Patent ductus arteriosus (PDA) is the failure of the ductus arteriosus to close after birth, allowing blood to flow inappropriately from the aorta into the pulmonary artery.
Illustration by Electronic Illustrators Group. © 2016 Cengage Learning®.
Congenital heart disease refers to various conditions present at birth that prevent the heart from working properly. Most of these are malformations that prevent the heart from pumping blood throughout the body.
Six-year-old David liked everything about the first grade. He especially liked his gym class, even though he always ended up feeling tired and worn out after only a few minutes of dodgeball or relays. One day after a game of dodgeball, David collapsed on his way back to the bench. After he was rushed to the hospital, a doctor discovered that he had a hole in his heart.
The doctor explained to David and his parents that the small hole located between the two chambers of David's heart was called a septal defect and that oxygenated blood was mixing with deoxygenated blood. This condition deprived David's organs of the oxygen that they need, which caused his collapse.
Congenital heart disease refers to heart defects that are present at birth that affect the ability of a person's heart to function properly. Congenital heart defects occur while a fetus * is still developing and can be attributed to many causes. The March of Dimes estimated that, as of 2013, each year nearly 40,000 babies (1 in every 100) were born in the United States with a heart defect. It is the most common congenital cause of infant death.
To understand the different types of congenital heart defects, one needs to understand how the heart works to pump blood through the body. The heart is a muscle made of four chambers. There is a left side and a right side. Two atria sit on top of two ventricles. The atria and ventricles are separated by one-way valves that keep blood flowing in one direction so it can get to the places in the body that need it. Each vein that carries blood to the heart and each artery that carries blood from the heart have a specific job.
Every time the heart contracts, all of these parts work together to keep the blood flowing throughout the body. The following statements describe the direction of blood flow through the heart:
It is very important that all of these parts work properly. When one or more of these important parts of the heart has a defect, the heart cannot do its job.
There are various types of defects that can be present at birth. Sometimes, a doctor, nurse, or technician will notice during a routine exam that the infant's heartbeat sounds abnormal. This abnormal sound is called a murmur. At other times, the condition may not be detected until the child is much older. Some congenital heart defects are more common than others. These include the following.
Septal defects, sometimes called a “hole in the heart,” are the most common types of congenital heart defects. When the septum (the muscular wall that separates the right and left sides of the heart) has a defect, proper blood flow is interrupted, causing a number of problems. The symptoms of septal defects vary depending on how much blood goes through the septal defect and, therefore, to the wrong chamber of the heart. Sometimes, minor holes close spontaneously. Other times, a doctor must repair them surgically. Depending on the type and severity, unrepaired septal defects may result in malnourishment, cyanosis (a bluish discoloration of the lips and skin), hypertension (high blood pressure), hypertrophy (enlarged heart), pulmonary edema (fluid in the lungs), congestive heart failure, and infections.
There are several types of septal defects:
Patent ductus arteriosus is similar to a septal defect in that it involves a hole in the heart. The fetus receives oxygen from its mother, not from its lungs. To make this process possible, there is an artery (ductus arteriosus) in the heart that bypasses the lungs and sends oxygenated blood directly to the body. Normally, this ductus closes soon after the baby is born. Certain problems may cause it to remain open. Medicine may be given to the baby to close the ductus, but in some cases, surgery is required.
A patent foramen ovale (PFO) happens when the septum between the two upper chambers of the heart develops normally in the uterus but the flap does not completely seal after birth. All people have a PFO before birth, but it seals correctly in 80 perecent of people. If PFO is diagnosed by a cardiologist (heart specialist), a patient may be given medication to correct the problem.
Tetralogy of Fallot (fal-LOW) (TOF) is a combination of four different problems and occurs in 9 to 14 percent of all congenital heart defects. TOF results in the following:
TOF is usually repaired surgically during infancy.
Coarctation of the aorta accounts for 9 to 11 percent of all congenital defects. The aorta is one of the major vessels of the heart and is responsible for delivering the oxygenated blood from the heart to the rest of the body. Sometimes babies are born with a defect that leaves part of their aorta very narrow. When this happens, the heart has to work much harder to pump the blood through the narrowed opening. This defect can be mild or severe, and it can be repaired surgically. There are a few options for repairing coarctation of the aorta. Doctors can replace the narrowed section entirely. They can also cut out the section and sew the normal sized ends together, or they can try to widen the vessel with a balloon (angioplasty).
