Soft-closure bileaflet mechanical heart valve design and hydrodynamic evaluation: an integrated iValve framework

Mechanical heart valves provide excellent long-term durability but remain associated with thromboembolism, hemolysis, and lifelong anticoagulation. These complications are influenced by valve geometry, hinge architecture, leaflet kinematics, leakage pathways, and rapid closure-associated flow phenomena. This study combines a mechanical and geometrical design framework with in vitro hydrodynamic evaluation of the iValve, a soft-closure bileaflet mechanical heart valve platform. The design framework emphasized curved leaflet geometry, controlled leaflet travel, exposed pivot regions, progressive leaflet-housing engagement, and distributed closure contact. Prototype iValve configurations were evaluated in a Leonardo-enabled pulse duplicator at approximately 5 L/min cardiac output, 70 beats/min, and 120/80 mmHg using saline. Projected dynamic valve area (PDVA), volumetric flow, regurgitant fraction, leakage area, and a derived regional velocity estimate were analyzed over 10 consecutive cycles. The iValve prototypes maintained large projected opening areas; i-v1.1 and i-v1.1 Al reached 3.18 ± 0.17 cm² and 3.20 ± 0.15 cm², respectively. Peak negative derived closure velocity was -4.3 ± 0.6 m/s for the original prototypes, compared with -22.5 ± 3.1 m/s for St. Jude Medical Regent and -56.4 ± 6.2 m/s for On-X. Revised i-v1.21 Al prototypes produced intermediate values (approximately -9.0 to -11.3 m/s) while reducing regurgitant fraction relative to the earlier prototypes. Because velocity was calculated as flow divided by PDVA in saline, these values should be interpreted as comparative hydrodynamic indicators rather than direct local jet velocity, shear stress, or thrombogenicity measurements. The results support further evaluation of soft-closure design strategies while identifying a central trade-off between closure transient attenuation and regurgitant performance.