Mild tricuspid regurgitation is usually caused by tricuspid valve closure insufficiency. There are two causes of tricuspid valve closure insufficiency: First, functional tricuspid valve closure insufficiency, which is more common and is generally due to enlargement of the right ventricle, enlargement of the annulus, and failure of the valve leaflets to close during systole. It is mostly seen in heart diseases with increased right ventricular systolic pressure and pulmonary hypertension, such as rheumatic mitral valve disease, congenital cardiovascular disease, and pulmonary heart disease. Second, organic tricuspid valve closure insufficiency, which is relatively rare, includes inferiorly displaced malformation of the tricuspid valve, wind heart disease, tricuspid valve prolapse, infective endocarditis, coronary artery disease, carcinoid syndrome, endocardial myocardial fibrosis, etc.