The left ventricular filling pattern was studied by pulsed Doppler echocardiography in 13 congestive heart failure patients with normal sinus rhythm. The first study was done when congestive heart failure was present; the second after the signs and symptoms of congestive heart failure disappeared. In 12 of the 13 patients, the peak mitral flow velocity in atrial systole (PFVA) increased after the congestive heart failure disappeared (mean increase from 50.5 cm/sec to 74.8 cm/sec : p = 0.0001, paired t test), and the peak mitral flow velocity in early diastole (PFVE) decreased significantly in all 8 patients in whom secondary mitral regurgitation became less severe after improvement of congestive heart failure (mean decrease from 90.8 cm/sec to 52.0 cm/sec : p = 0.0001, paired t test). The ratio of PFVA to PFVE (PFVA/PFVE) increased in all cases after the congestive heart failure improved (mean increase from 0.59 to 1.33 : p = 0.0001, paired t test). The PFVA/PFVE is a simple index of left ventricular diastolic function. A PFVA/PFVE greater than one indicates disturbed left ventricular diastolic function. However, when the PFVA/PFVE is in a normal range for the patients' age ("pseudo-normalization") and is accompanied by impaired left ventricular systolic function in congestive heart failure, markedly increased left ventricular end-diastolic pressure must be considered.