TY - GEN
T1 - Stability of flow through heart valves
T2 - Winter Annual Meeting of the American Society of Mechanical Engineers
AU - Bluestein, D.
AU - Einav, S.
AU - Hwang, N. H.C.
PY - 1992
Y1 - 1992
N2 - The presence of turbulence in blood flow through heart valves is indicative of valvular stenosis. As no satisfying analytical solutions of the stability of pulsatile flow exist, an accurate, unbiased flow stability criteria is needed for the identification of turbulence initiation. The traditional approach uses a stability diagram where α (the Wormersley parameter) is defined by the fundamental heart rate. The novel stability approach involves the decomposition of α into the preferred frequency components. According to this approach, α is derived from the preferred modes induced on the flow by the valve geometry protrusive nature and its leaflets vibrations, rather than the fundamental heart rate. The stability of the flow is represented by a cluster of points, each corresponding to a certain dominant mode apparent in the flow. Transition to turbulence in pulsatile flow through heart valves was investigated using three polymer aortic valve models representing: a normal aortic valve, a 65% stenosed valve and a 90% severely stenosed valve, and two mitral valve models representing a normal mitral valve and a 65% stenosed valve, respectively. Valvular velocity waveforms were measured by laser Doppler anemometry (LDA). Spectral analysis was performed on velocity signals at selected spatial and temporal points to produce the power density spectra, in which the preferred frequency modes were identified. In order to compare our results with those achieved by the traditional approach, the cluster of points was averaged to collapse into a single point, which represents the flow stability. The comparison demonstrates the bias of the traditional stability diagram, which leads to unreliable stability criteria. Our stability approach derives the stability information from measured flow phenomena known to initiate flow instabilities. It differentiates between stabilizing and destabilizing modes and depicts an unbiased and explicit stability diagram of the flow, thus offering a more reliable stability criteria.
AB - The presence of turbulence in blood flow through heart valves is indicative of valvular stenosis. As no satisfying analytical solutions of the stability of pulsatile flow exist, an accurate, unbiased flow stability criteria is needed for the identification of turbulence initiation. The traditional approach uses a stability diagram where α (the Wormersley parameter) is defined by the fundamental heart rate. The novel stability approach involves the decomposition of α into the preferred frequency components. According to this approach, α is derived from the preferred modes induced on the flow by the valve geometry protrusive nature and its leaflets vibrations, rather than the fundamental heart rate. The stability of the flow is represented by a cluster of points, each corresponding to a certain dominant mode apparent in the flow. Transition to turbulence in pulsatile flow through heart valves was investigated using three polymer aortic valve models representing: a normal aortic valve, a 65% stenosed valve and a 90% severely stenosed valve, and two mitral valve models representing a normal mitral valve and a 65% stenosed valve, respectively. Valvular velocity waveforms were measured by laser Doppler anemometry (LDA). Spectral analysis was performed on velocity signals at selected spatial and temporal points to produce the power density spectra, in which the preferred frequency modes were identified. In order to compare our results with those achieved by the traditional approach, the cluster of points was averaged to collapse into a single point, which represents the flow stability. The comparison demonstrates the bias of the traditional stability diagram, which leads to unreliable stability criteria. Our stability approach derives the stability information from measured flow phenomena known to initiate flow instabilities. It differentiates between stabilizing and destabilizing modes and depicts an unbiased and explicit stability diagram of the flow, thus offering a more reliable stability criteria.
UR - http://www.scopus.com/inward/record.url?scp=0026963109&partnerID=8YFLogxK
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AN - SCOPUS:0026963109
SN - 0791811166
T3 - American Society of Mechanical Engineers, Bioengineering Division (Publication) BED
SP - 427
EP - 431
BT - 1992 Advances in Bioengineering
PB - Publ by ASME
Y2 - 8 November 1992 through 13 November 1992
ER -