Radiofrequency catheter ablation therapy in the young: current status

Safety and Efficacy of Radiofrequency Catheter Ablation for Tachyarrhythmia in Children Weighing Less Than 10 kg

An increasing number of children are undergoing radiofrequency catheter ablation (RFCA) for tachyarrhythmia. However, infants and toddlers undergoing RFCA are often resistant to medication or need to eliminate arrhythmia substrate, and the risks of RFCA complications are still high in infants and toddlers. From April 2008 and December 2016, 285 children who underwent radiofrequency catheter ablation (RFCA) were stratified according to body weight (group A, less than 10 kg, n = 22; group B, over 10 kg, n = 263) and the clinical features of RFCA were retrospectively reviewed in these groups. Indications for RFCA included drug-refractory tachyarrhythmia or symptomatic tachycardia and tachycardia-induced cardiomyopathy. The acute success rate in this group was 90.9%, with a relatively low recurrence rate (15.0%) after 7.0 ± 1.6 years follow-up. We performed RFCA using only 2-4 catheters in all cases. Major complications included complete right bundle branch block in one patient. No significant differences in rates of success, recurrence, or complications were noted between children weighing less and more than 10 kg. RFCA is safe and efficacious for tachyarrhythmia even in patients weighing less than 10 kg.

Efficacy and safety of cryoablation of parahissian accessory pathways in children: a single institution study

BACKGROUND

Catheter cryoablation of supraventricular tachycardias involving the perinodal regions is considered to be a safer alternative compared to radiofrequency ablation. Limited information is available for efficacy, midterm outcomes, and complications regarding the ablation of parahissian accessory pathways (APs) in pediatric patients.

METHODS

A retrospective review of all pediatric patients who underwent cryoablation for treatment of a parahissian AP was performed.

RESULTS

Twenty-five patients (median age 13 years and weight 45.6 kg) underwent cryoablation of a parahissian AP. Median number of cryolesions applied was four (range: 3-6). Initial procedural success was achieved in 23 patients (23/25, 92%). Transient third-degree atrioventricular (AV) block was noted in two patients. There was no permanent AV block. Transient right bundle branch block (RBBB) was observed in one patient and permanent RBBB occurred in two patients. Of the patients successfully ablated with cryo, there was only one recurrence (1/23, 4.3%) over a follow-up of 17.5 months (range 6-34 months).

CONCLUSION

Cryoablation of parahissian APs is both safe and effective with a low risk of recurrence in pediatric patients.

Lengthier cryoablation and a bonus cryoapplication is associated with improved efficacy for cryothermal catheter ablation of supraventricular tachycardias in children

INTRODUCTION

Cryoablation is an effective treatment for children with supraventricular tachycardias (SVT). The present study documents the effect of two different cryoablation protocols on acute and chronic success rates.

METHODS AND RESULTS

Fifty-three consecutive patients (age range, 5-20 years) were treated; patients 1 to 17 were treated by a standard ablation protocol and patients 18 to 53 were treated by a modified ablation protocol that required lengthier cryoablations plus delivery of a bonus cryoapplication to consolidate the acutely successful irreversible lesion created at intervention. Electrophysiological study (EPS) was performed with diagnostic catheters and cryoablations were performed with a 7FR 4 mm tip catheter (CryoCath Technologies). Acute endpoints for non-inducibility of atrioventricular nodal re-entrant tachycardia (AVNRT) by programmed atrial stimulation at baseline or during isoproterenol performed 30 min post procedure, as well as non-inducibility and conduction block over the accessory pathway (AP). The chronic endpoint was arrhythmia recurrence post intervention. No permanent cryo-related complications or adverse outcomes were reported. Acute success rates for patients 1 to 17 and 18 to 53 were 88 and 100%, respectively. The cumulative percentage of patients without arrhythmia recurrence at 12 month follow-up was significantly different at 73 and 90%, respectively.

CONCLUSIONS

Lengthier cryoablation delivery, approximating 7 min per cryoablation, increases the acute success rate at intervention. Moreover, these lengthier cryoablation deliveries plus a bonus cryoapplication to consolidate the acutely successful irreversible lesion created at intervention may also significantly improve the chronic success rate, while also maintaining an excellent safety profile for cryoablation treatment of children with SVT such as AVNRT and AP located near the AV junction.

Transvenous cryothermal catheter ablation of re-entry circuit located near the atrioventricular junction in pediatric patients

OBJECTIVES

We investigated the safety and efficacy of cryoablation in the treatment of pediatric patients with accessory pathways (APs) located near the atrioventricular junction and with atrioventricular nodal re-entrant tachycardia (AVNRT).

BACKGROUND

Few studies concern cryoablation in a significant number of pediatric patients involving treatment for supraventricular tachycardias (SVTs) with the reentry circuit located near the atrioventricular junction.

METHODS

Twenty-six pediatric patients (age range: 5 to 20 years) were treated; 14 had AVNRT, 10 had Wolff-Parkinson-White syndrome, and 2 had re-entrant SVT due to a concealed AP. Electrophysiologic study was performed with diagnostic catheters, and cryoablations were performed with a 7-F 4-mm-tip catheter (Freezor, CryoCath Technologies Inc., Kirkland, Canada). Cryomapping, used to identify the tissue site for safe arrhythmia ablation, was performed at -30 degrees C for a maximum of 60 s. Cryoablations were from 4 to 8 min long at -75 degrees C. Acute end points were noninducibility of AVNRT by programmed atrial stimulation at baseline or during isoproterenol performed 30 min after procedure, as well as noninducibility and conduction block over the AP. The chronic end point was arrhythmia recurrence after intervention.

RESULTS

No permanent cryo-related complications or adverse outcomes were reported. Twenty-four (92%) patients were acutely successful. During follow-up (range: 1 to 22 months), seven (29%) acutely successful pediatric patients experienced arrhythmia recurrence.

CONCLUSIONS

Acute results demonstrate cryoablation of SVTs with the reentry circuit located near the atrioventricular junction to be safe and efficacious in pediatric patients. However, the etiology of recurrences reported after intervention need further investigation.