Abstract
We examined two dogs with Left bundle branch block (LBBB) by conventional echocardiography and tissue Doppler imaging (TDI) to assess cardiac function and interventricular asynchronicity. Conventional echocardiography was used to measure aortic preejection period and pulmonary preejection period (PEP). TDI was performed to assess the long axis function of the ventricles using apical four chamber view. Regions of interest (ROIs) were in the basal segments of the left and right ventricle lateral walls and septal wall. Regional wall motion was assessed quantitatively as myocardial velocities and time intervals. To assess systolic function, peak sustained systolic velocity (Sm) and time from the onset of QRS complex to Sm (Ts) for interventricular synchronicity. In LBBB cases, Ts was markedly longer in basal left lateral segment and basal septal segment than in basal right lateral segment. And Ts of these segments in LBBB cases were also longer than those of the control group. Sm of basal left lateral segment and basal septal segment in LBBB cases were markedly lower than that of basal right lateral segment. And these values were markedly lower than those of the control group. The relationship of the Ts difference in left and right lateral segments with QRS duration was similar to the relationship of the difference in aortic and pulmonary PEPs with QRS duration. Therefore, TDI was considered useful to measure Ts for evaluating interventricular asynchronicity and to measure Sm for evaluating ventriclular motility in cases with conduction disturbance of LBBB.
