An investigation of the effect of freezing storage on the biaxial mechanical properties of excised porcine tricuspid valve anterior leaflets

Duginski, Grace A.; Ross, Colton J.; Laurence, Devin W.; Johns, Cortland H.; Lee, Chung‐Hao

doi:10.1016/j.jmbbm.2019.103438

Cited by 29 publications

(7 citation statements)

References 43 publications

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“…Hearts were transported to the laboratory, cleansed of blood clots, and stored in a freezer at -20 °C until later testing. Freezing has been a common practice for effective tissue storage, and prior studies have shown minimal changes in the tissue mechanics of heart valve leaflets and other connective tissues following freezer storage (Duginski et al 2020;Foutz et al 1992;O'Leary et al 2014;Stemper et al 2007;Venkatasubramanian et al 2006).…”

Section: Tissue Preparationmentioning

confidence: 99%

Quantification of load-dependent changes in the collagen fiber architecture for the strut chordae tendineae-leaflet insertion of porcine atrioventricular heart valves

Ross

Hsu

Baumwart

et al. 2020

Biomech Model Mechanobiol

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Atrioventricular heart valves (AHVs) regulate the unidirectional flow of blood through the heart by opening and closing of the leaflets, which are supported in their functions by the chordae tendineae (CT).The leaflets and CT are primarily composed of collagen fibers that act as the load-bearing component of the tissue microstructures. At the CT-leaflet insertion, the collagen fiber architecture is complex, and has been of increasing focus in the previous literature. However, these previous studies have not been able to quantify the load-dependent changes in the tissue's collagen fiber orientations and alignments. In the present study, we address this gap in knowledge by quantifying the changes in the collagen fiber architecture of the mitral and tricuspid valve's strut CT-leaflet insertions in response to the applied loading by using a unique approach, which combines polarized spatial frequency domain imaging with uniaxial mechanical testing. Additionally, we characterized these microstructural changes across the same specimen without the need for tissue fixatives. We observed increases in the collagen fiber alignments in the CT-leaflet insertion with increased loading, as described through the degree of optical anisotropy.Furthermore, we used a leaflet-CT-papillary muscle entity method during uniaxial testing to quantify the chordae tendineae mechanics, including the derivation of the Ogden-type constitutive modeling parameters. Results from this study provide a valuable insight into the load-dependent behaviors of the strut CT-leaflet insertion, offering a research venue to better understand the relationship between tissue mechanics and the microstructure, which will contribute to a deeper understanding of AHV biomechanics.

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Section: Tissue Preparationmentioning

confidence: 99%

Quantification of load-dependent changes in the collagen fiber architecture for the strut chordae tendineae-leaflet insertion of porcine atrioventricular heart valves

Ross

Hsu

Baumwart

et al. 2020

Biomech Model Mechanobiol

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“…During mounting, the tissues’ circumferential ( C ) and radial ( R ) directions were aligned with the x - and y -directions of the biaxial testing device. Following our previously developed displacement-controlled protocols [ 9 , 10 , 36 , 46 , 47 ] for investigating the atrioventricular heart valve tissue’s nonlinear mechanical behaviors and material anisotropy, the specimen was next submerged in a PBS bath at 37 °C for the entire duration of mechanical testing. A preconditioning protocol was utilized with six equibiaxial and non-equibiaxial loading/unloading cycles, targeting a membrane tension of 25 N/m to restore the leaflets to their in-vivo physiological configurations [ 14 , 48 ].…”

Section: Methodsmentioning

confidence: 99%

A Pilot Study on Linking Tissue Mechanics with Load-Dependent Collagen Microstructures in Porcine Tricuspid Valve Leaflets

et al. 2020

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The tricuspid valve (TV) is composed of three leaflets that coapt during systole to prevent deoxygenated blood from re-entering the right atrium. The connection between the TV leaflets’ microstructure and the tissue-level mechanical responses has yet to be fully understood in the TV biomechanics society. This pilot study sought to examine the load-dependent collagen fiber architecture of the three TV leaflets, by employing a multiscale, combined experimental approach that utilizes tissue-level biaxial mechanical characterizations, micro-level collagen fiber quantification, and histological analysis. Our results showed that the three TV leaflets displayed greater extensibility in the tissues’ radial direction than in the circumferential direction, consistently under different applied biaxial tensions. Additionally, collagen fibers reoriented towards the direction of the larger applied load, with the largest changes in the alignment of the collagen fibers under radially-dominant loading. Moreover, collagen fibers in the belly region of the TV leaflets were found to experience greater reorientations compared to the tissue region closer to the TV annulus. Furthermore, histological examinations of the TV leaflets displayed significant regional variation in constituent mass fraction, highlighting the heterogeneous collagen microstructure. The combined experimental approach presented in this work enables the connection of tissue mechanics, collagen fiber microstructure, and morphology for the TV leaflets. This experimental methodology also provides a new research platform for future developments, such as multiscale models for the TVs, and the design of bioprosthetic heart valves that could better mimic the mechanical, microstructural, and morphological characteristics of the native tricuspid valve leaflets.

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“…Finally, the resected aneurysm tissue was temporarily stored in a freezer after surgical removal, and the effect of freezing on aneurysm tissues is not completely understood. Previous studies for other www.nature.com/scientificreports/ soft tissues found negligible differences before and after temporary freezing [62][63][64] , but future extensions would ideally use the fresh resected tissue for the characterizations. This pilot study has presented a multiscale characterization, the first of its kind, for aneurysm tissues including mechanical, collagen microstructural, and morphological characterizations.…”

Section: Study Limitations and Future Extensionsmentioning

confidence: 98%

A Pilot Study on Biaxial Mechanical, Collagen Microstructural, and Morphological Characterizations of a Resected Human Intracranial Aneurysm Tissue

et al. 2020

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An investigation of the effect of freezing storage on the biaxial mechanical properties of excised porcine tricuspid valve anterior leaflets

Cited by 29 publications

References 43 publications

Quantification of load-dependent changes in the collagen fiber architecture for the strut chordae tendineae-leaflet insertion of porcine atrioventricular heart valves

Quantification of load-dependent changes in the collagen fiber architecture for the strut chordae tendineae-leaflet insertion of porcine atrioventricular heart valves

A Pilot Study on Linking Tissue Mechanics with Load-Dependent Collagen Microstructures in Porcine Tricuspid Valve Leaflets

A Pilot Study on Biaxial Mechanical, Collagen Microstructural, and Morphological Characterizations of a Resected Human Intracranial Aneurysm Tissue

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