Central Pulmonary Artery Histopathology in Patients With Cyanotic Congenital Heart Diseases

Background: This study evaluated the pulmonary arterial (PA) wall histopathology and the risk factors related to histopathology and inadequate pulmonary artery growth in patients with cyanotic congenital heart diseases (CHDs) undergoing primary or second-stage operations after different types of systemic-to-PA shunts with or without pulmonary arterioplasty. Methods: Operatively excised full-thickness PA tissue from 150 consecutive patients (mean age, 90.8 ± 62.8 months; range, 6 months to 47 years) undergoing primary or second-stage procedures for different cyanotic CHDs were studied by light microscopy. The controls were 43 patients (23.8%) with normally developed central PAs and normal wall histology. Results: The incidence of elastic fragmentation, increased ground substance, smooth muscle disarray, intimal thickening, and fibrosis was 61.3%, 36.6%, 34.6%, 39.3%, and 42% respectively. The risk of inadequate PA growth was 174.8, 64.7, and 45.5 times higher in patients with muscle disarray of the PA, abnormal lamellar count, and absence of palliative shunting procedures. Conclusions: Almost all PA walls in shunted patients undergoing primary/second-stage procedures for cyanotic CHD indicate significant lamellar loss and intrinsic pulmonary arteriopathy. These changes are present in infancy, are more pronounced in patients with deep cyanosis, and may account for or may coexist with a higher incidence of PA hypoplasia and inadequate PA growth encountered in these patients.