Objective To investigate the risk factors,clinical features,treatments,and preventions of pulmonary hypertensive crisis(PHC)in children with idiopathic pulmonary arterial hypertension(IPAH)undergoing cardiac catheterization.Methods A retrospective study was performed on the children diagnosed IPAH,admitted to Department of Pediatric Cardiology of Beijing Anzhen Hospital,and underwent cardiac catheterization between January 2009 and December 2015.Medical histories,clinical manifestations,treatments,and results were analysed in those encountered PHC during the operations.Results 54 cases of children diagnosed with IPAH and underwent cardiac catheterization were enrolled.PHC were confirmed in 4 children by serious elevation of pulmonary artery pressure(PAP)and central venous pressure(CVP),combined with drop of aortic pressure,heart rate,and peripheral oxygen saturation(SpO2).Treatments with life support,improving cardiac output,reducing PAP,and correction of acidosis were done,and 3 of the 4 children recovered,while 1 died of severe right heart failure with irreversible PHC 3 days after operation.Potential PHC were considered in 6 other patients,whose PAP increased and exceeded aortic pressure,SpO2 relatively decrease,but CVP and vital signs were relatively stable.Low weight(P<0.05),general anesthesia(P<0.05),history of syncope(P<0.05),and poor cardiac function(P<0.01)were verified to be important risk factors for PHC in children with IPAH undergoing cardiac catheterization.Conclusions PHC in children with IPAH undergoing cardiac catheterization has relationship with Various factors,and can occur throughout the operations.Comprehensive treatments should be done for these patients,but in some cases PHC may be irreversible.Appropriate indications,adequate preparations,timely identification,and complete treatments could prevent PHC from happening and developing.