The mitral valve is a one-way valve structure for blood flow from the left atrium into the left ventricle, including the valve leaflets, annulus, and subvalvular structures such as the tendon and papillary muscle. During ventricular diastole, blood flow enters the left ventricle from the left atrium via the mitral valve; during ventricular systole, the mitral valve closes so that blood flow from the left ventricle cannot flow back to the left atrium via the mitral valve. The so-called mitral insufficiency is that during ventricular contraction, the mitral valve leaflets do not close together and do not close tightly, and the blood flow from the left ventricle partially flows back to the left atrium through the mitral valve. This results in enlargement of the left atrium and left ventricle, impairment of heart function, and even life-threatening heart failure. Etiology Congenital mitral valve insufficiency is a type of congenital heart disease, often combined with other heart malformations. The specific cause is not fully understood, but some studies have suggested that it is related to the following factors: (1) Infections, viral or bacterial infections in the first trimester, especially rubella virus, followed by coxsackievirus, have a higher incidence of congenital heart disease in infants born with them. (2) Other: such as lesions of amniotic membrane, fetal compression, early gestational pre-eclampsia, maternal malnutrition, diabetes, phenylketonuria, hypercalcemia, the application of radiation and cytotoxic drugs in early pregnancy, and the mother’s excessive age all have the potential to cause congenital heart disease in the fetus. Secondly, genetic factors: congenital heart disease has a tendency to develop in families to some extent, which may be caused by parental germ cell and chromosomal aberrations. Genetic studies have concluded that most congenital heart disease is formed by the interaction of multiple genes and environmental factors. The pathologic anatomy is divided into three main types: ① enlargement of the annulus, resulting in relative leaflet closure insufficiency; ② lesions of the leaflets themselves: the main indications include large or small valve fissures, leaflet defects, valve dysplasia at the junction, or absence of valve orifice; ③ lesions of the subvalvular structures: abnormal development of the tendon or papillary muscle, mitral valve prolapse due to tendon rupture, etc. Clinical manifestations of congenital mitral valve insufficiency Symptoms and signs: mild lesions may be asymptomatic Heart murmurs are often found on physical examination. In cases of moderate to severe mitral valve insufficiency, symptoms may appear at an early stage, such as developmental delay, shortness of breath after exercise, poor activity tolerance, recurrent upper respiratory tract infections, bronchopneumonia, etc. In severe cases, there may be pulmonary edema and heart failure. On physical examination, the heart may be enlarged, with an elevated apical pulsation, and a systolic tremor may be palpable. In the presence of other intracardiac malformations, the clinical symptoms and signs are dominated by the main malformation. For example, in primary foramen ovale septal defect combined with congenital mitral insufficiency, symptoms such as palpitations and shortness of breath are early and severe. Echocardiogram: It is very important for diagnosis. It can show the degree of mitral valve insufficiency and the pathological type of mitral valve insufficiency. Two-dimensional echocardiography is more accurate and should be used as a routine examination. Cardiac catheterization and left ventricular selective angiography: Cardiac catheterization shows increased pressure in the left atrium and large wave height. Pulmonary artery pressure is also increased Left ventriculogram can clearly show the general situation of mitral regurgitation, and other malformations can be detected at the same time But this is an invasive test and should not be included as a routine now. Diagnosis The diagnosis is not very difficult based on the history, clinical manifestations, and ancillary tests. However, rheumatic mitral valve insufficiency should be excluded: rheumatic mitral valve insufficiency mostly develops after youth and can be combined with multiple lesions such as mitral stenosis, aortic valve stenosis or insufficiency. There may be a significant history of rheumatic activity based on increased anti” O” and increased hematocrit. Echocardiography reveals mitral valve leaflet thickening, coiling, and junctional adhesions The main treatment modality for congenital mitral valve insufficiency is surgery. I: Indications for surgery: Mild mitral valve insufficiency has little effect on cardiac function, and the surgical effect is not obvious and can be observed on follow-up. Those with moderate or severe insufficiency should be surgically corrected before the development of heart failure. The combination of other intracardiac malformations should be corrected at the same time. Second: surgical methods: surgery is performed under hypothermic extracorporeal circulation, and the corresponding surgical methods are selected according to the anatomical type of closure insufficiency: broadly speaking, they can be divided into two major categories: plication and valve replacement. The specific methods are: 1, the mitral valve closure insufficiency caused by the expansion of the annulus, the correction method is for annuloplasty. The appropriate size of the artificial valve ring is selected and fixed on the mitral annulus to reduce the enlarged mitral annulus and prevent its further expansion. However, it is best not to perform an annuloplasty before the age of 10 to avoid relative stenosis of the annulus later in the child’s physical development. 2, mitral valve closure insufficiency caused by leaflet fracture: often occurs in the middle of the anterior leaflet, there is a fissure on the leaflet, the fissure can be large or small, the leaflet is divided into two, and the subvalvular structure is normal, sometimes combined with an enlarged annulus. The fissure is surgically sutured directly to the leaflet until no regurgitation is detected by water injection test. Sometimes it is necessary to repair the leaflet with a pericardial piece. 3.Triple leaflet malformation Triple leaflet closure may be due to enlargement of the posterior external border. Surgical junctional suture formation is possible. 4.Prolapse of the valve leaflets is usually corrected by rectangular resection suture of the valve. In case of mitral valve insufficiency due to tendon lengthening or papillary muscle lengthening, the method of shortening the tendon or papillary muscle can be used for correction. 5, valve replacement For forming difficulties or forming the effect of poor need to perform mitral valve replacement. The surgical principles for pediatric valve lesions are: prosthetic valve replacement for those who cannot be improved by shaping to maintain cardiac function, and shaping surgery for those who can be improved by shaping. The main problem with pediatric valve replacement is that the prosthetic valve cannot increase in caliber with the growth and development of the child, and the valve needs to be replaced again or even several times; secondly, lifelong anticoagulation is required, and if a biological valve is chosen, although lifelong anticoagulation is not required, the biological valve will be used for a limited time and will calcify and degenerate, which will require valve replacement again in the future.