The Doppler method makes possible to reveal the relaxation disturbances and the increased left ventricular (LV) stiffness-pathophysiologic mechanisms of diastolic myocardial dysfunction (DMD), exerting opposite influence on the correlation of transmitral flow peaks. The decrease of the "diastolic reserve" in the patients with lung congestion is useful to diagnose DMD. But the type of LV filling, when the relative role of early diastole is decreased and of the late diastole-increased, cannot itself be recognized as pathologic. From the other side, the normal transmitral flow graphics doesn't allow to exclude DMD completely. The interpretation of Doppler parameters must take into consideration other factors influencing the LV diastolic filling: preload, systolic dysfunction and mitral regurgitation.