Quantitation of mitral annular oscillations and longitudinal "ringing" of the left ventricle: A new window into longitudinal diastolic function

For diastolic function (DF) quantification, transmitral flow velocity has been characterized in terms of the geometric features of a triangle (heights, widths, areas, durations) approximating the E-wave contour, whereas mitral annular velocity has only been characterized by E′-wave peak amplitude. The fact that E-waves convey global DF information, whereas annular E′-waves provide longitudinal DF information, has not been fully characterized, nor has the physiological legitimacy of combining fluid motion (E)- and tissue motion (E′)-derived measurements into routinely used indexes (E/E′) been fully elucidated. To place these Doppler echo measurements on a firmer causal, physiological, and clinical basis, we examined features of the E′-wave (and annular motion in general), including timing, amplitude, duration, and contour (shape), in kinematic terms. We derive longitudinal rather than global indexes of stiffness and relaxation of the left ventricle and explain the observed difference between E- and E′-wave durations. On the basis of the close agreement between model prediction and E′-wave contour for subjects having normal physiology, we propose damped harmonic oscillation as the proper paradigm in which to view and analyze the motion of the mitral annulus during early filling. Novel, longitudinal indexes of left ventricular stiffness, relaxation, viscosity, and stored (end-systolic) elastic strain can be determined from the E′-wave (and any subsequent waves) by modeling annular motion during early filling as damped harmonic oscillation. A subgroup exploratory analysis conducted in diabetic subjects (n = 9) and nondiabetic controls (n = 12) indicates that longitudinal DF indexes differentiate between these groups on the basis of longitudinal damping (P < 0.025) and longitudinal stored elastic strain (P < 0.005).