Sustained Slow Pathway Conduction: Superior to Dual Atrioventricular Node Physiology in Young Patients with Atrioventricular Nodal Reentry Tachycardia?

Catheter ablation of orthodromic reciprocating tachycardia and atrioventricular nodal reentrant tachycardia in children with hypoplastic left heart syndrome

INTRODUCTION

Experience with catheter ablation of orthodromic reciprocating tachycardia (ORT) and atrioventricular nodal reentrant tachycardia (AVNRT) in young children with hypoplastic left heart syndrome (HLHS) is limited. We report the feasibility, safety, and outcomes of catheter ablation of ORT and AVNRT in children with HLHS.

METHODS AND RESULTS

This was a retrospective review of patients with HLHS who underwent catheter ablation for reentrant supraventricular tachycardias (excluding atrial tachycardias) between 2005 and 2017 at a single center. Descriptive data including demographics, clinical history, procedural data, and outcomes were recorded. Ten children with HLHS underwent eleven catheter ablation procedures. Median age and weight at ablation were 2.7 years (range: 0.1-10.5) and 11.4 kg (range: 3.6-30.4), respectively. Tachycardia mechanism was AVNRT in four, ORT in five (two with preexcitation), and both in one. Acute procedural success was 100% and there was no spontaneous recurrence of tachycardia orpreexcitationin median 92 months (range: 21-175 months) follow-up. Five patients underwent subsequent EP studies at catheterization (intracardiac) or after surgery (via epicardial wires): three were noninducible, one after AVNRT ablation had inducible atrial tachycardia, and one after initial ORT ablation had inducible ORT at fenestration closure and underwent successful repeat ablation. Thus, long-term freedom from clinical tachycardia was 100% and from inducible AVNRT or ORT was 80%.

CONCLUSION

Transcatheter ablation for ORT and AVNRT in children with HLHS can be performed with excellent acute and long-term success without major complications.

A simplified approach for evaluating sustained slow pathway conduction for diagnosis and treatment of atrioventricular nodal reentry tachycardia in children and adults

PURPOSE

During incremental atrial pacing in patients with atrioventricular nodal reentrant tachycardia, the PR interval often exceeds the RR interval (PR > RR) during stable 1:1 AV conduction. However, the PR/RR ratio has never been evaluated in a large group of patients with pacing from the proximal coronary sinus and after isoproterenol challenge. Our study validates new site of pacing and easier method of identification of PR > RR.

MATERIAL AND METHODS

A prospective protocol of incremental atrial pacing from the proximal coronary sinus was carried out in 398 patients (AVNRT-228 and control-170). The maximum stimulus to the Q wave interval (S-Q = PR), SS interval (S-S), and Q-Q (RR) interval were measured at baseline and 10 min after successful slow pathway ablation and after isoproterenol challenge (obligatory).

RESULTS

The mean maximum PR/RR ratios at baseline were 1.17 ± 0.24 and 0.82 ± 0.13 (p < 0.00001) in the AVNRT and controls respectively. There were no PR/RR ratios ≥1 at baseline and after isoproterenol challenge in 12.3% of the AVNRT group and in 95.9% of the control group (p < 0.0001). PR/RR ratios ≥1 were absent in 98% of AVNRT cases after slow pathway ablation/modification in children and 99% of such cases in adults (P = NS). The diagnostic performance of PR/RR ratio evaluation before and after isoproterenol challenge had the highest diagnostic performance for AVNRT with PR/RR > = 1 (sensitivity: 88%, specificity: 96%, PPV-97%, NPV-85%).

CONCLUSIONS

The PR/RR ratio is a simple tool for slow pathway substrate and AVNRT evaluation. Eliminating PR/RR ratios ≥1 may serve as a surrogate endpoint for slow pathway ablation in children and adults with AVNRT.

The low specificity of low voltage bridges associating atrioventricular nodal reentry in pediatric patients

PURPOSE

Patients with atrioventricular nodal reentry tachycardia (AVNRT) often are managed successfully by ablation of the slow pathway with success rates reported as high as 99%. Low voltage bridges (LVBs) have been demonstrated to be helpful in guiding AVNRT ablation. Patients may present to the electrophysiology lab without evidence of inducible arrhythmia. In these scenarios, the demonstration of LVBs may be diagnostic and guide catheter ablation treatment. The purpose of our study was to prospectively investigate the specificity of LVBs as a diagnostic marker of AVNRT.

