Bridge to success: A better method of cryoablation for atrioventricular nodal reentrant tachycardia in children

Comparative utility of omnipolar and bipolar electroanatomic mapping methods to detect and localize dual nodal substrate in patients with atrioventricular nodal reentrant tachycardia

BACKGROUND

Catheter-based slow pathway modification (SPM) for atrioventricular nodal reentrant tachycardia (AVNRT) is traditionally performed at empiric sites using anatomical landmarks and test ablation feedback within the triangle of Koch (TK). While studies have described more tailored techniques such as bipolar low voltage bridge (LVB) and wavefront collision identification, few have systematically compared the diagnostic yields of each and none have investigated whether omnipolar mapping technology provides incremental benefit. The objective of this study was to compare the utility of omnipolar and bipolar-derived qualitative and quantitative measurements in identifying and localizing dual AVN substrate in patients with versus without AVNRT.

METHODS

A retrospective case-control study of consecutive patients with paroxysmal supraventricular tachycardia undergoing electrophysiology study with both omnipolar and bipolar mapping from 2022-2023.

RESULTS

Thirteen AVNRT cases (median age 16.1 years, 512 TK points) were compared to nine non-AVNRT controls (median age 15.7 years, 332 TK points). Among qualitative variables, an omnipolar activation vector pivot, defined as a ≥45 degree change in activation direction within the TK, had the highest positive (81%) and negative predictive values (100%) for identifying AVNRT cases and had a median distance of 1 mm from SPM sites. Among quantitative variables, the optimal discriminatory performance for successful SPM sites was observed using bipolar voltage restricted to a peak frequency >340 Hz (c statistic 0.75).

CONCLUSIONS

Omnipolar vector pivot analysis represents an automated, annotation-independent qualitative technique that is sensitive and specific for AVNRT substrate and co-localizes with successful SPM sites. Bipolar voltage quantitatively describes SP anisotropy better than omnipolar voltage, and the addition of peak frequency signal analysis further optimizes the selection of SPM sites.

AVNRT cryoablation in children <26 kg: efficacy and safety of electrophysiologically guided low-voltage bridge strategy

The recently published "electrophysiologically guided low-voltage bridge (LVB) strategy" is effective in the ablation of atrioventricular nodal re-entry tachycardia (AVNRT) in children. This study aimed to evaluate its efficacy and safety in children <26 kgs. Fourteen children [64% males, median age 6.5 years (IQR 6-8 years), median weight 25.5 kg (IQR 24-26 kg)] with AVNRT were treated. In all patients, we detected a LVB associated to a typical slow pathway potential. The acute success rate was 100% with a mean of 5.5 cryoablation deliveries. All procedures were performed with near-zero fluoroscopic exposure (median time 0.15 min, IQR 0-0.7 min), in six patients fluoroscopy was 0 min. There were no complications or recurrences during the follow-up (median 20.91 months, IQR 11.7-26.7 months).

Ripple Mapping: A precise tool for atrioventricular nodal reentrant tachycardia ablation

INTRODUCTION

Ablation for atrioventricular nodal reentrant tachycardia (AVNRT) classically utilizes evaluation of signal morphology within the anatomic region of the slow pathway (SP), which involves subjectivity. Ripple Mapping (RM) (CARTO-3© Biosense Webster Inc, Irvine, CA) displays each electrogram at its 3-dimensional coordinate as a bar changing in length according to its voltage-time relationship. This allows prolonged, low-amplitude signals to be displayed in their entirety, helping identify propagation in low-voltage areas. We set out to evaluate the ability of RM to locate the anatomic site of the slow pathway and assess its use in guiding ablation for AVNRT.

METHODS

Patients ≤18 yrs with AVNRT in the EP laboratory between 2017 and 2021 were evaluated. RM was performed to define region of SP conduction in patients from 2019-2021, whereas standard electro-anatomical mapping was used from 2017-2019. All ablations were performed using cryo-therapy. Demographics, outcomes and analysis of variance in number of test lesions until success were compared between groups.

RESULTS

A total 115 patients underwent AVRNT ablation during the study; 46 patients were in the RM group and 69 were in the control group. There were no demographic differences between groups. All procedures, in both groups, were acutely successful. In RM group, 89% of first successful lesions were within 4mm of the predicted site. There was significantly reduced variability in number of test lesions until success in the RM group (p=0.01).

CONCLUSIONS

RM is a novel technique that can help identify slow pathway location, allowing for successful ablation of AVNRT with decreased variability. This article is protected by copyright. All rights reserved.

