An in vitro study of the hinge and near-field forward flow dynamics of theSt. jude Medical (R) Regent (TM) bileaflet mechanical heart valve

The most widely implanted prosthetic valve is the mechanical bileaflet. Rec ent clinical experiences suggest that some designs are more prone to thromb oembolic episodes than others. This study evaluated the hinge flow and near -field forward flow of the new St. Jude Medical(R) Regent(TM) bileaflet mec hanical heart valve. Laser Doppler velocimetry measurements were conducted within the hinge and near-field forward flow regions of the Regent(TM) valv e. These pulsatile flow velocity measurements were animated in time to visu alize the how fields throughout the cardiac cycle. During forward flow, a r ecirculation region developed in the inflow pocket of the Regent(TM) hinge but was subsequently abolished by strong backflow during valve closure. Lea kage velocities in the hinge region reached 0.72 m/s and Reynolds shear str esses reached 2,600 dyn/cm(2). Velocities in the near-field region were hig hest in the lateral orifice jet, reaching 2.1 m/s. Small regions of separat ed how were observed adjacent to the hinge region. Leaflet motion through t he Regent(TM) hinge creates a washout pattern which restricts the persisten ce of stagnation zones in its hinge. Based upon the results of these studie s, the hematological performance of the Regent(TM) series should be at leas t equivalent to the performance of the Standard series. (C) 2000 Biomedical Engineering Society. [S0090-6964(00)01105-X].