[A case of pheochromocytoma with an AMI-like ECG change corrected by an alpha-blocking agent].

A 59 year-old housewife was admitted to the emergency service with a sudden onset of chest pain and nausea. Initially she was treated as an acute myocardial infarction, but conventional treatments were not effective, and she was sent to our hospital for further evaluation. Her ECG showed several abnormal findings including T-wave inversion, atrial flutter, QT-time prolongation, ST-segment depression or elevation, and frequent ventricular ectopic beats. The echocardiogram, 201thallium scintigram and coronary angiography were almost normal. Both urinary and plasma levels of catecholamines were remarkably increased, and the plasma epinephrine was extremely high during attacks. Abdominal echotomography and CT-scanning showed a large left adrenal tumor. The 131MIBG scintiscan revealed a high accumulation in this tumor. Then the patient was diagnosed as having pheochromocytoma and catecholamine-induced myocarditis. The administration of phentolamine (10 mg) normalized the inversion of T-wave and the high blood pressure. But when propranolol (2 mg) was administrated in addition to phentolamine, the ECG showed a biphasic low T-wave change. According to these phenomena, we supposed that the alpha-adrenergic receptor was involved in the development of the ST-T changes of the ECG, and the alpha-adrenergic receptor of this patient might be sensitive under excessive catecholamines, according to the inhibition of the beta-receptor by propranolol.