[Coronary artery spasm under thoracic epidural anesthesia]

Three paroxysmal episodes of ST-segment elevation in lead II of ECG were observed during bullectomy and chest closing under epidural anesthesia supplemented with enflurane in compressed air in a patient who had history of variant angina with 50% obstruction of right coronary artery. The first and the third episodes were followed by ventricular tachycardia, complete A-V block and hypotension. These attacks were preceded by decreases in heart rate and blood pressure. It was suspected that coronary artery spasm developed with increased vagal tone under thoracic epidural block. The first and the second attacks were successfully treated with intravenous injection of nitroglycerin and lidocaine. The third attack needed additional treatments which included intravenous administrations of atropine, epinephrine, isoproterenol and phenylephrine and direct heart massage through the thoracic incision. Postoperative serial examinations of ECG showed inverted T in lead V1-V4, and serum enzymes (GOT, GPT, LDH, CPK, CPK-MB) were elevated. However ratio of CPK-MB to total CPK was only 1.5%. The patient was discharged two weeks after the operation with normal ECG and serum enzymes. It is speculated that coronary artery spasm was induced by hypotension and vagal stimulation under epidural anesthesia which blocks cardiac sympathetic nerves.