Pulmonary vascular disease in ventricular septal defect: Structural and functional correlations in lung biopsies from 85 patients, with outcome of intra‐cardiac repair

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Abstract
Pulmonary vascular structure was analysed using morphometric techniques, and arterial wall abnormalities in lung biopsy specimens taken from 85 cases of ventricular septal defect, aged 3 weeks to 30 years were described. The defect was closed in 53 patients, 12 died at operation and 11 survivors were recatheterized. Structural examination revealed a characteristic pathological picture which appeared to precede classical grade IV pulmonary vascular disease. This predilatation phase was identified by finding pre‐acinar obstructive intimal proliferation or fibrosis, associated with only a slight increase in intra‐acinar arterial muscularity, in the absence of stigmata of grade IV disease in patients with a pulmonary resistance greater than 6 units m2. Predilatation features occurred in 62 per cent of patients who either died at repair or who had post‐operative pulmonary hypertension. These findings help identify a high risk group in whom resistance is higher than expected in the absence of classical grade IV changes. In addition, a marked increase in muscularity without intimal obstruction can also be associated with a pre‐operative resistance of more than 6 units m2. The presence of medial hypertrophy only does not ensure either survival or a normal postoperative pulmonary arterial pressure. Early intra‐cardiac repair is recommended before obstructive intimal fibrosis develops during the second year.