Schematic of Doppler diastolic transmitral flow velocity

During diastole, there is an initial phase of rapid transmitral flow as the mitral valve opens and the left ventricle relaxes; this early filling phase results in a peak in the transmitral flow profile referred to as the E wave. The early filling phase is followed by a period of slow filling called diastasis, during which the slowing of left ventricular relaxation and the rise in left ventricular diastolic pressure result in a decrease in transmitral flow velocity. A late phase of rapid filling occurs with atrial contraction, resulting in a second peak in the transmitral flow profile referred to as the A wave. The isovolumic relaxation time (IVRT) is the interval between the closing of the aortic valve and the opening of the mitral valve, when left ventricular relaxation begins but before left ventricular volume begins to increase. The diastolic deceleration time (DDT) is the interval between the peak early diastolic filling velocity (the peak of the E wave) and the end of the E wave, when diastasis begins. The IVRT and DDT are prolonged in patients with impaired left ventricular relaxation and shortened in patients with restrictive physiology.