Relation between severity of mitral valve disease and results of routine lung function tests in non-smokers.

The effects of mitral valve disease on lung function have been studied in 26 non-smoking patients by relating values for lung volumes and carbon monoxide transfer factor (TLCO) to various indices of cardiac function measured at catheterisation. In general, more severe mitral disease was associated with greater abnormalities of lung function. Reductions of the one-second forced expiratory volume, vital capacity, TLCO and transfer coefficient, and increase in residual volume were all significantly related to the severity of mitral valve disease. In addition, the cardiothoracic ratio, measured radiographically, showed an inverse correlation with both vital capacity and total lung capacity. Although some of the consequences of mitral valve disease on lung function resemble those of primary airway disease, useful distinguishing points are the relative normality of the forced expiratory ratio and the absence of an increase in total lung capacity.