Effect of Carotid Endarterectomy on Carotid Chemoreceptor and Baroreceptor Function in Man

Abstract

The ventilatory response to inhaled carbon dioxide was measured during hyperoxia (Pao₂ over 200 torr) and hypoxia (Pao₂ of 40 torr) in 14 patients before and one to nine weeks after carotid endarterectomy for transient attacks of cerebral ischemia. Ventilatory response was unchanged in the seven patients undergoing unilateral carotid endarterectomy. All seven patients undergoing staged bilateral procedures lost their ventilatory response to hypoxia and showed a 5.8-torr increase in mean resting Paco₂. In four patients studied, hypoxia at constant Paco₂ increased systolic blood pressure before and clearly decreased it after bilateral surgery. Bilateral carotid endarterectomy results in a loss of carotid-body function, with loss of the usual compensatory respiratory or circulatory responses to hypoxia. Baroreceptor activity, as measured by the standard Valsalva maneuver, was minimal before and showed no consistent change as a result of surgery.