Tufts OpenCourseware
Authors: John Morgan, Bonnie F. Zimble

Congenital Heart Defects:

Definition and Types

Special Care in Dentistry
John Morgan, DDS
Tufts University School of Dental Medicine, 2008

Study Questions:     

  1. What is a congenital heart defect?

    1. Where can structural defects occur?

    2. What can happen with blood flow?

  2. Recognize the names and major characteristics of ten types of congenital heart defects.

What is a Congenital Heart Defect? 

According to the National Heart, Lung and Blood Institute (NHLBI) at the National Institutes of Health:

“A congenital heart defect is a structural problem (or defect) in the heart that is present at birth. A baby's heart begins to develop shortly after conception. During development, structural defects can occur. These defects can involve the walls of the heart, the valves of the heart, and the arteries and veins near the heart. Congenital heart defects can disrupt the normal flow of blood through the heart. The blood flow can:

  • Slow down

  • Go in the wrong direction or to the wrong place

  • Be blocked completely

Congenital heart defect is the most common type of major birth defect. Each year, more than 30,000 babies in the United States are born with congenital heart defects.” (National Heart, Lung and Blood Institute, 2006)

Click here to visit the NHLBI web site for more information on congenital heart defects. 

What are some of the different types of congenital heart defects? 

Here are some examples of congenital heart defects, with brief descriptions from NHLBI and the American Heart Association: 

Congenital Heart Defects




Aortic stenosis (AS)

“a narrowing of the aortic valve in the heart that causes it to open incompletely. This can reduce blood flow to the body” (NHLBI)

Atrial septal defect (ASD)


“a hole in the wall that separates the upper chambers (atria) of the heart. This causes blood to leak from one atrium to the other” (NHLBI)

Atrioventricular (A-V) canal defect


“A large hole in the center of the heart exists where the wall between the upper chambers joins the wall between the lower chambers.  Also, the tricuspid and mitral valves that normally separate the heart's upper and lower chambers aren't formed as individual valves.  Instead, a single large valve forms that crosses the defect.  The large opening in the center of the heart lets oxygen-rich (red) blood from the heart's left side – blood that's just gone through the lungs – pass into the heart's right side.  There, the oxygen-rich blood, along with venous (bluish) blood from the body, is sent back to the lungs.  The heart must pump an extra amount of blood and may enlarge.” (AHA)

Bicuspid aortic valve


“The normal aortic valve has three flaps (cusps) that open and close.  A bicuspid valve has only two flaps.  There may be no symptoms in childhood, but by adulthood (often middle age or older), the valve can become stenotic (narrowed), making it harder for blood to pass through it, or regurgitant (allowing blood to leak backward through it).” (AHA)

Coarctation of the aorta

a narrowing of the aorta. It slows or blocks the flow of blood from the heart to the body” (NHLBI)

Patent ductus arteriosis  


“…allows blood to mix between the pulmonary artery and the aorta.  Before birth an open passageway (the ductus arteriosus) exists between these two blood vessels.  Normally this closes within a few hours of birth.  When this doesn't happen, some blood that should flow through the aorta and on to nourish the body returns to the lungs.” (AHA)

Pulmonary stenosis


a narrowing of the pulmonary valve. The narrowing slows the flow of blood from the right side of the heart to the lungs. The heart must pump harder to push blood through the smaller opening” (NHLBI)

Subaortic stenosis


“…a narrowing of the left ventricle just below the aortic valve, which blood passes through to go into the aorta.  This stenosis limits the flow of blood out of the left ventricle.” (AHA)

Tetralogy of Fallot

“a combination of four defects:

  • Pulmonary valve stenosis is the narrowing of the pulmonary valve. The narrowing slows the flow of blood from the right ventricle to the lungs

  • VSD is a hole in the wall that separates the left and right ventricles

  • Overriding aorta is a defect in which the aorta is positioned between the left and right ventricles, over the VSD

  • Right ventricular hypertrophy is the thickening of the right ventricle. The thickening is caused by the heart having to work harder because of the other defects” (NHLBI)

Ventricular septal defect (VSD)


a hole in the wall that separates the lower chambers (ventricles) of the heart. This causes blood to leak from one ventricle to the other” (NHLBI)