Idiopathic Ventricular Fibrillation Complicated with Neurally Mediated Syncope and Exercise-Induced Premature Ventricular Complexes from the Right Ventricular Outflow Tract

A 53-year-old man experienced five episodes of syncope while seated and two of urinary incontinence while asleep over a period of three years. He had no family history of cardiac disease, arrhythmias, or sudden death. He was in good health before the episodes, although ventricular premature contraction had been identified during an annual health check-up. He visited our hospital after the second syncopal attack. A Bruce protocol exercise stress test induced ventricular premature complexes, of which surface electrocardiography suggested a monofocal origin at the right ventricular outflow tract. Echocardiography confirmed the absence of organic abnormalities. Six months later, he participated in a head-up tilt test at a different facility, and vasodepressor-type neurally-mediated syncope was diagnosed. Over the following year, he experienced two episodes of syncope and one episode of incontinence before suddenly losing consciousness while watching TV at home. When paramedics arrived, they detected ventricular fibrillation that was converted to sinus rhythm with a single direct counter shock. Electrocardiogram monitoring in the ambulance during transit to our facility revealed ventricular premature complexes followed by torsades de pointes. A subsequent surface electrocardiogram in the emergency room showed neither Brugada type nor early repolarization. Nine months after ICD implantation, an appropriate shock worked while the patient was asleep during the early morning. This is a notable example of idiopathic ventricular fibrillation complicated with neurally mediated syncope and exercise-induced ventricular arrhythmia that originated from the right ventricular outflow tract.