Potential Advantages of Trileaflet Mechanical Heart Valves Revealed by Researchers

According to data from the American Heart Association, valvular heart disease affects approximately 2.5% of adults in the United States, resulting in over 100,000 patients undergoing valve replacement surgeries each year. These procedures often require a balance between valve durability and the risk of blood clot formation, which can necessitate additional interventions.

In a recent effort to enhance replacement heart valves, researchers from Texas A&M University are exploring innovations that could reduce compromises faced by patients. Traditional mechanical heart valves are characterized by two rigid leaflets that rotate according to blood flow. In contrast, Novostia is developing a trileaflet mechanical valve designed to more closely imitate natural blood flow dynamics.

Bioprosthetic valves, made from bovine or porcine tissues, feature flexible leaflets that deform during the cardiac cycle, influencing clotting risks due to their structural differences. The research, led by Dr. Iman Borazjani from the J. Mike Walker '66 Department of Mechanical Engineering, compared three types of valves: Novostia's trileaflet mechanical valve, a bileaflet mechanical valve, and a bioprosthetic valve mimicking a natural aortic valve. The study aimed to evaluate their effects on blood flow mechanics.

Findings indicate that the trileaflet valve begins closing during forward blood flow, similar to bioprosthetic valves, whereas the bileaflet valve only starts to close during backward flow. This distinction is crucial because preventing regurgitation—backward flow—is a fundamental function of heart valves. The results were published in the Journal of Fluid Mechanics.

The research identified two key fluid-dynamic principles promoting timely valve closure: a strong central jet that decelerates to reduce pressure during late systole and leaflet closure directed at the center of the valve opening. These insights could inform the design of mechanical valves, aiming to lower regurgitation and clotting risks.

Mechanical engineering Ph.D. candidate Syed Samar Abbas highlighted that understanding these fluid-dynamic mechanisms moves us closer to creating durable and biocompatible valves with reduced clotting potential. The team used a fluid-structure interaction framework to simulate valve behavior, analyzing leaflet motion, pressure distributions, and flow velocities.

Borazjani emphasized that their initial findings suggest the trileaflet mechanical valve's closure behavior closely resembles that of bioprosthetic valves, with potential for decreased platelet activation and improved biocompatibility. Future development includes creating models to simulate platelet activation and clot formation under various mechanical and biochemical stimuli.

With advancements in materials and manufacturing technologies, the study advocates for a new generation of heart valves that overcome the traditional trade-offs of durability and clotting risks, potentially transforming heart valve replacement therapy.