To understand more about patent foramen ovale, it may be helpful to know how the heart typically works.

The typical heart has four chambers that pump blood:

The right upper chamber, also called the right atrium. This heart chamber receives oxygen-poor blood from the body. It pumps blood to the right lower heart chamber through the tricuspid valve.
The right lower chamber, also called the right ventricle. This heart chamber pumps blood to the lungs through a large vessel called the pulmonary artery. In the lungs, blood picks up oxygen. The blood moves through the pulmonary valve. The valve closes when the chamber relaxes between beats.
The left upper chamber, also called the left atrium. This heart chamber receives the oxygen-rich blood from the lungs. It sends blood through the pulmonary veins and mitral valve and into the left lower chamber.
The left lower chamber, also called the left ventricle. This chamber is the heart's main pumping chamber. It pumps the oxygen-rich blood to the rest of the body through the body's largest blood vessel, called the aorta. The blood passes through the aortic valve, which also closes when the chamber relaxes.

Patent foramen ovale

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