UNSTABLE CAROTID PLAQUES - PREOPERATIVE IDENTIFICATION AND ASSOCIATION WITH INTRAOPERATIVE EMBOLIZATION DETECTED BY TRANSCRANIAL DOPPLER

Objectives: To investigate whether unstable carotid plaque characteris tics, as determined by preoperative colour Duplex ultrasonography (CDU ) and postoperative histological examination, were associated with par ticulate embolisation, detected by transcranial Doppler (TCD), during the initial dissection of the carotid bifurcation during carotid endar terectomy(CEA). Design: A prospective, consecutive study was undertake n of 50 patients undergoing carotid endarterectomy(CEA). Setting: Leic ester Royal Infirmary, Leicester, U.K. Materials: Carotid plaques were assessed preoperatively using CDU. Intraoperative TCD monitoring of t he ipsilateral middle cerebral artery was performed using a Scimed 2MH z TCD. Carotid plaques removed at operation were processed histologica lly and multiple sections assessed microscopically. Chief outcome meas ures: Plaque composition tons classified ultrasonically and histologic ally according to the Gray-Weale classification and plaque surface cha racteristics were graded according to a five point classification. TCD detected emboli were identified and counted dui during the initial di ssection of the artery. Main results: Particulate embolisation occurre d in nine patients. Histologically, embolisation was associated with u lcerated plaque in three cases and ulcerated plaque with associated th rombus in six cases (p = 0.0005). However, the ability of CDU to posit ively predict embolisation based on the correct identification of an u nstable plaque surface was only 25%. Conclusions: Embolisation during dissection is strongly associated with ulcerated plaque with associate d thrombus. CDU is unable to reliably identify these characteristics p reoperatively. Intraoperative TCD monitoring can detect potentially ha rmful embolisation during this stage enabling surgical technique to be modified appropriately.