METHODS

Patients aged < 19 years with narrow complex tachycardia prospectively underwent electrophysiology study with intention to perform catheter ablation. In each patient, the primary objective was the collection of right atrial voltage data that was then used to identify LVBs.

RESULTS

Twenty-four patients were included after exclusion criteria were applied. Final diagnosis was 11 AVNRT and 13 non-AVNRT (nAVNRT). LVBs were identified in 11/11 AVNRT patients and 9/13 non-AVNRT patients (p = 0.09).

CONCLUSIONS

LVBs are not specific to patients with AVNRT and cannot solely be used for diagnosis. However, in patients with documented AVNRT, the LVB can be used to identify the location of the slow pathway.

Long-term outcomes for cryoablation of pediatric patients with atrioventricular nodal reentrant tachycardia

The long-term efficacy and complications of cryoablation for pediatric atrioventricular nodal reentrant tachycardia (AVNRT) have not been completely defined. We performed a retrospective review of pediatric patients diagnosed with AVNRT and treated with cryoablation therapy. A total of 73 patients underwent cryoablation for AVNRT from 2003 to 2008. Of the 73 patients, 61 were included in the present study. The mean interval from initial successful ablation was 3 + or - 1 years. Of the 61 patients, 4 had documented recurrence of AVNRT after the initially successful ablation, 3 with late recurrence 1 to 2 years after ablation. Procedural complications consisting of transient atrioventricular block developed in 10 patients, and 2 patients were diagnosed with new arrhythmias after AVNRT ablation (1 with junctional ectopic tachycardia and 1 with left ventricular outflow tract tachycardia originating near the region of the atrioventricular node 3 months after ablation). In conclusion, cryoablation is a safe and effective therapy for AVNRT. Recurrences can develop late, up to 2 years after initially successful ablation.

Documented narrow QRS tachycardia not inducible during electrophysiology study: should we modify the AV node or not

Ablation therapy is the widely accepted definitive therapy for atrioventricular reentry tachycardia. Noninducibility of the tachycardia is the targeted end point of the procedure. We report on 21 patients with documented narrow QRS tachycardia, in whom the clinical tachycardia could not be induced during the electrophysiologic study. After exclusion of an accessory pathway, we could treat them by slow pathway ablation, either with radiofrequency energy or with cryoenergy, successfully.

The Specific Electrophysiologic Characteristics in Children with the Atypical Forms of Atrioventricular Nodal Reentrant Tachycardia

BACKGROUND

Atrioventricular nodal reentrant tachycardia (AVNRT) is well known to be one of the most common supraventricular tachycardias in childhood. However, information about the atypical forms of AVNRT in childhood is limited. The purpose of this retrospective study was to investigate the clinical and electrophysiologic characteristics in pediatric patients with the atypical forms of AVNRT.

METHODS

One hundred and three pediatric patients with AVNRT were included (aged 8-18 years; 44 male, 59 female). There were 10 (9.7%) children with the atypical forms (group 1), 86 (83.4%) with the slow-fast form (group 2) and 7 (6.9%) with the fast-slow form of AVNRT (group 3). The electrophysiologic characteristics and results of the radiofrequency catheter ablation were compared among these 3 groups.

RESULTS

Group 2 patients were associated with an older age when compared with the other two groups. A significantly higher incidence of retrograde dual atrioventricular nodal pathways and a higher percentage of ventricular pacing- and extrastimulation-induced AVNRT were demonstrated in the children with the fast-slow form of AVNRT. The children with the atypical forms of AVNRT had a greater difference in the antegrade 1:1 conduction (100 +/- 73 vs. 52 +/- 41 vs. 35 +/- 26 ms, p = 0.003). Furthermore, the children with the slow-fast form of AVNRT had a greater difference in the retrograde 1:1 conduction (125 +/- 97 vs. 42 +/- 35 vs. 65 +/- 79 ms, p = 0.012).

CONCLUSION

This study demonstrated that the pediatric patients with the atypical forms of AVNRT had different electrophysiologic characteristics than those with the slow-fast or fast-slow forms of AVNRT. The results of radiofrequency catheter ablation were similar for all children with the slow-fast, fast-slow and atypical forms of AVNRT.