Cryo-therapy Ablation for High Septal Accessory Pathways in Children

Background: Radiofrequency (RF) ablation has become established therapy for tachy-arrhythmias in the pediatric population. High septal accessory pathways (APs) especially para-Hisian and antero-septal can be challenging targets for RF ablation, especially for pediatric patients. This study investigate the safety and efficacy of cryotherapy ablation in the treatment of pediatric patients with high septal accessory pathways. Methods: Fifty four pediatric patients (40 male (74%)), underwent 70 Cryoablation procedures for high septal AP (Para-Hisian AP 41/54 (75.8%), Antero-Septal AP 9/54 (16.7%) and Mid-Septal AP 4/54 (7.5%)). Four of them had 2 accessory pathways (3 manifest and one concealed). An acute success was defined as noninducibility of SVT and conduction block over the AP. Results: The average age was 15±3.8 years. Twenty two (40%) had EP study or RF ablation at other centers. Forty one children went one cryoablation procedure, ten children had 2 procedures and three children had 3 procedures, a total of 70 procedures. The acute success rate with cryoablation was 92.6% (50/54), one of the failed cryoablation had second failed attempt and the rest 3 patients were followed up and treated medically. The mean fluoroscopy time was 27.7±21.5 (3-78) minutes. The total Cryoablation time and the number of full Cryoablation applications were significantly higher in the second compared to the first procedure (820±315 second and 3.4±1.3 applications vs 350±130 second and 1.4±0.5 applications, respectively, P<0.01). Transient catheter-induced mechanical block of the AP was observed in three patients (5.5 %) and one had catheter induced RBBB, all of them had manifest preexcitation. In addition, three patients developed transient AVB during cryoablation (up to 30 second); all of them had concealed AP. Conclusions: Cryoablation is a safe and effective treatment for high septal AP in children. However, characterized with high rate of recurrence and repeated procedures to achieved high successful rate.