ABSENCE OF BRADYCARDIAC RESPONSE TO APNEA AND HYPOXIA IN HEART-TRANSPLANT RECIPIENTS WITH OBSTRUCTIVE SLEEP-APNEA

In patients with obstructive sleep apnea, the vagal stimulation caused by inspiration against the upper airway obstruction results in sinus bradycardia during the apnea followed by a reflex tachycardia at apnea termination. We report on five heart transplant recipients with obstr uctive sleep apnea who demonstrated no change in baseline heart rate i n spite of marked hemoglobin oxygen desaturation, presumably on accoun t of parasympathetic denervation of the allograft. Heart transplant re cipients with obstructive sleep apnea may be at an increased risk of d evelopment of potentially fatal ventricular arrhythmias if the allogra ft is unable to respond appropriately to hypoxia. Should cardiac paras ympathetic reinnervation occur, prospective polysomnography may be a m arker for this process in these patients.