How viscous is the beating heart? Insights from a computational study

Tikenogullari, Oguz Ziya; Costabal, Francisco Sahli; Jiang, Yao; Marsden, Alison L.; Kuhl, Ellen

doi:10.1007/s00466-022-02180-z

Cited by 5 publications

(2 citation statements)

References 55 publications

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“…Following this theory, our model assumes that the material response can be decomposed into a timeindependent initial stress function that depends only on the current stretch and a time-dependent relaxation function that depends only on time. The theory of quasi-linear viscoelasticity is widely used to model single cells [61] and tissues, such as tendons [45,66], skeletal muscle [59], or the heart [57]. Materials for which this assumption does not hold will require a different, fullynonlinear modeling approach [Tac et al, 2023b, 1, 20, 28, 63, 65].…”

Section: Limitations and Future Outlookmentioning

confidence: 99%

Automated model discovery for muscle using constitutive recurrent neural networks

Wang

Linka

Kuhl

2023

Journal of the Mechanical Behavior of Biomedical Materials

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Section: Limitations and Future Outlookmentioning

confidence: 99%

Automated model discovery for muscle using constitutive recurrent neural networks

Wang

Linka

Kuhl

2023

Journal of the Mechanical Behavior of Biomedical Materials

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“…One reason for this disagreement is because it is unclear if the time-scale and magnitude of cardiac tissue viscoelasticity is relevant at a heartbeat scale; our work will help to answer this question. 33,34 One computational study concluded that viscoelasticity plays an important role in the cardiac relaxation phase, with increasing importance during disease conditions. 35 Through Finite Element Analysis, the authors found that their viscoelastic model had reduced stroke volume compared to an elastic model.…”

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confidence: 99%

Stress relaxation rates of myocardium from failing and non-failing hearts

Gionet-Gonzales,

Gathman,

Rosas

et al. 2024

Preprint

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The heart is a dynamic pump whose function is influenced by its mechanical properties. The viscoelastic properties of the heart, i.e. its ability to exhibit both elastic and viscous characteristics upon deformation, influence cardiac function. Viscoelastic properties change during heart failure (HF), but, direct measurements of failing and non-failing myocardial tissue stress relaxation under constant displacement are lacking. Further, how consequences of tissue remodeling, such as fibrosis and fat accumulation, alter the stress relaxation remains unknown. To address this gap, we conducted stress relaxation tests on porcine myocardial tissue to establish baseline properties of cardiac tissue. We found porcine myocardial tissue to be fast relaxing, characterized by stress relaxation tests on both a rheometer and microindenter. We then measured human left ventricle (LV) epicardium and endocardium human tissue from non-failing, ischemic HF, and non-ischemic HF patients by microindentation. We found that the ischemic HF had slower stress relaxation than non-failing endocardium; and that slower stress relaxing tissues were correlated with increased collagen deposition and increased α-smooth muscle actin (α-SMA) stress fibers, a marker of fibrosis and cardiac fibroblast activation, respectively. In the epicardium, we found that ischemic HF had faster stress relaxation than non-ischemic HF and non-failing; and that faster stress relaxation correlated with Oil Red O staining, a marker for adipose tissue. These data show that changes in stress relaxation vary across the different layers of the heart during ischemic vs. non-ischemic HF. These findings reveal how the viscoelasticity of the heart changes, which will lead to better modeling of cardiac mechanics for in vitro and in silico HF models.

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