Time interval between onset of mitral inflow and onset of early diastolic velocity by tissue Doppler: a novel index of left ventricular relaxation: experimental studies and clinical application.

OBJECTIVES:The goal of this study was to examine the diagnostic utility of the time to onset of early (Ea) diastolic velocity of the mitral annulus by tissue Doppler (TD) in comparison with the time to onset of mitral inflow (T(Ea-E)) for the assessment of left ventricular (LV) relaxation. BACKGROUND:Tissue Doppler imaging of the mitral annulus provides useful information about myocardial function. So far, studies have focused on the measurement of peak Ea, but have not evaluated the diagnostic utility of the time to onset of Ea. METHODS:Simultaneous left heart catheterization and Doppler echocardiography (DE) were performed in 10 dogs. Left atrial pressures and LV volumes and pressures were measured before and after constriction of the circumflex (cx) coronary artery. The delay in Ea was next examined in 60 consecutive patients, undergoing simultaneous right heart catheterization and DE. Furthermore, (T(Ea-E)) was used to predict filling pressures in a prospective group of 33 patients. RESULTS:In canine studies, significant prolongation in the time interval (T(Ea-E)) was noted after cx constriction, which had a significant relation with tau (tau) (r = 0.93, p < 0.01). In human studies, Ea was significantly delayed in patients with impaired relaxation and pseudonormal LV filling in comparison with age-matched controls. In the prospective group, pulmonary capillary wedge pressure (PCWP) derived as: PCWP(Doppler) = LV(end-systolic pressure) x e(-IVRT/(T(Ea-E))), where IVRT is isovolumetric relaxation time; PCWP(Doppler) related well to PCWP(catheter) (r = 0.84, p < 0.001). CONCLUSIONS:T(Ea-E) is a useful novel index of LV relaxation. It can be used to identify patients with diastolic dysfunction and predict PCWP.