Sex, age, BMI, HR, SBP, DBP, sPAP, mPAP, dPAP, EF, CI, PVR, BNP, CK-MB, and serum miR-21 level were included in single-factor logistics regression analysis, and the age, BMI, sPAP, mPAP, EF, CI, PVR, BNP, CK-MB and miR-21 level of children with CHD-PAH were considered as independent risk factors for postoperative critical illness. The gene discussed is NPPB; the disease is pulmonary arterial hypertension.