Association of intraoperative transcranial Doppler monitoring variables with stroke from carotid endarterectomy

Background and Purpose-The outcomes of carotid endarterectomy (CEA) are, in addition to patient baseline characteristics, highly dependent on the safe ty of the surgical procedure. During the successive stages of the operation , transcranial Doppler (TCD) monitoring of the middle cerebral artery (MCA) was used to assess the association of cerebral microembolism and hemodynam ic changes with stroke and stroke-related death. Methods-By use of data pooled from 2 hospitals in the United States and the Netherlands, including 1058 patients who underwent CEA, the association of various TCD emboli and velocity variables with operative stroke and stroke -related death was evaluated by univariable and multivariable logistic regr ession analyses in combination with receiver operating characteristic (ROC) curve analyses. The impact of basic patient characteristics, such as age, sex, preoperative cerebral symptoms, and ipsilateral and contralateral inte rnal carotid artery stenosis, on the prediction of operative stroke was als o evaluated. Results-We observed 31 patients with ischemic and 8 patients with hemorrhag ic operative strokes. Four of these patients died. Emboli during dissection (odds ratio [OR] 1.5, 95% CI 0.8 to 2.9) and wound closure (OR 2.3, 95% CI 1.2 to 4.4) as well as greater than or equal to 90% decrease of MCA peak s ystolic velocity at cross-clamping (OR 3.3, 95% CI 1.3 to 8.5) and greater than or equal to 100% increase of the pulsatility index of the Doppler sign al at clamp release (OR 7.1, 95% CI 1.4 to 35.7) were independently associa ted with stroke. The ROC area of this model was 0.69. Of the patient charac teristics, only preoperative cerebral ischemia (OR 1.9, 95% CI 1.0 to 3.7) and greater than or equal to 70% ipsilateral internal carotid artery stenos is (OR 0.5, 95% CI 0.2 to 0.9) were associated with stroke. Adding these pa tient characteristics to the model, the area under the ROC curve increased to 0.73. Conclusions-In CEA, TCD-detected microemboli during dissection and wound cl osure, greater than or equal to 90% MCA velocity decrease at cross-clamping , and greater than or equal to 100% pulsatility index increase at clamp rel ease are associated with operative stroke. In combination with the presence of preoperative cerebral symptoms and greater than or equal to 70% ipsilat eral internal carotid artery stenosis, these 4 TCD monitoring variables rea sonably discriminate between patients with and without operative stroke. Th is supports the use of TCD as a potential intraoperative monitoring modalit y to alter the surgical technique by enhancing a decrease of the risk of st roke during or immediately after the operation.