Spirometric Changes following Open-Heart Surgery on Rheumatic Mitral Valves

Evaluation of pulmonary function by spirometry in adult patients undergoing cardiac surgery is a simple test to assess pulmonary reserve that has important implications in the operative morbidity. Pulmonary function was studied preoperatively, before discharge, and at the 3-month follow-up in 22 randomly selected patients who underwent open-heart surgery for rheumatic mitral valve disease (2 reconstructions, 20 replacements). The mean preoperative cardiothoracic ratio was 0.58. Lung function was found to be impaired preoperatively in all 22 patients and the majority suffered from restrictive lung disease. Better preoperative lung function was seen in nonsmokers, patients with a cardiothoracic ratio of less than 0.50, and those with a normal pulmonary artery pressure. After mitral valve surgery, the mean pulmonary artery pressure was 20.6 ± 2.9 mm Hg, the mean mitral valve pressure gradient was 3.6 ± 2.4 mm Hg, and the mean cardiothoracic ratio was 0.52 ± 0.09. A significant deterioration was seen in the predischarge spirometric values of forced vital capacity, forced expiratory volume in one second, peak expiratory flow rate, flow rate at 25% to 75% of expired vital capacity, and maximum volume ventilation. The deterioration was greater in smokers and those who had prolonged cardiopulmonary bypass (more than 80 minutes). No correlation was found with ventilation because all patients were electively ventilated overnight. There was an overall improvement in spirometric parameters at the 3-month follow-up although the values remained lower than predicted. Spirometry was found to be useful for assessing lung function in patients undergoing mitral valve surgery and we recommended it as a routine test.