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

Figures

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  FIGURE 1. (A) A schematic overview of the position and orientation of the electrode array (green rectangle) on the LA. (B) A picture of the LOM in a human specimen and the location of the electrode array during LOM mapping (striped rectangle). The white solid line marks the LOM. CS, coronary sinus; LA, left atrium; LAA, left atrial appendage; LIPV, left inferior pulmonary vein; LOM, ligament of Marshall; LSPV, left superior pulmonary vein; LV, left ventricle.

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  FIGURE 2. (A) Two activation maps from the same patient, constructed using unipolar LATs from only primary deflections (unipolarP, left) and a combination of primary deflections in case of single potentials and secondary deflections in case of double or fractionated potentials (unipolarS, right). (B) Voltage map from the same patient, using the voltages from unipolar primary deflections and the secondary deflections with the largest peak-to-peak amplitude (in case more than one secondary deflection was present).

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  FIGURE 3. Four examples of color-coded activation maps containing LOMs derived from different patients, constructed using all unipolar deflections. Examples of corresponding EGMs recorded at distinct locations of the LOM are shown outside the activation map, demonstrating the variable morphology of LOM potentials. EGM, electrogram; LOM, ligament of Marshall; TAT, total activation time. The bold black lines represent lines of conduction block and the black triangle in the EGM indicates a LOM potential. The white asterisk indicates a focal pattern of activation.

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  FIGURE 4. A color-coded activation map, constructed using unipolar EGMs in which all negative deflections are annotated. Additionally, examples of EGMs in the LOM area recorded at distinct moments of LOM activation are shown. The EGMs are depicted in chronological order of LOM activation and the color surrounding each EGM represents the LAT of the recording site within the LOM. EGM, electrogram; LAT, local activation time; LOM, ligament of Marshall; TAT, total activation time. The bold black lines represent lines of conduction block and the black triangle in the EGM indicates a LOM potential.

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  FIGURE 5. Unipolar and corresponding bipolar vertical and bipolar horizontal activation map obtained from one patient. The percentages on top of the activation maps show how often the amplitude of the LOM was larger than the amplitude of LA tissue for bipolar activation maps. (A) Map was constructed using unipolar EGMs in which all negative deflections were annotated (UEGM). (B) Map was constructed using bipolar EGMs, created by subtracting EGMs in vertical direction (BiEGMV). (C) Map was constructed using bipolar EGMs, created by subtracting EGMs in horizontal direction (BiEGMH). EGM, electrogram; LA, left atrium; LOM, ligament of Marshall; TAT, total activation time. The bold black lines represent lines of conduction block.