A preliminary study on the evaluation of relationship between left ventricular torsion and cardiac cycle phase by two-dimensional ultrasound speckle tracking imaging

Abstract

In normal subjects there is a certain corresponding relationship between the peak rotation angle of the apex and the base with respect to the phase of the cardiac cycle. We hypothesized that the myocardial contractile force and the delay of conduction may affect the correspondence of them. Our study aims to use speckle tracking imaging (STI) technique to analyze the relationship between the left ventricular rotation/torsion (LVrot/ LVtor ) characteristics and cardiac cycle phase, to investigate its clinical feasibility. The echocardiographic images of the short-axis view of the left ventricles (LV) at the apical and basal planes were acquired by STI in 32 healthy controls and 48 heart failure patients (New York Heart Association class I or II). LVtor angle, LVrot angle, the peak value and time of LVtor and LVrot were measured offline using frame-to-frame tracking of gray-scale speckle patterns at the standardized time point, respectively. All the acquired data of the two groups were compared and analyzed. In the healthy controls, there was no significant difference among the isovolumetric contraction time, peak time of clockwise rotation at the apical level and the peak time of clockwise rotation at the basal level segments (P > 0.05). There was no significant difference among systolic time, peak time of counterclockwise rotation at the apical level and peak time of counterclockwise rotation at the basal level segments (P > 0.05). There was no significant difference between systolic time and peak time of LVtor (P > 0.05). Compared with normal group, the peak of LVtor and LVrot angle were decreased at both apical and basal planes in heart failure group (P < 0.05). The peak time of LVtor was delayed in heart failure group (P < 0.05). The peak time of clockwise rotation at the apical level segments was longer than control group (P < 0.05) and continued to the ejection period. In the normal subjects, there is no sequence difference of LVrot between the basal and apical planes. They were correspondent to cardiac cycle. There is a temporal sequence difference of LVrot between basal and apical planes during LV contraction in heart failure group and decreased LVtor/rot have been demonstrated to influence left ventricular function. STI has shown great potential in early detecting the conduction variability in ventricular wall.