Some parents will find that their children often walk, run, or play games, suddenly squatting down to rest, after more than 10 seconds and then resume normal play. Some parents do not take this phenomenon seriously, not knowing that it may be a big mistake. What could be the problem if the child suddenly squats and rests while playing? If your child repeatedly experiences the above phenomenon, parents must be alert. Clinically, we call this phenomenon the squatting phenomenon. Squatting is most often seen in children with giant unclosed ductus arteriosus and pulmonary hypertension, or in children with predilection for tetralogy of Fallot. Squatting reduces blood return to the lower extremities, thereby reducing the load on the heart and lowering the pressure on the pulmonary arteries. In addition to squatting, these children often have symptoms such as being prone to colds or recurrent respiratory infections, shallow breathing, easy sweating, and purple and black lips and nails when crying. What is ductus arteriosus? The ductus arteriosus is a tube between the aorta and the pulmonary artery, which is an important pathway for fetal blood circulation. The fetus is unable to breathe while in the mother’s body and oxygen is obtained from the mother’s placenta through the umbilical artery. At this time, the fetus’ pulmonary circulation is closed while the heart has begun to work normally. After the blood from the right ventricle enters the pulmonary artery, a flooding channel is needed to divert it because the pulmonary circulation is closed, and this channel is the arterial catheter. After birth, with a cry, the pulmonary circulation begins to work normally and blood from the right ventricle enters the pulmonary circulation through the pulmonary artery, at which point the ductus arteriosus has completed its mission and needs to close naturally. Generally, the ductus arteriosus closes 10 hours after birth, but this time it is not stable and may open again. 8 weeks later, the ductus arteriosus will be completely closed and cannot open again. If the ductus arteriosus does not close after 6 months of age, the baby is said to have an unclosed ductus arteriosus. A very small number of patients will close between 6 and 12 months, but if it remains closed beyond 12 months, it is generally considered that it can no longer close naturally and requires treatment. How should I check my baby if I suspect a problem? If parents find that their baby has symptoms such as easy to catch a cold, developmental delay, or squatting phenomenon, they should take their child to the hospital as soon as possible. The doctor will use a stethoscope to listen to the baby’s heart for murmurs. This simple initial screening method is not only appropriate for patent ductus arteriosus, but also for other congenital heart defects such as atrial septal defect and ventricular septal defect, which is how many congenital heart defects are detected. If you suspect that your child has a heart problem, you will need to undergo cardiac ultrasound and other tests to further confirm the diagnosis. What is the best treatment for an unclosed ductus arteriosus? Once a child is diagnosed with an unclosed ductus arteriosus, he or she should be treated aggressively and the best age for surgery is 3-6 years old. And if heart failure and pulmonary hypertension develop during infancy and early childhood, they should be treated early. The traditional treatment is surgery. For pediatric patients without significantly elevated pulmonary artery pressure, the surgical approach is well established and is a relatively safe option. There are also patients with unclosed ductus arteriosus who can be treated with non-surgical interventional occlusion, or with thoracoscopic closure. It is important for parents to note that this interventional treatment, although relatively safe, is not without complications and dangers. The procedure should be performed in a hospital with cardiac surgical conditions, so that in the event of an accident during the process, the treatment can be changed to surgery in time to ensure the safety of the child.