ABSTRACT
Background
Low‐voltage bridge mapping (LVBM) is a recently introduced approach to atrioventricular nodal reentry tachycardia (AVNRT) ablation that may facilitate precise slow‐pathway targeting. Our center implemented LVBM for radiofrequency (RF) AVNRT ablation in children in April 2023. Early results demonstrated procedural advantages without prolonging procedure time.
Aim
The present study evaluates one‐year follow‐up outcomes after the introduction of LVBM.
Methods
We retrospectively analyzed all pediatric AVNRT RF ablations performed between January 1, 2019, and August 31, 2024. Outcomes of procedures performed using a traditional approach were compared with those guided by LVBM. Clinical success, complications, RF application parameters, and total procedure time were assessed at one‐year follow‐up.
Results
A total of 105 patients were included (61 controls, 44 LVBM). Baseline characteristics did not differ significantly between groups. At one‐year follow‐up, clinical success was higher in the LVBM group (90% vs. 80%), although the difference was not statistically significant. No complications were observed in either group.
Conclusions
Introduction of low‐voltage bridge mapping for RF AVNRT ablation in children reduces the number and duration of RF applications without prolonging procedure time. One‐year follow‐up demonstrates durable efficacy and safety, supporting LVBM as a valuable refinement of pediatric AVNRT ablation strategies.
Keywords: AVNRT ablation, children, low voltage bridge mapping
Introducing low‐voltage bridge mapping for RF AVNRT ablation in children reduces the number and duration of RF applications without prolonging procedure time. One‐year follow‐up demonstrates durable efficacy and safety, supporting LVBM as a valuable refinement of pediatric AVNRT ablation strategies.
1. Introduction
Recently, the use of 3D mapping systems for pediatric AVNRT ablations has become standard, with evolving new techniques such as low‐voltage bridge mapping (LVBM) that improve safety and accuracy. LVBM detects low‐amplitude atrial signals in the lower triangle of Koch, aiding precise target localization [1, 2, 3]. LVBM was initially developed with cryoablation [2, 4, 5, 6, 7, 8], but our group reported positive early results with RF ablation [9], showing increased accuracy and fewer RF applications. This study analyzes one‐year follow‐up outcomes of RF AVNRT ablations with LVBM.
2. Methods
We analyzed pediatric AVNRT ablations from Jan 1, 2019, to Aug 31, 2024, including only patients with normal heart anatomy and confirmed typical AVNRT. All procedures were performed by the same experienced operators using the CARTO system under general anesthesia, in accordance with commonly accepted criteria for AVNRT. In both groups, RF applications were delivered in temperature control mode at a max of 55°C with 20–35 W. If junctional rhythm was observed, the application continued for 60 s. If there was no reaction, it was stopped within 10 s. Any signs of AV nodal disturbance also stopped the application. Successful endpoints included non‐inducibility of AVNRT and signs of ablation, as well as modification of the slow pathway. Target selection methods differed by period: from Jan 2019 to Mar 2023, traditional 3D mapping was used for late atrial potentials with a 1:4 ratio in relation to the ventricular signal, combined with a characteristic appearance of the atrial potential (“hump‐and‐spike”). From Apr 2023 to Aug 2024, voltage mapping in sinus rhythm using the LVBM approach: a high‐density voltage gradient mapping of the triangle of Koch was performed using the ablation solid‐tip (7F NaviStar; J&J) catheter. The initial voltage bar settings were 0.01–1 mV; however, at the completion of the map, the upper limit had to be adjusted individually to better delineate the low‐voltage bridge. Once the LVB was visualized, target selection was guided by the LVB's location. Patients were followed at 3 months and 1 year; success was defined as no SVT and symptom resolution or marked improvement without arrhythmia documentation and no antiarrhythmic therapy (i.e., much less frequent, shorter, self‐limiting episodes of palpitations, with no arrhythmia documented on event‐Holter and no medication required). Statistical analysis used median and IQR for continuous variables, permutation tests with rank‐biserial r for group comparisons, and Fisher's exact or χ 2 tests with Cramér's V for categorical variables, at α = 0.05.
3. Results
A total of 105 patients met the inclusion criteria: 61 in the control group and 44 in the LVBM group. There were no significant differences in age, sex, or body weight between groups. Procedural outcomes, showing reductions in RF application number, duration, and delivered energy in the LVBM group, have been reported elsewhere [9].
