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Clinical and Electrophysiological Characteristics of Marshall Bundle-Related Atrial Tachycardia: Considerations Based
Yasuaki Tanaka1, Atsushi Takahashi1, Hirotaka Yano1
1Cardiovascular Center, Yokosuka Kyosai Hospital, Yokosuka, Japan.
Insights
Marshall bundle (MB)-related atrial tachycardia (AT) diagnosis was improved by inserting a catheter into the vein of Marshall (VOM). Chemical ablation showed no recurrence, unlike radiofrequency ablation, aiding AT treatment.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Conventional endocardial mapping has limitations in fully elucidating Marshall bundle (MB)-related atrial tachycardia (AT).
- Accurate diagnosis and targeted treatment of MB-related AT remain challenging.
Purpose of the Study:
- To clarify the clinical and electrophysiological characteristics of MB-related AT.
- To establish definitive diagnostic criteria for MB-related AT using catheter insertion into the vein of Marshall (VOM).
Main Methods:
- Forty-eight patients with AT post-mitral isthmus ablation were studied.
- A 1.6-F hexapolar electrode catheter was inserted into the VOM.
- MB-related AT diagnosis required VOM activation consistent with the AT circuit and specific pacing interval measurements.
Main Results:
- Twenty of 48 patients were diagnosed with MB-related AT.
- Activation along the VOM was predominantly descending.
- Chemical ablation with ethanol injection resulted in no recurrence, while radiofrequency ablation had a 57% recurrence rate.
Conclusions:
- Distinct clinical and electrophysiological characteristics of MB-related AT were identified.
- Catheter insertion into the VOM facilitates definitive diagnosis of MB-related AT.
- Chemical ablation appears more effective than radiofrequency ablation for MB-related AT treatment.
Background:
Conventional endocardial mapping cannot fully elucidate Marshall bundle (MB)-related atrial tachycardia (AT).
Objectives:
This study aimed to clarify the clinical and electrophysiological characteristics of MB-related AT definitively diagnosed using catheter insertion.
Methods:
Forty-eight patients with AT who had previously undergone mitral isthmus ablation were enrolled in this study. A 1.6-F hexapolar electrode catheter was inserted into the vein of Marshall (VOM) if endocardial left atrial mapping showed centrifugal propagation and post-pacing intervals after entrainment pacing suggested a macro-re-entrant mechanism. MB-related AT was diagnosed only when activation along the VOM was consistent with the propagation of the AT circuit, and post pacing interval within the VOM approximated the tachycardia cycle length.
Results:
Among 48 patients, 20 were diagnosed with MB-related AT. The activation direction along the VOM was predominantly descending (n = 13), rather than ascending (n = 7). There were diverse breakthrough sites to the endocardium along the course of the VOM. Two patients experienced persistent AT despite a conduction block in the VOM. Thirteen patients underwent chemical ablation with ethanol injection, and the remaining 7 underwent radiofrequency ablation at the earliest endocardial activation sites or mitral isthmus areas. Acute termination of AT was observed in 20 patients. No recurrence was observed in the group that underwent chemical ablation; however, 4 patients in the radiofrequency group experienced recurrence (n = 0 of 13 vs n = 4 of 7).
Conclusions:
Understanding the distinct clinical and electrophysiological characteristics of MB-related AT can facilitate the diagnosis and treatment of this AT type.
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