Is patent ductus arteriosus a congenital heart disease? How to treat it?

Author: Jin Mei, Chief Physician, Beijing Anzhen Hospital, Capital Medical University

Reviewer: Wang Fang, Chief Physician, Beijing Hospital

Patent ductus arteriosus is a very common congenital heart disease, accounting for about 15% of congenital heart diseases.

1. What is patent ductus arteriosus?

The ductus arteriosus is a channel between the aorta and the pulmonary artery. It is a normal physiological channel in the fetus and can close on its own after birth.

During pregnancy, the fetus mainly relies on the placenta for nutrient exchange. The lungs do not yet have respiratory function. Part of the blood from the right ventricle to the pulmonary artery goes through the ductus arteriosus to the descending aorta to supply blood to the lower body.

After birth, the baby cries, the lungs expand, the lungs have breathing function, and pulmonary circulation is established. The blood from the right ventricle is pumped to the pulmonary artery, and then to the left and right pulmonary arteries. The venous blood becomes arterial blood through gas exchange, and then returns to the pulmonary vein, to the left atrium, left ventricle, and aorta to supply the whole body, and normal pulmonary circulation and systemic circulation are established. The ductus arteriosus has no function, and most children close naturally. Generally, most of them can be closed within 72 hours after birth. If it is not closed within 3-6 months after birth, it can be diagnosed as patent ductus arteriosus.

Figure 1 Original copyright image, no permission to reprint

If the child is older and the ductus arteriosus is still relatively thick, it is unlikely to close on its own. If it is relatively thin, such as 1-2 mm, it can be observed to see if it can heal on its own.

2. What are the symptoms of patent ductus arteriosus?

Most children diagnosed with patent ductus arteriosus will have some symptoms.

The ductus arteriosus is a communication channel between the aorta and the pulmonary artery. When the pressure in the aorta is high and the pressure in the pulmonary artery is low, a left-to-right shunt will occur at the level of the aorta. Part of the blood in the aorta will go to the pulmonary artery, increasing the amount of blood in the lungs. If the ductus arteriosus is very thick and the shunt volume is relatively large, pneumonia is likely to occur, and in severe cases, heart failure may occur, and growth and development may even be affected, resulting in a lower weight and lower height than children of the same age.

If a child fails to grow taller or gain weight, or often suffers from pneumonia, these may be reasons for parents to take their child to see a doctor. When the doctor listens to the heart, he or she may find a heart murmur, and further examination will confirm the diagnosis.

Some children have thinner ductus arteriosus and less shunt flow, so they may have no symptoms and are not easy to be found. However, most of them go to the doctor for cold and fever, and the doctor can hear the heart murmur and will conduct further examination to confirm the diagnosis.

If the ductus arteriosus is relatively thick, the shunt volume is relatively large, and more blood is shunted to the lungs, it will affect the pulmonary artery over time, and the pulmonary artery will become thicker, the arterial wall will thicken, and the cavity will become smaller. If the patent ductus arteriosus is not treated in time, pulmonary hypertension will gradually form. Once the pulmonary artery pressure is higher than the aorta, a right-to-left shunt will form. A right-to-left shunt means that the patent ductus arteriosus has been combined with more severe pulmonary hypertension.

Severe pulmonary hypertension forms a right-to-left shunt, and the child's blood oxygen saturation will decrease, which is manifested by normal transcutaneous blood oxygen in the fingers and low in the toes. For example, the blood oxygen concentration in the upper limbs is 95%, and the blood oxygen concentration in the lower limbs is 85%, resulting in differential cyanosis.

If there is severe pulmonary hypertension, in addition to cyanosis, the child will feel a decrease in physical strength. For example, he used to be able to climb four floors, but now he is out of breath after climbing two floors. Parents will feel that the child is getting tired more and more easily and can't walk much, which means that the right heart function is also affected. He may even suddenly fall to the ground one day, faint, or even die suddenly, which is life-threatening.

Therefore, if a child is found to have patent ductus arteriosus, in principle, treatment should be given as soon as possible. The timing of surgery should be determined based on the child's age and the thickness of the ductus arteriosus. If the ductus arteriosus is thin, you can wait a little longer and have regular follow-up examinations. If the child's ductus arteriosus is thicker, the shunt volume is large, the child always gets pneumonia, and the weight does not increase, early treatment may be recommended. In short, if a child is found to have patent ductus arteriosus, he or she should be followed up under the guidance of a pediatric cardiologist to decide on the timing and method of treatment.

3. What are the treatments for patent ductus arteriosus?

Generally, there are two methods for treating patent ductus arteriosus. In the early stage, it is performed through thoracotomy, ligation of the ductus arteriosus or patching at the pulmonary artery end. In short, the shunt is blocked.

From the late 1990s to the present, patent ductus arteriosus has basically been treated with interventional methods, that is, without opening the chest, puncturing the femoral artery and femoral vein, and through echocardiography or angiography, choosing a suitable occluder based on the shape and size of the ductus arteriosus to block the patent ductus arteriosus and block the shunt.

Figure 2 Original copyright image, no permission to reprint

Currently, interventional therapy is the preferred method for patent ductus arteriosus, and 95%-98% of children can consider interventional therapy. This is because interventional therapy is much less invasive than open-chest surgery, and does not require general anesthesia. Local anesthesia plus intravenous sedation can avoid the risks of general anesthesia. The operation is also very simple, takes a short time, and the recovery is fast. The patient can be discharged from the hospital the next day after the operation.