Various techniques for the insertion of catheters from peripheral vessels into the heart chambers or great vessels for diagnosis and treatment. Since the inauguration of human cardiac catheterization in 1929, this technique has developed rapidly and is now one of the main methods for the diagnosis and treatment of cardiovascular disease. The insertion of cardiac catheters is generally performed by percutaneous vascular puncture technique, and can be divided into right heart catheterization and left heart catheterization according to the examination site. Right heart catheterization mainly has the following examination methods: 1. Under X-ray, a catheter is inserted from the peripheral vein to reach the central vein, right atrium, right ventricle and pulmonary artery to understand the cardiovascular anatomical changes and hemodynamic abnormalities through blood oxygen and pressure measurement, angiography or cardiac cavity imaging, and to provide a basis for the diagnosis of congenital heart disease, rheumatic heart disease and other diseases and the determination of treatment plans. 2.Floating catheterization. A balloon catheter is delivered to the distal end of the pulmonary artery at the bedside via a vein (mostly femoral or internal jugular vein) using monitored pressure changes. When the tip of the catheter reaches the right atrium, it fills the balloon and floats the balloon using blood flow to bring the catheter into the right ventricle and pulmonary artery. When the pressure pattern of the pulmonary artery changes to pulmonary capillary wedge pressure, the balloon is deflated to reproduce the pulmonary artery pressure pattern. The floating catheter can be used for continuous bedside monitoring of right atrial pressure, right ventricular pressure, pulmonary artery pressure and the measurement of pulmonary capillary wedge pressure, cardiac output, pulmonary circulation and body circulation resistance and right and left heart work index at any time, which are the main elements of clinical hemodynamic monitoring. It is mainly used for the monitoring of acute myocardial infarction, heart failure, shock and other critically ill patients with obvious hemodynamic changes, which can significantly improve the success rate of resuscitation. 3.Clinical electrophysiological examination and transcatheter radiofrequency ablation. 4.Endocardial artificial pacing (see artificial pacemaker). 5.Endomyocardial and myocardial biopsy. Biopsy forceps are used to remove tissue from the inner wall of the heart to understand the structure of the heart and its pathological changes. The transvenous right ventricular route is generally used, and the transarterial left ventricular route is occasionally used. The biopsies are examined by light and electron microscopy and histochemical or immunofluorescence methods to confirm the diagnosis of myocarditis, cardiomyopathy, cardiac amyloidosis, myocardial fibrosis, and other diseases. It is important for the determination of rejection reaction and evaluation of efficacy after heart transplantation. Left heart catheterization There are mainly the following examination methods: 1. The catheter is inserted through the peripheral artery and retrograde to the aorta and left ventricle for pressure measurement and cardiovascular imaging, which can understand the function of the left ventricle, wall motion and chamber size, aortic valve and mitral valve function, and can detect vascular lesions in the aorta, carotid artery, subclavian artery, renal artery and common iliac artery . 2.Selective coronary angiography. A contrast catheter is inserted into the coronary artery opening and a small amount of contrast is injected to visualize the coronary arteries. Using film or video recording, the coronary artery blood flow and anatomy are dynamically observed to understand the nature, location, extent and degree of coronary artery lesions, and to observe the presence of coronary artery malformations, calcifications and the formation of collateral circulation. In order to clearly reflect the lesion, coronary angiography needs to take multi-angle projection; if necessary, nitroglycerin test or lysergic acid test is needed to identify organic stenosis and coronary artery spasm. Coronary angiography is important for understanding coronary artery lesions before angina pectoris, myocardial infarction, coronary artery bypass grafting and other cardiac procedures, formulating treatment plans and evaluating prognosis, and providing a differential diagnosis of coronary artery disease. The progress of interventional cardiology in the past 20 years has made coronary angiography an essential test. Coronary angiography has certain complications, mainly angina pectoris, myocardial infarction and arrhythmia, but it is still a safe and effective examination method as long as the operation technique is mastered and intraoperative monitoring of pressure and electrocardiographic changes is paid attention to. 3.Percutaneous intracavitary coronary angioplasty.