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You have had a heart operation for a congenital deformity.

The heart pumps blood through the body. Inside the heart are 4 chambers. There are 2 heart atria and 2 ventricles. Both heart atria and both ventricles are separated from each other by a partition.

Major, important blood vessels branch out of the heart. The main artery (aorta), originating from the left lower chamber (ventricle) of the heart, supplies the whole body with oxygen-rich blood. The right ventricle pumps oxygen-poor blood through the pulmonary artery to the lungs, where the blood is then enriched with oxygen.

Your heart did not develop properly before you were born. As a result, just one ventricle was pumping the blood to both the body and to the lungs. This blood was a mixture of oxygen-poor and oxygen-rich blood.

The venae cavae are large blood vessels. They collect oxygen-poor blood from the body and carry it back to the heart. There is a superior and inferior vena cava. Your superior vena cava was connected to your pulmonary artery. So the oxygen-poor blood was flowing straight to the lungs from the upper part of your body. The ventricle no longer has to pump this blood through the lungs, so it is under less strain. Moreover, pure, oxygen-rich blood is being pumped around the body.