Use of Head-Up Tilt Testing to Determine a Possible Cause of Unexpected Cardiac Asystole During Epidural Anesthesia

Abstract

Head-up tilt testing is widely used in the diagnosis of syncope of unknown origin. In this report, head-up tilt testing elucidated the etiology of cardiac asystole of unexpected and sudden onset during orthopedic surgery under epidural anesthesia in a 30-year-old woman. Conventional diagnostic approaches were ineffective. Venous pooling in the lower legs as a result of vasodilation and subsequent vagotony due to epidural anesthesia, a condition mimicking orthostatic stress, is proposed as the mechanism of asystole. Follow-up examinations over 16 months revealed no further syncope and a good clinical course. Head-up tilt testing was useful in determining etiology in this case. (Jpn Circ J 1997; 61: 525 - 530)