Congenital Heart Disease: Symptoms, Diagnosis And Treatment Options For Patent Ductus Arteriosus

Congenital heart disease affects as many as one in every 100 babies — and patent ductus arteriosus affects between five and 10 percent of those cases in full-term infants, while striking premature babies at even higher rates. In fact, reports indicate that between 20 and 60 percent of preterm babies have patent ductus arteriosus, which is, in part, linked to the weight at which babies are born. For example, 80 percent of infants born weighing less than 1,200 grams and 40 percent of babies weighing less than 2,000 grams have patent ductus arteriosus. Additionally, almost half (48 percent) of children born weighing less than 1,000 grams have symptomatic patent ductus arteriosus.

Patent ductus arteriosus is essentially a hole in the aorta, the big artery that delivers oxygenated blood from the heart to the rest of the body.  This hole — known as the ductus arteriosus — is actually completely normal during the fetal stage. A fetus' lungs are, after all, fluid-filled and still non-functional, and the baby's circulatory system doesn't depend on the lungs for oxygenation. The ductus arteriosus forms a connection between the aorta and the main lung artery, and allows blood to bypass the lungs and go straight to the rest of the body. 

After birth, the lungs fill with air and start to function. The ductus arteriosus has outlived its use, and typically closes up very soon after a baby comes into the world. When that doesn't happen, and the hole remains, it's called patent (“open”) ductus arteriosus. Much more common in preterm babies, a patent ductus arteriosus can cause poorly-oxygenated blood to start circulating around the body as it has skipped the step that allows it become oxygen-rich. Patent ductus arteriosus is associated with significant morbidity and mortality, reaching rates of 30 percent.

What are the symptoms of patent ductus arteriosus?

Symptoms associated with patent ductus arteriosus vary from one patient to the next, depending on the size of the defect and whether the baby was born prematurely or at full term. Patients with a small patent ductus arteriosus can remain undiagnosed for a long time, even into adulthood, as they may not present with any symptoms. However, patients with a large patent ductus arteriosus can suffer from heart failure very soon after birth.

A large patent ductus arteriosus can cause the following symptoms, either during infancy or childhood:

• Not eating or feeding properly, leading to issues with growth.
• Sweating too much, particularly when crying or eating.
• Respiratory distress, constantly breathing fast or being breathless.
• Feeling tired very easily.
• Having a quick heart rate.
• Cardiomegaly, enlargement of the heart.
• Hepatomegaly, enlargement of the liver.
• Congestive heart failure.
• Tachycardia, a condition in which your heart beats more than a 100 times per minute.

How is patent ductus arteriosus diagnosed?

A doctor may suspect that your child has patent ductus arteriosus when, during a regular checkup, they hear a heart murmur while listening to the heart using a stethoscope — or some of the symptoms above may point the doctor in this direction. If the doctor suspects that your child may have a heart defect, they can ask for the following tests:

• Echocardiogram, sound waves to make images of the heart.
• A chest X-ray to create a detailed image of the chest, including the lungs and heart.
• Electrocardiogram, which measures the heart's electrical activity.
• Cardiac catherization, which uses a thin, flexible tube that is guided up to the heart to produce detailed images.

What risk factors are linked to patent ductus arteriosus?

Though the exact cause of patent ductus arteriosus is not quite known, we do have a good grasp on the factors that increase a baby's risk of the conditon:

• Premature birth.
• Family history or other genetic diseases. If heart defects or genetic diseases run in your family (such as Down syndrome), that increases your risk of patent ductus arteriosus.
• Viral infection during pregnancy. In particular, if you have a rubella infection during pregnancy, that increases the risk that your child will have heart defect, as the virus can cross the placenta and damage the blood vessels and other organs.
• Being born at a higher altitude. Studies have found that babies born at a high altitudes, such as 10,000 feet (3,048 meters), have a higher risk of patent ductus arteriosus.
• Gender — the condition is two times more common in females.

How is patent ductus arteriosus treated?

Treatment for this defect largely depends on the age of the patient, and the three options are:

• Careful observation and restriction of fluids. This is a conservative treatment approach for patent ductus arteriosus. When premature babies have a patent ductus arteriosus, it often closes on its own. The doctor may carefully monitor the heart to determine if the hole corrects itself. Many older children and adults who have a small patent ductus arteriosus, will only require careful observation, as well. Physicians often restrict fluids to reduce the load of the blood volume on the heart.
• Medications. For a premature baby with patent ductus arteriosus, the doctor may prescribe nonsteroidal anti-inflammatory drugs (NSAIDs) or indomethacin/ibuprofen lysine (non-selective COX inhibitors), as these drugs can help close the patent ductus arteriosus. However, these drugs won’t be able to close the patent ductus arteriosus as babies get older, because they lose their efficacy. Hence, it's best not to delay treatment. 
• Surgery. If medications don’t work and condition of the child is severe or causing complications, surgery will be required. Surgical repair for this defect usually involves either ligation or a combination of ligating and dividing the ductus arteriosus using surgical clips or sutures. Traditionally, during this operation, the surgeon will make a small incision between the child’s ribs and repair the open hole. Nowadays, video-assisted surgery allows surgeons to safely and effectively ligate the patent ductus arteriosus with minimal invasiveness.

What complications are associated with patent ductus arteriosus?

While small patent ductus arteriosus does not cause any issues, larger patent ductus arteriosus can lead to:

• High blood pressure in the lungs, as there is too much blood going through the arteries of the lungs.
• Heart failure, as patent ductus arteriosus can cause the heart to become large and weakened. This leads to heart failure, a condition in which the heart can’t pump blood properly.
• Endocarditis, a type of heart infection. People with heart problems such as patent ductus arteriosus are often at a higher risk of developing endocarditis.

Conclusion

While ductus arteriosus is a vital component of the fetal circulatory system, failure of the hole to close causes a defect that is associated with significant morbidity and mortality. Preterm infants are at higher risk of patent ductus arteriosus compared to full-term babies. Early diagnosis in this patient population is essential as delay in treatment reduces chances of success.