Congenital Heart Defects
Reviewed By: Robert I. Hamby, M.D.
What is congenital heart disease?
Congenital heart disease (CHD) is the name given to any heart defect or malformation that is present at birth. Most types of CHD involve a deformity within the heart and/or the large blood vessels connected to the heart (e.g., aorta, pulmonary artery).
In some patients, the defect(s) may be mild and unnoticed at birth, then diagnosed later in life. In other children, the effects of the defect(s) are so severe that diagnosis occurs either before birth or during the perinatal (newborn) period. With the sophisticated medical technology now available for diagnosis and treatment, many babies born with congenital heart disease can go on to lead healthy, normal and full adult lives.
Congenital heart disease is the most common of all major birth defects with approximately 36,000 American–born babies every year with CHD, according to the American Heart Association (AHA) 2006 Heart and Stroke Statistical Update. However, the number of children born with CHD outside the U.S. is substantially higher, due to the lack of adequate medical care in poorer countries. The March of Dimes estimates that over one million children were born with CHD worldwide in 2001.
The most common congenital heart defect requiring medical intervention is a ventricular septal defect (14 to 16 percent). Other common defects include tetralogy of Fallot (9 to 14 percent), transposition of the great arteries (10 to 11 percent) and coarctation of the aorta (8 to 11 percent). In 2004, more than 4,100 deaths were caused by congenital heart defects, making them the most common cause of infant death from birth defects. Fortunately, however, the overall death rate due to congenital heart disease has been steadily declining. Between 1979 and 1997, the death rate from all congenital heart defects declined 39 percent. The mortality rate varies significantly with the type of defect.
A quarter of the fatalities due to congenital heart disease occur within the first month of life.
Potential causes of congenital heart disease
In the vast majority of patients, the cause of congenital heart disease (CHD) is unknown. Some mothers blame themselves for their child’s illness. However, most researchers stress that congenital heart diseases are usually the result of an unknown combination of factors, rather than something related to the birth mother. However, there are some risk factors that have been associated with a higher rate of congenital heart disease.
These risk factors include:
- Chromosomal or genetic abnormalities (especially Down syndrome) in the child
- Certain medications taken during pregnancy
- Alcohol, drug abuse or smoking during pregnancy
- Maternal viral infection, such as rubella (German measles) in the first trimester
- Maternal diabetes mellitus, even if it is gestational diabetes.
Furthermore, the risk of having a child with congenital heart disease increases from eight in 1,000 to 16 in 1,000 if a parent or sibling has congenital heart disease.
Researchers are continuing to search for potential causes of CHD.
Recent findings include:
- Infants born to diabetic mothers are five times more likely than others to have heart defects. The researchers noted that all pregnant women with diabetes should have a special ultrasound of the fetal heart performed.
- Scientists are beginning to identify certain genes that appear linked to CHD. While it is too early to speculate future treatment options that may result from these discoveries, researchers hope the knowledge will lead them to discover additional genes that may play a role in the development of CHD.
- Exposure to pesticides during pregnancy may increase the risk of a specific type of CHD called transposition of the great arteries (TGA). Researchers found that mothers who reported exposure to herbicides during pregnancy were nearly three times as likely to have a child born with TGA, while women exposed to rat poison were five times as likely to have a child born with TGA. Most of the women noted home and garden exposures to the substances mentions, as opposed to workplace exposure. In addition, the critical exposures occurred during the first three months of pregnancy. However, researchers acknowledged that mothers of infants with CHD might be more likely to remember an exposure incident than mothers of healthy infants and stated that additional research was needed in this area.
- Patients with oral clefts are 16 times more likely to have a congenital heart defect. The reason for this association is unknown. However, researchers advise that patients with oral clefts should be examined for heart defects before undergoing reparative surgery.
Types and differences of heart defects
There are many types of congenital heart disease. Each is defined by the location and severity of the heart defects. To understand these different types of abnormalities, one must have a basic understanding of the normal human heart.
There are two sides of the heart. The right side of the heart pumps oxygen-poor or deoxygenated blood from the body to the lungs, where the blood picks up oxygen. The oxygen–rich or oxygenated blood then returns to the left side of the heart, which pumps the blood out to the body. There are five main areas in and around the heart that need to be fully functioning in order for this process to be carried out properly:
- The veins that carry the blood back to the heart from the body and the lungs.
