EFFECT OF MITRAL-VALVE SURGERY ON SEVERELY IMPAIRED PULMONARY-FUNCTION

To evaluate the effect of surgery on severely impaired pulmonary funct ion associated with mitral valve disease, we examined the relationship between postoperative improvements in pulmonary function and pulmonar y circulation in 238 patients who underwent mitral valve surgery. Of t hese patients 17 met the preoperative criteria for severely impaired p ulmonary function: forced expiratory volume in 1 second = FEV1 less-th an-or-equal-to 1000 ml. They showed average values for vital capacity (VC) of 1343 +/- 203 ml, for % of vital capacity for predicted values (%VC) of 52.0 +/- 6.5 %, and for FEV1 of 851 +/- 104 ml. Moderate elev ations of mean pulmonary arterial pressure (PAP: 36.2 +/- 10.2 mmHg), mean pulmonary arterial wedge pressure (PAWP: 23.0 +/- 9.6 mmHg), and pulmonary vascular resistance (PVR: 329 +/- 147 dyne . sec . cm-5) wer e also observed. Postoperatively, 4 of the 17 patients required long-t erm respiratory support for more than one week, and 3 patients died in hospital; this mortality rate, however, was not significantly differe nt to that of patients with preoperative FEV1 > 1000 ml. In long-survi ving patients, pulmonary function improved in the late postoperative p eriod. Significant relationships were recognized between DELTAFEV1 (DE LTA: postoperative value - preoperative value) and DELTAPAP, DELTAPAWP , and DELTAPVR. The DELTAVC and DELTA%VC also correlated significantly with DELTAPAP, DELTAPAWP and DELTAPVR. In conclusion, in patients wit h mitral valve disease impaired pulmonary function cannot be used to e xclude patients from operation. Furthermore, severely impaired pulmona ry function should improve with the improvement of pulmonary circulati on after surgery.