The Functional Role of Longitudinal, Circumferential, and Radial Myocardial Deformation for Regulating the Early Impairment of Left Ventricular Contraction and Relaxation in Patients With Cardiovascular Risk Factors: A Study With Two-Dimensional Strain Imaging

Abstract

Two-dimensional strain imaging allows rapid and accurate analysis of regional left ventricular (LV) systolic and diastolic mechanics in the longitudinal, radial, and circumferential directions. The aim of this study was to assess precisely the differences in early impairment of LV myocardial contraction and relaxation among the 3 directions in 70 patients with cardiovascular risk factors and preserved LV pump function. The patients were classified into 2 groups according to the ratio of early diastolic to atrial systolic velocity (E/A) of transmitral flow: E/A > or = 1 (n = 35, 57 +/- 6.8 years) or E/A < 1 (n = 35, 60 +/- 4.9 years). The longitudinal strain and strain rate curves were determined in apical 2- and 4-chamber views, and radial and circumferential strain and strain rate curves and LV torsion curve were determined in the parasternal short-axis views. The mean peak systolic longitudinal strain and strain rate were lower, whereas the mean peak systolic circumferential strain and strain rate were greater in the E/A < 1 group. There were no significant differences in the mean peak systolic radial strain and strain rate between the 2 groups. The mean peak early diastolic longitudinal strain rate was markedly lower in the E/A < 1 group. The mean peak LV strain rates during atrial systole in all 3 directions were greater in the E/A < 1 group. The mean peak LV systolic longitudinal strain and longitudinal strain rate during atrial systole were independent predictors related to E/A in all patients. There were no significant differences in torsion and torsional and untwisting rates between the 2 groups. LV myocardial contraction and relaxation were first impaired in the longitudinal direction among the 3 directions in subclinical patients with cardiovascular risk factors. However, LV pump function and LV filling were compensated by circumferential shortening at ventricular systole and 3 directional lengthenings at atrial systole, respectively.