The finding of thrombus at carotid endarterectomy and its relationship to the timing of surgery.

The clinical, angiographical, operative and histological records of 52 patients undergoing carotid endarterectomy for transient cerebral ischaemic attacks were reviewed. Thrombus or other friable material was present in 66 per cent of the 24 patients operated upon within 4 weeks of a clinical attack, but in only 21 per cent of the 28 patients in whom the time interval was longer. The data favour an embolic explanation for the clinical episodes and further suggest that thrombus formation on atheromatous stenosis and ulceration is intermittent.