Control of multiform ventricular tachycardia by propranolol in a child with no identifiable cardiac disease and sudden death

Catecholaminergic polymorphic ventricular tachycardia: a current overview

Catecholaminergic polymorphic ventricular tachycardia occurs in healthy children and young adults causing syncope and sudden cardiac death. This is a familial disease, which affect de novo mutation in 50% of the cases. At least two causative genes have been described to be localized in the chromosome 1; mutation of the ryanodine receptor gene and calsequestrin gene. The classical clinical presentation is syncope triggered by exercise and emotion in children and adolescents with no structural heart disease. Polymorphic ventricular tachycardia during treadmill testing, or after isoproterenol infusion, is the most common feature. Therapeutic options include, beta-blockers, calcium-channel blockers and, an implantable cardioverter defibrillator is indicated in high-risk patients. Risk stratification of this disease is very challenging, since some risk factors proved to be useful in some series but not in others. However, family history of sudden cardiac death and symptoms initiated in very young children are important predictors.

Catecholaminergic polymorphic ventricular tachycardia in children. A 7-year follow-up of 21 patients

BACKGROUND

Primary ventricular tachyarrhythmias are rarely seen in children. Among them, catecholaminergic polymorphic ventricular tachycardia has a poor spontaneous outcome. Its diagnosis is often delayed after the first symptoms, which is unacceptable because treatment with the appropriate beta-blocker prevents sudden death.

METHODS AND RESULTS

We observed 21 children (mean +/- SD age, 9.9 +/- 4 years) at the time of the diagnosis who had no structural heart disease and a normal QT interval on routine ECG. They were referred for stress- or emotion-induced syncope related to ventricular polymorphic tachyarrhythmias. The arrhythmia, consisting of isolated polymorphic ventricular extrasystoles followed by salvoes of bidirectional and polymorphic tachycardia susceptible to degeneration into ventricular fibrillation, was reproducibly induced by any form of increasing adrenergic stimulation. There was a familial history of syncope or sudden death in 30% of our patients. On receiving therapy with the appropriate beta-blocker, the patients' symptoms and polymorphic tachyarrhythmias disappeared. During a mean follow-up period of 7 years, three syncopal events and two sudden deaths occurred, probably due to treatment interruption.

CONCLUSIONS

The entity of adrenergic-dependent, potentially lethal tachyarrhythmia with no structural heart disease deserves to be individualized. It may form a variant of the congenital long QT syndrome in which the ECG marker is lacking; this primary ventricular arrhythmia must be looked for in a pediatric patient with stress- or emotion-induced syncope because only beta-blocking therapy can prevent sudden death and therefore must be given for the patient's lifetime.

Idiopathic ventricular tachycardia and fibrillation

Important data have recently been added to our understanding of sustained ventricular tachyarrhythmias occurring in the absence of demonstrable heart disease. Idiopathic ventricular tachycardia (VT) is usually of monomorphic configuration and can be classified according to its site of origin as either right monomorphic (70% of all idiopathic VTs) or left monomorphic VT. Several physiopathological types of monomorphic VT can be presently individualized, according to their mode of presentation, their relationship to adrenergic stress, or their response to various drugs. The long-term prognosis is usually good. Idiopathic polymorphic VT is a much rarer type of arrhythmia with a less favorable prognosis. Idiopathic ventricular fibrillation may represent an underestimated cause of sudden cardiac death in ostensibly healty patients. A high incidence of inducibility of sustained polymorphic VT with programmed ventricular stimulation has been found by our group, but not by others. Long-term prognosis on Class IA antiarrhythmic medications that are highly effective at electrophysiologic study appears excellent.