Session: 07-08-04: Computational Modeling in Biomedical Applications

Paper Number: 193383

A Computational Analysis of Bileaflet Mechanical Heart Valve 

With the rising prevalence of cardiac valvular diseases and conditions among the population, the need for cardiac valve replacement has surged. Patients facing valve replacement weigh the advantages and trade-offs between bioprosthetic and mechanical heart valves (MHVs). Bioprosthetic heart valves, made from bovine (cow), porcine (pig), or human donor tissue, do not require lifelong medication; however, they have a higher risk of reoperation due to tissue deterioration. Although patients who receive MHVs have a lower risk of reoperation, physicians must prescribe them lifelong anticoagulants to prevent thrombosis and ensure device effectiveness. The risk of thrombosis formation is prominent in MHV concerns since the rigid and nonphysiological characteristics of MHV market models are linked to triggering the immune system’s response to clot. Thrombosis formation can lead to valve obstruction or create a traveling clot that can lead to stroke, both requiring immediate medical attention and possible operation. Along with the financial cost of the medication and routine blood test, there are additional negative impacts, such as patients adjusting their diet to prevent medication interference and reducing extreme physical activity, since the risk of significant trauma or injury when on blood thinners can lead to major bleeding episodes and prolonged healing. The patient’s dependence on blood thinners after surviving open-heart surgery for valve replacement emphasizes the need for research into MHV design modifications to improve patients’ quality of life.

This study employs a mechanical engineering approach to the design analysis of aortic mechanical heart valves, with the aim of reducing postoperative dependence on lifelong anticoagulants. The aortic valve is the primary focus since it experiences a significant pressure load to drive oxygenated blood from the left ventricle into the aorta for transport throughout the human body. The aortic valve is also prone to several diseases and conditions, such as aortic stenosis, regurgitation, and congenital aortic bicuspid defect, in some cases, warranting full valve replacement. It is theorized that the need for anticoagulants stems from the hemolytic activity caused by the inherent MHV design and subsequent interaction with blood flow. Hence, this computational study aims to reduce hemolysis by minimizing flow disturbances that generate significant fluid shear stress while maintaining valve durability and function. Literature on MHV geometry and valvar dynamics is reviewed to gain insight into the necessary considerations and methods to develop a 3D Computer-Aided Design model of a 21 mm aortic Bileaflet MHV. The aortic Bileaflet MHV model in its open position (ninety degrees) is tested under peak systole conditions (120 mmHg) in a Fluid-Structure Interaction (FSI) simulation using Finite Element Analysis (FEA). Blood flow is assumed Newtonian, incompressible, uniform, and steady, and a preliminary material analysis is conducted based on durability and biocompatibility. The results confirm that the hinge region of the MHV induces the greatest fluid shear stress during peak systole conditions. Therefore, the hinge geometry can be considered a major contributor to hemolytic activity, thrombosis formation, and the consequential need for anticoagulants. This study supports the need for further modifications to FDA-cleared Bileaflet MHV market models to minimize coagulation and hemolysis susceptibility, ultimately contributing to cardiac technological advancements for improved human longevity and quality of life.

Presenting Author: Peyman Honarmandi Manhattan University

Presenting Author Biography: Dr. Peyman Honarmandi earned his Ph.D. in Mechanical Engineering from the University of Toronto in 2007. Following his doctoral studies, he worked as a Postdoctoral Associate in the Mechanical and Bioengineering Department at the Massachusetts Institute of Technology. In 2010, he joined the Mechanical Engineering Department at the City College of New York as a faculty member. Since 2016, he has served as an Associate Professor at Manhattan University, where he has been instrumental in advancing the Solid Mechanics, Biomechanics and Aerospace concentrations within the Mechanical Engineering Department.
His research focuses on solid mechanics, with a particular emphasis on bioengineering and materials. Dr. Honarmandi has received numerous prestigious awards, including the Ontario Graduate Scholarship (OGS) and funding from the Natural Sciences and Engineering Research Council of Canada (NSERC). Additionally, he is an active member of several esteemed engineering societies, such as Sigma Xi, ASME, and SAE, and holds a Professional Engineer (PE) license.

Authors:

Ashley Zegler Manhattan University
Peyman Honarmandi Manhattan University