twisting: a temporal link between left ventricular relaxation and suction.

(LV) untwisting starts early during the isovolumic relaxation phase and proceeds throughout the early filling phase, releasing elastic energy stored by the preceding systolic deformation. Data relating untwisting, relax-ation, and intraventricular pressure gradients (IVPG), which represent another manifestation of elastic recoil, are sparse. To understand the interaction between LV mechanics and inflow during early diastole, Doppler tissue images (DTI), catheter-derived pressures (apical and basal LV, left atrial, and aortic), and LV volume data were obtained at baseline, during varying pacing modes, and during dobutamine and esmolol infusion in seven closed-chest anesthetized dogs. LV torsion and tor-sional rate profiles were analyzed from DTI data sets (apical and basal short-axis images) with high temporal resolution (6.5 0.7 ms). Repeated-measures regression models showed moderately strong corre-lation of peak LV twisting with peak LV untwisting rate (r 0.74), as well as correlations of peak LV untwisting rate with the time constant o