[Hemodynamics and histology of the lung in 175 ventricular septal defects]

Lung biopsies obtained during operation from 175 patients with isolated or combined ventricular septal defect were examined histologically. The degree of the pulmonary hypertensive vasculopathy was classified according to the Heath and Edwards-grading. These morphological findings were compared to the hemodynamic data (pulmonary/systemic ratios of systolic pressure, resistance, and flow as well as mean pulmonary artery pressure). Pressure and resistance showed a good correlation to the histological changes. The combination of both variables, however, did not further improve the prediction of the severity of the vascular lesions. No relation was found between flow and pulmonary vasculopathy. Higher grades of the vasculopathy were associated with systolic pressure ratios exceeding at least 0.65, in most patients with even marked higher ratios. On the other hand an elevation of pulmonary blood pressure of pulmonary arterial resistance does not mean a more severe vasculopathy implicitly, since there were some patients with a considerable hemodynamic hypertension without at least severe histological changes. We conclude that patients with a systolic pulmonary pressure not exceeding about 75% of systemic pressure have a very low risk of a morphologically fixed hypertension. Therefore an urgent operation of such patients to prevent fixation of the pulmonary hypertension seems not to be necessary.