Pulmonary hyperinflation in ventricular septal defect.

Pulmonary hyperinflation (PH) has frequently been seen in patients with ventricular septal defect (VSD). Mean age of patients at the time of cardiac catherization and operation was less in Group II (PHI) than in Group I (normal pulmonary inflation). There is a statistically significant difference in the ratio of mean pulmonary to mean systemic blood flow and the ratio of mean peak pulmonary to mean peak systemic systolic pressures, with the higher values recorded for Group II. There is no statistically significant difference in the pulmonary vascular resistance in the two groups. Thirty-five of the 44 patients with PHI developed normal inflation within a month after surgical correction of VSD. Possible mechanisms of PHI in VSD are discussed. PHI is prolong and perpetuate respiratory distress and can lead to progressive lung disease. PHI is therefore another indication for early surgical correction of VSD.