Intra-operative monitoring and internal shunts: are they necessary in carotid endarterectomy?

287 tion of stroke — the viscosity factor. blood flow, haematocrit and viscosity in subjects with a high oxy-THE purpose of carotid endarterectomy is to reduce the risk of future stroke. Unless the incidence of stroke related to the surgery is extremely low, there is little likelihood of benefit for patients. It is widely held that clinically significant ischemia is a relatively common sequel to temporary carotid clamping. 1 "* As a result, there has been great emphasis since the inception of carotid endarterectomy 5 on the development of methods to protect the brain from ischemic insult, and to identify those patients at particular risk. The use of local or regional anaesthesia, which undoubtedly exaggerates the risk of ischemia, has given way in most clinics to the use of general anaesthesia which increases the tolerance of the brain to temporary carotid occlusion by enhancing cerebral blood flow, reducing cerebral metabolic requirements, and improving the control of arterial gas concentrations. 6 However, anxiety persists regarding the possibility of intra-operative stroke directly attributable to critical reductions in flow during cross-clamping. The result is a voluminous and generally uncritical clinical literature in which prominent advocates offer contradictory advice as to the necessity and best means of affording cerebral protection by the use of intra-operative monitoring and internal shunts. These are more than minor technical matters for the surgeon, and a rational resolution of the controversies raised is highly desirable. The expectation of perfect results from carotid endarterec-tomy is increasingly great, and the prospect of litigation , however unjustified, is constantly present. If the likelihood of hemodynamic ischemia is not as great as generally supposed, then undue emphasis has been gen affinity haemoglobin variant. A: Treatment of acute cerebral ischemia with low molecular dextran. Results of a retrospective study. A controlled trial of Ancrod in the treatment of acute ischemic stroke. Clinical Hemorheology (in press) given to this aspect of the surgical problem and perhaps insufficient emphasis to patient selection, anaesthetic technique, and the importance of meticulous surgery. As well, certain assumptions regarding the ischemic tolerance of the brain may be brought into question. Internal shunts are not without their own risks, and may provide the surgeon with a false sense of security. Their unwarranted use will expose the patient needlessly to the risk of embolization of athero-matous debris, or intimal dissection and acute occlu-sion, and may limit the exposure of the plaque and …