Cardiography may be harmful to the human body and can lead to bleeding or hematoma, contrast nephropathy, and very rare risks for patients. 1. Bleeding or hematoma: cardiography requires a tube to be placed at the puncture site to connect the outside world to the blood vessels, which can lead to local bleeding, hematoma at the puncture site, etc. In severe cases, vasospasm, damage to the blood vessel wall, and arterial occlusion can occur. 2. Contrast nephropathy: cardiography requires the use of contrast medium, which needs to pass through the kidneys when metabolizing, especially those with renal insufficiency are more likely to suffer from contrast nephropathy. 3. Rare risk: cardiography can cause patients to develop acute myocardial infarction, coronary artery perforation, arrhythmia and so on. It is recommended to consult a doctor in time, under the guidance of the doctor, and follow the doctor’s instructions to choose the appropriate examination.