HYDROACOUSTICS OF THE MECHANICAL BILEAFLET HEART VALVE

Abstract

The results of experimental researches of hydrodynamic noise generated by a jet flow through the mechanical bileaflet mitral valve prosthesis of the Italian company Sorin are given. Physical simulation was carried out in laboratory conditions on the model of the left atrial chamber and the left ventricular chamber of the heart. The hydrodynamic noise of the flow through the artificial bileaflet mitral valve increased with increasing water flow. It was found that the greatest intensity of hydrodynamic noise and its spectral components was observed near the central jet of the bileaflet mitral valve. The obtained average pressure values in the near wake of the open mitral valve near the side jet are (10 – 20) % higher than near the central jet. It was determined that the power spectral densities of pressure fluctuations near the central jet are higher than near the side jet, especially in the frequency range (10 – 100) Hz. It was established that the small-scale vortex structures, which broke away from its leaflets and generated pressure fluctuations in the frequency range (20 – 70) Hz, degenerated starting from a distance of 2.5 valve diameters downstream. Increased levels of pressure fluctuations were observed near the central jet by more than (12 – 13) dB relative to hydrodynamic noise inside the atrial chamber and by more than (5 – 7) dB higher relative to pressure fluctuations near the side jet inside the left ventricular chamber in the frequency range (12 – 15) Hz. With an increase in water flow in the near wake of the mitral valve, an increase in the spectral levels of pressure fluctuations in the frequency range (60 – 80) Hz was observed. At a distance of more than below the open mechanical bileaflet mitral valve, the hydrodynamic noises near the central and side jets became approximately equal in the entire frequency range under consideration. The research results showed that hydroacoustic diagnostics of the operation of the mechanical bileaflet heart valve can be an effective means of diagnosing thrombus formation on the artificial valve leaflets.