SERIAL IMAGING OF THE CAROTID BIFURCATION AND CEREBROVASCULAR RESERVEAFTER CAROTID ENDARTERECTOMY

A radioisotopic method of quantifying mean cerebral transit time was u sed to assess the immediate effects of carotid endarterectomy on cereb rovascular reserve (CVR) in 69 patients. In addition, serial postopera tive data were acquired on CVR, clinical status and non-invasive imagi ng of the internal carotid arteries in 56 patients over a period of 6- 48 (median 24) months. Twenty-one patients (30 per cent) had preoperat ive evidence of impaired CVR in the symptomatic hemisphere. Within 4 d ays of surgery, however, reserve had returned to normal in 17 of the 2 1 patients. During follow-up, four of the 56 patients developed recurr ent stenosis ( > 50 per cent) or occlusion of the artery operated on b ut only two of these had impairment of CVR and none was symptomatic. T hree patients suffered recurrent transient ischaemic attacks (TIAs) bu t none had recurrent internal carotid artery disease or impaired CVR. One patient suffered a TIA in the territory of the non-operated artery during follow-up in association with disease progression and CVR impa irment. However, the TIA preceded recognition of either of these chang es. Twelve other patients had (or developed) stenosis ( > 50 per cent) in the non-operated artery during follow-up but none was symptomatic or developed impairment of CVR. Although assessment of CVR provided us eful information on the frequency of haemodynamic compromise before ca rotid endarterectomy and on the natural history of disease progression , neither serial assessment of reserve nor non-invasive imaging of the carotid bifurcation influenced clinical practice during follow-up.