Thickening of the pulmonary valve is usually caused by pulmonary hypertension, pulmonary stenosis, congenital heart disease, and infection. 1. Pulmonary arterial hypertension: pulmonary arterial hypertension may be caused by heart failure, abnormal function of pulmonary blood vessels, etc. It usually has symptoms such as chest pain, fatigue, etc., and may also have symptoms of pulmonary valve thickening. 2. Pulmonary stenosis: Pulmonary stenosis is usually caused by family genetics, congenital developmental abnormalities, etc. Patients may have symptoms such as dyspnea, lung infection, heart failure, palpitations, etc., and may also have symptoms of secondary thickening of the pulmonary valve. 3. Congenital heart disease: congenital heart disease usually refers to congenital cardiovascular anomalies caused by chromosomal aberrations and intrauterine hypoxia, etc. Patients may have symptoms such as cardiac arrhythmia and developmental delay, and may also have symptoms of pulmonary valve thickening. 4. Infection: Infection caused by bacteria such as hemolytic streptococcus can damage the pulmonary valve, causing inflammation of the valve, which can further lead to thickening of the valve. It is recommended that the patient consult a doctor in a timely manner to determine the cause of the disease and treat it under the guidance of the doctor.