Leaflet Kinematics of Mechanical and Bioprosthetic Aortic Valve Prostheses

Abstract

The hemodynamic performance of artificial aortic valves (AVs) and the probability for structural valve deterioration can be linked to the valve kinematics. Comparability among different studies is limited because of variations in the experimental setups and physiologic boundary conditions. This study presents results of kinematic measurements of bioprosthetic and mechanical AVs that were tested in an identical experimental setting such that they can be directly compared with each other. The kinematics of AVs is typically presented in the form of the geometric orifice area and its temporal evolution. These parameters cannot capture asynchronous leaflet motion and out-of-plane leaflet velocity. In this work, each leaflet was tracked individually for a more detailed understanding of the leaflet kinematics, asynchronous leaflet motion, and leaflet tip velocities. A bioprosthetic valve, Edwards INTUITY (EINT), and two mechanical valves, Medtronic ADVANTAGE (MADV) and a Lapeyre-Triflo FURTIVA (TFUR), were tested in a compliant model of the aortic root in a physiologic flow loop. TFUR and MADV opened alike with maximum leaflet tip velocities of 0.77 and 0.66 m/s, respectively. The opening of EINT showed significantly higher local in-plane leaflet velocities of more than 2 m/s. EINT and TFUR exhibited similar early and slow closure. MADV closed significantly later with increased velocity. TFUR had a median maximum leaflet tip velocity of 0.39 m/s during valve closure and that of MADV was 0.83 m/s, whereas EINT exhibited a median maximum local in-plane leaflet velocity of 0.37 m/s. EINT experienced leaflet fluttering during systole with a flapping frequency of 36 Hz.

Short‐term evaluation of thromboresistance of a poly(ether ether ketone) (PEEK) mechanical heart valve with poly(2‐methacryloyloxyethyl phosphorylcholine) (PMPC)‐grafted surface in a porcine aortic valve replacement model

“…For the two mechanical valves advocating improved thromboresistance (i.e., the On‐X and Lapeyre‐Triflo), their design‐related features can contribute to thromboresistance . In contrast, the effect of material‐related features (i.e., surface properties) of the mechanical valves on their thromboresistance remains controversial.…”

“…Moreover, it may be better to redesign the bileaflet shape of the PEEK‐ g ‐PMPC valve. In vitro studies revealed that traditional bileaflet designs show a behavior unlike bioprosthetic valves and generate non‐physiological flows in the cardiac cycle at the aortic position, which may trigger platelet activation . Taken together, the thromboresistance of a mechanical valve made of the thromboresistant material (i.e., PEEK‐ g ‐PMPC) requires improvement by a combination with design‐related thromboresistance.…”

“…For the two mechanical valves advocating improved thromboresistance (i.e., the On-X and Lapeyre-Triflo), their designrelated features can contribute to thromboresistance. [7][8][9][10][11] In contrast, the effect of material-related features (i.e., surface properties) of the mechanical valves on their thromboresistance remains controversial. Pure pyrolytic carbon, the material of the On-X valve, is alleged to improve valve thromboresistance, 7 but Goodman et al 23 showed that platelet adhesion and morphology were unaffected by the silicon alloy concentration in pyrolytic carbon over a reasonable range (0.54-13.5 wt %).…”

“…Improved thromboresistance of the On‐X valve might be attributed to its design‐related features, including a flared inlet, increased height to cylinder ratio, 180° leaflet opening, and increased “washing” of hinge points, as well as its material (i.e., pure pyrolytic carbon) . On the other hand, owing to its trileaflet design, the Lapeyre‐Triflo valve (Novostia, Neuchâtel, Switzerland) produces hemodynamics and kinematics similar to those obtained with bioprosthetic valves at the aortic site . This design‐related feature is expected not to activate platelets and the coagulation cascade, rendering the Lapeyre‐Triflo valve as the first heart valve designed to be free of anticoagulation therapy; however, its clinical data have not yet been reported).…”

“…7 On the other hand, owing to its trileaflet design, the Lapeyre-Triflo valve (Novostia, Neuchâtel, Switzerland) produces hemodynamics and kinematics similar to those obtained with bioprosthetic valves at the aortic site. [8][9][10][11] This design-related feature is expected not to activate platelets and the coagulation cascade, 10 rendering the Lapeyre-Triflo valve as the first heart valve designed to be free of anticoagulation therapy; however, its clinical data have not yet been reported). Although the thromboresistant potential of these two mechanical valves appeared to be induced mainly by their design-related features, no study to date has clearly reported that material-related features of mechanical valves are responsible for their thromboresistance.…”