Introduction: Because of haemodynamic instability or risk of complications, recurrent episodes of atrioven-tricular nodal reentrant tachycardia (AVNRT) in chil-dren may need catheter ablation of the slow pathway in order to eliminate the arrhythmia. The theoretical risk of injuring cardiac structures in small children is hi-gher and might depend specifically on the parameters that influence lesion size. Although the consequences of X-ray exposure during catheter ablation are not yet completely known, it is well established that radiation exposure is associated with increased incidence of ge-netic defects, dermatitis, cataracts, and malignancy.
Methods: We present two clinical cases of patients with AVNRT. The first case is of a 6-year-old female pati-ent with AVNRT that presented for recurrent episo-des of supra-ventricular tachycardia, 3 short episodes in a week, during the last year. The patient was under treatment with beta-blockers (Propanolol 10 mg 2×1/ zi). The second case is a 13-year-old female patient who has experienced frequent episodes of fast and regular palpitations triggered by effort. The last episode of pal-pitations was 4 months before the patient\’s admission to hospital and the ECG during tachycardia was cha-racteristic for AVNRT. After this episode, the patient followed treatment with beta-blockers (Propanolol 20 mg 2×1 day).
Using a 3D system (NAVX-Ensite Velocity) we de-fined anatomical and electrical landmarks of the tri-angle of Koch, without using X-ray, for both patients. An electrophysiological study was performed that con-firmed the dual node physiology and induced AVNRT for both cases. Three-D mapping system was exclusi-vely used for catheter placement, movement and navi-gation inside the right atrium during both procedures. The ablation catheter\’s tip was positioned in the pos-terior zone of the triangle of Koch and radiofrequency application abolished the conduction through the slow pathway for both patients. Patients were observed for at least 30 min following the successful ablation. Both of the patients did not develop AVNRT recurrences during the follow-up period.
Conclusions: In order to avoid the cumulative risks of X rays especially in children, ionizing radiation cathe-ter ablation should be taken into consideration for su-pra-ventricular tachycardia treatment in children.