Hypoxic ventilatory response and carotid endarterectomy

Abstract

Carotid endarterectomy is reported to abolish hypoxic ventilatory responsiveness. This effect is thought to be due to denervation or destruction of the carotid bodies by surgical exposure. The technique of carotid endarterectomy, however, does not require the sacrifice of these structures. Six patients who had bilateral carotid endarterectomy with careful preservation of the carotid bodies and their innervation were studied pre- and postoperatively with respect to hypoxic ventilatory responsiveness and the latter was taken as a measure of chemoreceptor activity. Five patients showed a weak or absent response to hypoxia before surgery. In four of these there was a significant increase in reactivity after the procedure (p less than 0.01 in one case, p less than 0.05 in three others). The fifth patient had a non-significant increase and the sixth had a normal response before and after surgery. Thus, loss of chemoreceptor function after bilateral carotid endarterectomy was not observed in this group of patients with preserved carotid bodies. The low ventilatory hypoxic sensitivity before surgery and its occasional increase after removal of the plaque suggests that atherosclerosis might well impair the microscopic blood supply to the carotid bodies, inducing sensor dysfunction but this hypothesis requires further investigation.