Pulmonary Function in Adults with Intracardiac Septal Defect

Abstract

Pulmonary function has been assessed in 45 patients with atrial or ventricular septal defect. Moderate and severe dyspnea occurred almost exclusively in patients with high pulmonary artery pressure irrespective of whether this was due to high pulmonary blood flow or high pulmonary vascular resistance. Evidence is presented suggesting that this raised pulmonary artery pressure causes lung damage shown by a low compliance and high nonelastic resistance. These findings suggest an abnormal alveolar-capillary membrane and an abnormality of ventilation-perfusion relationships, which in turn cause a relatively low pulmonary diffusing capacity requiring excessive hyperventilation on exercise to maintain oxygen requriments. In patients with moderate or severe dyspnea, the abnormally high minute volume of ventilation during mild exertion is associated with a high work of breathing, the dual abnormality separating them from patients with only slight dyspnea on exertion.