Coarctation of the aorta (COA)

At Children’s Hospital Boston, we’re known for our science-driven approach. We’re home to the world’s most extensive pediatric research enterprise, and we partner with elite institutions around the world. But as specialists in family-centered care, we always remember that your baby is precious, not just a patient.

Coarctation of the aorta is a challenging condition to treat. But as world pioneers in innovative heart care, Children’s specialists are uniquely qualified to treat your child.

What is COA?

In COA, there’s a narrowing of the aorta, the main artery that delivers oxygen-rich (red) blood to the body.

Although the narrowing can occur anywhere in the aorta, it’s usually found in the segment in the segment just beyond the aortic arch—beyond the vessels that bring blood to the upper body, and before the vessels that bring blood to the lower body. This is why in COA, blood pressure in the arms will be high, and blood pressure in the legs and ankles will be low.

Why is COA a concern?

The narrowing in the aorta restricts the amount of oxygen-rich blood that can travel to the lower part of the body; the left ventricle must pump under higher than normal pressure in order to get oxygen-rich (red) blood through the narrowed opening and out to the body. The left ventricle becomes thick (hypertrophied). If the muscle becomes too thick and is no longer able to function efficiently and handle its workload, it will eventually fail (congestive heart failure).

Coarctation of the aorta causes several additional problems, including:

• Blood pressure is higher above the narrowing, and lower below the narrowing. Older children may have headaches from too much pressure in the vessels in the head, or cramps in the legs or abdomen from too little blood flow in that region. Also, the kidneys may not make enough urine since they require a certain amount of blood flow and a certain blood pressure to perform this task.
  
  An extra word about the kidneys and blood pressure: The kidneys are among the organs that “control” blood pressure. In COA, the kidneys receive their blood supply just below the level of the coarctation, so the pulsing pattern of blood flow to the kidneys is disrupted. The kidneys interpret this abnormal flow as low blood pressure, so they send out chemicals/molecules that tell the body to increase the blood pressure.

• The walls of the ascending aorta, the aortic arch or any of the arteries in the head and arms may become weakened by high blood pressure. Spontaneous tears in any of these arteries can occur, which can cause a stroke or uncontrollable bleeding.

A bicuspid aortic valve—an aortic valve that has two flaps (leaflets) instead of the usual three—and a ventricular septal defect (VSD) can be accompanying defects to COA.

How common is coarctation of the aorta? 

• Coarctation of the aorta occurs in about 6 to 8 percent of all children with congenital heart disease.
• COA occurs twice as often in boys as girls (as is the case with many “left heart” diseases).

What causes coarctation of the aorta? 

• Coarctation of the aorta (COA) may be due to improper development of the aorta in the first eight weeks of fetal growth.
• The condition may develop as a result of disrupted flow patterns in the heart associated with other abnormalities, and usually affecting the valves on the left side of the heart (mitral or aortic).
• COA can also form when tissue from the ductus arteriosus (the in utero connection between the pulmonary artery and aorta that diverts blood away from the lungs to the placenta for oxygenation) migrates into the aorta. When the ductus closes at birth, the ductal muscle in the aorta contracts, narrowing the caliber (diameter) of the aorta.
• Some congenital heart defects may have a genetic link—occurring due to a defect in a gene, a chromosome abnormality or environmental exposure, causing heart problems to occur more often in certain families. But most of the time this heart defect occurs by chance, with no clear reason for its development.

How do you diagnose COA?

The first line of diagnosis for COA is clinical exam, beginning with obtaining the child’s vital signs. The pediatric cardiologist obtains a four-limb blood pressure—measuring the blood pressure in both arms and both legs. (Part of the newborn discharge exam is to be able to feel four good pulses.)

The first suspicion of a coarctation is when the doctor notes a lower blood pressure in the legs. The baby’s thigh or foot pulses will be weak and therefore difficult for the doctor to feel.

Other tests that help with the diagnosis—or with planning for treatment—may include:

• echocardiogram (echo, cardiac ultrasound): At Children’s, the echocardiogram is the primary diagnostic tool to confirm a diagnosis of COA.
• electrocardiogram (ECG or EKG): An EKG is useful for measuring the patient’s vital signs.
• cardiovascular MRI (magnetic resonance imaging): We often use MRI to plan a catheterization procedure if the patient needs a balloon or stent.
• chest x-ray: At Children’s today, x-ray is only occasionally used to diagnose COA.

For more details, see Tests.

