Embolic cerebral ischemia in carotid surgery: a model for human embolic stroke?

BACKGROUND

If carotid endarterectomy (CEA) is a clinical model of embolic stroke, then it should be possible to determine the relevance of embolus size and of the total quantity of embolic material (embolus load) for ischemic stroke.

MATERIAL/METHODS: Thirty-one patients underwent a total of 33 CEAs. Diffusion weighted imaging (DWI) was performed on the day before and after CEA. A new hyperintense signal on the postoperative DWI was considered a new ischemic lesion. Intraoperatively detected microembolic signals (MES) were quantified (in cm) by multiplying embolus velocity by the embolus presence within the Doppler sample volume. With this relative index, emboli were classified into small (<0.56 cm), medium-sized (0.56-1.12 cm) and large (1.12-1.70 cm).

RESULTS

For each category of embolus size, embolus load (in cm/minute) was expressed as the sum of all quantified emboli divided by minutes of CEA duration. By logistic regression analysis, the occurrence of a new ischemic lesion was related to an embolus load with medium-sized emboli (without lesion, 0.029 cm/minute; with lesion, 0.157 cm/minute; p=0.018), and with large emboli (without lesion, 0.015; with lesion, 0.055; p=0.038), but not to an embolus load with small emboli or the largest embolus per CEA.

CONCLUSIONS

The leading reason for cerebral ischemia in CEA is multiple embolism with emboli of medium and large size. This conceptual model may also apply to carotid artery disease.