- The upper chambers of the heart atria, which collect the blood returning to the heart.
- The lower chambers of the heart ventricles, which pump the blood out from the heart to the lungs or the body.
- The four valves of the heart. These valves allow blood to move only in the proper direction in the heart without allowing any blood to leak back in the other direction. These four valves are the tricuspid valve (between the right atrium and ventricle), the pulmonic valve (between the right ventricle and the pulmonary artery to the lungs), the mitral valve (between the left atrium and the left ventricle) and the aortic valve (between the left ventricle and the aorta to the body).
- The aorta (which carries oxygen–rich blood from the left ventricle to the rest of the body) and the pulmonary artery (which carries oxygen–poor blood from the right ventricle to the lungs).
Defects that may occur within these vital areas in or around the heart include:
- Defects in the wall septum between the atria or ventricles, which allow mixing of blood between the right and left sides of the heart.
- Narrowing (stenosis) or complete closure (atresia) of one of the four valves, which impedes or totally obstructs blood flow.
- Leakage (insufficiency or regurgitation) of one of the four valves, which allows blood to leak back into the chamber from which it came.
- Abnormal connections among the veins, heart and great arteries (aorta and pulmonary). These abnormal connections can allow oxygen–poor blood to flow to the body instead of the lungs, or to allow oxygen–rich blood to flow to the lungs instead of the body.
- Narrowing (stenosis) of either the veins leading into the heart, or the great arteries leaving the heart. The narrowing decreases blood flow.
In addition, heart muscle abnormalities may be congenital and lead to progressive muscle weakness cardiomyopathy and heart failure.
Signs and symptoms of heart defects
The signs of congenital heart disease (CHD) vary according to the defect(s) that may be present. A number of defects lead to a bluish tint to the skin, fingernails and lips called cyanosis (or blue baby in infants). Also, there are a number of different types of congenital heart disease that can lead to heart failure.
Defects that cause either decreased blood flow to the lungs, or a mixing of oxygen–rich and oxygen–poor blood flowing to the body, can result in cyanosis. This condition results when the body is not getting its full supply of oxygen. The classic signs of cyanosis are a bluish tinge to the skin, most often around the lips, fingernail beds and tongue. Infants may have fast breathing and poor feeding. Older patients may have a low tolerance for exercise. Defects that can cause cyanosis include:
Low blood flow to the lungs
- Critical pulmonary stenosis. A narrowing of the pulmonic valve (between the right ventricle and the pulmonary artery to the lungs), which reduces blood flow to the lungs.
- Pulmonary atresia. Complete closure of the pulmonic valve, which prevents blood flow from the right ventricle to the lungs.
- Tetralogy of Fallot. A condition that involves the “tetralogy” of the following four elements: ventricular septal defect, enlargement of the right ventricle, narrowing of the pulmonic valve and a displaced/deviated aorta.
- Tricuspid atresia. Complete closure of the tricuspid valve, which prevents blood flow from the right atrium to the right ventricle.
- Ebstein’s anomaly. The tricuspid valve is both displaced and malformed. The leaky valve allows oxygen–poor blood to flow back into the right atrium instead of out to the lungs for fresh oxygen.
Mixing of oxygen–rich and oxygen–poor blood
- Transposition of the great arteries. A congenital heart defect in which oxygen–rich blood from the left side of the heart is mixed with oxygen–poor blood from the right side of the heart because of the reversed locations of the two major arteries, the pulmonary artery and the aorta.
- Hypoplastic left heart syndrome (HLHS). A heart defect that can be fatal unless repaired early in life. The chambers, valves and related vessels on the left side of the heart are so underdeveloped that they cannot efficiently pump blood to the rest of the body.
- Total anomalous pulmonary venous return (TAPVR). A condition in which the four pulmonary veins that bring oxygen–rich blood from the lungs back to the heart are not connected to the left atrium.
Some types of congenital heart defects can also lead to heart failure. Some of these defects allow the blood to flow from the left side of the heart to the right side (a left–to–right shunt), progressively overloading the heart until heart failure results. Other defects may involve leakage of the valves resulting in enlargement and decreased efficiency of one or more of the heart's chambers.