Can COA be diagnosed prenatally, and is there an advantage to receiving a prenatal diagnosis?

COA through cardiac ultrasound can sometimes be detected prenatally: The ultrasound can pick up the size discrepancy between the left heart and the right heart, as well as the narrowing of the aortic arch.

But the aortic arch isn’t usually obstructed in the fetus because of the open ductus arteriosus (the prenatal connection that ensures blood flow between the aorta and the pulmonary artery), so there’s no need to treat the fetus in utero. The obstruction can become evident after birth once the ductus arteriosus closes.

Being able to diagnose COA through prenatal cardiac ultrasound does give doctors a head-start in determining next steps. We can plan in advance for your baby’s delivery, and for his immediate stabilization and care once he’s born. Upon the baby’s birth, our team will bring together the pediatric and obstetric specialists needed for his care.

The coarctation due to migration of ductal tissue into the aorta (see question on Causes, above) cannot be diagnosed until after birth, when the ductus closes.

What are the signs and symptoms of COA, and when do they emerge?

The more severe the narrowing, the more signs and symptoms a child will have, and the earlier the problem will be noticed. In infants, the onset of symptoms in a previously “fine” baby can be sudden and severe. (On the other end of the spectrum, mild narrowing may not cause any symptoms at all.)

Common signs include:

• heavy and/or rapid breathing
• pale skin
• sweating
• irritability

The most common physical finding for COA in an infant is that the baby’s femoral (thigh) or leg pulses (and possibly groin and feet pulses) are weak and difficult for the doctor to feel.

In some cases, COA may not be noted until school-age, adolescence or even adulthood—often during a routine blood pressure test. As the child grows, his aorta will not grow at the same rate; so with the vessel’s relative narrowing later in life, signs and symptoms can appear, such as:

• high blood pressure
• nosebleeds
• a heart murmur
• headaches (from high blood pressure above the COA)
• cramps in the lower sections of the body (from low blood pressure below the COA)

How do you treat COA?

Coarctation of the aorta is treated with repair of the narrowed vessel. Infants who are very sick and require care in the cardiac intensive care unit (CICU) may need emergency repair of the coarctation. Others who show few symptoms may have the repair scheduled on a less urgent basis.

Surgery. For most infants, surgery is the standard treatment. (A small percentage of infants treated surgically will need either a repeat surgery or a balloon dilation to stretch the narrowed area.) The surgeon cuts out the narrowed segment and sews the two healthy ends of the aorta back together, reconstructing the arch and establishing normal blood flow through the vessel.

If your child also has a VSD, the surgeon will repair the defect at the time of the coarctation surgery. If there is a bicuspid aortic valve, it will need to be followed by the cardiologist to make sure that no stenosis (obstruction) or regurgitation (backwards flow) develops later.

Cardiac catheterization (usually as a second procedure for older children). The cardiologist guides a small, thin, flexible tube (catheter) to the inside of the heart through a blood vessel in the groin. The doctor passes an inflated balloon through the narrowed section of the aorta to stretch it open. A small rigid metal tube, called a stent, may also be placed in the narrowed area after the balloon dilation to keep the aorta open.

Why is surgery preferable for infants? When is catheterization or stenting useful? The fibrous band of abnormal tissue that creates the coarctation is not usually amenable to balloon dilation—it must be cut out surgically. Surgery also gives the surgeon a chance to neatly reconstruct the aortic arch.

But with time, the repaired area itself can also become narrowed with fibrous tissue. As a second procedure, a catheterization/balloon dilation can be effective. In older children, teens or adults who are diagnosed for the first time, cardiologists might also insert a stent, since these patients are close enough to fully grown that they won’t outgrow the stent.

For more details, see Treatment & care.

Will my baby be OK?

If your child’s COA is repaired in infancy—before there’s any permanent damage such as high blood pressure—the long-term outlook is excellent. Your child may need repeat surgery or catheterization if the repaired area re-narrows (re-narrowing occurs in up to 20 percent of infants in the first or second year after repair). But in general, most children who’ve had surgery for COA will live healthy lives, with activity levels, appetite and growth eventually returning to normal.                                                                                         

What about patients diagnosed in childhood or adulthood?

Patients diagnosed later in life—in childhood or adulthood—who already have chronic high blood pressure need to be followed, and some will need to be treated for their high blood pressure. Once surgery repairs the COA, the thickening in the heart muscle (hypertrophy) that will have formed because of continued obstruction will usually become normal over time.

