Abstract 2339: Evaluation of Left Ventricular Relaxation Using Two-Dimensional Ultrasound Speckle Tracking
Background: Tissue Doppler echocardiography is applied to assess left ventricular (LV) relaxation. However, annular velocities from even 4 or 6 sites, depend on regional function, excluding many myocardial segments. We examine global diastolic strain rate by 2-D speckle tracking from all myocardial segments as a measure of LV relaxation.
Methods: Seven adult dogs were imaged transthoracically with simultaneous LV micromanometer pressure recordings at baseline, caval occlusion, infusion of saline, dobutamine and esmolol. Real-time 2D images from apical 4, 2 and 3 chamber views were acquired (80 –100 frames/second) and analyzed offline using 2D speckle tracking package (GE) without knowledge of pressure data. The whole LV myocardium was defined as region of interest for speckle tracking. A global strain rate tracing was obtained for each apical view (Fig 1A⇓). Peak expansion strain rate during isovolumic relaxation (SRIVR) and early diastolic filling (SRE) were measured (Fig 1B⇓).
Results:With data from 36 stages, LV end diastolic pressure (EDP) decreased during caval occlusion and increased with volume loading, and tau shortened with dobutamine and increased with esmolol (both: P<0.05). On univariate analyses, heart rate (r=0.45, P=0.007), LV minimum pressure (r=-0.53, P=0.001), LV dp/dtmin (r=0.71, P<0.001, Fig 1C⇓) and tau (r=-0.84,P<0.001, Fig 1D⇓), but not LVEDP, were significantly related to SRIVR. SRIVR was determined by tau or LV dp/dtmin and minimum pressure on multivariate analysis. SRE was related only to LVEDP (r=0.50, P=0.002).
Global SRIVR can be used to assess LV relaxation being independent of preload. Global SRE can be used to assess LVEDP.