Combined ethanol and radiofrequency ablation for the elimination of focal atrial tachycardia originating from the Marshall bundle

Abstract

Introduction and importance: Atrial tachycardias (AT) originating from the Marshall bundle (MB) are rare and present significant challenges in diagnosis and management. The authors present the case of a 29-year-old male with recurrent AT successfully treated with a combined ethanol and radiofrequency ablation approach. This case highlights the effectiveness of this dual ablation strategy in resolving AT originating from the MB, contributing valuable insights into managing complex AT cases.

Case presentation: A 29-year-old male with recurrent, symptomatic palpitations was initially suspected of orthodromic atrioventricular reentrant tachycardia, but an initial electrophysiological study (EPS) failed to induce arrhythmia. Subsequent spontaneous episodes led to a detailed EPS, revealing automatic AT originating presumably from an epicardial focus on the posterior wall of the left atrium (LA). Detailed mapping identified the earliest activation at the vein of Marshall (VoM) ostium within the coronary sinus (CS). Suspecting the involvement of MB structures, VoM ethanol ablation was performed. Complete arrhythmia elimination was achieved with radiofrequency ablation (RFA) at the VoM ostium within the CS, with no recurrence.

Discussion: Most cases in the literature are associated with atrial fibrillation (AF) or AT within AF, typically involving re-entry mechanisms. The given case is unique as it presents a highly probable VoM origin of automatic AT with no concomitant AF. The VoM's anatomical and electrophysiological properties make it a potential source of refractory AT. In this case, ethanol ablation supplemented by targeted, limited RFA emerged as an effective strategy, highlighting the importance of comprehensive mapping and tailored ablation approaches in managing complex atrial arrhythmias.

Conclusion: The potential implications for clinical practice include recognizing the VoM as a critical target in refractory AT cases and adopting a combined ablation strategy to improve patient outcomes in similarly challenging scenarios.

Keywords: Marshall bundle; coronary sinus; ethanol ablation; focal atrial tachycardia; radiofrequency catheter ablation; vein of Marshall.

Figure 1

12-Lead ECG during sustained tachycardia episode.

Figure 2

Endocardial electroanatomical left atrium (LA) mapping. The color distribution pattern indicates a focal tachycardia mechanism. The earliest activation zone (white color) is broad, and located in the posterior-inferior aspect of LA (marked with dashed lines). The latest activation zone (purple) is localized in the left upper pulmonary vein.

Figure 3

Contrast coronary sinus (CS) venography with the identification of the Marshall vein (black solid arrows). The ablation catheter (black dashed arrow) is positioned at the site of earliest activation on the CS roof, anatomically corresponding to the ostium of the vein of Marshall.

Figure 4

Balloon placement in the middle portion of vein of Marshall (VoM). Dashed arrows indicate a balloon over the wire (1) inside the VoM, facilitated by sub-selector use (2) and coronary sinus engagement with the delivery system (3).

Figure 5

Immediate arrhythmia ceasing and SR restoration after radiofrequency ablation (RFA) initiation at the VoM ostium. Shown are surface ECG leads I, II, III, V1 (traces 1–4 sequentially), and 5 bipolar coronary sinus (CS) signals from distal to proximal (CS 1–2, CS 3–4, CS 5–6, CS 7–8, CS 9–10), followed by distal, proximal and unipolar signals from ablation catheter positioned in the CS (Abl d, Abl p, Abl uni). The vertical solid line indicates the start of RF delivery.