At 3‐month follow‐up, symptom recurrence occurred in 9 patients (14.7%) in the control group and in 3 patients (6.8%) in the LVBM group. Overall clinical improvement was observed in 85.3% and 93% of patients, respectively, without a statistically significant difference. At one‐year follow‐up, 45 control patients (80%) clinically improved, while 11 (20%) were classified as recurrences. In the LVBM group, 40 patients (90%) were asymptomatic or improved, and 4 (10%) experienced recurrence. Although the success rate was clearly numerically higher in the LVBM group, the difference did not reach statistical significance. No late complications were observed. Patient symptom transitions are illustrated in Figure 1.
FIGURE 1.
Panel A—success rates in study and control groups, at early and one‐year follow‐up. Panel B—Sankey plot showing the transition of patients between the success groups from early follow‐up to 1‐year follow‐up.
4. Discussion
Safety is crucial in pediatric AVNRT ablation because of the benign nature of the arrhythmia and the risk of severe AV node injury; thus, any safety improvements are valuable. Our group previously reported favorable procedural outcomes after introducing LVBM for RF ablation in children with AVNRT [9]. Now, we extend these by presenting one‐year follow‐up results. The main finding is that LVBM's procedural benefits—fewer, shorter RF applications—are linked to a favorable, durable one‐year outcome. Although the difference in success rates between LVBM and control groups was not statistically significant, there was a clear numerical improvement (90% vs. 80%) at one year, consistent with other pediatric studies [10, 11, 12]. Because slow‐pathway ablation in children already has a high success rate, larger multicenter studies would be needed to demonstrate significant efficacy improvements. Our data show that LVBM‐guided RF ablation offers high success, safety, and durability and requires less RF energy than traditional methods. This suggests that targeting visualized lesions can effectively modify the slow pathway while minimizing unnecessary energy use. Although LVBM was mainly developed with cryoablation, it isn't limited to that. Current literature on AVNRT ablation in children shows no evidence favoring one energy source over another [13]. Currently, alternative mapping methods for AVNRT, such as late activation mapping, are under investigation [14]. Some studies suggest that slow‐pathway late activation mapping predicts the successful ablation spot better than LVBM, especially for patients with multiple slow pathways [15]. Further research is needed to identify which technique, or combination of techniques, provides the optimal balance of efficacy and safety.
Our analysis shows that early symptom absence is a strong prognostic marker, as no patients in either group with complete early success experienced full recurrence at 1‐year follow‐up. Both groups had a subset that reported partial symptom improvement, such as fewer, shorter episodes of palpitations without documented arrhythmias or the need for medication. This group needs closer follow‐up, as some developed recurrence and required medication or redo procedures.
The LVBM group exhibits less variability in RF application time and count, indicating better consistency and easier reproducibility [9]. This streamlines training and suggests LVBM integrates quickly into pediatric EP labs. Since 3D mapping is standard in pediatric EP, adding LVBM—done with existing mapping catheters without extra time or cost—is a practical upgrade. LVBM also works across different platforms. Low‐voltage bridge mapping enhances RF ablation in children with AVNRT by making it safer and more efficient without increasing procedure time. One‐year outcomes show it is feasible, safe, durable, and a valuable refinement of pediatric AVNRT ablation methods.
Funding
The authors have nothing to report.
Ethics Statement
The study has been reviewed by the Bioethical Committee of the Medical University of Warsaw.
Conflicts of Interest
The authors declare no conflicts of interest.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.
