Jt. Ellis et al., An in vitro study of the hinge and near-field forward flow dynamics of theSt. jude Medical (R) Regent (TM) bileaflet mechanical heart valve, ANN BIOMED, 28(5), 2000, pp. 524-532
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].