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An Investigation of Layer-Specific Tissue Biomechanics of Porcine Atrioventricular Valve Anterior Leaflets

40 Pages Posted: 28 Jan 2019 First Look: Accepted

See all articles by Katherine Kramer

Katherine Kramer

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

Colton Ross

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

Anju Babu

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

Yi Wu

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

Rheal Towner

Oklahoma Medical Research Foundation - Advanced Magnetic Resonance Center

Arshid Mir

University of Oklahoma - Division of Pediatric Cardiology

Harold M. Burkhart

University of Oklahoma - Division of Cardiothoracic Surgery

Gerhard A. Holzapfel

Graz University of Technology - Institute of Biomechanics; Norwegian University of Science and Technology (NTNU) - Department of Structural Engineering

Chung-Hao Lee

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory; University of Oklahoma - Institute for Biomedical Engineering, Science and Technology

Abstract

The atrioventricular heart valves (AHVs) are composed of structurally complex and morphologically heterogeneous leaflets. The coaptation of these leaflets during the cardiac cycle facilitates unidirectional blood flow and prevents regurgitation. Valve regurgitation is treated preferably by surgical repair if possible or replacement based on the disease state of the valve tissue. A comprehensive understanding of valvular morphology and mechanical properties is crucial to refining computational models, serving as a patient-specific diagnostic and surgical tool for preoperative planning. Previous studies have modeled the stress distribution throughout the thickness of the heterogeneous leaflet, but validations with layer-specific biaxial mechanical experiments are missing. In this study, we sought to fill this gap in literature by investigating the impact of microstructure constituents on mechanical behavior throughout the thickness of the AHVs’ anterior leaflets. Porcine mitral valve anterior leaflets (MVAL) and tricuspid valve anterior leaflets (TVAL) were micro-dissected into 3 layers (atrialis/spongiosa, fibrosa, and ventricular) and 2 layers (atrialis/spongiosa and fibrosa/ventricularis), respectively, based on their relative distributions of extracellular matrix (ECM) components as quantified by histological analyses: collagen, elastin, and glycosaminoglycans. Our results suggest that: (i) the atrialis/spongiosa layer, for both valves, is the most extensible and anisotropic layer, (ii) the intact TVAL response is stiffer than the atrialis/spongiosa layer but more compliant than the fibrosa/ventricularis layer, and (iii) the MVAL fibrosa and ventricularis layers behave nearly isotropic. These novel findings emphasize the biomechanical variances throughout the AHV leaflets, and our results will be useful to better inform AHV computational models.

Keywords: biaxial mechanical testing, the mitral and tricuspid valves, valve tissue biomechanics, morphological analysis, microdissection, extracellular matrix

Suggested Citation

Kramer, Katherine and Ross, Colton and Babu, Anju and Wu, Yi and Towner, Rheal and Mir, Arshid and Burkhart, Harold M. and Holzapfel, Gerhard A. and Lee, Chung-Hao, An Investigation of Layer-Specific Tissue Biomechanics of Porcine Atrioventricular Valve Anterior Leaflets (January 24, 2019). Available at SSRN: https://ssrn.com/abstract=3321895

Katherine Kramer (Contact Author)

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

307 W Brooks
Norman, OK 73019
United States

Colton Ross

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

307 W Brooks
Norman, OK 73019
United States

Anju Babu

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

307 W Brooks
Norman, OK 73019
United States

Yi Wu

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

307 W Brooks
Norman, OK 73019
United States

Rheal Towner

Oklahoma Medical Research Foundation - Advanced Magnetic Resonance Center

825 NE 13th St
Oklahoma City, OK 73104
United States

Arshid Mir

University of Oklahoma - Division of Pediatric Cardiology

OK
United States

Harold M. Burkhart

University of Oklahoma - Division of Cardiothoracic Surgery

OK
United States

Gerhard A. Holzapfel

Graz University of Technology - Institute of Biomechanics

Kopernikusgasse 24/IV
Graz, Styria A-8010
Austria

Norwegian University of Science and Technology (NTNU) - Department of Structural Engineering

Trondheim NO-7491
Norway

Chung-Hao Lee

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory ( email )

307 W Brooks
Norman, OK 73019
United States

University of Oklahoma - Institute for Biomedical Engineering, Science and Technology ( email )

307 W Brooks
Norman, OK 73019
United States

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