Signs of heart failure include:
- Rapid breathing
- Difficulty eating and sucking
- Poor weight gain
- Recurrent respiratory infections
- Low tolerance for exercise
Defects that can result in heart failure include:
- Ventricular septal defect (VSD). A heart defect characterized by a hole in the wall septum that divides the two lower chambers of the heart (ventricles). This is the most common congenital heart defect requiring intervention. Also, many babies born with a small VSD will spontaneously heal without the need for medical intervention.
- Patent ductus arteriosus (PDA). A condition in which the prenatal channel between the aorta and the pulmonary artery (ductus arteriosus) remains open (patent) at birth. Normally, the ductus arteriosus should close as the baby starts breathing.
- Hypoplastic left heart syndrome (HLHS). A heart defect that can be fatal unless repaired early in life. The chambers, valves and related vessels on the left side of the heart are so underdeveloped that they cannot efficiently pump blood to the rest of the body.
- AV septal defect (also called atrioventricular canal defect or endocardial cushion defect). A condition in which the center portion of the heart fails to develop, creating a hole between the atria and ventricles, and abnormal mitral and tricuspid valves.
- Truncus arteriosus. A rare birth defect of the heart in which the major heart arteries fail to separate and the baby is born with one single arterial trunk that supplies blood to both the lungs and the body. This defect may also cause cyanosis.
- Interrupted aortic arch. A heart defect in which there is literally an interruption along the aorta. A ventricular septal defect (a hole in the wall between the left and right ventricles) may also be present.
Still other defects are characterized by the abnormal narrowing of a structure within the heart. These are known as stenotic defects and, depending on their severity, may cause either the right or left ventricle to fail. Stenotic defects include:
- Aortic stenosis. A narrowing of the aortic valve, restricting the amount of blood that can be pumped from the left ventricle out the aorta.
- Pulmonary stenosis. A narrowing of the pulmonic valve, restricting the amount of blood that can be pumped from the right ventricle out the pulmonary artery.
- Coarctation of the aorta. A condition in which the aorta (the main artery carrying oxygen–rich blood from the heart to the rest of the body), is pinched, constricted or narrowed at some point along its length.
- Peripheral pulmonary artery stenosis. A narrowing of part of the pulmonary artery, restricting the amount of blood that can travel through the pulmonary artery and to the lungs.
Fetal heart development
The fetal heart begins to form shortly after conception. By the end of the second month, the fetal heart is fully formed. Research has shown that congenital heart defects tend to form in this very early stage in pregnancy. Using advanced diagnostic tools, physicians are now able to detect some congenital heart defects before the baby is born.
During pregnancy, the fetal heart differs from the adult heart in some very important ways. Because the fetus does not use its lungs, the right side of the heart, which is responsible for pumping oxygen–poor blood to the lungs in an adult, is bypassed in a fetal heart. Before birth, there are two connections between the right and left sides of the heart. They are:
The ductus arteriosus
An open channel in every fetus that connects the two great arteries (the pulmonary artery and the aorta), allowing blood to bypass the lungs, which are not used by the fetus until it takes its first breath after birth. The ductus arteriosus should permanently close within a few hours to a few days after birth. If the ductus arteriosus remains open after birth (patent ductus arteriosus [PDA]), the heart may be overworked to the point of heart failure. If the baby is very premature this extra blood flow may increase the work of breathing. The neonatologist (newborn specialist) may give a medicine to stimulate the PDA to close. However, in some cases, the physician may need to keep the PDA open and may administer medications to accomplish this. This is often done when other congenital heart defects are preventing the normal flow of blood through the heart.
The foramen ovale
This is an opening between the right and left atria that allows the oxygen–rich blood from the placenta to bypass the right side of the heart and flow directly to the left ventricle (because the blood does not need to go to the lungs to get oxygen). After birth, these channels normally close as the baby breathes and blood flows to the lungs. If the foramen ovale fails to close, the child has a patent foramen ovale (PFO). A very small PFO may persist in about 10 to 15 percent of the general population. Usually this is of no significance, although some medical conditions, such as stroke, may be traced back to the presence of a PFO.
