Congenital Heart Disease
Congenital heart disease
Definition
Congenital heart disease, or congenital heart defect, includes a variety of structural problems of the heart or its major blood vessels, which are present at birth.
Description
The heart, which is completely developed about eight weeks after conception, is one of the earliest organs to completely develop. Congenital heart defects occur when the heart or blood vessels near the heart do not develop properly before birth. Some infants are born with mild types of congenital heart defects, but most need surgery in order to survive. In some cases, the defect may be mild and unnoticed at birth, then diagnosed later in life.
Research is ongoing, and at least 35 congenital heart or cardiovascular defects have been identified. Each defect is defined by its location and severity. Most congenital cardiovascular defects obstruct the flow of blood in the heart or nearby blood vessels, or cause an abnormal flow of blood through the heart. Rarer congenital cardiovascular defects occur when the newborn has only one ventricle (lower chamber), when the pulmonary artery (leading to the lungs) and the aorta (the largest artery that brings blood to the body) come out of the same ventricle, or when one side of the heart is not completely formed.
Patent ductus arteriosus
Ductus arteriosus refers to an open passageway—or temporary blood vessel (ductus)—that carries blood from the heart via the pulmonary artery to the aorta before birth. This passageway allows blood to bypass the lungs, which are not yet functional in the fetus. The ductus should close spontaneously in the first few hours after birth. When it does not close in the newborn, some of the blood that should flow through the aorta returns to the lungs. Patent ductus arteriosus is common in premature babies, but rare in full-term babies. It has been associated with mothers who had German measles (rubella ) while pregnant. Patent ductus arteriosus accounts for 6–11 percent of all cases of congenital cardiovascular defects in the United States.
Hypoplastic left heart syndrome
Although rare, hypoplastic left heart syndrome, a condition in which the left side of the heart is underdeveloped, is the most serious congenital cardiovascular defect. With this syndrome, blood returning from the lungs must flow through an opening or hole in the wall between the atria, called an atrial septal defect . The right ventricle pumps blood into the pulmonary artery and blood reaches the aorta through a patent ductus arteriosus (see description in the previous section). In hypoplastic left heart syndrome, the baby seems normal at birth, but as the ductus closes, blood cannot reach the aorta and circulation fails. If left untreated, hypoplastic left heart syndrome is always fatal.
Heart rhythm problems
An arrhythmia is an abnormal heart beat. Normally, the heart beats at 50–150 beats per minute, depending on the child's age. Bradycardia is an irregularly slow heart rhythm, and tachycardia is an irregularly fast heart rhythm. Both conditions reduce the heart's pumping ability.
Obstruction defects
When heart valves, arteries, or veins are narrowed, they partially or completely block the flow of blood. The most common obstruction defects are pulmonary valve stenosis, aortic valve stenosis, and coarctation of the aorta . Coarctation of the aorta accounts for 8–11 percent of all cases of congenital cardiovascular defects in the United States.
Stenosis is a narrowing of the valves or arteries. In pulmonary stenosis, the pulmonary valve does not open properly, forcing the right ventricle to work harder. In aortic stenosis, the improperly formed aortic valve is narrowed. As the left ventricle works harder to pump blood through the body, it becomes enlarged. In coarctation of the aorta, the aorta is constricted, reducing the flow of blood to the lower part of the body and increasing blood pressure in the upper body.
Bicuspid aortic valve and subaortic stenosis are less common obstruction defects. A bicuspid aortic valve has only two flaps instead of three, which can lead to stenosis in adulthood. Subaortic stenosis is a narrowing of the left ventricle below the aortic valve that limits the flow of blood from the left ventricle.
Septal defects
When a baby is born with a hole in the septum (the wall separating the right and left sides of the heart), blood leaks from the left side of the heart to the right. A major leakage can lead to enlargement of the heart and failing circulation. The most common types of septal defects are atrial septal defect, an opening between the two upper heart chambers (atria), and ventricular septal defect, an opening between the two lower heart chambers (ventricles). Atrial septal defects account for 4–10 percent of all cases of congenital cardiovascular defects in the United States; ventricular septal defects account for about 14–16 percent.
Two variations of septal defects include atrioventricular canal defect and Eisenmenger's complex. Atrioventricular canal defect (also called endocardial cushion defect or atrioventricular septal defect) is a large hole in the septum, accompanied by abnormal tricuspid and mitral valves that are not formed as individual valves. Instead, a single large valve crosses the defect. The defect allows oxygen-rich blood from the lungs to flow from the left side of the heart to the right side of the heart and back again to the lungs. The heart must work harder to accommodate this extra blood and may become enlarged. Eisenmenger's complex is a ventricular septal defect coupled with pulmonary high blood pressure, an enlarged right ventricle, and sometimes an aorta that is not positioned correctly. With this syndrome, blood flows abnormally from the right side of the heart to the left.
Cyanotic defects
Heart disorders that cause a decreased, inadequate amount of oxygen in blood pumped to the body are called cyanotic defects. Cyanotic defects result in a blue discoloration of the skin due to low oxygen levels. Cyanotic defects include truncus arteriosus, total anomalous pulmonary venous return, tetralogy of Fallot, transposition of the great arteries , tricuspid atresia, and pulmonary atresia.
