Medical Conditions - Prolonged Qt

QT interval in the electrocardiogram represents ventricular depolarization. Prolongation of QT occurs in delayed ventricular repolarization. This condition triggers tachycardia. Delayed ventricular repolarization occurs due to left ventricular hypertrophy, heart failure, hypertension, diabetes, etc. Lightheadedness, heart palpitations, etc., are the symptoms.