Pulmonary vascular disease in complete transposition of the great arteries: A study of 200 patients

Lung specimens of 200 patients with transposition of the great arteries were examined microscopically for evidence of pulmonary vascular disease. In patients with an intact ventricular septum or a small ventricular septal defect, advanced pulmonary vascular disease was uncommon; only 9 of 107 such patients (8.4 percent) demonstrated greater than grade 2 (Heath-Edwards) pulmonary vascular disease. A persistent large patent ductus arteriosus appeared to promote progressive pulmonary vascular disease in this group since each of the five infants less than 1 year of age with grade 3 or 4 disease had this lesion. In contrast, pulmonary vascular disease was common in patients with a large ventricular septal defect; 37 of 93 patients (40 percent) with this defect had greater than grade 2 pulmonary vascular disease. Among patients more than 1 year of age, 26 of 35 (75 percent) had grade 4 disease. The catheterization data suggest that the calculated pulmonary vascular resistance may underestimate the degree of disease, probably by overestimating the pulmonary blood flow (Fick method). Pulmonic stenosis appeared to protect the lungs from progressive pulmonary vascular disease, and pulmonary arterial banding was protective when performed before age 6 months. Our studies indicate that a persistent large patent ductus arteriosus should be closed as early as possible in view of its association with advanced pulmonary vascular disease in these patients. In infants with a large ventricular septal defect, pulmonary arterial banding or corrective surgery with closure of the defect should be performed between the ages of 4 and 6 months to prevent progressive pulmonary vascular damage.