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Effect of Percentage Reduction in Action Potential Duration of M-cells on Re-entry in Short QT Syndrome

Ponnuraj Kirthi Priya, Srinivasan Jayaraman

    Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference
    |October 6, 2020
    PubMed

    Insights

    Short QT syndrome type 2 (SQTS2) involves arrhythmia due to altered repolarization. This study found that the degree of action potential duration shortening in M-cells, relative to other cardiac cells, is critical for sustaining re-entrant waves in SQTS2.

    Area of Science:

    • Cardiac Electrophysiology
    • Computational Biology
    • Medical Science

    Background:

    • Short QT syndrome type 2 (SQTS2) is linked to increased transmural dispersion of repolarization and a diminished QT interval, contributing to arrhythmia.
    • The precise extent of action potential duration (APD) shortening in different ventricular cell types during SQTS2 remains unclear.

    Purpose of the Study:

    • To investigate the role of varying APD shortening percentages in M-cells on the occurrence of re-entry in a computational model of SQTS2.
    • To elucidate the conditions under which re-entrant waves are sustained in the context of SQTS2.

    Main Methods:

    • A 2D anisotropic transmural heart model was developed using modified TP06 equations to simulate endocardial, M, and epicardial cell electrophysiology.
    • A discrete network of 250x100 cells interconnected by gap junctions was used to generate a pseudo-ECG.
    • The model was paced with premature beats under simulated SQTS2 conditions, varying the APD shortening in M-cells.

    Main Results:

    • Re-entry was sustained longer when APD shortening in M-cells was greater than in epicardial or endocardial cells, specifically when M-cell APD reduction was 5-7% less than in other cell types.
    • No re-entry was generated when the percentage reduction in APD of M-cells was similar to that of epicardial or endocardial cells.

    Conclusions:

    • The relative percentage reduction in APD of M-cells compared to epicardial and endocardial cells plays a crucial role in maintaining re-entrant waves in SQTS2.
    • These findings highlight the importance of transmural heterogeneity in APD shortening for arrhythmogenesis in SQTS2.

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