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Patent Ductus Arteriosus

Definition

A patent ductus arteriosus (PDA) is a type of congenital (present at birth) heart problem. All babies have a small passageway (called the ductus arteriosus) connecting the pulmonary artery and the aorta, which is open at birth.
The pulmonary artery is a blood vessel that moves blood from the heart to the lungs. The aorta is a blood vessel that moves blood from the heart out to the rest of the body. Before birth, the baby gets its oxygen from the mother, so its lungs are not used. The ductus arteriosus is a passageway between the pulmonary artery and the aorta that allows blood in the baby to bypass the unused lungs and carry oxygen to the other organs.
In most babies, the ductus arteriosus closes within a few hours of birth. This is normal. When the ductus arteriosus stays open, blood travels in the wrong direction between the aorta and pulmonary artery. This causes too much blood to flow through the lungs. This can cause problems for a baby, often calling for medical or surgical attention.
Patent Ductus Arteriosus
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Causes

In most cases, the cause is not known. However, in a small number of cases, PDA could be caused by exposure during pregnancy to a viral infection, rubella, drugs, or alcohol. In some children, congenital heart disease, including PDA, may be caused by genetic factors.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. Premature babies are at relatively high risk for PDA, although a patent ductus often closes when the baby becomes more mature. PDA may be more common in female babies or babies born at high altitudes. In most cases occurring in full term babies, there are no known risk factors for PDA.

Symptoms

Symptoms vary with the size of the ductus and the amount of blood that flows through it. If the ductus is small, there may be no symptoms. When symptoms occur, they include:
  • Rapid breathing
  • Increased work to breathe
  • Getting tired quickly
  • Poor growth
  • Respiratory infections (such as colds, pneumonia) occurring more often
In some babies, symptoms may not occur until a few weeks or months after birth. Occasionally it is not found until a much later age.
Even when there are no symptoms, the baby is at higher risk for a serious infection called endocarditis.

Diagnosis

A PDA causes a heart murmur because of the blood flow from the aorta to the pulmonary artery. This characteristic sound can be heard during a physical exam. In premature babies, this heart murmur—accompanied by heart failure—is enough to diagnose PDA. A chest x-ray shows an enlarged heart and extra blood flow in the lungs.
In older children, a chest x-ray is usually normal. An echocardiogram is done to show the flow of blood through the PDA and confirm the diagnosis.

Treatment

In symptomatic newborns, if the heart failure can be managed easily, extra time may be allowed to see if the PDA will close on its own. Fluids may be restricted somewhat for 2-3 days to help it close. If the symptoms are serious or the PDA is not likely to close on its own, medicine or surgery is used to close it. The medicine, indomethacin, helps tighten the muscle in the wall of the PDA to close it. If this does not work, surgery is performed to tie off the PDA.
If a PDA is present after the newborn period, it usually will not close on its own or with indomethacin. Surgery is required to prevent complications.
In older children, small coils can be used in place of surgery to close a PDA. The coils are placed in the PDA during cardiac catheterization, a procedure in which a small hollow tube is inserted into the heart through a large vein. The coils pass through the tube, placed directly into the ductus arteriosus, then expanded to block the flow of blood.
Surgery and coil placement are both quite safe, although the risk of complication rises if associated heart failure is very severe.

Prevention

There are no guidelines for preventing PDAs.

RESOURCES

American Heart Association http://www.heart.org

Children's Heart Institute http://www.childrenheartinstitute.org

CANADIAN RESOURCES

Canadian Cardiovascular Society http://www.ccs.ca

Canadian Family Physician http://www.cfpc.ca

RESOURCES

American Heart Association website. Available at: http://www.americanheart.org.

Patent ductus arteriosus. In: The Heart Center Encyclopedia. Cincinnati Children's Hospital Heart Center at the Cincinnati Children's Hospital Medical Center website. Available at: http://www.cincinnatichildrens.org. Accessed December 2002.

Understanding congenital heart defects. Mayo Adult Congenital Heart Disease Clinic, Mayo Foundation for Medical Education and Research website. Available at: http://www.mayoclinic.com. Accessed October 2002.

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