The heart is a muscle about the size of an adult male fist. Its job is to pump blood to all parts of the body.

The heart is made up of four chambers that hold and pump blood. The top two chambers are the right atrium and left atrium. The atria collect blood returning to the heart from the veins. The atria then release the blood into the bottom chambers through valves. Heart valves act as one-way doors to separate the chambers and keep the blood moving forward.

The bottom two chambers are called the right ventricle and left ventricle. A wall (septum) separates the two right chambers from the two left chambers. Because of this, you may hear your heart described as two pumps, the “right heart” and the “left heart.” When the ventricles contract, they force blood out of the heart to different parts of the body.

The heart is surrounded by a tough protective sac called the pericardium.

Valve Conditions

There are four heart valves that act as oneway doors to keep blood moving in the right direction through the heart. Valve disease occurs when a valve doesn’t work the way it should. If a valve doesn’t close all the way, blood may leak backward. This is called regurgitation or insufficiency. If a valve doesn’t open all the way, less blood moves through the opening. This is called stenosis. Valve problems cause the heart to work harder to pump the same amount of blood. Fluid may back up in the lungs or body and can cause swelling, shortness of breath and dizziness.

Septal Defects

The atrial septum is a wall of tissue that separates the upper chambers of the heart. An atrial septal defect (ASD) is a hole or opening in this wall that fails to close during the body’s development before birth. The ventricular septum divides the two lower chambers (ventricles) of the heart. A ventricular septal defect (VSD) is an opening that can be caused by a birth defect or by an extensive heart attack.

If the hole in the septum is large enough to cause problems in pressure between two heart chambers, surgery may be needed. During surgery, the hole is covered by a patch or simply closed by sewing the edges of the opening together. Some holes particularly ASDs, can be closed with a plug that is delivered by a catheter.