Spirometric changes after open mitral surgery

New York Heart Association (NYHA) functional classification of cardiac patients is assessed by subjective impairment of respiratory reserve. We objectively studied pulmonary function by spirometry in 31 random patients (average age 27.2 years) with rheumatic mitral valve (MV) disease undergoing open surgery (7 reconstruction, 24 replacement) preoperatively, predischarge and at 3 month follow-up. Better preoperative spirometric parameters were observed in class II nonsmoker patients with smaller cardiothoracic ratio (CTR) and normal pulmonary artery pressure (PAP). After surgery mean PAP decreased to 19.0 +/- 6.7 mmHg, MV gradient dropped to 3.4 +/- 2.9 mmHg, average CTR decreased to 52.3 /- 5.5%. MV area increased significantly from 0.8 +/= 0.49 to 2.45 +/- 1.23 cm2. Forced vital capacity (FVC), forced expiratory volume in one second FEV1), flow rates at 25%-75% of expired vital capacity (FEF 25-75%) and maximum voluntary ventilation (MVV) decreased significantly in all patients at discharge. Prolonged postoperative ventilatory support over 10 hours led to markedly reduced predischarge FVC, FEV1, FEF50, MVV and maximum mid expiratory flow rate (MMEFR). Prolonged cardiopulmonary bypass over 80 minutes caused further decrease in FVC. After 3 months all these parameters improved in all above the preoperative level but remained below the predicted values. Despite improvement in NYHA class, impaired spirometry was observed in 11 patients. Functional or hemodynamic improvement did not correlate with spirometric changes.