Showing papers by "Stephane Carlier published in 1994"

Determination of the severity of valvular regurgitation by the integral of the power spectrum of Doppler signals

Abstract: In order to study the correlation between valvular regurgitation flows and the power spectrum (PS) of Doppler recordings, the authors have developed an in-vitro model of a regurgitation based on a stationary turbulent free jet. Flows up to 4 l/min through orifices ranging from 2 to 4.5 mm in diameter are available. The authors' model has been validated by laser Doppler anemometry. Raw Doppler signals have been digitised from a Toshiba SSH-160A with an A/D board in an IBM PC. Spectral analysis was computed with FFT. The integrals of the PS and of the PS weighted by the velocity were correlated with the flows. In PW mode, with the sampling volume in the potential core of the jet, the flow and the integral of the main peak of the weighted PS were linearly correlated with a r2=0.88. In CW mode, the integral of the weighted PS and the flow had a r2=0.91. In conclusion, the analysis of the PS of Doppler signals allows a quantitative evaluation of flows. >