Carotid Endarterectomy for Ophthalmic Manifestations: What Do We Do?

In the use of carotid endarterectomy (CE), the Department of Clinical Neurological Sciences in London, Ontario, follows the guidelines derived from the North American Symptomatic Carotid Endarterectomy Trial (1), which was organized at our institution. In our hospital, three surgeons perform between 100 and 110 CEs and between 10 and 20 cervical carotid stents each year. Most patients are referred from the southwestern Ontario region. Our complication rate for CE is 1% for death and 1% for major stroke. This is how we currently manage patients with the four major ophthalmic indications for CE: 1) Transient monocular visual loss (TMVL): These patients undergo carotid Doppler ultrasound and transesophageal echocardiography (TEE). TEE is preferred over transthoracic echocardiography because TEE allows a better look not only at the left atrium, but also the ascending aorta, which is often an unrecognized source of emboli. If the carotid ultrasound shows hemodynamically significant stenosis, the next step would be cerebral angiography. More recently, contrast-enhanced magnetic resonance angiography (MRA) and computed tomographic angiography (CTA) have been used with increasing frequency. The reason for this shift is that MRA and CTA are less dangerous because they do not involve catheterization and are also cheaper and quicker. If the echocardiogram test shows a plausible source of emboli, the patient would be anticoagulated with warfarin. Eighty-one milligrams of aspirin per day may be added if atherosclerotic carotid arteries were also found, although this increases the risk of bleeding and must be individualized. If the internal carotid artery shows more than 70% stenosis, CE is offered to the patient. If a cardiac or aortic source has been found by echocardiography and the patient has been anticoagulated, the anticoagulation would be stopped to do the CE and then started up again after the surgery. Carotid stenting may be offered if there are significant medical problems precluding CE. If there is 50%-70% stenosis of the internal carotid artery, CE is performed only in men who have also suffered one or more hemispheric transient ischemic attacks, particularly if the transient ocular ischemic attack has occurred within 48 hours. In the 50%-70% stenosis group, less benefit has been shown for women, and surgery is seldom recommended. If there is less than 50% internal carotid artery stenosis, we do not perform CE. 2) Central retinal artery occlusion (CRAO): This condition is also initially evaluated with carotid ultrasound and TEE, as well as a sedimentation rate (to exclude temporal arteritis). Management guidelines for CE are the same as for TMVL. 3) Asymptomatic Hollenhorst plaque (cholesterol retinal emboli): CE is not performed, irrespective of the degree of internal carotid artery stenosis. Such patients undergo TEE to exclude a cardiac or aortic source of emboli and a carotid ultrasound if the TEE is negative. We do not operate on these asymptomatic patients because the stroke rate is very low and there is no difference between medical treatment and CE. 4) Ocular ischemic syndrome (OIS): Patients with OIS typically have severe internal carotid artery stenosis or complete occlusion. Those with more than 70% stenosis are offered CE because it may help in stopping the progression of the ocular ischemia. CE is not offered for total carotid artery occlusion because the success rate of opening the artery in an occlusion is low and there is a high complication rate of stroke. Acknowledgment The authors gratefully acknowledge the help of Dr. Don Lee and Dr. Gary Ferguson.

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