease. Patients should continue all cardiac medications up to the morning of surgery. Both asymptomatic and symptomatic patients are recommended to start aspirin prior to the CEA, and symptomatic patients should also be on a statin medication.
In addition to the standard ASA monitoring, intraoperative arterial blood pressure monitoring is essential. The EKG should focus on leads II and V5 particularly for rhythm or ST segment changes. Central access and a pulmonary arterial catheter are often unnecessary if adequate peripheral access is obtained.
CEA is an absolute contraindication in asymptomatic complete carotid artery occlusion. Relative contraindications ...