Koch's triangle voltage mapping for cryoablation of slow pathway in children: preliminary data of a novel high-density technique

PURPOSE

Different authors have described three-dimensional (3D) voltage mapping of the Koch's triangle (KT) in order to find low-voltage bridges (LVB) as targets for a successful transcatheter ablation (TCA) of the slow pathway (SP) in children. Recently, the Advisor High Density (HD) Grid™ mapping catheter was introduced as new multipolar catheter for HD mapping. The aim of the study was to describe our preliminary experience with the use of HD Grid™ catheter in LVB and electrophysiologically guided cryoablation of SP in children.

METHODS

Twenty-one children (mean age 13±3 years) with atrioventricular nodal re-entrant tachycardia (AVNRT) underwent cryoablation of SP guided by voltage HD mapping of the KT using HD Grid™ catheter. In order to better highlight the differences with conventional mapping, point collection was performed in each patient with this new multipolar catheter and with a quadripolar catheter.

RESULTS

The conventional mapping collected 871±262 points and used 211±80 points in 887±275 s, whereas HD mapping collected 7468±2947 points, using 604±165 points in 513±181 s (p<0.001). Moreover, the LVB area mapped with HD Grid™ was about one-half smaller and clearly delineated. Cryoablation acute success rate was 100%. Overall median fluoroscopy exposure was 0.08 (0.01-5.42) μGy/m2, with a median fluoroscopy time of 0.1 (0.0-0.6) min. During the follow-up (4.8 ± 3.7 months), there were no recurrences. No complications occurred.

CONCLUSIONS

Our preliminary experience shows that HD mapping is faster and offers higher spatial resolution and definition. Procedural time can be reduced maintaining the TCA safe, with reduced fluoroscopy use and success.

Identifying an appropriate endpoint for cryoablation in children with atrioventricular nodal reentrant tachycardia: Is residual slow pathway conduction associated with recurrence?

BACKGROUND

Cryoablation is increasingly used to treat atrioventricular nodal reentrant tachycardia (AVNRT) due to its safety profile. However, cryoablation may have higher recurrence than radiofrequency ablation (RFA), and the optimal procedural endpoint remains undefined.

OBJECTIVE

The purpose of this study was to identify the association of cryoablation procedural endpoints with postprocedural AVNRT recurrence.

METHODS

We performed a single-center, retrospective analysis of pediatric patients following successful first-time cryoablation for AVNRT between January 1, 2011, and December 31, 2019. Preablation inducibility of AVNRT was recorded. Procedural endpoints, including slow pathway (SP) conduction (presence of jump or echo beats) with and without isoproterenol, were identified. Recurrence was established from clinical notes and/or direct patient contact.

RESULTS

Of 256 patients, 147 (57%) were assessed on isoproterenol precryoablation, and 171 (47%) were assessed on isoproterenol postcryoablation. Mean cryolesion time was 2586 ± 1434 seconds. Following ablation, 104 (41%) had some evidence of residual SP conduction. With median follow-up time of 1.9 [0.7-3.7] years, recurrence occurred in 14 patients (5%). Complete elimination of SP conduction (with and without isoproterenol) had a hazard ratio for recurrence of 1.26 (95% confidence interval [CI] 0.42-3.8; P = .68) on univariate analysis and 1.39 (95% CI 0.36-5.4; P = .63) on multivariate analysis (including demographics, ablation time, 8-mm cryocatheter, and baseline inducibility).

CONCLUSION

The observed AVNRT recurrence rate after cryoablation was comparable to that of RFA. The presence of residual SP conduction was not associated with recurrence. This suggests that jump or single echo beat may be an acceptable endpoint in AVNRT cryoablation.

Low-voltage bridge strategy to guide cryoablation of typical and atypical atrioventricular nodal re-entry tachycardia in children: mid-term outcomes in a large cohort of patients

AIMS

In the current literature, results of the low-voltage bridge (LVB) ablation strategy for the definitive treatment of atrioventricular nodal re-entry tachycardia (AVNRT) seem to be encouraging also in children. The aims of this study were (i) to prospectively evaluate the mid-term efficacy of LVB ablation in a very large cohort of children with AVNRT, and (ii) to identify electrophysiological factors associated with recurrence.

METHODS AND RESULTS

One hundred and eighty-four children (42% male, mean age 13 ± 4 years) with AVNRT underwent transcatheter cryoablation guided by voltage mapping of the Koch's triangle. Acute procedural success was 99.2% in children showing AVNRT inducibility at the electrophysiological study. The overall recurrence rate was 2.7%. The presence of two LVBs, a longer fluoroscopy time and the presence of both typical and atypical AVNRT, were found to be significantly associated with an increased recurrence rate during mid-term follow-up. Conversely, there was no significant association between recurrences and patient's age, type of LVB, lesion length, number of cryolesions or catheter tip size.

CONCLUSION

The LVB ablation strategy is very effective in AVNRT treatment in children. Recurrences are related to the complexity of the arrhythmogenic substrate.

