Catecholaminergic polymorphic ventricular tachycardia.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a highly malignant form of arrhythmogenic disorder characterized by exercise- or emotional-induced polymorphic ventricular tachycardia in the absence of detectable structural heart disease. Because of the typical pattern of arrhythmias (bidirectional ventricular tachycardia and the occurrence and severity of arrhythmia correlated well with exercise workload) during exercise stress test, CPVT can be identified promptly. Molecular genetic screening of the genes encoding the cardiac ryanodine receptor and calsequestrin is critical to confirm uncertain diagnosis of CPVT. With the exception of beta-blockers, no pharmacologic therapy of proven effectiveness is available: although beta-blockers reduce the occurrence of ventricular tachycardia, 30% of patients treated with beta-blockers still experience cardiac arrhythmias and eventually require implantable cardioverter defibrillator implantation to prevent cardiac arrest.