In the present study, the levels of interleukin-6 (IL-6), malondialdehyde (MDA), and endothelin-1 (ET-1) in the serum and the change of oxygen index (OI) and respiratory index (RI) were measured to investigate the effect of PAP with HTK on lung protection in infant with CHD after CPB. The gene discussed is EDN1; the disease is coronary artery disorder.