How the heart works

To understand congenital heart defects, it’s worth reminding ourselves what the heart does. It’s really a muscle – about the size of your fist. Its job is to send blood around the body, and that blood provides the oxygen and nutrients the body needs.

How the heart worksThe right side of the heart gets blood from the body and pumps it to the lungs, while the left side does the opposite by getting blood from the lungs and pumping it to the rest of the body. The heart is divided into four chambers:

The left atrium collects blood coming from the lungs;

The left ventricle pumps blood to the body;

The right atrium collects blood from the body;

The right ventricle pumps blood to the lungs.

As well as these four chambers, the heart has four valves. Their job is to control the flow of blood in the heart and around the body. These are called the mitral valve, the aortic valve, the tricuspid valve and the pulmonary valve.

If any of the four chambers or valves doesn’t grow properly during pregnancy, this can cause CHD.

Below is our animation that shows how a baby’s heart develops during pregnancy.