Truncus arteriosus is a complex malformation in which only one artery comes from the heart and forms the aorta and pulmonary artery. Total anomalous pulmonary venous return is a condition in which the pulmonary veins that bring oxygen-rich blood from the lungs back to the heart are not connected to the left atrium. Instead, the pulmonary veins drain through abnormal connections to the right atrium.
Nine to fourteen percent of cases of congenital cardiovascular defects in the United States are tetralogy of Fallot, which includes four defects. The major defects are a large hole (ventricular septal defect) between the ventricles, which allows oxygen-poor blood to mix with oxygen-rich blood, and narrowing at or beneath the pulmonary valve. The other defects are an overly muscular right ventricle and an aorta that lies over the ventricular septal defect.
In transposition (reversal of position) of the great arteries, the positions of the pulmonary artery and the aorta are reversed, causing oxygen-rich blood to re-circulate to the lungs while oxygen-poor blood goes to the rest of the body. Transposition of the great arteries comprises 10–14 percent of congenital cardiovascular defect cases in the United States.
In tricuspid atresia, the baby lacks a triscupid valve and blood cannot flow properly from the right atrium to the right ventricle. In pulmonary atresia, the baby lacks a pulmonary valve and blood cannot flow properly from the right ventricle into the pulmonary artery and on to the lungs.
Other defects
Ebstein's anomaly is a rare congenital syndrome that causes malformed tricuspid valve leaflets, which allow blood to leak between the right ventricle and the right atrium. This condition may cause a hole in the wall between the left and right atrium, called an atrial septal defect. Treatment often involves repairing the tricuspid valve. Ebstein's anomaly may be associated with maternal use of the psychiatric drug lithium during pregnancy.
Brugada syndrome is another rare congenital cardiovascular defect that appears in adulthood and may cause sudden death if untreated. Symptoms, which include rapid, uneven heart beat, often appear at night. Scientists believe that Brugada syndrome is caused by mutations in the gene SCN5A, which involves cardiac sodium channels.
Infants born with DiGeorge sequence can have heart defects such as a malformed aortic arch and tetralogy of Fallot. Researchers believe DiGeorge sequence most often is caused by mutations in genes in the region 22q11.
Marfan syndrome is a connective tissue disorder that causes tears in the aorta. Since the disease also causes excessive bone growth, most Marfan syndrome patients are over 6 ft (1.8 m) tall. In athletes and others, it can lead to sudden death. Researchers believe the defect responsible for Marfan's syndrome is found in gene FBN1 on chromosome 15.
Heart muscle abnormalities may lead to congestive heart failure. In heart failure, the heart does not pump blood well enough for the body to get the nourishment it needs for normal function and activity. When the heart does not function properly, fluid can build up in the lungs, causing difficult breathing. Fluid can also build up in the rest of the body, causing swelling.
Demographics
About 44,000 infants (about eight of every 1,000 infants or 1 percent of live births) are born every year with congenital cardiovascular defects, the most common birth defect. It is the number one cause of death from birth defects during the first year of life. Nearly twice as many children die from congenital cardiovascular defects in the United States than from all forms of childhood cancers combined. Most of these children can benefit from surgical treatment, even if the defect is severe. Overall, the mortality rate from congenital cardiovascular defects has significantly declined in the past few decades. About one million adults (over age 20) with cardiovascular defects are currently living in the United States.
Causes and symptoms
Causes
In most cases, the causes of congenital cardiovascular defects are unknown. Genetic and environmental factors, and lifestyle habits can all be involved. However, only a few genes have been discovered that have been linked to the presence of heart defects. The likelihood of having a child with a congenital cardiovascular defect increases if the mother or father, another child, or another relative had congenital cardiovascular defects, or there is a family history of sudden death.
Women with diabetes and phenylketonuria (an inherited liver condition also called PKU) are at higher risk of having children with congenital heart defects. Many cases of congenital cardiovascular defects result from the mother's excessive use of alcohol or history of taking illegal drugs, such as cocaine, while pregnant. The mother's exposure to certain prescription drugs such as anticonvulsant and dermatologic medications during pregnancy also can cause congenital cardiovascular defects. Her exposure to industrial chemicals, solvents, and ionizing radiation (x ray) also increases the risk of having children with congenital heart defects.
The occurrence of some infections during pregnancy, including viral infections such as rubella (German measles), can cause congenital cardiovascular defects. In addition, there are many genetic conditions, such as Down syndrome or Turner's syndrome, which affect multiple organs and can cause congenital cardiovascular defects. Children with oral clefts are 16 times more likely to have a congenital cardiovascular defect than the normal population, although the reason for this association is unknown.
Symptoms
General symptoms of congenital cardiovascular defects include:
- shortness of breath or rapid breathing
- difficulty feeding in infancy
- sweating
- cyanosis (bluish discoloration of the skin, lips, and fingernails)
- heart murmur
- respiratory infections that recur excessively
- poor weight gain in infants
- stunted growth
- underdeveloped limbs and muscles
Some infants and children have no signs or symptoms of congenital cardiovascular defects.
