Pulmonary arterial changes in patients with ventricular septal defects and severe pulmonary hypertension

Summary

In 25 patients, aged eight months to 31 years, with ventricular septal defect (VSD; isolated in 15, the others with atrial septal defect, PDA, coarctation or patent ductus arteriosus + coarctation), each with severe pulmonary artery hypertension (pulmonary artery systolic pressure [Ppa] at least 75% of systemic and an elevated pulmonary vascular resistance), we related morphologic and morphometric data from open-lung biopsy to hemodynamic measurements obtained at cardiac catheterization during the same hospital admission. Of the hemodynamic features measured, only the ratios of pulmonary-to-systemic flow and pulmonary-to-systemic resistance correlated significantly with structure. Neither pulmonary artery pressure (Ppa) nor pulmonary vascular resistance correlated significantly with any structural feature studied. The increased external diameter of respiratory bronchiolar arteries in those with the more advanced Heath-Edwards grades reflects dilatation and suggests that it is in the small arteries of the distal arterial bed that the changes of pulmonary hypertension are most significant. Neither age nor body weight correlated significantly with the degree of structural or hemodynamic abnormality.

In the ten patients who underwent VSD closure, Ppa was measured postoperatively. The Heath-Edwards grade (no more than one grade-III lesion) and arterial density (at least one-half that normal for age) were the best correlates of the difference between preoperative Ppa and Ppa immediately after corrective surgery. The presurgical catheterization data, including pulmonary resistance and the resistance ratio, did not correlate significantly with change in Ppa following VSD closure. Lung biopsy is an important diagnostic aid because it helps in predicting the early response in postoperative Ppa in patients with VSD and elevated pulmonary vascular resistance.