Where can my child find care and support when he grows up?

• Our Boston Adult Congenital Heart and Pulmonary Hypertension Service (BACH) provides long-term inpatient and outpatient care and advanced therapeutic options for patients with congenital heart disease and pulmonary hypertension as they progress into adulthood.

BACH is an international center for excellence, with physicians and services from Children’s, Brigham and Women’s Hospital and Beth Israel Deaconess Medical Center. The center promotes and supports clinical and scientific research for the advancement of care of these patients, and is a leader in the education of providers caring for this unique population.

• The Adult Congenital Heart Association (ACHA) is a national not-for-profit organization dedicated to improving and extending the life of adults with congenital heart defects, now thought to number at least one million. The organization serves and supports many such adults, their families and the medical community, as well as conducting research and providing advocacy, outreach and education.

FAQ

Q: What is coarctation of the aorta (COA)?
A: In COA, there’s a narrowing of the aorta, the main artery that delivers oxygen-rich (red) blood to the body. Although this narrowing can occur anywhere in the aorta, it’s usually found in the segment just beyond the aortic arch.

Q: How common is COA?

A: COA occurs in about 6 to 8 percent of all children with congenital heart disease. The defect occurs twice as often in boys as girls, as is the case with many “left heart” diseases.

Q: If my child has COA, will he be OK?
A: While coarctation of the aorta is very serious, Children’s has vast experience treating infants and children with the condition—with generally excellent short- and long-term outcomes. Open-heart surgery at Children’s has one of the highest success rates in the United States among large pediatric cardiac centers.

Q: How does Children’s treat newborns with COA?
A: For most infants, surgery is the standard treatment. The surgeon cuts out the narrowed segment and sews the two healthy ends of aorta back together, reconstructing the arch and establishing normal blood flow through the aorta.

But the repaired area can itself sometimes become re-narrowed, fibrous tissue (re-narrowing occurs in up to 20 percent of infants in the first or second year after repair). So, as a second procedure, a catheterization/balloon dilation can be effective.

Q: How does Children’s treat older children with COA?
A: In older children, teens or adults who are diagnosed with COA for the first time, we might insert a stent (rigid metal tube), because these patients are close enough to fully grown that they won’t outgrow the stent.

For details, see Treatment & care.

Q: What are the signs and symptoms of COA?
A: The more severe the narrowing, the more signs and symptoms a child will have, and the earlier the problem will be noticed. (Mild narrowing may not cause any symptoms at all.) The most common signs in infants include:

• irritability
• pale skin
• sweating
• heavy and/or rapid breathing

In some cases, coarctation can be detected in infancy. The most common physical finding for COA in an infant is that the baby’s femoral (thigh) or foot pulses are weak and difficult for the doctor to feel.

In other cases, COA may not be noted until school-age, adolescence or even adulthood—usually because of an elevated blood pressure.

Q: If my child has COA, what should I ask my doctor?
A: If your child is diagnosed with coarctation of the aorta, you may feel overwhelmed with information. You may find it helpful to jot down questions as they arise—so that, when you talk to your child’s doctors, you can be sure that all of your concerns are addressed.

You may want to ask:

• What is happening to my child, and why?
• Will further tests be needed to confirm my child’s diagnosis?
• Are there any other heart defects besides the COA?
• What treatment options are there?
• Are there alternative therapies?
• What will his recovery be like?
• Will there be restrictions on my child’s activities? If so, for how long?
• What can we do at home?
• Will there be long-term effects?

Q: When is COA usually diagnosed, and how?
A: On physical exam, the main sign of a coarctation is usually that the femoral (thigh) or foot pulses are weak and therefore difficult for the doctor to feel. (Part of the newborn discharge exam is to be able to feel four good pulses.)

Tests to confirm a diagnosis may include:

• echocardiogram (echo, cardiac ultrasound)
• electrocardiogram (ECG or EKG)
• magnetic resonance imaging (MRI)
• chest x-ray (used only occasionally at Children’s to diagnose COA)

Q: What benefit is there to a prenatal (fetal) ultrasound that detects COA while the baby is still in the womb?

A: COA can be detected prenatally through cardiac ultrasound: The test can pick up the size discrepancy between the left heart and the right heart, as well as the narrowing of the aortic arch.

The aortic arch isn’t usually obstructed in the fetus because of the open ductus arteriosus (the prenatal connection between the aorta and the pulmonary artery), so there’s no need to treat the fetus in utero. The obstruction can become evident once the ductus arteriosus closes after birth.

