Pharmacological therapy in children with nodal reentry tachycardia: when, how and how long to treat the affected patients.

Atrio-ventricular nodal reentrant tachycardia (AVNRT) is a rare supra-ventricular tachycardia (SVT) in children and becomes more frequent in adolescents. Most of children with an AVNRT have a healthy heart thus rarely experiencing severe symptoms. Because of haemodynamic instability or risk of complications, recurrences of SVT may require a chronic therapy. Interruption of dual atrio-ventricular nodal physiology is the basic mechanism to terminate AVNRT. This may be achieved by using anti-arrhythmic drugs or through Radiofrequency catheter ablation (RF). We aim to review the literature on the use of anti-arrhythmic drugs for the management of AVNRT in children aged more than 1 year and discuss the recommended dosages and the duration of a long term therapy. In the absence of comparative trials of risks and benefits between pharmacological therapy and RF and because of a greater clinical experience with anti-arrhythmic drugs, these last but not the least continue to be first-line therapy in the management of most SVT in children. Trials on pharmacotherapy in children with SVT in general and AVNRT in particular are lacking, use of anti-arrhythmic drugs being extrapolated from adult literature. Although Adenosine is becoming more used since it is the safest and effective drug in the acute setting, Digoxin continue to be the drug of first choice. Beta-blockers and Class I anti-arrhythmic are the second choice drugs with Flecainide being the preferred anti-arrhythmic drug for treatment failures. Amiodarone is rarely used as a chronic therapy in resistant cases. With the new advances in the RF technology, this therapy is becoming more safe and effective for AVNRT in children. Therefore, additional well-designed controlled trials are needed to further evaluate the comparative efficacy of anti-arrhythmic drugs in the management of AVNRT in children, as well as to evaluate dosing and toxicity in various age groups and determine the duration of a chronic therapy as compared to a potential RF.