What is mitral stenosis? Mitral stenosis refers to thickening of the mitral valve leaflets, junctional adhesions, fusion, and subvalvular tendon contracture resulting in reduced opening or obstruction of the mitral valve orifice, causing obstruction of blood flow to the left atrium. What are the causes of mitral stenosis? Mitral stenosis can be classified as congenital or acquired (acquired). Most mitral stenoses seen clinically are acquired, and the vast majority are sequelae of rheumatic fever, although only 60% have a clear history of rheumatic fever. Among the rare causes, the main ones are mitral annulus or subannular calcification in the elderly; rarer causes are carcinoid or connective tissue diseases, such as systemic lupus erythematosus, and Lutembacher syndrome, in which mitral stenosis is combined with atrial septal defect, is mostly acquired. Approximately 25% of patients with rheumatic heart disease have simple mitral stenosis and 40% have mitral stenosis combined with mitral valve insufficiency. Approximately 2/3 of mitral stenosis patients are women. In the course of rheumatic fever, the time between initial infection and stenosis formation is usually at least 2 years. It is estimated to take at least 2 years, often more than 5 years. Most patients have an asymptomatic period of 10 to 20 years or longer. What kind of damage does mitral stenosis cause to the body? The normal mitral orifice area is about 4-6 cm2. When the mitral valve is attacked by rheumatic lesions, the orifice area gradually shrinks over time. When the mitral orifice area is reduced to 2.0 cm2, an increase in left atrial pressure (LAP, normal value 4-12 mmHg) is necessary to maintain normal cardiac output. the increase in LAP leads to an increase in pulmonary venous pressure and pulmonary gross pressure, and breath-holding during activity. As the disease progresses, chronic elevation of LAP leads to pulmonary hypertension, tricuspid and pulmonary valve closure insufficiency, and eventually right heart failure. Patients with mitral stenosis will have progressive enlargement of the left atrium, which can often lead to two complications. One is atrial fibrillation (Af), a complication that can occur in about 40% of patients. with Af, atrial systolic function is lost and the filling time during diastole is reduced, decreasing cardiac output. Left ventricular function is usually normal. Another complication is left atrial appendage thrombosis. Approximately 20% of patients with mitral stenosis with left atrial appendage thrombus have a history of embolism. High risk factors for embolism are: older than 35 years; combined Af; low cardiac output; and large left atrium. What are the clinical manifestations of mitral stenosis? 1. Symptoms Dyspnea, which can be exertional, paroxysmal, or in severe cases, inability to lie down or with paroxysmal nocturnal suffocation. Hemoptysis, blood in sputum, pulmonary infarction, thromboembolism. Hoarseness due to enlargement of the left atrium compressing the recurrent laryngeal nerve and dysphagia due to compression of the esophagus. In addition, there may be poor appetite, abdominal distension, nausea, vomiting, urinary insufficiency, and edema. 2. Physical signs Mitral valve face. There may be lifting-like pulsation at the left edge of the sternum. The heart border is enlarged to the left on percussion. Patients with atrial fibrillation may have a short pulse. Typical auscultations include: hyperacusis of the apical first heart sound; a limited mid- to late-diastolic incremental rumble-like murmur may be heard, pronounced in left lateral recumbency or to the left after activity, and may be accompanied by diastolic tremor. When the patient has good valve elasticity, an open valve sound can be heard, which is the main indication to consider mitral junction dissection. In addition, there is a hyperactive second pulmonary artery sound with mild splitting. In patients with severe mitral stenosis, a total systolic murmur or a third heart sound from the right ventricle may be present in the tricuspid region. In a small number of patients with mitral stenosis, there is no diastolic murmur in the apical region, called “mute mitral stenosis,” because the mitral orifice is highly stenosed or the patient’s right ventricle is highly enlarged, occupying the apical region so that the murmur cannot be heard at conventional auscultation sites. How is mitral stenosis diagnosed? 1, The clinical symptoms described above. 2, Mitral valve auscultation area can be heard in the mid to late diastolic rumble-like murmur. 3, electrocardiographic changes: in mild mitral stenosis, the electrocardiogram can be normal. The characteristic ECG changes are enlarged P waves in the left atrium, widened P waves, and bimodal type, called mitral valve P waves. 4, chest X-ray: the performance is related to the degree of mitral stenosis and the stage of disease development. 5.Echocardiography: It has a high specificity for the diagnosis of mitral stenosis. It can clarify the degree of mitral stenosis, the size of the heart chambers, and the presence of thrombus formation in the left atrium. Esophageal ultrasonography is generally not required unless the patient is scheduled for mitral stenosis balloon dilation. 6. Cardiac catheterization and angiography: All patients aged 50 years or older, or with a history of angina pectoris, should routinely undergo coronary angiography to clarify the presence or absence of combined coronary artery disease before undergoing surgical procedures. How is mitral stenosis treated? 1, clear mitral stenosis, orifice area <1.5CM2, clear opening sound can be heard, ultrasonography confirms that the valve is still elastic, no left atrial thrombus formation, sinus rhythm, balloon dilatation or mitral junctional closure separation can be considered. 2, symptomatic patients with moderate mitral stenosis, ultrasonography confirmed left atrial thrombus, or patients with more than moderate cardiac enlargement by regular medical treatment may be considered for mitral valve replacement. 3, Patients with symptoms, ultrasonography confirmed severe mitral stenosis, leaflet stiffness, severe calcification, serious structural changes under the valve, difficult repair, or accompanied by severe mitral valve closure insufficiency, may be considered for mitral valve replacement.