The subject of this report is a 38-year-old woman who often experienced syncope since childhood. Syncope occurred 10 times a year and was associated with convulsion during exercise and emotionally exciting situations. The patient’s 13-year-old daughter had also experienced frequent episodes of syncope and developed ventricular fibrillation (VF) during treadmill exercise testing that was successfully defibrillated with electric shock. Witnessing this situation, the patient also lost consciousness, with documented VF that was converted to sinus rhythm by cardiopulmonary resuscitation without electric defibrillation.

Both the patient and her daughter were admitted to our hospital. We performed echocardiography, coronary angiography, and cardiac CT, the results of which revealed no structural heart disease. Resting 12-lead ECG did not indicate any abnormalities, including long-QT syndrome or Brugada syndrome. A signal-averaged ECG revealed no late potentials. Treadmill exercise testing easily induced bigeminal ventricular premature contractions (VPCs) with a right bundle branch block configuration and inferior axis (Figure 1A), and the exercise was terminated because of intolerable symptoms. Catecholamine stress test was started with administration of continuous intravenous infusion of epinephrine in a stepwise manner from 0.025 μg/kg per minute. 1 During epinephrine infusion at a rate of 0.1 μg/kg per minute, multifocal VPCs (VPC# 1, right bundle branch block configuration and superior axis; VPC# 2, right bundle branch block configuration and inferior axis [the same VPC configuration as that induced during the treadmill exercise testing]; and VPC# 3, left bundle branch block configuration and inferior axis) appeared, and VPC# 1 following VPC# 2 subsequently induced VF (Figure 1B).