Patent Ductus Arteriosus

Patent ductus arteriosus is a congenital heart disease (a heart condition present from birth) that is quite common in premature births. Patent ductus arteriosus occurs when a fetal blood vessel, the ductus arteriosus, fails to close after birth. Without treatment, patent ductus arteriosus places strain on the heart. In severe cases, this congenital heart disease can contribute to the development of congestive heart failure.

Ductus Arteriosus versus Patent Ductus Arteriosus

The ductus arteriosus is a temporary fetal blood vessel that connects the aorta (which carries blood to the body) to the pulmonary artery (which carries blood to the lungs). Before birth, the ductus arteriosus allows blood to bypass the lungs, which are filled with amniotic fluid (the unborn child receives oxygen through the umbilical cord).

After birth, the lungs provide oxygen to the blood. If the ductus arteriosus remains open, oxygenated blood from the aorta can mix with unoxygenated blood from the pulmonary artery, causing the heart to overexert itself as it reoxygenates blood that is not fully depleted. To prevent this, healthy infants have a natural mechanism that causes the ductus arteriosus to close within three days of birth. However, patent (meaning open) ductus arteriosis occurs if the artery does not fully close.

Causes of Patent Ductus Arteriosus

The exact cause of patent ductus arteriosus is unknown. In 95 percent of births, the ductus arteriosus closes normally. Risk factors associated with the development of patent ductus arteriosus include:

• Down's syndrome
• maternal rubella (German measles)
• premature delivery.

Patent Ductus Arteriosus Symptoms

Symptoms of patent ductus arteriosus vary depending on the size of the unclosed artery. While a small patent ductus arteriosus is often asymptomatic (showing no symptoms), more serious cases result in more blood exchanged between the aorta and pulmonary arteries. These larger openings produce symptoms of congestive heart failure.

Symptoms associated with a large patent ductus arteriosus include:

• difficulty breathing
• difficulty feeding
• fatigue
• frequent lung infections
• poor growth
• poor weight gain
• rapid breathing.

Diagnosing Patent Ductus Arteriosus

The method of diagnosing patent ductus arteriosus depends on the size of the ductus arteriosus opening. For example, a small patent ductus arteriosus may go unnoticed until a heart murmur is detected during a routine medical visit. A heart murmur is an unusual sound heard during the heartbeat.

Because a larger patent ductus arteriosus can cause congestive heart failure symptoms within months of birth, these are generally detected early. Premature babies with large patent ductus arteriosus tend to be diagnosed earlier than full-term babies with the same condition, as premature babies are more vulnerable to this condition and, therefore, more likely to display symptoms.

Once patent ductus arteriosus is suspected, doctors will use one or a combination of the following tests to diagnose or rule out this condition:

• Chest X-rays can show enlarged heart chambers and fluid in the lungs, two signs of patent ductus arteriosus.

• Echocardiograms, tests that use sound waves to construct images of the heart and arteries, can detect the size of a patent ductus arteriosus to confirm or rule out any co-existing heart defects.

• Electrocardiograms use skin electrodes to measure the heart's electric activity. While monitoring the child's heartbeat, an electrocardiogram can determine if heart chambers are enlarged, another symptom of patent ductus arteriosus.

Although chest X-rays and electrocardiograms provide important supportive data during a patent ductus arteriosus diagnosis, neither tool is as effective as the echocardiogram.

Patent Ductus Arteriosus Treatments

Surgery to correct patent ductus arteriosus isn't always necessary. A newborn with few symptoms or controllable symptoms may be observed to see if the patent ductus arteriosus closes by itself. If further treatment is necessary, options include:

• Cardiac catheterization: Instead of surgery, an older child with patent ductus arteriosus may be a candidate for cardiac catheterization. During cardiac catheterization a small tube, or catheter, is inserted into an artery in the arm or groin. The catheter is threaded through the arteries to the patent ductus arteriosus, where it deposits a small coil or plug to close the ductus arteriosus. If, however, an older child has a large patent ductus arteriosus, surgery may be a better alternative than cardiac catheterization.

• Medications: Although medication can help close a patent ductus arteriosus, it only works under certain circumstances. Ibuprofen and idomethacin constrict blood vessels, encouraging patent ductus arteriosus closure. However, both medications can cause bleeding and kidney damage. If lab tests don't return with normal kidney readings, medication will not be part of the patent ductus arteriosus treatment regimen.

• Surgery: Surgery may also be an option for treating newborns and premature babies with patent ductus arteriosus. The typical procedure used is simple: After a small incision is made between the ribs, the patent ductus arteriosus is tied closed and then cut off, restoring normal blood flow.

Endocarditis Prevention

Endocarditis refers to an infection that develops in the heart tissue. Because children with a patent ductus arteriosus are at higher than normal risk of endocarditis, they require prophylactic antibiotics prior to dental work and surgery to lower the risk of endocarditis. Once the patent ductus arteriosus is closed, antibiotics can be discontinued after six months.

Patent Ductus Arteriosus Saves Lives

In rare cases, patent ductus arteriosus can save, rather than threaten, lives. When other congenital heart defects are present, such as transposition of the great arteries and hypoplastic left heart syndrome, an open ductus arteriosus provides a vital alternative blood pressure. In such cases, the ductus arteriosus is kept open with medication until the other heart defect has been treated.

Resources

American Heart Association (n.d.). Patent ductus arteriosus (PDA). Retrieved September 14, 2007, from the AHA Web site: www.americanheart.org/presenter.jhtml?identifier=1672.

Cincinnati Children's Hospital Medical Hospital (n.d.). Patent ductus arteriosus (PDA). Retrieved September 14, 2007, from the Cincinnati Children's Hospital Medical Hospital Web site: www.cincinnatichildrens.org/health/heart-encyclopedia/anomalies/pda.htm.

National Heart, Lung, and Blood Institute (n.d.). Patent ductus arteriosus. Retrieved September 14, 2007, from the NHLBI Web site: www.nhlbi.nih.gov/health/dci/Diseases/pda/pda_what.html.