Importance of the vein of Marshall involvement in mitral isthmus ablation

Taishi Fujisawa, Takehiro Kimura, Kazuaki Nakajima, Takahiko Nishiyama, Yoshinori Katsumata, Yoshiyasu Aizawa, Keiichi Fukuda, Seiji Takatsuki

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Background: Epicardiac conduction via the vein of Marshall (VOM) can bypass the mitral isthmus (MI) line, making MI ablation difficult. This study aimed to assess the contribution of the VOM in achieving MI conduction block. Methods: This study included 143 consecutive patients with nonparoxysmal atrial fibrillation who underwent initial MI ablation. They were retrospectively classified into two groups, a VOM-guided group (n = 28) and a conventional group (n = 115), according to the use of a 2-Fr electrode catheter inserted in the VOM. The acute success rate of achieving MI block and the ablation data were assessed. When the bidirectional block was verified exclusively in the VOM or coronary sinus (CS) electrodes, we defined it as a pseudo MI block. In the VOM-guided group, we ascertained the complete MI block, verified both in the VOM and CS electrodes. Results: In the VOM-guided group, the pseudoblock was observed in 33.3% of the patients during MI ablation. With significantly less radiofrequency energy (19 322.6 ± 11 352.8 vs 25 389.3 ± 19 951.9, P = 0.04), we achieved a similar level of success rate in MI ablation in the VOM-guided group (96.4% vs 91.3%, P = 0.36). Notably, after achieving complete MI block, atrial burst pacing induced two perimitral flutters in the VOM-guided group, which were successfully terminated by the additional radiofrequency application. Conclusions: Assessment of electrical conduction through the VOM could clarify the existence of a pseudo MI conduction block. However, the existence of a slow conduction through the MI could be detected only after induction of perimitral atrial tachycardia with atrial programmed stimulation.

Original languageEnglish
Pages (from-to)617-624
Number of pages8
JournalPACE - Pacing and Clinical Electrophysiology
Issue number6
Publication statusPublished - 2019 Jun


  • atrial fibrillation
  • catheter ablation
  • mitral isthmus
  • perimitral flutter
  • vein of Marshall

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


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