Cardiac catheterization refers to the insertion of different functional catheters from peripheral vessels into the heart and vascular cavity to detect various physiological parameters and perform cardiac catheterization to obtain the required physiological and anatomical information, i.e. diagnostic cardiac catheterization. Indications for diagnostic cardiac catheterization The purpose is to provide precise anatomical and physiological information for surgical procedures and interventions, mainly including: 1. Preoperative diagnosis of complex precardiac disease Comprehensive anatomical malformation diagnosis and physiological status evaluation are required before surgical procedures for complex precardiac disease, of which obtaining complete physiological information is the most important, and cardiac catheterization must provide the necessary physiological parameters according to the type of procedure being performed. 2. Evaluation of pulmonary artery pressure and resistance The evaluation of pulmonary artery pressure and resistance is very important for the selection of surgical indications and surgical approaches in precardiac disease, especially in left-to-right shunt precardiac disease with severe pulmonary hypertension and certain certain pulmonary congestive complex precardiac diseases, including complete transposition of the great arteries, right ventricular double outlet without pulmonary stenosis, and single ventricle without pulmonary stenosis. In addition, only cardiac catheterization can determine the severity and nature of pulmonary vascular lesions, i.e., whether pulmonary hypertension is dynamic or organic, which can help in the selection of surgical indications and postoperative prognosis. 3. Aortic arch lesions mainly include aortic narrowing, arch interruption, and arteriovenous catheterization, etc. Cardiac catheterization is incomparable to other examination methods for detailed understanding of anatomical malformations of the aortic arch and also for evaluation of hemodynamics. 4. Preoperative evaluation of aortic stenosis and pulmonary valve stenosis Cardiac catheterization is useful for diagnosis of anatomic malformations and obtaining accurate hemodynamic information, which helps in the selection of surgical indications and methodology. 5. Arteriovenous fistulas and abnormalities of vascular return, including pulmonary arteriovenous fistulas, coronary arteriovenous fistulas, ectopic pulmonary venous drainage and abnormalities of body venous return, can be accurately diagnosed through the exploration of abnormal pathways, blood oxygen measurement and angiography. Diagnostic cardiac catheterization has an irreplaceable role in the selection of surgical indications and procedures for complex and severe precardiac disease, and is the most important diagnostic method. The precordial diseases that routinely require cardiac catheterization in our hospital include, pulmonary atresia, tetralogy of Fallot, right ventricular double outlet, single ventricle, corrected transposition of the great arteries, complete transposition of the great arteries, tricuspid atresia, etc.