Aspects Concerning the Simulation of a Mechanical Monoleaflet Heart Valve Closure

Cavitation is one of the factors related to the fluid mechanics of mechanical heart valve closure, which is supposed to be instrumental in valvular prosthetics complications. The basic mechanisms of MHV (mechanical heart valve) cavitation are still unresolved, requiring more detailed research on valve closing dynamics. Such research is very important for optimizing the build of MHVs, and, in the long run, for the design of a new generation of this kind of prostheses. This paper reviews the experimental and theoretical work on a monoleaflet valve closure, conducted by the authors in order to investigate the conditions and the mechanisms involved in cavitation occurrence. The paper treats aspects related both to the in vitro experiment which allowed the observation of cavitation in a OS (OmniScience) valve implanted in the mitral position of a cardiac simulator, and to the numerical simulation, based on an FSI (fluid structure interaction) model, of the closure motion of a generic-monoleaflet valve, to which the geometry of the aforementioned valve had been reduced. Results of the numerical simulation show the presence of areas of large negative pressures, indicating the potential for cavitation occurrence, at the instants and locations where cavitation bubbles were visualized in the in vitro experiment