Pulsed-wave Doppler tracings of mitral inflow are frequently used to study LV filling (30). During early diastole, the flow velocity of blood filling the LV reflects the pressure gradient between the LV and the left atrium (LA) just after opening of the mitral valve. Under normal loading conditions, the relatively low LA-LV pressure gradient causes low velocity mitral inflow, with peak velocities typically around 1 m/s. If active relaxation is slowed (i.e., if tau is increased), early inflow velocity is slower and lasts for a longer duration (Figure 2). These changes are responsible for the echocardiographic finding of E/A reversal seen in patients with impairments in active relaxation that accompany normal aging and hypertrophy (Figure 3, grade 1). Such patients have normal mean LA pressures, further evidence that increased tau, alone, is not sufficient to account for symptomatic heart failure and does not explain the elevated filling pressures seen in HFNEF patients at rest (31). When LA pressure is increased, there is a higher LA-LV gradient, so that there is increased velocity of early inflow. Because ventricular and atrial pressures equilibrate quickly, early ventricular filling is terminated abruptly, causing a shortening of the time period during which early filling occurs and deceleration time is decreased (31). When volume overload is modest, the combination of prolonged relaxation and elevated LA pressure may be balanced, creating filling velocities and deceleration times similar to those seen with normal load and normal relaxation (Figure 3, grade 2). This pattern on the echocardiogram is generally referred to as pseudo-normalization. When volume overload is severe, early filling is rapid and the deceleration time is short (Figure 3, grade 3). This echocardiographic pattern is called “restrictive” (31). Therefore, it is obvious that Doppler mitral inflow patterns are determined primarily by loading conditions (32) and do not unambiguously signify an intrinsic abnormality of the LV musculature. This is underscored by the fact that the transmitral flow pattern may be changed by Valsalva's maneuver, which decreases venous return, or by medications that change preload, such as nitroglycerin (Figure 4) (33). Furthermore, the Doppler filling profile does not provide any insights into the relative position of EDPVR. For example, a restrictive pattern has been observed in subjects with leftward/upward-shifted EDPVRs characteristic of idiopathic hypertrophic/restrictive cardiomyopathies, but is also well described in patients with severe systolic heart failure characterized by a dilated LV with rightward/downward-shifted EDPVRs (34).