Atrioventricular nodal reentrant tachycardia in children: curative treatment by radiofrequency catheter ablation

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) is one of the most common forms of supraventricular tachycardia in the pediatric popu lation. Patients and methods: 41 children with a mean age of 9.6 (3.7-16) years wit h recurrent atrioventricular nodal reentrant tachycardia (AVNRT) refractory to medical treatment (n=38) and recurrent syncope (n=3) underwent electrop hysiologic (EP) study. In all patients dual AV-nodal physiology could be de monstrated during EP study and typical form of AVNRT (mean heart rate 220/m in) could be induced by programmed atrial stimulation. A steerable 7 F abla tion catheter was placed at the inferoparaseptal region of the tricupid val ve annulus close to the orifice of the coronary sinus with the intention to record a late fractionated local atrial electrogram during sinus rhythm. S tarting at this point radiofrequency current (500 M-Iz) with a target tempe rature of 70 degrees C was delivered with the intention to ablate the slow pathway. If a slowly accelerated junctional rhythm (<120/min) occurred duri ng energy discharge, programmed atrial stimulation was repeated. Otherwise radiofrequency current was delivered step by step up to a septal position n ext to the tricuspid valve annulus. Slow pathway ablation was defined as la ck of evidence of dual AV nodal pathways during repeated atrial stimulation . Slow pathway modulation was defined as maximal one atrial echoimpulse aft er ablation. Results: The number of energy applications ranged from 1-19 (median 6). In 35/41 patients slow pathway ablation could be achieved: in six patients the slow pathway was modulated. In none of the patients permanent high grade A V block was observed. During followup (mean 4.1 years) two patients had a r ecurrent episode of AVNRT after slow pathway modulation. All other patients are still free of AVNRT without medical treatment. Conclusion: Selective radiofrequency current ablation/modulation of the slo w pathway is a safe and curative treatment of AVNRT in young patients.