Objective To determine whether the extent of airflow obstruction is associated with left ventricular function in mild-to-moderate chronic obstructive pulmonary disease (COPD) patients.Methods Left ventricle end diastolic volume ( LVEDV ),left ventricle end systolic volume ( LVESV ),left ventricle stroke volume( LVSV),left ventricle ejection fraction( LVEF),heart rate ( HR),cardiac output ( CO) and cardiac index (CI) were measured by ultrasonic cardiogram.Thirty-one patients with chronic bronchitis,42 mild-to-moderate COPD patients and 16 controls with normal lung function were recruited.The relations between the extent of airflow obstruction and the impairment of left ventricular function were analyzed.Results There were no significant differences of LVEDV,LVESV,LVSV,HR,CO or CI between the control and chronic bronchitis groups.LVEDV,LVESV,LVSV,CO and CI of chronic bronchitis group were significantly higher than those of mild-to-moderate COPD group while HR was lower.LVEDV,LVESV,LVSV,CO and CI had a positive correlation with forced expiratory volume in 1 second ( FEV1 ),forced vital capacity (FVC) and FEV1/FVC ratio.And HR had a negative correlation with FEV1 and FEV1/FVC.LVEF was positively correlated with FVC,but not with FEV1 and FEV1/FVC.LVEDV,LVESV,LVSV,HR,CO and CI were linearly related with FEV1.Conclusions Left ventricular function is maintained in chronic bronchitis patients. Left ventricular function,especially left ventricular end diastolic filling,deteriorates among the mild-to-moderate COPD patients.The extent of airflow obstruction may reflect the impairment of left ventricular function in COPD patients.