Catecholaminergic polymorphic ventricular tachycardia

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is an inherited heart rhythm disorder caused by a mutation in voltage gated ion channels and resulting in arrhythmias. CPVT may cause exercise-induced ventricular arrhythmias and/or syncope occurring during physical activity or acute emotion, but demonstrates no structural problems of the heart. Ventricular tachycardia may self-terminate or degenerate into ventricular fibrillation, causing sudden death without immediate cardiopulmonary resuscitation. The majority of events occur during childhood and more than 60% of affected individuals will have a first episode of syncope or cardiac arrest by age 20.

Inheritance
CPVT has an autosomal dominant inheritance pattern. There are two genes currently associated with CPVT: RYR2 (majority) and CASQ2 (1-2%). The Ryanodine receptor (RYR2) is involved in intracardiac Ca2+ handling; Ca2+ overload triggers abnormal cardiac activity. Calsequestrin (CASQ2) is a calcium buffering protein of the sarcoplasmic reticulum.

Diagnosis
CPVT is diagnosis based on reproducing ventricular arrhythmias during exercise stress testing, syncope occurring during physical activity and acute emotion, and a history of exercise or emotion-related palpitations and dizziness with an absence of structural cardiac abnormalities. The resting electrocardiogram is usually unremarkable but can show sinus bradycardia and a prominent "U". Genetic testing is sometimes available and is particularly useful for presymptomatic diagnosis of related individuals.

Treatment
CPVT is treated with beta blockers, verapamil or an ICD (implantable cardiac defibrillator).