As you already know about the large blood vessels – the aorta and pulmonary artery – it’s easy to learn about the birth defect called Patent Ductus Arteriosus (or PDA).
What is a Patent Ductus Arteriosus?
As a child develops inside its mother’s womb, it is not able to “breathe”. So, even though the child’s lungs are well developed, they do not carry out their normal work.
The blood which flows through the right ventricle and pulmonary artery to the lungs has no function. It is “wasted” blood flow.
In an attempt to make use of this flow, nature provides man with a “shunt” or “bypass”. A small tube, or blood vessel, connects the pulmonary artery to the large artery called the aorta. This tube is the ductus arteriosus.
Through this tube, blood which enters the pulmonary artery, instead of going to the lungs, flows into the aorta. From the aorta, the blood reaches other parts of the body. It is now useful to these other parts, which get energy to do their work.
At birth, when the child draws its first breath, the lungs begin to work. Now, when blood flows into the lungs, it is mixed with oxygen and “purified”. At this time, the ductus arteriosus normally closes. At first, it closes by spasm or contraction of the muscle in its wall. Later, the tube becomes permanently blocked by a scar.
Sometimes, it does not close normally. It then remains open, and the condition is called Patent Ductus Arteriosus – or PDA.