The word carotid is derived from the Greek term karotide or karos meaning to stupefy or plunge into deep sleep. The term was applied to the arteries of the neck because compression of these vessels during combat produced stupor or sleep. The 31st metope from the south side of the Parthenon in Athens demonstrates that the ancient Greeks were aware of the significance of the carotid artery.
Over the centuries since the early Greeks, many noted surgeons have advanced the science of carotid artery surgery. The first carotid endarterectomy, or cleaning out of the cholesterol plaque in the wall of the artery, was performed in 1953, by Dr. Michael DeBakey. Today, it ranks as the most frequently performed peripheral vascular surgical procedure in the United States.
Cerebrovascular disease is the third leading cause of death in the western world, accounting for 9% of all deaths in the United States. About 450,000 new strokes occur each year in this country, and nearly 75% result from thromboembolic (blood clot) disease. Two major prospective studies were mounted in the 1980s to evaluate the role of surgery in the treatment of symptomatic carotid artery disease. These trials were designed to test surgery against conventional medical therapy.
Conventional medical therapy was defined as control and treatment of those risk factors thought to be of importance in the pathogenesis of atherosclerosis, or plaques, of the carotid artery and their contribution to the development of ischemic cerebrovascular events.(Strokes, TIA’s). The drug aspirin was used in both studies. Given the results of these two trials, it is certain now that carotid surgery is more effective than conventional therapy in symptomatic patients with stenosis, or narrowing of the artery in the range of 70% to 99%. It also appears that the gradient of risk increases as the degree of stenosis increases; that is, stenosis of 90% to 99% is more dangerous than is stenosis of 70% to 79%.
In the NASCET study, the combined morbidity and mortality rate during surgery and postoperatively was 2.1%. The surgical mortality rate was 0.6%. The medically treated patients had a stroke rate of 3.3% and a mortality rate of 0.3% for the first 30 days. For the patient that had surgery, the cumulative risk of stroke at 2 years was 9%. For the medically treated patients, the cumulative risk of stroke was 26%. This represented a risk reduction of 17% when patients were treated with surgery. For major or fatal stroke, the risk for the surgically treated patients was 2.5% compared to 13.1% for the medically treated patients. This represents an absolute risk reduction of 10.6%.
Both studies came to the conclusion that patients with greater than 70% stenosis had a significantly reduced stroke rate if they were offered surgery instead of relying on medical therapy. Given the results of these two studies, it is certain now that carotid surgery is more effective than medical therapy for symptomatic stenosis greater than 70%.
Asymptomatic patients are a different sunset based on population studies. A recently published trial on asymptomatic carotid stenosis reported that 50% of patients had a stroke without any warning symptoms. A bruit, or a noise, can occur in the carotid artery with stenosis as minimal as 20 to 30%. It is therefore important that physicians listen to the neck of patients to see if a noise can be heard in the artery as part of a routine physical exam. With patients with stenosis of less than 50%, the annual rate of stoke is minimal. As the area of reducing stenosis increases from 50% to 70%, and then to greater than 75%, the incidence of symptoms called TIA’s or transient ischemic attacks increases significantly. A 75% stenosis is a threshold lesion for considering surgical intervention in asymptomatic patients.
The most common clinical situation is the patient referred by his family doctor with a cervical bruit or noise in the carotid artery who either has no symptoms or intermittent episodes of nonspecific symptoms such as dizziness, visual changes or lightheadedness. These patients should undergo a carotid ultrasound test. If the results show a greater than 75% stenosis, a digital subtraction angiogram in which dye is put in the artery and a cine x ray test performed should be considered. Patients with significant peripheral vascular disease have significant carotid disease in 33% of patients, 6.8% of patients with coronary artery disease, and 5.9% with significant risk factors.
Patients with significant stenosis as outlined above by Doppler exam or angiography should be considered for surgery. Patients with significant coronary artery disease should be further evaluated by dobutamine echocardiogram and EKG.
The procedure is called carotid endarterectomy and is usually performed with the patient awake under cervical neck block or general anesthesia. The surgery takes 30 to 40 minutes to complete and the patient is released from the hospital the next day.
The expected mortality rate for surgery is small and the comorbid complication rate is small.
If severe stenosis is found on both sides of the neck, the most severe side is usually operated on first and the opposite side a month later.
Most patients are back to work in 10 to 12 days with only a small incision on their neck to show their friends.