Anesthesia for carotid endarterectomy
Atherosclerosis is a systemic disorder that manifests itself as vascular occlusive or aneurysmal disease in one or more regional circulations. Patients with vascular occlusive disease of the carotid or vertebral arteries are therefore likely to have occlusive disease in other circulations, the most important of which is the coronary circulation (Table 1).1, 2 In the development of carotid endarterectomy operations, innovations in anesthetic and surgical techniques naturally focused on the prevention of cerebrovascular accidents, the prime objective of the operation. However, it soon became apparent that almost half the mortality from this operation was the result of heart disease, particularly myocardial infarction. Despite this, it has been recognized only recently that some methods designed to protect the brain from ischemic damage during operation may in fact be inducing myocardial ischemia.3 Therefore, a critical appraisal of methods of “cerebral protection” is warranted.
Cerebral protection during carotid end-arterectomy in its most general sense included two different approaches (Table 2). The objective of the first was to increase the tolerance of the brain to ischemia during carotid cross-clamping, obviating the need for a shunt. The second consisted of devising methods for diagnosis of cerebral ischemia during cross-clamping so that an intraluminal shunt could be inserted only when indicated. Some methods have never had an adequate clinical trial, e.g., large doses of thiopental. Other methods, e.g., shunting of all patients, stump pressures or electroencephalogram (EEG), have strong advocates whose positions are supported by their results.
The present situation is epitomized by the recent report . . .