Color M-mode Doppler determination of left ventricular (LV) early diastolic flow (Vp) is useful in assessing LV diastolic performance. Left bundle-branch block (LBBB) is associated with impaired systolic and diastolic function as well as abnormal depolarization and repolarization. In patients with LBBB, measurements of Vp have not been well studied. The objectives of this study were to characterize Vp in patients with LBBB and to establish whether Vp is influenced by altered electrical activation of the LV or by underlying heart disease.
We studied Vp in 38 consecutive patients with LBBB, 77+/−10years old (47%male), admitted to our institution. Vp was determined as the slope of the first aliasing velocity from color M-mode Doppler recordings oriented from the LV apex to the tips of the mitral leaflets.
97% of patients showed a Vp<45cm/sec (mean=23+/−10). On univariate analysis, Vp correlated directly with LV ejection fraction (LVEF) (r=.43, p=0.008), inversely with LV end-systolic dimension (ESD)(r=−.40, p=0.04), and inversely with E-point septal separation (EPSS) (r=−.51, p=.0007). Vp did not relate to age, heart rate, LV mass, QRS duration, QRS axis, Q-T interval, deceleration time, or E/A ratio. On multiple regression analysis, Vp correlated only with LVEF (r2=0.62, p<0.0001).CONCLUSIONS: Flow propagation is frequently abnormal in patients with LBBB. These findings suggest that Vp is determined by LV systolic function and dimensions but not by altered electrical activation or diastolic parameters.CLINCAL IMPLICATIONS: The relationship between Vp and clinical symptoms and the prognostic value of Vp in patients with LBBB are unknown and merit further study.
J.M. Lazar, None.