Children with left heart hypoplasia refer to poor development of the left ventricle. The cause of poor development is generally attributed to problems with the inlet mitral valve and outlet aortic valve of the left ventricle, which may be dysplasia or direct atresia. The left ventricular cavity is smaller, and the chain reaction is to make the ascending aorta smaller together, from a large blood vessel that should have been to a small blood vessel.
We know that the left ventricle is very important to the human body, and the blood pumped out must support the systemic circulation. The left ventricle is small and the aorta coming out is small, which reduces the blood flow pumped out to the systemic circulation, causing ischemia and hypoxia in children. In order to maintain the pumped blood flow enough to maintain the systemic circulation, the child's heart can only work faster, leading to and aggravating heart failure. Then a series of clinical symptoms mentioned above appeared.
To sum up, several links of the left heart system interacted with each other during the development process and all went wrong, so it is called left heart hypoplastic syndrome.
Why does the child's current symptoms appear to be mild
"Because of multiple atrial septal defects, he was shunted, and the ductus arteriosus was patent." Xie Wanying added part of her own speculation and judgment.
We have talked about the situation of the baby in the mother's womb in the chapter on the atrial septum. The cardiac circulatory system during the fetal period is different from that after birth. The same is true for this disease. Only when the child breathes on his own after birth can he finally experience the serious consequences of this abnormal heart, and then the symptoms of this disease will gradually appear.
In this way, it seems that the best state for the child to be free from ischemia and hypoxia is, theoretically speaking, perhaps the best situation is to let the child's heart and circulatory system return to the child's fetal period. The atrial septal defect is very large, just like the unclosed wall of the fetus as a shunt. At the same time, the ductus arteriosus is not closed during the fetal period, allowing blood from the pulmonary artery to flow to the aorta to support systemic circulation as it did during the fetal period.
As classmate Xie said, this child's heart has grown like this, no wonder the symptoms are mild.
Can this situation continue
The answer is impossible. First of all, according to normal conditions, the ductus arteriosus starts to close within a few hours to a few days after birth, and anatomically closes after one or two months, which is the same as the closure of the foramen ovale. Even if it is not closed, if this situation continues for a long time—
"It is absolutely impossible not to have the operation immediately. If you delay it, you may develop pulmonary hypertension. There is no possibility of Fontan operation for pulmonary hypertension." Xie Wanying said.
This is to say that according to the above principles, whether it is a patent ductus arteriosus or an atrial septal defect to support the shunt, it only solves the problem of insufficient blood flow in part of the systemic circulation, but it cannot prevent the existence of arterial mixed blood, and the mixed blood is pumped out into the systemic circulation. It also causes hypoxia in the body. The Fontan operation performed a total cavopulmonary anastomosis, connecting the superior and inferior vena cava directly to the pulmonary artery. This allows only arterial blood with high oxygen content in the heart chamber, avoiding the mixing of arterial blood. The pumped blood only has arterial blood in the systemic circulation, which can greatly improve the body's hypoxia.
The prerequisite for Fontan surgery is good pulmonary circulation and no pulmonary hypertension. What to do, it’s about Norwood surgery, the first choice for the treatment of left heart dysplasia, simply cut off the entire atrial septal defect and expand the room’s communication.
The main pulmonary artery was then cut at the bifurcation of the left and right pulmonary arteries, the side of the main pulmonary artery was connected to the side of the aorta and the aorta was enlarged.