Established and Novel Clinical Applications of Diastolic Function Assessment by Echocardiography

A cardiac cycle consists of systolic (contraction) and diastolic (relaxation and filling) phases that are linked closely together for optimal function of the heart. Normal diastolic function allows adequate filling of the heart without an excessive increase in diastolic filling pressure both in the resting state and with stress or exertion.1 The diastolic phase is remarkably well designed to ensure that the ventricle is optimally filled for a given clinical condition.2 Basically, at the end of systole, left ventricular (LV) relaxation begins as an initial diastolic process, and LV pressure falls rapidly as the LV expands. This relaxation phase is accompanied by active movement of the mitral annulus away from the apex. The velocity of LV dilatation and mitral annular movement during early diastole correlates well with how fast the LV fills and relaxes, respectively.3,4 Myocardial relaxation continues during early diastole to reach the minimal LV diastolic pressure, which helps with “sucking” or “pulling” the blood actively into the LV (Figure 1, online-only Data Supplement Video 1A). The minimal LV diastolic pressure or completion of relaxation normally occurs by 3.5 times the value of tau—the time constant of relaxation (normal <45 ms)—after the mitral opening.5 LV pressure then rises to be equilibrated with left atrial (LA) pressure, at which time the early diastolic filling decelerates to close the mitral valve until the time of atrial contraction when LA pressure increases to initiate the late filling to complete diastole (Figure 1, online-only Data Supplement Video 1B).Figure 1. Top, Schematic diagram of mitral inflow and mitral medial annulus velocities from normal to progressive stages of diastolic dysfunction. Mitral inflow E is sensitive to preload, becoming higher with shorter deceleration time (time from the peak to the baseline) as diastolic function becomes worse with increasing filling …