Study of left ventricular function and mechanical motion pattern in left bundle branch block / 中华超声影像学杂志

ABSTRACT

Objective:To evaluate the left ventricular myocardial work parameters of the animal models with left bundle branch block (LBBB) and evaluate the effects of LBBB on left ventricular function and motion pattern by pressure-strain loops (PSL) of speckle tracking imaging (STI).Methods:In Twenty-four healthy male beagles, LBBB was induced by radio frequency ablation under anesthesia, and blood pressure was measured at the same time. Electrocardiograms and echocardiography images were acquired before (baseline), 30 minutes after (acute-LBBB) and 3 months after(chronic-LBBB) the creation of LBBB respectively. STI was applied to measure the left ventricular global longitudinal strain (GLS) and obtain the the PSL of each time point to evaluate the left ventricular global and segmental myocardial work parameters.Results:Compared to the baseline, the global work efficiencies(GWE) were obviously reduced ( P<0.05) and global wasted works(GWW) were significantly increased ( P<0.01) in the acute-LBBB and chronic-LBBB, significant differences were observed in GLS between acute-LBBB and baseline( P=0.04). In baseline, the work efficiency (WEsept) and the constructive work (CWsept) in the basal and middle segments of the septal wall were both obviously higher than the corresponding segments of left ventricular lateral wall( P<0.01), while the distribution of the wasted work(WWsept) was opposite( P<0.01). In acute-LBBB, the WEsept of all segments were significantly decreased ( P<0.05), the WWsept were obviously increased( P<0.05), the CWsept of basal segment was significantly reduced( P=0.01), while the wasted work in the basal segment of lateral wall(WWlat) was increased( P=0.04) compared with the baseline. Compared with the acute-LBBB, the WEsept of basal and middle segments were mildly recovery( P=0.03) in chronic-LBBB, but were still lower than the baseline ( P=0.001), the changes of the other myocardial work parameters of septal and lateral wall were similar to the acute-LBBB. Conclusions:Both acute-LBBB and chronic-LBBB can lead to the changes of left ventricular global and segmental myocardial work parameters. The myocardial work parameters of left ventricle can quantitatively analyze the changes of left ventricular function and motion pattern of the LBBB.