@article{Gerach2024,

title = {Differential effects of mechano-electric feedback mechanisms on whole-heart activation, repolarization, and tension},

author = {Tobias Gerach and Axel Loewe},

editor = {John Wiley The Physiological Society},

url = {https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP285022},

doi = {https://doi.org/10.1113/JP285022},

year  = {2024},

date = {2024-01-07},

urldate = {2024-01-07},

journal = {The Journal of Physiology},

abstract = {The human heart is subject to highly variable amounts of strain during day-to-day activities and needs to adapt to a wide range of physiological demands. This adaptation is driven by an autoregulatory loop that includes both electrical and the mechanical components. In particular, mechanical forces are known to feed back into the cardiac electrophysiology system, which can result in pro- and anti-arrhythmic effects. Despite the widespread use of computational modelling and simulation for cardiac electrophysiology research, the majority of in silico experiments ignore this mechano-electric feedback entirely due to the high computational cost associated with solving cardiac mechanics. In this study, we therefore use an electromechanically coupled whole-heart model to investigate the differential and combined effects of electromechanical feedback mechanisms with a focus on their physiological relevance during sinus rhythm. In particular, we consider troponin-bound calcium, the effect of deformation on the tissue diffusion tensor, and stretch-activated channels. We found that activation of the myocardium was only significantly affected when including deformation into the diffusion term of the monodomain equation. Repolarization, on the other hand, was influenced by both troponin-bound calcium and stretch-activated channels and resulted in steeper repolarization gradients in the atria. The latter also caused afterdepolarizations in the atria. Due to its central role for tension development, calcium bound to troponin affected stroke volume and pressure. In conclusion, we found that mechano-electric feedback changes activation and repolarization patterns throughout the heart during sinus rhythm and lead to a markedly more heterogeneous electrophysiological substrate.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fröhlich2024,

title = {Numerical evaluation of elasto-mechanical and visco-elastic electro-mechanical models of the human heart},

author = {Jonathan Fröhlich and Tobias Gerach and Jonathan Krauß and Axel Loewe and Laura Stengel and Christian Wieners},

editor = {Gesellschaft Mechanik},

url = {https://onlinelibrary.wiley.com/doi/10.1002/gamm.202370010},

doi = {https://doi.org/10.1002/gamm.202370010},

issn = {1522-2608},

year  = {2024},

date = {2024-01-02},

urldate = {2024-01-02},

journal = {GAMM Mitteilungen},

volume = {46},

issue = {2},

abstract = {We investigate the properties of static mechanical and dynamic electro-mechanical models for the deformation of the human heart. Numerically this is realized by a staggered scheme for the coupled partial/ordinary differential equation (PDE-ODE) system. First, we consider a static and purely mechanical benchmark configuration on a realistic geometry of the human ventricles. Using a penalty term for quasi-incompressibility, we test different parameters and mesh sizes and observe that this approach is not sufficient for lowest order conforming finite elements. Then, we compare the approaches of active stress and active strain for cardiac muscle contraction. Finally, we compare in a coupled anatomically realistic electro-mechanical model numerical Newmark damping with a visco-elastic model using Rayleigh damping. Nonphysiological oscillations can be better mitigated using viscosity.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}