Distensibility characteristics of the human pulmonary vascular bed. Study of the pressure-volume response to exercise in patients with and without heart disease.

The changes in pulmonary blood flow, pressure, and volume during supine exercise are studied in seven patients without cardiovascular abnormality, 12 patients with aortic valve disease, 13 patients with mitral valve disease, and five patients with primary myocardial or pericardial disease. The degree of distensibility of the pulmonary vascular bed is assessed by the simultaneous changes in the magnitude of the pulmonary distending pressure (average of pulmonary artery and left atrial pressure) and of the pulmonary blood volume.