CUR - The Council on Undergraduate Research

An Investigation of the Effect of Specimen Size on the Tricuspid Valve Leaflet Biaxial Mechanical Response

Hunter M. Lau, Brennan T. Mullins, and Dr. Chung-Hao Lee, School of Aerospace and Mechanical Engineering, University of Oklahoma, 660 Parrington Oval, Norman, OK 73019

Valvular heart disease is prevalent in about 2.5% of the population in the United States. The tricuspid valve (TV), a cardiac heart valve with limited literature available, allows for the unidirectional blood flow from the right atrium to the right ventricle.  Every year approximately 1.6 million people are affected by tricuspid regurgitation (TR), in which there is backflow of blood between the right ventricle and right atrium due to improper closure of the TV leaflets. Unfortunately, surgical correction of the TV has a high recurrence rate (~20%) of moderate-to-severe TR and there is limited pre-operative information regarding surgical outcomes. An important technique to help physicians visualize surgical methods and improve clinical outcomes are computational models with a patient-specific heart geometry. Our group has previously investigated the mechanical properties of the TV leaflets to help develop these computational models; however, the specimen dimensions varied among these studies and it is unknown how these dimensions may alter the quantified mechanical response. In this study, we investigated how the TV leaflet specimen’s size influences the TV leaflet’s mechanical properties. Biaxial testing was performed to quantify the tissue deformations between different sizes of the same leaflet (9x9 mm, 7.5x7.5 mm, 6x6mm, and 4.5x4.5 mm) under various physiological loading conditions. Preliminary results show a trend of increased maximum circumferential stretch as the tissue size decreases for all three leaflets of the TV. This data can be used to expand current finite element simulations to further observe how size and boundary conditions influence the mechanical response of the TV which will also allow us to understand the influence of specimen size from previous studies.  

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