The article presents a case study of 16-year-old adolescent boy with recurrent dizziness and syncope. Sinus bradycardia was revealed by an electrocardiogram (ECG), a heart rate of 47 beats/min, and a QT interval of 663 ms. Other symptoms and diagnosed problems were long QT syndrome (LQTS), and recurrent nonsustained polymorphic ventricular tachycardia.