Abstract 2570: Effects Of Exercise On Left Ventricular Diastolic Function Depend On Homogenous Increase In Diastolic Strain Rates
Objectives: It has been speculated that early diastolic left ventricular (LV) suction depends on LV apex relaxing more promptly than LV base, and that these relationships are accentuated during exercise. In this study, we sought to determine impact of exercise on the relationship between parameters of LV diastolic mechanics (peak early longitudinal (E SrL), circumferential (E SrC) and radial (E SrR) strain rate, and peak LV untwisting velocity) and intraventricular pressure gradient (IVPG) as marker of diastolic suction.
Methods: We studied 23 healthy volunteers (age 38 ± 10 years, 13 females) by Vivid 7 ultrasound machine (GE) during supine bicycle stress. Segmental diastolic strain rates and untwisting velocity were obtained by speckle tracking software (EchoPac, GE Medical) while IVPG was measured by applying the Euler equation to the transmitral color Doppler M mode of the LV inflow. Segmental diastolic strain rates were averaged over basal, mid, and apical levels.
Results: Absolute values of E SrL, E SrC and E SrR homogenously increased during exercise (P<0.001 for all) by the same degree at all LV three levels (p=NS for the difference between levels). (see table⇓) Untwisting velocity during exercise increased from -1.54 ± 0.69 to -3.40 ± 1.54 rad/s while IVPG increased from 1.41 ± 0.67 to 3.90 ± 1.69 mmHg (p<0.001 for both). Out of strain parameters, average E SrL increase during exercise showed strongest correlation with IVPG (r=0.64, p<0.001) and untwisting velocity (r=0.62, p<0.001). Higher untwisting velocity was associated with the greater IVPG (r=0.70, p<0.001).
Conclusions: Increase of suction during exercise is related to homogeneous augmentation of relaxation throughout left ventricle. Longitudinal strain rate was the best predictor of the increase of untwisting velocity and IVPG. These data could serve as a reference for diastolic stress testing.