Squatting phenomenon refers to a special forced position, mainly due to congenital tetralogy of Fallot children, he is walking, or in the time of sitting will appear to bend the legs with the special position of the fraud section, and then will return to normal walking, this situation will occur repeatedly. So what is the reason for the appearance of squatting phenomenon? The following will give you an introduction. The reasons for the emergence of squatting phenomenon: due to pulmonary artery stenosis, blood entry into the pulmonary circulation is blocked, causing compensatory hypertrophy of the right ventricle, right ventricular pressure increases, pulmonary artery stenosis severe right ventricular pressure is similar to the left ventricular pressure, blood flow through the ventricular defect occurs biphasic shunt, most of the right ventricular blood into the aorta, if the pulmonary valve atresia, all the blood in the right ventricle into the aorta, the blood supply to the lungs rely on the arterial duct As the aorta straddles over the left and right ventricles, it receives blood from both the left and right ventricles to transport the whole body, leading to cyanosis. Due to the narrowing of the pulmonary artery, the blood flow for exchange in the pulmonary circulation is reduced, which aggravates cyanosis. However, in young children, cyanosis may not be obvious or light because the arterial duct is not yet closed and the blood flow in the pulmonary circulation is increased, but with the closing of the arterial duct and the gradual aggravation of the narrowing of the funnel, cyanosis becomes more and more obvious and the red blood cells and hemoglobin increase compensatively. Patients are advised to go to professional and regular hospitals immediately once the above symptoms appear, so as not to delay the disease and cause irreversible damage.