Hypoplastic left heart syndrome occurs in 4 to 8 percent of all congenital heart defects. It is a complex condition in which the left side of the heart, which is responsible for pumping oxygenated blood throughout the body, has not developed properly. The structures that are affected include the left ventricle, the mitral valve, the aorta, and the aortic valve. In babies with this condition, the left ventricle of the heart is so small that the heart cannot pump blood needed by the body. The mitral and aortic valves are very narrow or closed, and the aorta is also very narrow. This creates a situation in which the right side of the heart has two jobs, instead of one. First, it must send the blood to the lungs to be oxygenated. Second, it must pump blood to the rest of the body via a patent ductus arteriosus, which typically closes soon after birth. This condition is often fatal if not treated shortly after birth.
Babies who are born with heart disease may or may not show symptoms of the defect right away. Sometimes, children may not show symptoms until they are much older. In very few cases, individuals may not learn of their condition until adulthood. Specific symptoms depend on the severity of the defect. These may include an odd skin color (gray or cyanotic, commonly called blue baby syndrome); swelling (edema) in the legs, feet, or abdomen; shortness of breath; difficulty feeding; and immediate fatigue during play or sports.
As of 2016, causes for congenital heart defects were not fully understood. Researchers believed that both environmental and genetic factors played a role. While changes in single genes have been associated with congenital heart disease, researchers believe this accounts for a very small percentage of cases.
Scientists also suspected that viral infections may play a key role in the development of congenital heart defects. These infections include German measles (rubella) and the flu. Pregnant women should make certain that they are vaccinated against rubella and the flu; they should avoid coming in contact with people who are sick; and they should avoid all forms of alcohol, tobacco, drugs (both legal and illegal), and toxic chemicals.
According to the March of Dimes, researchers identified certain medications as potential causes of congenital heart defects. These include some antiseizure medications, the acne medication Isotretinoin, and Thalidomide.
Many congenital heart defects, such as those attributed to heredity, are not preventable. Still, there are specific steps that women can take in preparation for and during pregnancy to prevent certain complications during pregnancy:
In most cases, congenital heart defects are diagnosed in early infancy after a baby shows outward signs of problems. These may include shortness of breath, difficulty eating, or ashen or cyanotic skin tones. Other times, problems may not arise until childhood, as in David's case. More rarely, defects are discovered during routine examinations before birth or during adulthood.
In all of these cases, doctors will conduct further testing to identify and treat whatever problem is present. These routine tests include:
Most congenital heart defects can be repaired or improved surgically. Because of advances in cardiology over the last century, children who are born with serious cardiac defects can go on to live happy, healthy lives.
Often babies who are born with heart defects undergo surgery immediately, and the defects that they were born with never interfere with their lives. Other times, the surgery may only provide temporary improvement, not a solution. These are cases in which the defect is so severe that the only way to completely fix the problem is through a heart transplant. According to the International Society for Heart and Lung Transplantation, approximately 350 to 500 heart transplant procedures are performed worldwide each year. In 2012, 512 children received heart transplants.
See also Birth Defects: Overview • Heart Disease: Overview • Heart Murmur • Pregnancy
American Heart Association/American Stroke Association. “Statistical Fact Sheet 2016 Update: Congenital Cardiovascular Defects.” https://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd/documents/downloadable/ucm_483962.pdf (accessed June 19, 2016).
Gerber, Max. My Heart vs. the Real World: Children with Heart Disease, in Photographs and Interviews. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press, 2008.
Association of Maternal and Child Health Programs. “Issue Brief: State Newborn Screening and Birth Defects Program Roles in Screening for Critical Congenital Heart Defects (CCHD).” October 2013. http://www.amchp.org/programsandtopics/CHILD-HEALTH/projects/newborn-screening/Documents/AMCHP_Screening_for_CCHD_Issue_Brief_FINAL-Oct2013.pdf (accessed July 16, 2015).
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Genetics Home Reference. “Critical Congenital Heart Disease.” U.S. National Library of Medicine. http://ghr.nlm.nih.gov/condition/critical-congenital-heart-disease (accessed July 16, 2015).
American Heart Association. 7272 Greenville Ave., Dallas, TX 75231-4596. Toll-free: 800-AHA-USA1. Website: http://www.heart.org/HEARTORG (accessed June 8, 2016).
March of Dimes. 1275 Mamaroneck Ave., White Plains, NY 10605. Website: http://www.marchofdimes.org (accessed May 6, 2016)
* fetus (FEE-tus) is the term for an unborn human after it is an embryo, from nine weeks after fertilization until birth.
* ultrasound, also called a sonogram, is a diagnostic test in which sound waves passing through the body create images on a computer screen.
* catheter (KAH-thuh-ter) is a small plastic tube placed through a body opening into an organ (such as the bladder) or through the skin directly into a blood vessel. It is used to give fluids to or drain fluids from a person.