Effects of mitral valve replacement on ventilation, volumes, diffusing capacity and regional perfusion of lungs in patients with mitral valve disease.

The effects of mitral valve replacement on ventilation, lung volumes, diffusing capacity and regional perfusion of the lungs were studied in eight patients with long-standing mitral valve disease. Eight patients of the same age with coronary artery disease who underwent coronary bypass operation were tested as controls. Preoperatively, the patients with mitral valve disease had significantly higher perfusion of the upper lung fields and the ratio of residual volume to total lung capacity than the control patients. Vital capacity, forced expiratory volume in one second and maximal expiratory flow at 50% of vital capacity were lower in comparison with the control group. Seven days after open heart surgery the values of all the parameters mentioned above had decreased significantly from the preoperative levels in both groups. Three months post-operatively, the values returned to preoperative levels. The abnormal overperfusion of the upper lung fields and other derangements in the ventilatory pattern did not subside even though cardiac haemodynamics were corrected by mitral valve replacement.