I. Clinical characteristics and diagnosis of cardiac tumors in children Some children in this group heard heart murmurs of different nature. Some of the children were asymptomatic and the tumor was only found during physical examination. Some children showed arrhythmia, chest tightness, shortness of breath, and change of murmur nature when the position changed. Chest X-ray and electrocardiogram are not specific for the diagnosis of cardiac tumor. Cardiac ultrasound can indicate the morphology, location and extent of the tumor, and can also assess the degree of blood flow obstruction and cardiac function status caused by the tumor; however, it cannot detect particularly small intracardiac tumors. The accuracy of localization by ultrasound examination in our group reached 100%. Magnetic resonance imaging (MRI) and CT are more accurate than ultrasound in describing the extent of cardiac tumors and their relationship to adjacent tissues, but in younger children, absolute silence or even anesthesia is required to eliminate artifacts caused by activity, breathing, and tachycardia. Vascular enhancement is important in identifying thrombosis and cardiac tumors and is worth considering in children with impaired coagulation mechanisms. Cardiac angiography has the ability to understand the status of the coronary arteries and whether they are combined with other cardiac malformations. The disadvantage is that it is somewhat invasive and costly. Primary malignant cardiac tumors are more common in adults and less common in children. There are no malignant cases reported by our group and Coardm. Malignant tumors are more common in the country with mesothelioma. Primary cardiac tumors in children are commonly seen as rhabdomyosarcoma, fibroma, mucinous tumor, fibroma, smooth muscle tumor, etc. Inflammatory myofibroblastic tumor is the most common benign tumor invading the heart valves. The prognosis of multiple cardiac tumors is difficult to predict due to the difficulty of complete resection, so outpatient follow-up is recommended. Primary malignant cardiac tumors have a poor prognosis, with an overall 3-year mortality rate of about 5()%. Surgery is performed to clarify the diagnosis and eliminate or alleviate clinical symptoms. Solitary primary cardiac tumors in children. Surgical resection is the main focus. Among them, mucinous tumors are mostly seen in older children, with the possibility of sudden heart failure or cardiac arrest, tumor detachment and embolization; hemangiomas are prone to arrhythmia or blood flow obstruction; rhabdomyosarcomas tend to occur in the right ventricle. All of them have clear indications for surgery. Fibromas are slow growing and can be followed up and observed, but can also be treated surgically. The principle of surgery is to remove the tumor completely and minimize the impact on cardiac function. The first choice of surgical route is right atrial incision; or left heart tumor exploration through aortic incision and left atrial incision. If necessary, a ventricular incision should be added. When removing the tumor, it is recommended to prevent damage to the adjacent conduction system, coronary vessels, atrioventricular valves and aortic valves, especially in 4,JL rhabdomyosarcoma. Mucinous tumors are likely to obstruct the atrioventricular foramen and cause cardiac arrest. Minimize moving the heart before extracorporeal circulation; avoid touching the tumor during intubation or trousseau exploration. After cutting open the atrium, block the atrial valve orifice with wet gauze. Prevent tumor fragments from dislodging and causing embolism. Due to the susceptibility to recurrence and distant implantation. The mass must be excised completely, not in stages, and repeatedly flushed after excision to thoroughly remove any debris left in the town. The effect of cardiac tumor on the coagulation mechanism of children should be paid attention to, especially children with mucinous tumor often have heparin resistance phenomenon. After removal of cardiac tumor, valve function should be tested routinely and valvuloplasty should be performed if necessary. Postoperative management Children with cardiac tumors often have myocardial structural changes and ventricular incisions during surgery, so postoperative cardiac hypoperfusion may be greater. Early detection of signs of hypocardial function and enhanced treatment can prevent the emergence of malignant heart failure. In conclusion, primary cardiac tumors in children are mainly benign with variable symptoms, and about 50% have heart murmurs. Cardiac ultrasound can basically clarify the diagnosis. Surgical resection is effective. Preoperative surgical planning; intraoperative attention to myocardial protection and prevention of adjacent tissue damage; and postoperative strengthening of monitoring and treatment are the key aspects to achieve successful treatment.