Abstract 715: Assessment of Left Ventricular Systolic and Diastolic Function by 2D Speckle Tracking Echocardiography
Left ventricular (LV) torsion (or twist) due to counter-directional basal and apical rotation, along with circumferential strain (C-strain) have been proposed as sensitive markers of both regional and global LV systolic function. More recently, the LV untwisting rate (UR) has been used for assessment of LV diastolic function by speckle tracking echocardiography (STE). However, the accuracy of STE has not been compared to systolic and diastolic function indices derived from pressure-volume relationships obtained using high-fidelity intraventricular conductance techniques. The aim of this study is to assess the accuracy and reliability of left ventricular twist, C-strain and untwisting rate as non-invasive indices of LV systolic and diastolic functions during acute changes in hemodynamic states. In 9 open-chest pigs, simultaneous echocardiographic imaging and LV pressure-volume (PV) measurements using Millar conductance catheter were performed during pharmacological interventions. Apical and basal rotations were measured from short-axis images using automatic frame-to-frame tracking. Dobutamine and esmolol infusions led to opposite changes in heart rate, end systolic pressure, dP/dtmax, end systolic volume, ESPVR and time constant (Tau). Global peak apical rotations significantly increased from 5.3 ± 1.2° to 8.5 ± 1.6° with dobutamine and decreased to 2.5 ± 0.8° with esmolol (P < 0.05). However, global peak basal rotations slightly increased with dobutamine and decreased with Esmolol. Apical C-strain increased during dobutamine infusion but did not change during esmolol infusion, while basal C-strain remained the same. Dobutamine and esmolol significantly altered both global peak apical and basal UR. Apical and basal rotations closely correlate with indices of systolic function based on PV relationship: dP/dt max (r = 0.86, r = 0.68, P < 0.05), ESPVR (r = 0.93, r = 0.89, P < 0.05). On the other hand, apical and basal UR closely correlate with the time constant of LV relaxation (r = 0.93, r = 0.89, P < 0.05). LV rotation and untwisting rates by STE provide quantitative and reproducible indices of global LV systolic and diastolic function during acute changes in hemodynamics.
This research has received full or partial funding support from the American Heart Association, AHA Western States Affiliate (California, Nevada & Utah).