AUTHOR=Langmuur Sanne J. J. , Taverne Yannick J. H. J. , van Schie Mathijs S. , Bogers Ad J. J. C. , de Groot Natasja M. S. 

TITLE=Optimization of intra-operative electrophysiological localization of the ligament of Marshall

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2022.1030064

DOI=10.3389/fcvm.2022.1030064

ISSN=2297-055X

ABSTRACT=Background: The ligament of Marshall (LOM) may play a role in the pathophysiology of several tachyarrhythmias and accurate electrophysiological localisation of this structure is crucial for effective ablation therapy. This study therefore quantifies electrophysiological properties of the LOM, and identifies which electrogram (EGM) recording (uni- or bipolar) and processing technologies (local activation time and/or voltage mapping) are most suitable for accurate localisation of the LOM.
Methods: The LOM was electrophysiologically identified in 19 patients (mean age 66 ± 14 years; 12 male) undergoing elective cardiac surgery using intra-operative high-density epicardial mapping, to quantify and visualise EGM features during sinus rhythm.
Results: Only a third of LOM potentials that were visualised using unipolar EGMs, were still visible in bipolar activation maps. Unipolar LOM potentials had lower voltages (P50: LOM: 1.51 (0.42 – 4.29) mV vs. left atrium (LA): 8.34 (1.50 – 17.91) mV, p <0.001), less steep slopes (P50: LOM: -0.48 (-1.96 – -0.17) V/s vs. LA: -1.24 (-2.59 – -0.21) V/s, p <0.001), and prolonged activation duration (LOM: 20 (7.5 – 30.5) ms vs. LA: 16.5 (6 – 28) ms, p = 0.008) compared to LA potentials. Likewise, bipolar LOM voltages were also smaller (P50: LOM: 1.54 (0.48 – 3.28) mV vs. LA: 3.12 (0.50 – 7.19) mV, p <0.001). 
Conclusions: The LOM was most accurately localised in activation and voltage maps by using unipolar EGMs with annotation of primary deflections in case of single potentials and secondary deflections in case of double or fractionated potentials.