Clinical study on relationship between ventricular dyssynchrony and QRS duration in patients with chronic congestive heart failure

Objective To assess the prevalence of interventricular and intraventricular contractile dyssynchrony in chronic heart failure patients with either normal or prolonged QRS duration.Methods Ninety-six patients with chronic congestive heart failure were divided into three groups according to QRS duration.The aortic pre-ejection time was measured from the beginning of QRS complex to the beginning of aortic flow velocity curve recorded by pulsed-wave(PW) Doppler detection at apical 5-chamber view.The pulmonary pre-ejection time was measured from the beginning of QRS complex to the beginning of the pulmonary flow at left parasternal view.The difference between these two values determined the interventricular mechanical delay(IVMD).Pulse Tissue Doppler Imaging was performed to record the time dispersity of electromechanical motion of mitral annulus at four positions(septal,lateral,anterior and inferior wall) at the level of basal and medium segments.Results Interventricular and intraventricular dyssynchrony were commonly seen in patients with chronic congestive heart failure regardless of QRS duration.Interventricular dyssynchrony was found in 13.9%,53.8%and 68.1% of patients in Group Ⅰ,Ⅱand Ⅲ respectively(P0.05).Intraventricular dyssynchrony was observed in 30.6%,61.5% and 72.3% of patients in Group Ⅰ,Ⅱand Ⅲ respectively(P0.05).There was a substantial proportion of chronic heart failure patients with normal QRS duration exhibiting dyssynchrony.The inerventricular delay was significantly related to QRS duration.Conclusion A substantial proportion of chronic heart failure patients with normal QRS or slightly prolonged QRS may exhibit ventricular dyssynchrony.Both standard echocardiography and TDI can be applied for evaluation of mechanical abnormalities due to ventricular dyssynchrony.