I28: Other diseases of pulmonary vessels

I28.0: Arteriovenous fistula of pulmonary vessels

You need lungs to breath. When we breathe in, oxygen enters the lungs and accumulates in the blood. This blood then flows to the heart. The heart then pumps the oxygen-rich blood throughout the body. All of the organs are supplied with oxygen as a result. The arteries carry the blood from the heart to the lungs. The veins carry the blood from the lungs back to the heart.

You have a connection between the arteries and the veins in your lungs. As a result of this, some of the oxygen-poor blood is flowing straight back to your heart without the blood being mixed with oxygen. These connections are usually congenital, which means you were born with them.