Studies on Carotid Artery Flow and Pressure

F oR the past 1~ years in our clinic, determinations of intravascular pressure have been carried out, in a nun> ber of patients undergoing gradual ligation of the common carotid ar tery for the t reatment of intraerania] ancurysms, particularly those situated on the internal carotid artery. These measurements have been made at the t ime of application of the clamp to determine the per-cent reduction in pressure in the distal carotid system following occlusion of the proximal common caroti(l artery. In general, it has been found that patients with a considerable reduction in pressure, e.g., 60 per cent or greater, require a longer period for closure of the clamp and are more likely' to have a neurologic complication as a result of ligation than patients with less reduction in pressure, t lowever, the relationship of reduction in pressure to lhe rate of neurologic complications has not always been as predicted. For inslanee, we have observed serious neurologic complications as a result, of closure of the claml) in patients with a reduction in pressure less than 40 per cent and, contrariwise, patients in whom the reduction in pressure has been as high as 70 per cenl have tolerated gradual closure without difficulty. I t is felt that all accurate knowledge of blood flow through the carotid ar tery 1o be ligated might provide more information regarding the change in intracranial circulatory dynamics a t tendant upon carotid liga-