Relation of carotid stump pressure to safety of carotid artery ligation.

Twenty-four patients underwent ligation of the internal carotid artery for a variety of clinical indications. These included cerebral embolization from surgically inaccessible carotid lesions, carotid disruption and resultant hemorrhage, unreconstructible carotid endarterectomies, and inoperable intracranial carotid aneurysms. The relation of preoperative stump pressures to safety of ligation was evaluated. the data reflect that a systolic stump pressure in excess of 70 mm Hg (13 patients) indicates adequacy of collateral hemispheric blood flow to allow safe ligation of the carotid artery. Pressures of 55 mm Hg or less constitute an unacceptable vulnerability to stroke (two of three patients), and intermediate pressures of 55 to 68 mm Hg constitute a genuine hazard (four of eight patients). The mechanisms of stroke appear to be thromboembolic with late propagation of thrombus into an intracranial low-flow system. Postligation maintenance of appropriate systemic blood pressure is essential, and systemic heparinization is recommended to reduce the morbidity and mortality in patients in the intermediate pressure zone (55 to 68 mm Hg). It is concluded that whenever carotid ligation becomes a therapeutic consideration, the preoperative or preligation measurement of carotid stump pressure is presently the most reliable determinant of safety of the operation.