Safety issues in the treatment of paediatric supraventricular tachycardias.

Paroxysmal supraventricular tachycardia caused by atrioventricular re-entry is the most frequent arrhythmia in children of all age groups. It represents the most frequent clinical situation where antiarrhythmic drug therapy has to be considered in a child. Acute termination of an episode of tachycardia in all paediatric age groups is nowadays best achieved with an intravenous bolus injection of adenosine. Since the introduction of adenosine into clinical practice, the need to proceed to electrocardioversion has been limited to the infant (or in rare cases an older child) with severe cardiovascular collapse. In the haemodynamically stable infant or child, several other antiarrhythmic agents such as flecainide or propafenone can be used with relative safety and with a high probability of immediate success. The same is true for verapamil, although intravenous administration should be avoided in the first year of life. In newborns and in infants with first presentation of an episode of tachycardia, drug prophylaxis of recurrences is usually recommended for the whole of the first year of life. Prophylactic treatment may consist of oral digoxin as first choice, with a beta-blocker as an alternative. In an infant with Wolff-Parkinson-White syndrome it may be wise to avoid digoxin and to start treatment with a beta-blocker. Antiarrhythmic class Ic drugs such as propafenone or flecainide, and the class III agent sotalol, are widely used as the next steps of therapy when digoxin and beta-blockers fail to prevent recurrences. These agents are about equivalent with regard to their efficacy and risk profile. Amiodarone is considered to be an agent that should be reserved for use in situations when the tachycardia is refractory to the previously named agents. Older children may commence treatment with a beta-blocker and the subsequent steps of treatment are the same as those for infants. Curative catheter ablation of accessory pathways has been shown to be as efficient and well tolerated in the paediatric age group as it is in adults. This treatment option is nowadays quite often offered to older children. However, in infants and smaller children, ablation is used as a last resort. Rare forms of paediatric supraventricular tachycardia (other than atrioventricular re-entry through the atrioventricular node or accessory pathways) are occasionally difficult to treat and present special problems. For each of these arrhythmias, a specially tailored individual therapeutic approach is needed.