Systemic and pulmonary hemodynamic changes immediately following mitral valve replacement in man.

The immediate hemodynamic effects of mitral valve replacement were studied in patients with and without severe pulmonary arterial hypertension (systolic pressure greater than 50 mm Hg). In patients with severe pulmonary hypertension, mitral valve replacement resulted in significantly decreased pulmonary arterial pressure, pulmonary vascular resistance and pulmonary capillary wedge pressure. Cardiac index increased significantly while heart rate remained unchanged. These data support the hypothesis that a reflexly induced reversible component is often responsible for the disproportionate pulmonary hypertension encountered in patients with mitral valve disease. "Fixed" or irreversible pulmonary hypertension was not encountered in this series.