Elsevier

Heart Rhythm

Volume 20, Issue 7, July 2023, Pages 1018-1025
Heart Rhythm

Pediatric and Congenital EP
High-density electroanatomic activation mapping to guide slow pathway modification in patients with persistent left superior vena cava

https://doi.org/10.1016/j.hrthm.2023.03.1537Get rights and content

Background

Slow pathway (SP) mapping and modification can be challenging in patients with persistent left superior vena cava (PLSVC) due to anatomic variance of the Koch triangle (KT) and coronary sinus (CS) dilation. Studies using detailed 3-dimensional (3D) electroanatomic mapping (EAM) to investigate conduction characteristics and guide ablation targets in this condition are lacking.

Objectives

The purpose of this study was to describe a novel technique of SP mapping and ablation in sinus rhythm using 3D EAM in patients with PLSVC after validation in a cohort with normal CS anatomy.

Methods

Seven patients with PLSVC and dual atrioventricular (AV) nodal physiology who underwent SP modification with the use of 3D EAM were included. Twenty-one normal heart patients with AV nodal reentrant tachycardias formed the validation group. High-resolution, ultra-high-density local activation timing mapping of the right atrial septum and proximal CS in sinus rhythm was performed.

Results

SP ablation targets were consistently identified by an area in the right atrial septum with the latest activation time and multicomponent atrial electrogram adjacent to a region with isochronal crowding (deceleration zone). In PLSVC patients, these targets were located at or within 1 cm of the midanterior CS ostium. Ablation in this area led to successful SP modification, reaching standard clinical endpoints with a median of 43 seconds of radiofrequency energy or 14 minutes of cryoablation without complications.

Conclusion

High-resolution activation mapping of the KT in sinus rhythm can facilitate localization and safe SP ablation in patients with PLSVC

Introduction

Slow pathway (SP) ablation is a well-accepted procedure for treatment of atrioventricular nodal reentrant tachycardia (AVNRT) and nonreentrant AV nodal tachycardia in adult and pediatric populations. Although Haissaguerre et al1 and Jackman et al2 provided descriptions of signature SP potentials to guide an electrogram (EGM)-based ablation approach of SP modification, the approach remains anatomically dependent as SP potentials are systematically explored from the inferior paraseptum in a superior direction toward the His bundle. In addition, these potentials may be absent or variable in distribution, and nonspecific to the SP in abnormal anatomy.

Recent studies have used 3-dimensional electroanatomic mapping (3D EAM) systems in the ablation of AVNRT to evaluate the anatomic location and electrophysiological (EP) characteristics of the SP with the aim of optimizing workflow, efficacy, and safety.3, 4, 5, 6, 7 SP targets have been identified by the site of colliding voltage wavefronts inside the Koch triangle (KT) in sinus rhythm,5 sinus voltage propagation by ripple or sparkle mapping to identify the latest site of activation,8 and the pivot point where fast and SP wavefronts collided and pivoted back to the AV node.4 Recently, high-density mapping during AVNRT has been performed to identify fractionated EGMs consistent with SP activation.9 However, these techniques have not been validated in pediatric patients or applied in those with abnormal cardiac anatomy.

The presence of a persistent left superior vena cava (PLSVC) poses challenges to SP ablation because of the distorted anatomy of the KT and limitations of conventional anatomic criteria based predominantly on fluoroscopy, which we have noted to result in poorer outcomes for these patients. There is a lack of a systematic approach to identify the SP in these patients, with previous data limited to case reports and highly variable approaches including transseptal, EAM, and fluoroscopy-based techniques.10, 11, 12 In this study, we present a novel combined EGM and high-density mapping-guided approach using conventional local activation timing (LAT) maps to facilitate SP ablation in patients with PLSVC. Validation of this technique was demonstrated in a cohort of adult and pediatric patients with normal coronary sinus anatomy.

Section snippets

Study population

This case series included patients with PLSVC who had undergone electrophysiological study (EPS) using 3D mapping systems and ablation targeting SP modification. The study also included another series of patients with structurally normal hearts who underwent the same procedure as a validation of concept. All procedures were conducted between November 2018 until May 2022 in Southampton University Hospital and in accordance with the principles of the Declaration of Helsinki. The study was

PLSVC patients

Seven patients with PLSVC were included in this series (5 female; median age 25 years [19–47]). Typical AVNRT was diagnosed in 6 patients, whereas 1 patient had a nonreentrant AV nodal tachycardia. Table 1 lists baseline and procedural characteristics of the patients.

High-density activation mapping of the right atrial septum including the CS ostium in sinus rhythm identified late areas with surrounding isochronal deceleration in these cases. Sites and signals targeted for ablation are shown in

Discussion

Here we provide a detailed description of a novel EGM and high-density activation mapping approach to guide SP ablation in patients with PLSVC. This approach was validated in a separate cohort of pediatric and adult patients with normal CS anatomy. The key findings were as follows. (1) Use of isochronal activation mapping during sinus rhythm to localize the SP is feasible in patients with normal anatomy and in those with PLSVC. (2) Criteria for the successful targets include the latest

Conclusion

This study serves as proof of concept on how to approach and treat typical AVNRT in patients with PLSVC using atrial activation mapping in sinus rhythm. SP localization and ablation can be challenging and potentially associated with higher risk because of unconventional KT anatomy. Our observations in both cohorts are in line with previous observations of patients with normal cardiac anatomy and can help in better understanding of anatomic–physiological correlations in typical AVNRT. Further

References (21)

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Funding Sources: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors Disclosures: The authors have no conflicts of interest to disclose.

1

Dr Dimitrios Gerontitis and Dr Michael T.B. Pope are joint first authors.

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