The pulmonary artery (PA) is a vital and specialized artery connected to the right ventricle of the heart. The name is actually a little deceiving because there are two pulmonary arteries. These arise from the pulmonary trunk (sometimes called the main artery) and are called right and left pulmonary arteries. Their function is to carry blood from the right ventricle to the lungs.
When blood returns to the heart’s right ventricle it is blue blood, lacking oxygen, and needs to head back to the lungs in order to become oxygenated. Through the contractions or pumping of the right ventricle, the heart feeds the blood into the main pulmonary artery or trunk, and then this blood travels through the left or right pulmonary arteries to reach the lungs. Once oxygenated, the blood returns to the heart’s left ventricle and is pumped to the body.
There is only one time in life when most people don’t have much need for the pulmonary artery or trunk. As fetuses, people don’t rely on breathing to create oxygen in the lungs. Instead they rely on the mother’s oxygen supply through the umbilical cord. Once born, children and then adults need the PAs to sustain normal function. However, there are some diseases that may affect the pulmonary artery.
In adults, the most common disease affecting these arteries is pulmonary hypertension. This leads to increased pressure in the arteries, usually from some type of obstruction, mild or severe, in the PAs. Pulmonary hypertension weakens the right ventricle over time because it must pump harder to feed blood to the lungs.
Some of the most devastating illnesses affecting a pulmonary artery are congenital or present at birth. These can include pulmonary stenosis, which means narrowing of a PA, or complete absence or no function of the PAs, called atresia. Through surgery, it is possible to correct stenosis, and sometimes surgery will involve replacement of the artery. Other times surgery is not even open-heart surgery anymore, and doctors can use things like balloon catheterization to widen the arteries and prevent pulmonary hypertension.
When the PAs are extremely damaged or almost absent, greater corrective surgery measures might be required. Some of these, like the Fontan surgery, involve completely rerouting the heart’s circulatory patterns so that blood flows passively into the lungs and is not pumped to the lungs. In some instances, when one of the heart’s ventricles is very weak, the PA may be removed when the Fontan is performed since it is no longer necessary.