Key result
New self-closing mechanical mitral valve slows final closing speed ~82% vs conventional valves in vitro.
Why the study?
Conventional mechanical mitral valves start closing after systole, unlike natural valves that start closing before systole, motivating development of a self-closing valve.
Does a self-closing mechanical mitral valve prototype improve closing dynamics compared to a conventional mechanical valve in an in vitro model?
Does a self-closing mechanical mitral valve prototype improve closing dynamics compared to a conventional mechanical valve in an in vitro model?
Absolute Event Rate: 0.34% vs 1.9%
A prototype self-closing mechanical mitral valve demonstrated the ability to start closing before systole with slower final closing speeds in an in vitro model, providing a design strategy for future prototyping.
Anatural mitral valve starts closing before systole. Conventional mechanical mitral valves start their closing motion after systole. In order to let the mechanical mitral valves start closing before systole, we propose a new self-closing valve by adjusting the center of gravity of the leaflet. As a first step, we adjusted the center of gravity by attaching a block of lead to the leaflet of a CarboMedics bileaflet valve and evaluated it using a pulse duplicator and an x-ray high-speed video camera. Comparative study was conducted under 60 bpm and 4 L/min as the mean flow rate. It was clarified that the self-closing valve started closing before systole, no influence on inflow volume was found, the final closing speed of the self-closing valve just before complete closure was slower than the conventional valve (1.9-0.34 m/s), a design strategy of a self-closing valve (sewing ring diameter 29 mm) was obtained from the experiment that momentum of inertia of the leaflet should be less than 14.9 x 10-9 kg.m2 and the torque caused by gravity should be more than 4.2 x 10-6 N. m, and only one leaflet should be designed as self-closing, and surgeons need to pay attention to the positioning of the two leaflets. In conclusion, the preliminary study showed the ability of starting to close before systole and the design strategy for future prototyping.
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Naemura et al. (1999) studied this question. Self-closing mechanical mitral valve vs. Conventional mechanical mitral valve was evaluated on Final closing speed just before complete closure (m/s). A new self-closing mechanical mitral valve started closing before systole and had a slower final closing speed (0.34 m/s) compared to a conventional valve (1.9 m/s) in a pulse duplicator model.
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