References
- 1. Bailin S. J., Korthas M. A., Weers N. J., and Hoffman C. J., “Direct Visualization of the Slow Pathway Using Voltage Gradient Mapping: A Novel Approach for Successful Ablation of Atrioventricular Nodal Reentry Tachycardia,” Europace 13, no. 8 (2011): 1188–1194, 10.1093/europace/eur112. [DOI] [PubMed] [Google Scholar]
- 2. Drago F., Battipaglia I., Russo M. S., et al., “Voltage Gradient Mapping and Electrophysiologically Guided Cryoablation in Children With AVNRT,” Europace 20, no. 4 (2018): 665–672, 10.1093/europace/eux021. [DOI] [PubMed] [Google Scholar]
- 3. Malloy L., Law I. H., and Von Bergen N. H., “Voltage Mapping for Slow‐Pathway Visualization and Ablation of Atrioventricular Nodal Reentry Tachycardia in Pediatric and Young Adult Patients,” Pediatric Cardiology 35, no. 1 (2014): 103–107, 10.1007/s00246-013-0748-7. [DOI] [PubMed] [Google Scholar]
- 4. Drago F., Calvieri C., Russo M. S., et al., “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,” Europace 23, no. 2 (2021): 271–277, 10.1093/europace/euaa195. [DOI] [PubMed] [Google Scholar]
- 5. Drago F., Raimondo C., Tamborrino P. P., et al., “AVNRT Cryoablation in Children <26 kg: Efficacy and Safety of Electrophysiologically Guided Low‐Voltage Bridge Strategy,” Pacing and Clinical Electrophysiology 46, no. 6 (2023): 543–547, 10.1111/pace.14660. [DOI] [PubMed] [Google Scholar]
- 6. Drago F., Russo M. S., Silvetti M. S., Des A., Iodice F., and Naso Onofrio M. T., “Cryoablation of Typical Atrioventricular Nodal Reentrant Tachycardia in Children: Six Years' Experience and Follow‐Up in a Single Center,” Pacing and Clinical Electrophysiology 33, no. 4 (2010): 475–481, 10.1111/j.1540-8159.2009.02623.x. [DOI] [PubMed] [Google Scholar]
- 7. Drago F., Tamborrino P. P., Porco L., et al., “Koch's Triangle Voltage Mapping for Cryoablation of Slow Pathway in Children: Preliminary Data of a Novel High‐Density Technique,” Journal of Interventional Cardiac Electrophysiology 63, no. 3 (2022): 621–628, 10.1007/s10840-021-01081-0. [DOI] [PubMed] [Google Scholar]
- 8. Reddy C. D., Ceresnak S. R., Motonaga K. S., et al., “Bridge to Success: A Better Method of Cryoablation for Atrioventricular Nodal Reentrant Tachycardia in Children,” Heart Rhythm 14, no. 11 (2017): 1649–1654, 10.1016/j.hrthm.2017.07.018. [DOI] [PubMed] [Google Scholar]
- 9. Ksiazczyk T. M., Pietrzak R., Obsznajczyk K., Franke M., and Werner B., “Introduction of the Low Voltage Bridge Mapping for the AVNRT RF Ablation in Children ‐ Early Follow‐Up Results,” Journal of Cardiovascular Electrophysiology 36, no. 5 (2025): 1032–1037, 10.1111/jce.16635. [DOI] [PubMed] [Google Scholar]
- 10. Siebels H., Sohns C., Nurnberg J. H., Siebels J., Langes K., and Hebe J., “Value of an Old School Approach: Safety and Long‐Term Success of Radiofrequency Current Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in Children and Young Adolescents,” Journal of Interventional Cardiac Electrophysiology 53, no. 2 (2018): 267–277, 10.1007/s10840-018-0367-6. [DOI] [PubMed] [Google Scholar]
- 11. Reents T., Springer B., Ammar S., et al., “Long‐Term Follow‐Up After Cryoablation for Adolescent Atrioventricular Nodal Reentrant Tachycardia: Recurrence Is Not Predictable,” Europace 14, no. 11 (2012): 1629–1633, 10.1093/europace/eus103. [DOI] [PubMed] [Google Scholar]
- 12. Walsh M. A., Gonzalez C. M., Uzun O. J., et al., “Outcomes From Pediatric Ablation: A Review of 20 Years of National Data,” JACC: Clinical Electrophysiology 7, no. 11 (2021): 1358–1365, 10.1016/j.jacep.2021.03.012. [DOI] [PubMed] [Google Scholar]
- 13. Shah M. J., Baskar S., Kennedy K. F., et al., “Effect of Ablation Energy Source on Outcomes of Slow Pathway Modification for AVNRT in Children,” JACC Clin Electrophysiol 10, no. 10 (2024): 2214–2223, 10.1016/j.jacep.2024.05.010. [DOI] [PubMed] [Google Scholar]
- 14. Sahin A. T., Ozyesil B., Kan H., Keskin O., Sertdemir A. L., and Gul E. E., “High‐Density Electroanatomic Mapping‐Guided Ablation in AVNRT: The Role of Slow Pathway Late Activation Mapping Technique,” Journal of Interventional Cardiac Electrophysiology 69 (2025): 513–519, 10.1007/s10840-025-02170-0. [DOI] [PubMed] [Google Scholar]
- 15. Tseng W. C., Wu M. H., Lu C. W., et al., “Combination of Slow Pathway Late Activation Maps and Voltage Gradient Maps in Guidance of Atrioventricular Nodal Reentrant Tachycardia Cryoablation,” Heart Rhythm 20, no. 7 (2023): 1026–1032, 10.1016/j.hrthm.2023.04.006. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.