Pulmonary vascular dynamics after percutaneous mitral valvotomy.

Hemodynamic studies were performed immediately before, within 1/2 hour, and every 8 hours for 24 hours after percutaneous mitral valvotomy in 22 patients with severe mitral stenosis and pulmonary hypertension. The mean pressure in the left atrium decreased from 27 +/- 2 mm Hg to 14 +/- 1 mm Hg (p less than 0.01) immediately after successful valvotomy. There was no significant further drop in left atrial pressure (or pulmonary capillary wedge pressure) over 24 hours. Mean cardiac output increased from 3.9 +/- 0.3 L/min to 4.6 +/- 0.3 L/min immediately after successful valvotomy (p less than 0.01). Cardiac output continued to rise for the next 8 hours and plateaued during the 24-hour period of observation. Pulmonary vascular resistance dropped immediately after the relief of mitral valve obstruction in all patients. In the group of patients who had elevated pulmonary vascular resistance after valvotomy, resistance continued to drop significantly (p less than 0.05) over the next 24 hours. In some cases it did not fall to normal levels despite adequate relief of mitral stenosis.