On mitral valve dynamics and its connection to early diastolic flow

In the field of cardiology, the current ability to accurately detect diastolic dysfunction is unsatisfactory due to the lack of an effective diagnostic index. Isolated indexes obtained from echocardiography are all restricted to a certain aspect of ventricular diastolic function only, and individually cannot be regarded as a global representative for the left heart diastolic function. Due to complexity of cardiac motion, a reliable measure for diastolic performance should be a parameter that independently correlates with several aspects of cardiac function. The presence of trans-mitral vortex ring and its influence on dynamics of the mitral valve is a topic that has been recently received more attention in cardiovascular research. One obvious reason for this attention is to find better solutions to overcome our inability in interpretation of Doppler mitral inflow patterns for distinguishing a normal trans-mitral flow from a pseudonormal pattern. In the present study, we investigated the relationship among the ventricular early pressure drop, trans-mitral thrust as a force generated during diastolic filling and mitral annulus recoil through the index of vortex formation time. As a result, we found that vortex formation time is independently correlated to trans-mitral thrust, minimal ventricular pressure and pressure drop time-constant of isovolumic relaxation phase. Results also showed that trans-mitral thrust is maximized when the non-dimensional vortex formation time is in the range of 4 and 5.5 regardless of the shape of the waveform or the value of the pressure drop time-constant. In conclusion, this study confirms that vortex formation time, a non-dimensional measure for duration of E-wave, can be used as an index to assess diastolic ventricular function.