Laser Doppler study of intracardiac jets: Validation and applications of M mode color Doppler imaging for studying the jet development in pulsatile conditions

For studying both the temporal and the spatial distribution of velocities in pulsatile models of intracardiac jets, we have developed an M mode color display of laser Doppler measurements. M Mode images of the transverse velocity profile demonstrated the stability of the diameter during ejection. M mode images of the evolution of the centerline longitudinal velocity profile showed a linear propagation of the wave front, independent of the contemporary velocity at the jet origin and allowed the calculation of the speed of propagation. Using a fine velocity resolution, we demonstrated the presence, within the jet boundary layer of temporal pulsations corresponding to eddies. Time delays separating consecutive peaks allowed the calculation of frequencies that was confirmed using FFT analysis of velocity curves.