Cardiac rhabdomyomas are associated with ventricular arrhythmias, but mechanisms remain uncertain. A 10-year-old boy with tuberous sclerosis complex developed verapamil-sensitive fascicular ventricular tachycardia adjacent to a residual cardiac rhabdomyoma. Electrophysiological mapping demonstrated Purkinje-mediated reentry. Catheter ablation at a tumour-adjacent site eliminated the arrhythmia, suggesting that residual rhabdomyoma may anchor a localised reentrant substrate.