Persistence of Palpitations After Slow Pathway Modification for AVNRT in Young People

Symptoms are the most common indication for ablation in children with atrioventricular nodal reentrant tachycardia (AVNRT). After the procedure, patients may continue to report palpitations. The objective of this study was to quantify the risk and duration of palpitations after pediatric slow pathway modification as well as demographic and technical associations. This was a retrospective review of consecutive patients at a pediatric center who underwent slow pathway modification for AVNRT from 2012 to 2018. Patients with a prior ablation attempt or congenital heart disease were excluded. Palpitations were documented in 35% of patients after ablation. Neither post-ablation echo beats nor other evidence of residual dual AV nodal physiology were associated with a higher risk of post-ablation palpitations. Of the 35 patients with post-ablation palpitations, the median time to resolution of palpitations was 48 months. Acute procedural success was achieved in all 100 cases. There were two recurrences of AVNRT during long-term follow-up and one instance of ectopic atrial tachycardia (3% SVT recurrence). Palpitations after AVNRT ablation occurred in approximately one-third of cases, despite a low recurrence of true arrhythmia. Prior to ablation, patients and families should be counseled that post-ablation palpitations are common and AVNRT recurrence is rare.

Cryoablation with an 8-mm tip catheter for typical AVNRT in children: a single center 5-year experience

BACKGROUND

In children with typical atrioventricular nodal reentrant tachycardia (tAVNRT), cryoablation is preferred over radiofrequency ablation (RFA) because of its safety profile and acceptable long-term success rates. In this study, we have assessed the utility of 8-mm tip cryocatheters for tAVNRT ablation in our center.

METHODS

All pediatric AVNRT patients who underwent cryoablation with an 8-mm tip cryocatheter in our center between 2013 and 2018 were included. EnSite™ (St. Jude Medical Inc., St. Paul, MN, USA) was used in all patients.

RESULTS

A total of 120 patients (64 females, 53%) were included in this study, and the mean age was 13.9 years with a standard deviation of 2.5 years. Eleven patients (9.1%) had structural heart disease, and 12 patients (10%) had additional arrhythmia substrate. The mean number of effective cryolesions was 8 with a standard deviation of 2.3. Fluoroscopy was used in three patients (2.5%). There were minor complications in only four patients (3.3%)-transient first-degree atrioventricular block or transient incomplete right bundle branch block. Acute success rate of cryoablation was 108/120 (90%). In twelve patients, cryoablation was suboptimal, or it failed. The procedure was completed successfully with RFA in the same session in ten patients. Overall acute success rate of ablation (Cryo ± RFA) was 98.5%. During a mean follow-up period of 24.6 months with a standard deviation of 11.3 months, three patients had recurrence (2.5%). Time between the beginning of the effective cryolesion and termination of AVNRT was found associated with acute success of cryoablation (p = 0.013).

CONCLUSIONS

Cryoablation of AVNRT with an 8-mm tip catheter in children appears to be safe, with an acceptable acute success rate and a low recurrence rate. A faster termination of AVNRT during the cryolesion, slowing down before ending with atrioventricular block, is a good indicator for acute success.

Using coronary sinus ostium as the reference for the slow pathway ablation of atrioventricular nodal reentrant tachycardia in children

BACKGROUND

Successful slow pathway (SP) ablation sites for atrioventricular nodal reentrant tachycardia (AVNRT) are usually located inside the Koch's triangle (KT). This study aimed to determine the ablation site of SP using the coronary sinus (CS) ostium (CSO) as the reference and to evaluate the efficacy of the CSO-guided SP ablation.

METHODS

A regional geometry around the KT was constructed by 3D mapping in 52 consecutive patients under age 18 with AVNRT. SP cryoablation was performed. If initial cryoablation was unsuccessful or cryoablation was deemed not suitable, then radiofrequency (RF) ablation was performed. The successful ablation site direction relative to the CSO was expressed as o'clock with the CSO viewed as a clock.

RESULTS

Cryoablation was used as the primary energy source in 40 patients. Of which, 32 were successful and eight required additional RF ablation. Direct RF ablation was performed in 11 patients. Using the CSO as reference, the successful site with cryoablation was at its 2.2 ± 0.6 o'clock; the RF ablation success site was at CSO 2.7 ± 0.5 o'clock (P = .006). During a median follow-up of 12 month, there was 98% success of SP ablation in these patients, with one patient with RF ablation had a tachycardia recurrence.

CONCLUSIONS

Using CSO as reference, the cryoablation site at its 2:00 o'clock and RF ablation at its 3:00 o'clock are highly efficacious for SP ablation with good short-term outcomes, and may be a useful tool in guiding the ablation target for 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.