Current Understanding of the Biomechanics of Ventricular Tissues in Heart Failure

Figures

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  Figure 1. (A)–(B) Stress–strain curves obtained from different directions in isotropic and anisotropic materials, respectively; (C)–(D) stress–strain curves obtained from loading and unloading periods of cyclic deformation in nonlinear elastic and viscoelastic materials, respectively.

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  Figure 2. Different mechanical tests for the viscoelastic properties measurement. (A) Stress relaxation test, (B) creep test, and (C) displacement-controlled cyclic tensile mechanical test. The upper panels illustrate the mechanical inputs and the lower panels illustrate the mechanical responses of the material in these tests.

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  Figure 3. Diagrams of the uniaxial (left) and biaxial (right) tissue mechanical tests. Dashed rectangles illustrate the deformed configurations of the sample after the mechanical stretch.

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  Figure 4. Hysteresis stress–strain loop obtained from the cyclic tensile mechanical tests. Triangle or sinusoidal mechanical loadings are typically applied during the cyclic stretches. (A)–(B) Representative strain and stress curves as a function of time in the tensile mechanical test; (C) representative hysteresis loop derived from the synchronized stresses and strains in (A) and (B).

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  Figure 5. Diagram of the pressure–volume (PV) loop obtained from cardiac catheterization. The loop in solid line denotes a steady-state PV loop, whereas the loop in dotted line denotes a transient loop obtained by brief vena cava occlusion to reduce the ventricle filling. ESPVR: end-systolic pressure-volume relationship; EDPVR: end-diastolic pressure-volume relationship.

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  Figure 6. Change in the right ventricle (RV) viscosity after three-month pressure elevation in adult sheep. Pressure elevation was induced by pulmonary artery constriction (PAC). (A) Viscosity is defined as the loop width (w) at the 50% of the maximal stress of the loop; (B) Loop width normalized by the average loop width of the control RVs in the individual direction. CTL: control; PAC: pulmonary artery constriction. * p < 0.05 vs. CTL in the same direction.

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  Figure 7. Collagen accumulation in hypertensive ovine RVs. (A)–(B) Representative histology images of the Picro Sirius Red staining of RVs in control and hypertensive groups, respectively; (C) Increase in type III collagen in the hypertensive RVs. CTL: control; PAC: pulmonary artery constriction. † p = 0.05 vs. CTL.