Being able to diagnose COA through prenatal cardiac ultrasound does give doctors a head-start in determining next steps. We can plan in advance for your baby’s delivery, and for his immediate stabilization and care once he’s born. Upon the baby’s birth, our team will bring together the pediatric and obstetric specialists needed for his care.

The coarctation due to migration of ductal tissue into the aorta cannot be diagnosed until after birth, when the ductus closes.

Q: What should we do at home after COA surgery?
A: Your child’s cardiologist will follow your child’s progress closely, and will offer recommendations for post-operative follow-up care—including:

• wound care
• a nutritional program to encourage weight gain
• an appropriate exercise routine (which will help keep his blood pressure in check)
• an oral hygiene program to prevent infection (if needed)

Q: What is the long-term outlook for COA-affected children?
A: If your child’s COA is repaired in infancy—before there’s any permanent damage such as high blood pressure—the long-term outlook is excellent.

Your child may need repeat surgery or catheterization if the repaired area re-narrows (re-narrowing occurs in about 20 percent of infants in the first or second year after repair). But in general, most children who’ve had surgery for COA will live healthy lives—with activity levels, appetite and growth eventually returning to normal.

Q: What causes COA?
A: It’s important to understand that as parents, you’ve done nothing to cause COA and its associated defects. Nothing you’ve ingested or have been exposed to environmentally has been linked to having a child with COA. Familial cases have been reported, but a genetic link is still being researched.

COA is the result of the abnormal development of the fetal heart during the first eight weeks of pregnancy. But it’s not understood why the heart doesn’t develop normally. Congenital heart defects usually occur sporadically (by chance), with no clear reason for their development.

Q: What is Children’s experience treating congenital heart defects?
A: Children’s surgeons treat some of the most complex pediatric heart conditions in the world, with top success rates. Our experts have pioneered some of medical science’s most advanced heart treatments, now in use around the globe. For example, Children’s is the world’s largest and most experienced program for fetal heart intervention.

Q: What heart research and innovations are coming from Children’s?
A: Children’s is a world pioneer in the development and use of innovative fetal interventionto treat certain rare congenital heart defects. Thanks to Children’s research and refinements of technique, our Advanced Fetal Care Center offers the world’s largest and most experienced program for fetal heart intervention.

Children's is a world leader in "translational research"—bringing laboratory advances to the bedside and doctor's office as soon as possible. All senior medical staff in the Department of Cardiology do clinical research, and many also do laboratory research.

Causes

It’s important to understand that as parents, you’ve done nothing to cause COA and any associated defects. Nothing you’ve ingested or have been exposed to environmentally has been linked to having a child with COA. Familial cases have been reported, but a definitive genetic link is still being researched.

COA is the result of abnormal development of the fetal heart during the first eight weeks of pregnancy. But it’s not understood why some babies’ hearts don’t develop normally. Congenital heart defects usually occur sporadically (by chance), with no clear reason for their development.

Signs and symptoms

The more severe the narrowing, the more signs and symptoms a child will have, and the earlier the problem will be noticed. In infants, the onset of symptoms in a previously “fine” baby can be sudden and severe. On the other end of the spectrum, mild narrowing may not cause any symptoms at all.

Common signs include:

• heavy and/or rapid breathing
• pale skin
• sweating
• cold feet and legs
• irritability

The most common physical finding for COA in an infant is that the baby’s thigh or foot pulses are weak—making them hard for the doctor to feel.

COA may not be noted until school-age, adolescence or adulthood. As the child grows, his aorta will not grow at the same rate; so with the vessel’s relative narrowing later in life, signs and symptoms can appear.

When to seek medical advice

For infants. In infancy, COA is very serious and can be fatal if untreated. Call your health care provider immediately if your infant:

• is having difficulty breathing or is breathing rapidly
• is unusually pale
• is feeding poorly
• is lethargic
• has cold feet and legs

For children or teens. Call your provider if your older child or teen is experiencing unexplained high blood pressure, a heart murmur, nosebleeds, headaches (from high blood pressure above the COA) or cramps in his lower body (from low blood pressure below the COA).

Questions to ask your doctor

After your child is diagnosed with COA, you may feel overwhelmed with information. To avoid losing track of the questions that occur to you, you may want to jot you’re your questions as you think of them. Then, when you talk to your child’s doctors, you can be sure all your concerns get addressed.

