Digital particle image velocimetry investigation of the pulsating flow around a simplified 2-D model of a bileaflet heart valve.
OBJECTIVE
Strong interactions are believed to exist between the pulsating valvular flow and the valve leaflet motions. Hinge position, indicated by d/W (d = distance between the two axes of the hinge pivots; W = width of the testing section in the middle plane), plays a critical role in MHV performance. An optimized hinge position for a bileaflet heart valve can be identified as a design criterion for better valve performance.


METHODS
A two-dimensional (2-D) digital particle image velocimetry (DPIV) system was used to map the transient flow field of a simplified 2-D model of a bileaflet heart valve with a hydraulic diameter enlarged three-fold under pressure waveforms which was expanded based on Womersley number and Euler number considerations. Six different hinge positions were investigated.


RESULTS
At extreme hinge positions (d/W <0.2 or d/W >0.3), large-scale and long-duration stagnation of flow was found in the central orifice, and instability and highly disturbed flow was noted in plots of velocity vectors.


CONCLUSIONS
The transient flow pattern in the vicinity of the valve was greatly affected by the hinge position of moving leaflets. An optimum d/W in the range 0.2-0.3 yielded good velocity field and opening and closing behaviors.
Zhao
J B
JB
School of Mechanical and Production Engineering, Nanyang Technological University, Singapore.
Shi
Y B
YB
Yeo
T J
TJ
Hwang
N H
NH
D001783:Blood Flow Velocity / Q000502:physiology; D006349:Heart Valve Diseases / Q000503:physiopathology*; D006350:Heart Valve Prosthesis; D018056:Hemorheology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011673:Pulsatile Flow / Q000502:physiology*