Blood flow velocity in the middle cerebral artery, determined by transcranial Doppler ultrasonography, was monitored during 31 carotid endarterectomies. Electroencephalogram (EEG) was also monitored, and regional cerebral blood flow (rCBF) was measured. The relation between rCBF and mean velocity was dependent on the rCBF level; the correlation was strong if rCBF was less than 20 ml/100 g/min but weak if rCBF was greater than that level. Ipsilateral EEG suppression was related to a rCBF threshold of 9 ml/100 g/min and to a mean velocity threshold of 15 cm/sec; the rCBF threshold was more specific for EEG change. Postischemic hyperemia was evident in measurements of mean velocity but not of rCBF. These disparities between mean velocity and rCBF seemed to be due to three factors: 1) disproportionately high mean velocity in patients with stenosis of the middle cerebral artery, 2) a nonlinear relation between mean velocity and rCBF, and 3) the anatomically different regions of the brain in which mean velocity and rCBF are measured. The velocity measurement appeared to be relatively more sensitive than rCBF to hemodynamic events in the corpus striatum and internal capsule. Because blood velocity is influenced by blood vessel diameter, there is uncertainty about its relation to cerebral blood flow. We address this problem by comparing MCA blood velocity with simultaneous measurements of regional cerebral blood flow (rCBF) during carotid endarterectomy.
Subjects and MethodsThirty-one carotid endarterectomies were performed in 24 men and six women, all white, aged 48-81 years; one man underwent bilateral operations on separate occasions. The indications for surgery included a history of transient ischemic attacks or stroke and angiographic demonstration of >50% stenosis of the origin of the internal carotid artery.From the
This series shows that patients at high risk can undergo carotid endarterectomy with stroke rates equivalent to the rates of patients at low risk. The cardiac morbidity rate may be increased in the high-risk group. Carotid stenting is unlikely to offer any improvement in stroke risk as compared with carotid endarterectomy, but stenting may reduce non-stroke morbidity rates associated with some high-risk cases.
PTAS carries a higher neurologic risk and requires more monitoring than CEA in the treatment of patients with carotid artery stenosis with LRA. The proposed benefit for the use of PTAS to avoid general anesthesia cannot be justified when compared with CEA performed with LRA.
After evaluating hospital charges, PTAS for the treatment of carotid stenosis cannot currently be justified on the basis of reduced costs alone. With future cost-containing measures, total hospital charges can be reduced in both groups.
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