Usefulness of multimodality imaging for detecting differences in temporal occurrence of left ventricular systolic mechanical events in healthy young adults.

摘要

Detailed information about the absolute temporal occurrence of myocardial motion and deformation events during the cardiac cycle is still lacking. However, the normal time range of these parameters may be of great importance as a reference for detecting and interpreting mechanical dyssynchrony and for identifying a delayed contraction in case of left ventricular (LV) dysfunction. The aim of this study was to determine in young healthy subjects and for different LV segments the value of (1) time to peak systolic longitudinal velocity, displacement, strain rate, and strain using tissue Doppler imaging (TDI); (2) time to minimum systolic volume using real-time 3-dimensional echocardiography; and (3) time to maximum thickness using cardiac magnetic resonance imaging (MRI). Twenty 20 young healthy volunteers (13 men, mean age 32 +/- 4 years) underwent cardiac MRI and echocardiographic examination, including TDI and real-time 3-dimensional echocardiography. To define LV ejection time and isovolumic relaxation time, aortic valve closure and opening and mitral valve opening were identified. For all LV segments, longitudinal peak systolic velocity and strain rate were early systolic events. Peak systolic longitudinal displacement and strain in turn occurred in late systole, or in 20% to 30% of LV segments, during isovolumic relaxation time, similarly to minimum systolic volume and maximum myocardial thickness. In conclusion, the present study provides a systematic report of the normal time range of measurements obtained by TDI, real-time 3-dimensional echocardiography, and cardiac MRI. Peak systolic longitudinal velocity and strain rate significantly precede peak longitudinal displacement, strain, minimum systolic volume, and maximum thickness.