Septal Defects

(Atrial Septal Defect; Atrioventricular Canal Defect; Atrioventricular Septal Defect; Endocardial Cushion Defect; Ventricular Septal Defect)


Septal defects are problems with the structure of the heart. They are present at birth. Septal defects are located on the inside of the heart. They are on a wall that separates the chambers of the heart. There are 2 upper chambers of the heart called atria. 2 lower chambers of the heart are called ventricles.In a healthy heart, the blood flows from the body to the right atrium. The blood then goes into the right ventricle. The right ventricle pumps this blood to the lungs to pick up fresh oxygen. The blood then returns to the left side of the heart. It enters the left atrium first, then down to the left ventricle. The left ventricle pushes the blood out to the rest of the body.Septal defects allow the blood to move between the left and right chambers. The blood most often moves from the left side of the heart into the right side. This means that blood that has just returned from the lungs may end up being sent right back to the lungs. As a result, both the heart and lungs have to work harder than they need to work.There are 3 main types of septal defects:
  • Atrial septal defect (ASD)—a hole in the wall between the 2 upper chambers (atrium) of the heart
  • Ventricular septal defect (VSD)—a hole in the wall between the 2 lower chambers (ventricles) of the heart
  • Atrioventricular septal defect (AVSD)—a combination of ASD, VSD, and problems with opening between chambers called valves
The stress of pushing extra blood to the lungs may lead to heart failure. The following information applies to all 3 of these defects except where noted.
Ventricular Septal Defect
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In most cases the cause is not known.

Risk Factors

Factors that may increase the risk of septal defects include:
  • Family history of congenital heart defects
  • Exposure to a viral infection, drugs, or alcohol during pregnancy
  • Certain medications, such as those used to treat seizure disorder

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