Secundum atrial septal defect with severe pulmonary hypertension. Open lung biopsy diagnosis of operative indication.

In 14 of 15 patients ranging in age from 1 to 62 years (mean of 34) with secundum atrial septal defect (ASD) and pulmonary hypertension over 60 mm Hg peak pressure, operative indication was determined by morphometric diagnosis of open biopsy of lung specimens. In one patient, open lung biopsy was also performed during corrective surgery. Pulmonary arterial changes in the 15 patients were grouped into four classifications as follow: (1) plexogenic pulmonary arteriopathy (six patients); (2) thromboembolism in small pulmonary arteries (three patients); (3) "musculoelastosis," intimal proliferation of longitudinal smooth muscle bundles and elastic fibers (three patients); and (4) combinations of (1), (2) or (1), (3) (three patients). We conclude concerning the operative indication that group 2 patients are operable in all cases and group 1 patients with Yamaki's index of pulmonary vascular disease of 2.2 or less; group 3 patients with the absence of complete occlusion of the small pulmonary arterial lumen are operable, and patients with clear evidence of severe plexogenic pulmonary arteriopathy in group 4 are not operable. Comparative analysis of pulmonary pathology and hemodynamic performance revealed that open lung biopsy should be performed to determine operative candidacy in cases with a pulmonary vascular resistance greater than 8 unit X m2, which is considered to represent the borderline of operability.