Demonstration of electrical and anatomic connections between Marshall bundles and left atrium in dogs: Implications on the generation of P waves on surface electrocardiogram

Chikaya Omichi, Chung Chuan Chou, Moon Hyoung Lee, Che Ming Chang, Angela C. Lai, Hideki Hayashi, Shengmei Zhou, Yasushi Miyauchi, Yuji Okuyama, Akira Hamabe, Chun Hwang, Michael C. Fishbein, Shien Fong Lin, Hrayr S. Karagueuzian, Peng Sheng Chen

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Marshall Bundle and P Wave. Introduction: The muscle bundles within the ligament of Marshall (LOM) are electrically active. The importance of these muscle bundles (Marshall bundle [MB]) to atrial activation and the generation of the ECG P wave is unclear. Methods and Results: We used optical mapping techniques to study epicardial activation patterns in isolated perfused left atrium in four dogs. In another seven dogs, P waves were studied before and after in vivo radiofrequency (RF) ablation of the connection between coronary sinus (CS) and the LOM. Computerized mapping was performed before and after RF ablation. Optical mapping studies showed that CS pacing resulted in broad wavefronts propagating from the middle and distal LOM directly to the adjacent left atrium (LA). Serial sections showed direct connection between MB and LA near the orifice of the left superior pulmonary vein in two dogs. In vivo studies showed that MB potentials were recorded in three dogs. After ablation, the duration of P waves remained unchanged. In the other four dogs, MB potentials were not recorded. Computerized mapping showed that LA wavefronts propagated to the MB region via LA-MB connection and then excited the CS. After ablation, the activation of CS muscle sleeves is delayed, and P wave duration increased from 65.3 ± 14.9 msec to 70.5 ± 17.2 msec (P = 0.025). Conclusion: In about half of the normal dogs, MB provides an electrical conduit between LA free wall and CS. Severing MB alters the atrial activation and lengthens the P wave. MB contributes to generation of the P wave on surface ECG.

Original languageEnglish (US)
Pages (from-to)1283-1291
Number of pages9
JournalJournal of Cardiovascular Electrophysiology
Volume13
Issue number12
DOIs
StatePublished - Dec 1 2002
Externally publishedYes

Keywords

  • Electrocardiography
  • Marshall bundle
  • P wave

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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    Omichi, C., Chou, C. C., Lee, M. H., Chang, C. M., Lai, A. C., Hayashi, H., Zhou, S., Miyauchi, Y., Okuyama, Y., Hamabe, A., Hwang, C., Fishbein, M. C., Lin, S. F., Karagueuzian, H. S., & Chen, P. S. (2002). Demonstration of electrical and anatomic connections between Marshall bundles and left atrium in dogs: Implications on the generation of P waves on surface electrocardiogram. Journal of Cardiovascular Electrophysiology, 13(12), 1283-1291. https://doi.org/10.1046/j.1540-8167.2002.01283.x