The heart's lower-right chamber (the right ventricle) and lower-left chamber (the left ventricle) are divided by a wall called the septum. The septum ensures that blood does not mix between the right and left ventricles. The right ventricle pumps oxygen-poor blood into the pulmonary arteries and on to the lungs. The left ventricle pumps oxygen-rich blood into the aorta and on to the rest of the body.

In truncus arteriosus, there is a large hole in the septum between the two ventricles (called a ventricular septal defect). This lets oxygen-poor blood from the right side of the heart mix with oxygen-rich blood from the left side of the heart. When this mixture of blood is pumped into the body, it may cause the lips, fingers, and toes to appear blue. This condition is called cyanosis.

Truncus arteriosus also causes the arteries to form abnormally. Instead of the pulmonary artery connecting to the right ventricle and the aorta connecting to the left ventricle, the heart has just one big artery that connects to both ventricles. The pulmonary arteries then branch off this common artery.

What are the symptoms?

The defect may cause too much blood flow to the lungs and force the heart to work too hard. Babies born with truncus arteriosus have trouble breathing, feeding, and growing normally.

How is it treated?

Surgery to correct this condition is usually done in infancy. The pulmonary arteries are separated from the common artery and attached to the right ventricle with a tube. The hole in the septum is usually covered with a patch.

See also on this site: Congenital Heart Disease

See on other sites:

MedlinePlus
www.nlm.nih.gov/medlineplus/ency/article/001111.htm
Truncus Arteriosus

American Heart Association
www.heart.org/HEARTORG/Conditions/CongenitalHeartDefects/
AboutCongenitalHeartDefects/Truncus-Arteriosus_UCM_307040_Article.jsp  
Truncus Arteriosus

Texas Adult Congenital Heart Center (TACH) program 
www.baylorclinic.com/services-specialties/cardiologytach/index.cfm enables patients with congenital heart disease to receive a seamless continuation of care from birth to old age.
  

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Updated August 2012