Exercising pulmonary blood flow in mitral stenosis with anomalous pulmonary venous connection.

Exercising pulmonary blood flow was estimated from indicator-dilution curves in a patient with the infrequent combination of rheumatic mitral stenosis and anomalous pulmonary venous connection from the left lung. During supine exercise against progressively increasing external workloads, the proportion of flow to each lung remained nearly constant. The pulmonary vascular resistance was highest in the left lung, which emptied into the low-pressure systemic vein. Although right and left atrial pressures differed markedly during supine exercise, the proportion of pulmonary blood flow shunted to the systemic venous sytem remained essentially unchanged.