Some of the questions you may want to ask are:

• What is happening to my child, and why?
• Will further tests be needed to confirm my child’s diagnosis?
• Are there any other heart defects besides the COA?
• What treatment options are there?
• Are there alternative therapies?
• What will his recovery be like?
• Will there be restrictions on my child’s activities? If so, for how long?
• What can we do at home?
• Will there be long-term effects?

Who’s at risk

Certain syndromes, such as Turner syndrome (a chromosomal abnormality in girls), can be associated with COA and bicuspid aortic valve.

But most congenital heart defects occur sporadically (by chance), with no clear reason for their development. So, it’s difficult to predict who’s at risk. Familial cases have been reported, but a definitive genetic link is still being sought by researchers.

Complications and risks

Aside from the usual complications from any surgery, such as bleeding or infection, complications from COA surgery are very rare.

• The greatest risk—but still very rare—is damage to nerves in the region of the aortic arch. (In extremely rare instances, this could result in larynx/vocal cord damage.)
• Another complication (rarely seen today) is bacterial endocarditis(inflammation of the heart lining) after the child’s discharge from the hospital. The risk is somewhat higher if:
• artificial patch material (instead of the child’s own native tissue) is used to repair the coarctation
• the patient has particularly poor dental hygiene
• the patient has another systemic infection

If endocarditis is a risk, your child's cardiologist may recommend preventive antibiotics.

• Risks of aneurysm: There are two types of aneurysm that can present a risk:
• A brain aneurysm—a burst blood vessel—can be associated with vascular disease and high blood pressure.
• An aneurysm at the site of the coarctation repair, particularly if the patient has had a balloon dilation, can weaken the blood vessel wall. If a patient has had a dilation, the doctor will follow him over time with CT scans or MRIs to make sure an aneurysm doesn’t develop. If an aneurysm does develop, it must be repaired.
• Complications from not treating COA: Failure to treat mild to moderate COA can lead to high blood pressure, which puts a child’s vascular system at risk and can pose long-term risks of:
• stroke
• heart attack
• ventricular hypertrophy (thickening)
• impaired cardiac function
• rupture of the aorta
• brain (cerebral) aneurysm (see bullet above)
• organ failure (e.g., kidney, liver) resulting from blood pressure that’s too low

Long-term outlook

If your child’s COA is repaired in infancy—before there’s any permanent damage such as chronic high blood pressure—his long-term outlook is excellent. Your child may need repeat surgery or catheterization if the repaired area re-narrows (re-narrowing occurs in about 20 percent of infants in the first or second year after repair). But most kids who’ve had surgery for COA will live healthy lives—with activity levels, appetite and growth eventually returning to normal.

Your cardiologist will help create a long-term care plan as your baby grows into childhood and his teen years. Most people who have had congenital heart disease repair have an ongoing relationship with their cardiologist. We’ll consult with you; treat your child if complications arise; and advise on daily-life issues such as exercise, activity levels, nutrition and, for females, pregnancy precautions.

For teens

As a teen with a congenital heart defect, you have a lot to deal with. Besides the typical issues any teenager faces—from social acceptance to body changes and more—you also have to cope with:

• medical appointments and procedures
• feeling different
• assuming some personal responsibility for your health

The good news is that your COA repair is very likely to be successful, and your cardiologist visits will probably be mostly for monitoring. Even so, if you (or your parents) feel down or anxious through this time, speak to your doctor, nurse, parent or counselor—they’re all on your team, and they all want to help.

What you can do at home

Your child’s cardiologist will follow his progress closely, and will offer recommendations for follow-up care after treatment—including:

• wound care
• a nutritional program to encourage weight gain
• an appropriate exercise routine (this will help keep his blood pressure in check)
• an oral hygiene program to prevent infection (if needed)

Consult your child’s cardiologist for guidance on specific steps for follow-up care at home. And as your baby recovers and grows, be sure to follow a regular program of well-baby/well-child checkups.

Prevention

As parents, you need to know that you’ve done nothing to cause your child’s COA and any accompanying defects; there are no precautions you could have taken to prevent it. A congenital heart defect usually occurs sporadically (by chance), with no clear reason for its development.

