Effects of a ventricular untwisting on intraventricular diastolic flow and color M-mode Doppler echocardiograms

Intraventricular hemodynamics during diastole was numerically analyzed in order to investigate effects of a ventricular untwisting on flow and a pattern of a color M-mode Doppler echocardiogram. Results showed that the ventricular untwisting affected secondary flows by inducing spiral flows in the ventricular cavity especially in the apical region. On the other hand, flows in the long-axis plane were not affected. Timing of formation, size and growing manner of the annular vortex were almost the same regardless of the presence of the ventricular untwisting; the vortex firstly arose in the base region, expanded towards the apex and eventually occupied the upper half of the ventricular cavity. A pattern of a color M-mode Doppler echocardiogram, that is, a spatiotemporal map of velocity along the long axis, was topologically the same as quantitatively confirmed by comparison of propagation velocity (0.43 m/s and 0.42 m/s for the case without and with the ventricular untwisting, respectively). These results suggested that this technique can exclusively capture flow dynamics produced by ventricular expansion with little influence of the ventricular untwisting. Therefore, we concluded that this is advantageous for assessing a left ventricular diastolic function.