Cerebrovascular resistance and blood flow velocity changes after carotid endarterectomy

BACKGROUND: To study the pattern of cerebral blood flow velocity and cerebral resistance changes after carotid endarterectomy. PATIENTS AND METHODS: In 81 patients (mean age +/- SD, 64 +/- 8 years) with unilateral carotid endarterectomy (CEA) the systolic, diastolic and mean blood velocities, and the pulsatility index (PI) were recorded in both middle cerebral arteries preoperatively and repetitively postoperatively with the use of transcranial Doppler ultrasound (TCD). RESULTS: In the middle cerebral artery ipsilateral to CEA mean blood velocity was increased 6 hours (64 +/- 25 cm/sec; p < 0.005) and 7 days (54 +/- 15 cm/sec; p < 0.05) after CEA and had returned to the preoperative level (49 +/- 11 cm/sec) after 3 months. Compared to preoperatively (0.86 +/- 22), the PI was significantly increased at 6 hours examination (1.03 +/- 23, p < 0.005), and remained increased thereafter. A pathologically increased mean blood velocity (> 83 cm/sec) 6 hours after CEA occurred in 11 patients, two of them developed a slight hyperperfusion syndrome. In the contralateral middle cerebral artery, only the diastolic blood velocity showed significant changes (preoperatively, 35 +/- 12 cm/sec; 3 months after CEA, 33 +/- 8 cm/sec; p < 0.05). CONCLUSIONS: Using TCD, hemodynamic changes occur predominantly in the middle cerebral arteries ipsilateral to CEA. Early postoperative TCD studies may be of help to identify patients at risk to develop a hyperperfusion syndrome.