Diagnosis methods for congenital heart disease
A physician may become suspicious about the presence of congenital heart disease if the child has one or more symptoms, is not growing normally, or has a heart murmur. Physicians will order tests in order to determine the nature of the problem. The most common tests include:
Electrocardiogram (EKG)
An electrocardiogram (EKG) is a recording of the heart’s electrical activity as a graph on a moving strip of paper or video monitor. The highly sensitive electrocardiograph machine helps detect heart irregularities, disease and damage by measuring the heart's rhythms and electrical impulses.
Echocardiogram
This test uses sound waves to visualize the structures and functions of the heart, including the septum (the wall between the left and right sides of the heart). A moving image of the patient’s beating heart is played on a video screen, where a physician can study the heart’s thickness, size and function. The image also shows the motion and structure of the four heart valves, revealing any potential leakage (regurgitation) or narrowing (stenosis). During this test, a Doppler ultrasound may be done to evaluate blood flow. This is usually considered to be the best diagnostic test for congential heart disease. No sedation is necessary and there is no risk or side effect from this test.
Chest x-ray
This test evaluates the size of the heart and the blood flow to the lungs. It also helps in evaluating whether there are any secondary problems within the lungs because of the heart problem.
Pulse oximeter
A sensor placed on the tip of the finger or earlobe that reads the amount of oxygen in the blood.
XMR
XMR is a new diagnostic technique that combines magnetic resonance imaging (MRI) and conventional x–rays to create a three–dimensional image of the heart, greatly improving a physician’s ability to measure blood flow and tell how the heart is beating. Imaging tests such as an MRI usually require significant sedation in the case of infants and young child since the patient must stay perfectly still during the imaging.
The physician may also need to do a more invasive test that uses cardiac catheterization. This is a procedure that requires thin tubes (catheters) to be fed from blood vessels in the arm or leg, up into the heart. The catheters measure the pressures in the different heart chambers and can detect mixing of blood between the two sides of the heart. Pictures of the heart (angiograms) can also be taken by injecting a special dye contrast medium through the catheters and into the heart and great arteries. Certain congenital heart lesions can be treated using special catheters (interventional catheterization).
In some cases, CHD can be diagnosed while the infant in still in the mother's womb. Studies have found that early detection of CHD in the womb improves the newborn’s chances during surgery to correct the defects. Prenatal detection of hypoplastic left heart syndrome (HLHS) and other severe forms of CHD can allow parents to receive counseling, have more time to consider their options, and plan to give birth in a facility best equipped to treat their infants.
Treatment options for congenital heart disease
Treatment for a congenital heart defect depends on a number of factors, including the type and severity of the defect, age of the patient and other related elements.
Prescription medications may be the first line of treatment and can include:
- Digoxin. Improves the function of the heart muscle.
- Diuretics. Allow the body to remove excess fluid that builds up in heart failure.
- Prostaglandin E1. Allows the ductus arteriosus to remain open. Injected intravenously, prostaglandin is used in babies who need more blood flow to the lungs, or in babies who have difficulty getting blood to their lower body. This is usually used to temporarily increase blood flow in the heart until an underlying congenital defect can be fixed surgically.
- ACE inhibitors. Decrease the constriction of the arteries and allows the blood to flow more easily to the body.
- Beta blockers. Slow the heart rate and lower blood pressure, which reduces the workload on the heart.
- Inotropes. Often given through an intravenous (I.V.) line, these medications strengthen the heart’s contractions so that it can circulate more blood with each beat.
- Indomethicin. Given to neonates who have a large PDA that is overworking the lungs and resulting in respiratory distress, especially in premature infants.
If medications are not effective, then a more invasive treatment may be necessary.
Catheter-based procedures may be used in the following situations:
- Aortic stenosis or pulmonary stenosis may be treated by inflating a balloon–tipped catheter inside the narrowed valve to create a larger opening.
- Patent ductus arteriosus can be closed by placing a stainless steel coil or other device inside the vessel and allowing it to close.
- Certain types of atrial septal defects can be closed by inserting a device or patch through a catheter and using it to cover the hole.
- A balloon–tipped catheter that expands, opening the narrowed pulmonary artery, can treat narrowing stenosis of the pulmonary artery. If balloon dilation is not effective, then a wire mesh metal tube stent can be placed inside the narrow part and expanded to hold the vessel open.
