EFFECTS OF SITE OF VENTRICULAR SEPTAL-DEFECT AND AGE ON PULMONARY HEMODYNAMICS AT SEA-LEVEL

In 1,265 patients with isolated ventricular septal defects (Natural Hi story Study of congenital heart defects, 1977), older children and adu lts were classified into those with and without pulmonary hypertension . To ascertain why relatively distinct pulmonary hypertensive and norm otensive groups consisted of older children and adults, we reexamined the sea level cardiac catheterization data of 829 patients according t o defect sire (using the Gorlin formula) and patient age. In patients <2 years of age, the average pulmonary vascular resistance was not sig nificantly elevated and was not dependent on defect size. Pulmonary hy pertension was due to increased blood flow, except for the 2.7% of pat ients with Eisenmenger-like physiology. For those >2 years of age, bot h pulmonary arterial pressure and resistance were higher (p <0.05) in patients with defect sizes of >0.5 cm(2)/m(2) than in those with small er defects, and the Eisenmenger-like physiology was more common in old er patients (17.4% in patients aged >10 years). The group with distinc tly higher pressure after 4 years of age reflected higher pulmonary va scular resistances in those in whom large defects persisted, However, 84% of patients aged >4 years who underwent cardiac catheterization ha d smaller defects (<0.5 cm(2)/m(2)), accounting for the group observed with low pressure.