Why is patent foramen ovale afraid of cold?

summary

The foramen ovale is usually closed in the first year after birth. If the foramen ovale is still not closed in children over 3 years old, it is called patent foramen ovale. In adults, 20% - 25% of the foramen ovale are not completely closed. Patent foramen ovale (PFO) is the most common congenital heart abnormality in adults at present. It can be detected in about 4 normal people. Today let me tell you about patent foramen ovale. Why are you afraid of cold?.

Why is patent foramen ovale afraid of cold?

First, because the pressure of the left atrium is 1.07-1.30kpa (8-10mmhg) higher than that of the right atrium (0.4-0.67kpa (3-5mmhg), the atrial septal defect will make the blood flow of the left atrium shunt to the right atrium, and the amount of the shunt depends on the atrial pressure gradient and the size of the defect. In early childhood, the atrial pressure of both sides is close, the shunt is not large, and the clinical symptoms are not obvious.

Second, with the increase of age, the atrial pressure difference increases, and the left to right shunt increases gradually, which can reach 2-4 times of systemic blood flow. The right atrium, right ventricle and pulmonary artery gradually enlarged and the pulmonary artery pressure increased with the aggravation of right heart load. At the initial stage, pulmonary arteriole spasm, then intimal hyperplasia and medial thickening, narrow lumen and increased resistance eventually lead to obstructive pulmonary hypertension. The pressure of right atrium and right ventricle increased, the shunt decreased, and even right atrium to left atrium countercurrent occurred.

Third: foramen ovale is a vital channel for fetal development, through which the umbilical vein blood from the mother enters the left cardiac cavity of the fetus, and then distributes to the whole body to provide oxygen and nutrients for fetal development. When a child is born, with the first cry, the left atrial pressure rises, and the valve of the oval fossa is pressed on the edge of the oval fossa to form a functional closure, while the anatomic complete closure usually takes 5-7 months after birth. Therefore, it is possible to keep the foramen ovale open within one year old, there may be a small amount of shunt, and even 5% - 10% of people keep the foramen ovale open but not closed for life, but it has no effect on the hemodynamics of the heart.

matters needing attention

It takes a period of time for the foramen ovale of the newborn heart to close. If it is not closed in infancy, it is a normal physiological phenomenon. At this time, we need not worry too much. But if it's still not closed at the age of one, it's better to repair it in time.