Paired Pressure-Volume Loop Analysis and Biaxial Mechanical Testing Characterize Differences in Left Ventricular Tissue Stiffness of Volume Overload and Angiotensin-Induced Pressure Overload Hearts
| Autor: | Jun Liu, Keith J. Gooch, Aaron J. Trask, Pamela A. Lucchesi, Rachel C. Childers |
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| Rok vydání: | 2020 |
| Předmět: |
Pressure overload
Materials science Ventricular tissue Angiotensins 0206 medical engineering Biomedical Engineering Volume overload Stiffness 02 engineering and technology 030204 cardiovascular system & hematology 020601 biomedical engineering 03 medical and health sciences 0302 clinical medicine In vivo Physiology (medical) Pressure volume loop Renin–angiotensin system medicine medicine.symptom Ex vivo Biomedical engineering |
| Zdroj: | Journal of biomechanical engineering. 143(8) |
| ISSN: | 1528-8951 |
| Popis: | Pressure overload (PO) and volume overload (VO) of the heart result in distinctive changes to geometry, due to compensatory structural remodeling. This remodeling potentially leads to changes in tissue mechanical properties. Understanding such changes is important, as tissue modulus has an impact on cardiac performance, disease progression, and influences on cell phenotype. Pressure–volume (PV) loop analysis, a clinically relevant method for measuring left ventricular (LV) chamber stiffness, was performed in vivo on control rat hearts and rats subjected to either chronic PO through Angiotensin-II infusion (4-weeks) or VO (8-weeks). Immediately following PV loops, biaxial testing was performed on LV free wall tissue to directly measure tissue mechanical properties. The β coefficient, an index of chamber stiffness calculated from the PV loop analysis, increased 98% in PO (n = 4) and decreased 38% in VO (n = 5) compared to control (n = 6). Material constants of LV walls obtained from ex vivo biaxial testing (n = 9–10) were not changed in Angiotensin-II induced PO and decreased by about half in VO compared to control (47% in the circumferential and 57% the longitudinal direction). PV loop analysis showed the expected increase in chamber stiffness of PO and expected decrease in chamber stiffness of VO. Biaxial testing showed a decreased modulus of the myocardium of the VO model, but no changes in the PO model, this suggests the increased chamber stiffness in PO, as shown in the PV loop analysis, may be secondary to changes in tissue mass and/or geometry but not an increase in passive tissue mechanical properties. |
| Databáze: | OpenAIRE |
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