Strain-dependent stress relaxation behavior of healthy right ventricular free wall

Liu, Wenqiang; Labus, Kevin M.; Ahern, Matt; LeBar, Kristen; Avazmohammadi, Reza; Puttlitz, Christian M.; Wang, Zhijie

doi:10.1016/j.actbio.2022.08.043

Cited by 7 publications

(3 citation statements)

References 49 publications

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“…The goodness of the fit was examined by the R 2 value. The calculated relaxation rates from all strain levels were then used to determine the type of tissue viscoelastic behavior, where a fully nonlinear viscoelastic behavior is indicated if a strain-dependent behavior is observed ( Troyer and Puttlitz, 2012 ; Liu et al, 2021 ; Liu et al, 2022 ). Lastly, the dependence of the relaxation rate or initial stress on the input strain was examined by curve fitting, and linear and nonlinear (quadratic) relations between these parameters and the input strain were determined as described previously ( Shetye et al, 2014 ; Liu et al, 2022 ).…”

Section: Methodsmentioning

confidence: 99%

“…The calculated relaxation rates from all strain levels were then used to determine the type of tissue viscoelastic behavior, where a fully nonlinear viscoelastic behavior is indicated if a strain-dependent behavior is observed ( Troyer and Puttlitz, 2012 ; Liu et al, 2021 ; Liu et al, 2022 ). Lastly, the dependence of the relaxation rate or initial stress on the input strain was examined by curve fitting, and linear and nonlinear (quadratic) relations between these parameters and the input strain were determined as described previously ( Shetye et al, 2014 ; Liu et al, 2022 ). The fit with a quadratic polynomial formular generated better fitting outcomes, which indicates that the RV exhibits a unique nonlinear viscoelastic behavior with a quadratic relation between relaxation rate or initial stress and the input strain.…”

Section: Methodsmentioning

confidence: 99%

“…Thus, the biaxial viscoelastic behavior of adult RVFW remains little investigated. Our group originally examined the biaxial viscoelasticity of RVFW in healthy adult sheep ( Liu et al, 2021 ; 2022 ), but the changes in the viscoelastic behavior in pathological conditions are unclear. Furthermore, at the cell level or in papillary muscles, it has been shown that the myocardial viscoelasticity is increased in hypertrophy/diseased hearts and significantly weakens the muscle’s contractile function ( Cooper, 2006 ; Caporizzo et al, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

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Alterations of biaxial viscoelastic properties of the right ventricle in pulmonary hypertension development in rest and acute stress conditions

Liu

LeBar

Roth

et al. 2023

Front. Bioeng. Biotechnol.

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Introduction: The right ventricle (RV) mechanical property is an important determinant of its function. However, compared to its elasticity, RV viscoelasticity is much less studied, and it remains unclear how pulmonary hypertension (PH) alters RV viscoelasticity. Our goal was to characterize the changes in RV free wall (RVFW) anisotropic viscoelastic properties with PH development and at varied heart rates.Methods: PH was induced in rats by monocrotaline treatment, and the RV function was quantified by echocardiography. After euthanasia, equibiaxial stress relaxation tests were performed on RVFWs from healthy and PH rats at various strain-rates and strain levels, which recapitulate physiological deformations at varied heart rates (at rest and under acute stress) and diastole phases (at early and late filling), respectively.Results and Discussion: We observed that PH increased RVFW viscoelasticity in both longitudinal (outflow tract) and circumferential directions. The tissue anisotropy was pronounced for the diseased RVs, not healthy RVs. We also examined the relative change of viscosity to elasticity by the damping capacity (ratio of dissipated energy to total energy), and we found that PH decreased RVFW damping capacity in both directions. The RV viscoelasticity was also differently altered from resting to acute stress conditions between the groups—the damping capacity was decreased only in the circumferential direction for healthy RVs, but it was reduced in both directions for diseased RVs. Lastly, we found some correlations between the damping capacity and RV function indices and there was no correlation between elasticity or viscosity and RV function. Thus, the RV damping capacity may be a better indicator of RV function than elasticity or viscosity alone. These novel findings on RV dynamic mechanical properties offer deeper insights into the role of RV biomechanics in the adaptation of RV to chronic pressure overload and acute stress.

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