A pheochromocytoma is a rare tumor that develops from adrenomedullary chromaffin cells and produce ones or more catecholamines, including adrenaline, norepinephrine, and dopamine. On rare occasions a pheochromocytoma is hormonally inactive. Cyanotic heart disease is also a relatively rare pathology. One of its least frequently occurring variants is the single ventricle of the heart. Presumably, in patients with cyanotic heart defects, the occurrence of pheochromocytes and paragangliomas will be higher due to the presence of certain germinative and somatic mutations. In cyanotic heart defects, the development of malignant arrythmias is one of the frequent causes of death. A combination of a pheochromocytoma with a single ventricle of the heart is extremely rare: only eight such cases have been described in the literature. This article describes a young patient with a unique case of a single ventricle of the heart, pheochromocytoma and sustained ventricular tachycardia. The cause of the ventricular tachycardia, in all likelihood, was inappropriate medical care – in this case, a prescription for verapamil. The surgical excision of the pheochromocytoma and the referral of the patient for cardiac surgery became possible only after correcting the antihypertensive and antiarrhythmic therapy. Verapamil was replaced with a combination of doxazosin and amiodarone, resulting in relatively satisfactory blood pressure readings and sinus rhythm.