To investigate whether transcranial Doppler (TCD) monitoring can identify patients at risk of hyperperfusion following carotid endarterectomy (CEA), the hemodynamics of CEA were investigated in 10 patients by electromagnetic flowmetry, digital subtraction angiography (DSA) and stable Xe-computed tomography (CT) . The continuous measurement of flow velocity (FV) and pulsatile index (PI) in the middle cerebral artery (MCA) was performed by TCD every day, starting pre-CEA and continuing until 7 days after CEA. Cerebral circulation time (CCT) was calculated during intra-arterial DSA with morphological evaluation. Cerebral blood flow (CBF) on the MCA territory was measured by stable Xe-CT, and cerebrovascular reserve capacity (CVRC) was also calculated by acetazolamide activation. Ten patients were divided into two groups depending on their risk factors for hyperperfusion after CEA (i.e. ratio of carotid stenosis, collateral circulation, stump pressure and carotid blood flow) . Reduced CVRC and delayed CCT investigated preoperatively suggested increased cerebrovascular resistance (CVR) in the high-risk group. In the postoperative study, increased FV and PI were both observed in the high-risk group 7 days after surgery, with significant differences in the FV and PI between the high-risk group and low-risk group observed on the second day after CEA. It is important to know the conditions of CVR and CBF in order to understand hyperperfusion after CEA. The continuous measurement of PI and FV along with preoperative CCT may be a useful method to prevent severe complications caused by hyperperfusion.
