Heath, Donald

A study was made of the configuration of the elastic tissue of the pulmonary trunk in 6 cases of idiopathic pulmonary hypertension. The ages of the patients ranged from 12 to 54 years. The pattern was that of the adult pulmonary type in the 5 female patients, whereas it more closely resembled the fetal, aorta-like type in the single male patient. These data are interpreted as indicating that idiopathic pulmonary hypertension is acquired in most cases but that it may be present from birth in a minority of instances.

The relative importance of organic changes and vasoconstrictive influences in the production of increased pulmonary vascular resistance in congenital heart disease is problematic. With use of a grading system previously described, a study was made of the relation between each of the grades of hypertensive pulmonary vascular disease associated with ventricular or atrial septal defects and the change of pulmonary artery blood pressure immediately following closure of the abnormal communications. The immediate reversibility of the pulmonary hypertension varies inversely with the severity of the structural changes.

Progressive histologic changes occur in the pulmonary arteries and arterioles, as a complication of chronically elevated pulmonary arterial blood pressure, in patients with congenital septal defects of the heart. This progression is so stereotyped as to allow a division of the structural effects into 6 grades. The histologic features of each grade are described in detail in this communication. These results afford a basis for comparing the magnitude of these changes to the clinical findings.