The aim of the study was Doppler echocardiographic assessment of the effect of mitral stenosis (MS) on pulmonary venous flow (PVF), and of any changes occurring after mitral valve replacement. Fifty patients with MS (22 in atrial fibrillation (AF)) and 28 healthy subjects (control group) underwent transthoracic echocardiographic evaluation of PVF. Fourteen of the 22 patients in AF were submitted in addition to transesophageal echo study before and after mitral valve replacement. Pulmonary wedge pressure was measured in 18 patients. Patients in sinus rhythm (SR) and more than mild MS showed significantly decreased peak velocity and flow velocity time integral of the systolic forward PVF. This finding was more exaggerated in MS with AF. Concerning diastolic forward PVF, patients in SR showed significantly decreased peak velocity and velocity time integral, irrelevant of the degree of MS, while patients with AF exhibited adequate signs of flow. In all patients duration, deceleration time (D-DT) and pressure half-time (D-PHT) of the diastolic forward PVF were significantly increased. The last two parameters correlated with the corresponding variables of mitral flow and with echocardiographically determined mitral valve area and the D-DT of the pulmonary wedge pressure. Concerning reversed PVF, patients with more than mild MS exhibited significantly increased peak velocity and velocity time integral. After mitral valve replacement, a significant increase of diastolic forward peak velocity and velocity time of the PVF were detected. The duration of diastolic forward peak velocity of PVF, D-DT and D-PHT decreased. The systolic forward phase did not change significntly after the valve replacement.(ABSTRACT TRUNCATED AT 250 WORDS)