While COA can’t be prevented, early detection can help. Discuss with your child’s doctor the risk of COA or another heart defect if:

• your daughter has Turner’s syndrome
• your family has a history of congenital heart disease
• your child already has another heart defect

COA Glossary

• aorta: one of the heart’s two great arteries. In a normal heart, the aorta arises from the left ventricle and pumps oxygen-rich blood out to the body. In COA, the aorta is narrowed and/or obstructed, usually just beyond the arch, preventing proper red blood flow out to the body.
• bicuspid aortic valve: a defect of the aortic valve in which the valve has two flaps (leaflets) instead of the usual three. The aortic valve opens when the left ventricle pumps blood into the aorta, then closes after the blood is ejected to prevent the ejected blood from going back into the heart.
• cardiac/cardio-: pertaining to the heart
• cardiac catheterization: provides detailed visual information and measurements about the structures inside the heart, cardiac catheterization is a procedure that can be performed on a fetus, a baby, a child or an adult. Catheterization can be diagnostic-only, diagnostic and therapeutic, or diagnostic and interventional.
• cardiac intervention: a minimally invasive procedure, such as cardiac catheterization or angioplasty, to diagnose and/or treat heart disease
• cardiac surgery: surgical procedure performed on the heart
• cardiac surgeon: doctor who performs surgery on the heart. A pediatric cardiac surgeon performs surgery on the hearts of infants and children.
• cardiologist: doctor who diagnoses and treats heart problems non-surgically. A pediatric cardiologist treats infants and children with heart problems.
• cardiovascular MRI (magnetic resonance imaging): a diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body.
• The Center for Families at Children’s: dedicated to helping families find the information, services and resources they need to understand their child’s medical condition and take part in their care
• coarctation of the aorta (COA): a narrowing of the aorta, the main artery that delivers oxygen-rich (red) blood to the body. Although this narrowing can occur anywhere in the aorta, it’s usually found in the segment just beyond the aortic arch
• congenital heart defect: heart defect present at birth. The heart usually forms in the first eight weeks of fetal development. It is thought that most congenital heart defects develop during this period.
• diagnosis: medical determination of illness or disease based on physical examinations and advanced technology diagnostic testing tools
• ductus arteriosus: the prenatal connection that ensures blood flow between the aorta and the pulmonary artery, which usually closes shortly after birth
• echocardiogram (echo, cardiac ultrasound): a diagnostic tool that evaluates the structure and function of the heart using electronically recorded sound waves that produce a moving picture of your child’s heart and heart valves.
• electrocardiogram (ECG, EKG): a diagnostic tool that evaluates the electrical activity of your child’s heart.
• (bacterial) endocarditis(inflammation of the heart lining)
• fetal echocardiogram (fetal ultrasound): a diagnostic tool that uses sound waves to evaluate the structure and function of the baby’s heart while still in utero. The ultrasound can detect a COA defect in the fetus.
• fetal magnetic imaging (MRI): a non-invasive diagnostic tool that uses 3-D imaging technology produced by magnets to accurately determine the blood flow and functioning of your child’s heart in utero. Drawing on our expertise in pediatric imaging, Children’s is setting a new standard in fetal MRI.
• interventional cardiologist: doctor who specializes in performing minimally invasive procedures, such as cardiac catheterization or angioplasty, to diagnose and treat heart disease
• native tissue: the body’s own tissue (as opposed to artificial tissue)
• symptoms: the presenting reasons why a child needs medical attention; something a patient feels, rather than something discovered by exam or testing. A symptom’s characteristics—including but not limited to onset, quality, triggers and severity—help diagnosticians to determine an illness or disease, or to determine what further testing is needed to determine the illness or disease.
• patent (open) ductus arteriosus (PDA): a blood vessel (the ductus arteriosus) that connects the two great arteries (the aorta and the pulmonary artery) and usually closes soon after birth. As long as the PDA remains open (patent), blood can pass from the right ventricle and pulmonary artery to the aorta and body, allowing some oxygen-rich blood to circulate.
• perfusion: the passage of blood through the blood vessels of the circulatory system
• secondary defect: a defect that accompanies (“is secondary to”) a main defect
• stent: a rigid metal tube inserted during a catheterization procedure to widen or keep open  a blood vessel
• sporadic: occurring by chance, occasionally, not inherited
• VSD: ventricular septal defect; an opening in the wall (septum) between the left and right ventricles of the heart; often a secondary defect to a COA
• x-ray: a diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones and organs onto film.

For a more complete list of cardiovascular terms, visit our Cardiovascular Glossary.

For in-depth visual information on several of the conditions, diagnostic tools and procedures described above, visit our cardiovascular Multimedia Library.