Rise of the new generation of mechanical heart valve prostheses: An in-depth in vitro study

Valvular heart disease, particularly aortic valve (AV) calcification, remains a significant issue, with AV replacement surgeries among the most common procedures. Current surgical options include mechanical heart valves (MHVs) and bioprosthetic valves, each with inherent limitations. MHVs offer long-term durability but require lifelong anticoagulation therapy, while bioprosthetic valves provide superior hemodynamics but lack durability. The MHV's non-physiological flow patterns through the hinges and spikes in regional backflow velocity (RBV) during closure may contribute to the need for anticoagulation. This study evaluates two emerging MHVs, the iValve and Triflo, alongside established prosthetic valves. The iValve, featuring a novel bileaflet design, and the Triflo, a trileaflet valve, aim to overcome current MHV limitations. In vitro testing used a pulse duplicator system to assess projected open area (POA), volumetric flow rate, regurgitant volumes, and trans-AV pressure relative to mean pressure (pressure ratio). POA and volumetric flow rates were used to calculate flow velocity and RBV. Results indicate that the iValve and Triflo achieved comparable pressure ratios and significantly lower mean and peak RBV values than traditional MHVs like the SJM and On-X. This suggests improved flow dynamics and reduced shear stress on blood components, potentially minimizing anticoagulation requirements. The iValve prototypes showed regurgitant volumes comparable to conventional MHVs, while the Triflo performed similarly to the control valve. These findings underscore the potential of next-generation MHVs to combine durability, hemodynamic performance, and reduced thrombogenic risk closer to the native valve.