Objective: The reference values and impact of physiologic variables on echocardiographic quantification of left ventricular (LV) synchrony in a large series of healthy persons are unknown. This study prospectively investigated the impact of age, gender, and other physiologic parameters on LV longitudinal and radial synchrony.
Methods: LV longitudinal systolic and diastolic synchrony using tissue Doppler imaging were measured as the standard deviation of times to 12 regional peak myocardial systolic Sm (SDTs) and early diastolic Em (SDTe) velocities in 122 healthy volunteers (age 19-68 years, 64 men). By using 2-dimensional speckle tracking, radial synchrony was measured as the standard deviation of times to 6 regional peak strain (SDTrepsilon) in the short-axis papillary muscle level. Longitudinal systolic synchrony was also measured as the standard deviation of times to 12 regional peak strain (SDTlepsilon).
Results: The mean QRS duration and LV ejection fraction were 87 +/- 12 msec and 61% +/- 5.5%, respectively. The mean SDTs and SDTe were 37.1 +/- 17.4 msec and 17.3 +/- 6.7 msec, respectively. Gender and the mean Sm velocity from the 6 basal LV segments were independent predictors of SDTs, whereas the isovolumic relaxation time and mean Em velocity independently predicted SDTe. The mean SDTrepsilon was 19.2 +/- 14.6 msec. SDTrepsilon did not correlate with any clinical or echocardiographic parameters. The mean SDTlepsilon was 40.4 +/- 11.8 msec. Isovolumic relaxation time, pulmonary S/D ratio, and mean Sm independently predicted SDTlepsilon. There was no correlation between LV longitudinal and radial synchrony. Intraobserver and interobserver variability analyses showed the highest correlation for SDTs compared with SDTrepsilon and SDTlepsilon.
Conclusion: This study establishes normal reference ranges for LV systolic and diastolic synchrony measured with tissue Doppler velocity-based and 2-dimensional speckle tracking-based methods in a large group of healthy subjects of both genders across a wide age group. SDTs is gender specific and dependent on global LV systolic function, whereas SDTe is dependent on global LV diastolic function. Two-dimensional speckle-derived radial synchrony is independent of any clinical and echocardiographic variables but has higher intraobserver and interobserver variability compared with SDTs. LV longitudinal synchrony does not correlate with radial synchrony.