- Coarctation of the aorta can be treated through either balloon dilation or stenting.
- Arterial-venous fistulas are abnormal blood vessels that can be closed with stainless steel coils.
If none of the catheter–based procedures were, or would be, effective, then surgery may be necessary. Surgery may either be palliative, which relieves symptoms but does not cause blood to flow normally, or reparative, which fixes the underlying problem.
Examples of reparative surgery include:
- Closing ventricular septal defects (VSDs) and atrial septal defects (ASDs) with sutures or a patch made from either artificial material or the patient’s own tissue.
- Repairing the atrioventricular valves and closing the VSDs and/or ASDs associated with AV septal defect.
- Widening the pulmonic valve and closing the VSD associated with Tetralogy of Fallot.
- Switching the great arteries back to their normal position and repositioning the coronary arteries in children who have transposition of the great arteries.
- Widening the narrowed aorta in children with coarctation of the aorta.
Examples of palliative surgery that is used to improve the patient’s condition, but does not completely repair the heart include:
- Modified Blalock-Taussig procedure. A tube is inserted to connect the aorta to the pulmonary artery to increase blood flow to the lungs.
- Pulmonary artery band. A band is placed around the pulmonary artery to decrease blood flow to the lungs.
- Fontan procedure. A surgery that is performed when only one ventricle exists (single ventricle). The Fontan procedure allows deoxygenated blood to drain into the lungs by bypassing the heart. The single ventricle then pumps oxygenated blood to the body.
Medications
Diuretics
Diuretics often are given to treat symptoms of heart failure. Diuretics allow the heart to function more efficiently, which helps improve breathing difficulty and swelling.
Vasodilators
Vasodilator medicines decrease blood pressure by relaxing blood vessels, allowing more blood to flow through the vessels.
Prospects for recovery with heart defects
The prospects for recovery depend upon the following:
- The nature and severity of the abnormality and the function of the heart muscle
- The condition of the patient before surgery
- The availability of medical resources and appropriate treatment
Recent studies note that while CHD children tend to have lower IQ scores than their peers, the CHD children are in age–appropriate grade levels and engaged in normal youth activities. There is still evidence that children with CHD are more likely to struggle with learning disabilities or neurological problems, but researchers say that the gap in these areas between CHD and healthy children is narrowing. Some of the newer techniques in treating CHD, such as interventional catheterization, may improve the long-term neurological outlook since correction is possible without using a heart-lung machine in the process of correcting the defect.
Pediatric heart transplants
In patients with some forms of CHD, such as hypoplastic left heart syndrome (HLHS), heart transplant surgery may be necessary. A heart transplant involves replacing the baby’s defective heart with a donated healthy heart (a relatively new procedure in newborns). The baby’s eligibility for a transplant is determined by the results of blood tests and other specific factors relating to the baby’s health and potential for survival. Once that determination is made, he or she is entered into a computerized national waiting list.
There is a shortage of heart donors, especially within the newborn population. Therefore, transplantation usually involves a long waiting period with no guarantees in which the infant is on “standby” for a suitable heart. Some patients’ hearts give out before a suitable donor heart can be found.
Even if a donor heart match is made, transplantation carries a risk of rejection and the early development of conditions such as coronary artery disease or lymphoma – cancer of the lymph nodes. Lifelong use of medication to prevent rejection and infection must be taken, and these drugs tend to weaken the immune system. Lifelong medical management will be necessary, and the long–term results for newborn transplantations are not yet known.
Questions for your doctor
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to congenital heart disease (CHD):
- How do I know if I (or my child) have congenital heart disease?
- Am I at greater risk for having a child with CHD?
- What tests can best evaluate my child's condition?
- What type of congenital heart defect does my child have?
- What types of treatment options are available to my child?
- What are the benefits and risks of these treatments?
- Are there any medications my child can take to improve the defect?
- How quickly does my child need to be treated for CHD?
- How will the defect affect my child's development?
- What signs or symptoms indicate a medical emergency?
- If I have one child with CHD, what are the chances my other children will be born with one?
- How soon in my pregnancy can a heart defect be detected in my child?