Usefulness of ultrasonologic examinations on microemboli and hemodynamics for the prevention of complications associated with carotid endarterectomy.

The purpose of this study was to investigate the correlation between plaque characteristics and microembolic signals using transcranial Doppler during endarterectomy. We also investigated successive changes of the pulsality index and average flow velocity in the ipsilateral middle cerebral artery. The subjects of the study were 28 patients who underwent carotid endarterectomy. Transcranial Doppler monitoring was performed before, during, and after carotid endarterectomy. Plaques were classified into 3 types by the brightness on B-mode ultrasonogram. In addition, extracted specimens were macroscopically examined to observe the presence of plaque ulcerations and intraplaque hemorrhages. The blood flow of the internal carotid artery in all cases was measured intraoperatively using an electromagnetic flow meter. The patients who had plaque ulcerations showed significantly more microembolic signals preoperatively than those who had intraplaque hemorrhage during an endarterectomy. Flow velocity in the ipsilateral middle cerebral artery increased immediately after the operation and reached its peak on the day after the operation. The pulsatility index reached its peak on the day of the operation, and remained at this point until 2 days after the operation. We conclude that (1) the patients who had intraplaque hemorrhage had a high risk for embolization of manipulation during dissection and carotid endarterectomy, and (2) systemic management, including that of blood pressure under transcranial Doppler monitoring, was necessary for at least 3 postoperative days in order to prevent hyperperfusion.