Symptoms of specific types of congenital cardiovascular defects are as follows:
- Patent ductus arteriosus—quick tiring, slow growth, susceptibility to pneumonia , and rapid breathing. If the ductus is small, there are no symptoms.
- Hypoplastic left heart syndrome—ashen color, rapid and difficult breathing, and inability to eat.
- Abnormal heart rhythm—feeling of skipped heart beats, dizziness , lightheadedness, fainting, shortness of breath, and fatigue.
- Obstruction defects: cyanosis (skin that is discolored blue)—chest pain , unusual fatigue or quick tiring, dizziness or fainting, and high blood pressure.
- Septal defects—difficulty breathing, stunted growth, and high blood pressure. Sometimes there are no symptoms.
- Cyanotic defects: cyanosis—sudden rapid breathing or unconsciousness, and shortness of breath and fainting during exercise .
- Congestive heart failure—difficulty breathing, swelling, quick tiring, and feeding problems in infants.
When to call the doctor
The parent or caregiver should call the child's pediatrician or cardiologist when the child has these symptoms or conditions:
- infant who has feeding problems, difficulty sucking, or vomiting more than two or three feedings per day
- poor weight gain in young children
- swelling in the ankles or feet
- swollen abdomen
- poor exercise tolerance
- recurrent chest colds and respiratory infections
- abnormal blood pressure
- signs of infection including sore throat , general body aches or fever
The parent or caregiver should seek emergency treatment by calling 911 in most areas when the child has these symptoms or conditions:
- bluish skin tone
- bluish coloration around the lips, fingernail beds, and tongue
- breathing difficulties or rapid breathing
- dizziness or fainting
- uncontrolled coughing or coughing with blood
- irregular heart beats or palpitations (abnormal heart beats that feel like fluttering in the chest)
- chest pain (rare in children)
Diagnosis
Severe congenital cardiovascular defect is diagnosed in infancy and usually becomes evident shortly after birth. However, significant cardiovascular defects may be found anytime during childhood. In a few cases, a cardiovascular defect is not detected until the child is a teenager or adult.
The medical and family history help the physician determine if the child has any conditions or disorders that might contribute to or cause the cardiovascular defect. A family history of cardiovascular defects might suggest a genetic predisposition to the disease.
During the physical exam, the child's blood pressure is measured, and a stethoscope is used to listen to sounds made by the heart and blood flowing through the arteries. Some heart murmurs (abnormal heart sounds) can indicate a congenital heart defect. The child's pulse, reflexes, and height and weight are checked and recorded. The child's blood oxygen level can be measured using a pulse oximeter, a sensor placed on the fingertip or earlobe. Internal organs are palpated, or felt, to determine if they are enlarged.
Blood and urine tests are performed to detect the presence of any abnormal substances that may indicate congenital cardiovascular defects.
Echocardiography and cardiac magnetic resonance imaging (MRI) may be used to confirm congenital cardiovascular defects when suggested by the child's symptoms and physical exam results.
An echocardiogram (echo) uses ultrasound, or high-frequency sound waves, to display an image of the heart's internal structures. It can be used to detect valve and other heart problems. A Doppler echo uses sound waves to measure blood flow. Fetal echocardiography is used to diagnose congenital cardiovascular defects in utero, usually after 20 weeks of pregnancy. Between 10 and 14 weeks of pregnancy, physicians may use an ultrasound to look for a thickness at the nuchal translucency, a pocket of fluid in back of the embryo's neck, which may indicate a cardiac defect in 55 percent of cases.
Cardiac MRI, a scanning method that uses magnetic fields and radio waves to create three-dimensional images of the heart, can help physicians evaluate congenital cardiovascular defects, but is not always necessary. MRI reveals how blood flows through the heart and how the heart is working. Physicians also may use a chest x ray to look at the size, shape, and location of the heart and lungs.
An electrocardiogram (ECG, EKG) helps the physician evaluate the electrical activity of the heart. During an EKG, small electrode patches are attached to the skin on the chest and connected to a computer that measures the heart's electrical impulses and records them in a zigzag patter on a moving strip of paper.
Stress tests may be performed to provide information about how the heart responds to stress. The test may involve actual exercise or a medication that simulates exercise. Increasing levels of exercise difficulty are monitored while the electrocardiogram, heart rate, and blood pressure are recorded.
Special monitors may be used to evaluate an abnormal heart rhythm. Ambulatory monitors are small portable electrocardiograph machines that record the heart's rhythm. Each type of monitor has unique features related to length of recording time and ability to send the recordings over the phone.
In some cases, these tests are not conclusive enough to confirm the diagnosis of congenital cardiovascular defects. More invasive diagnostic procedures, such as angiography and cardiac catheterization, may be performed to show the type and severity of heart disease. These procedures should be performed by a specially trained physician and diagnostic team in a well-equipped heart center.
During catheterization, a long, slender tube, called a catheter, is inserted into a vein or artery and slowly directed to the heart using x-ray guidance. To better view the heart and blood vessels, contrast material (dye) is injected through the catheter and viewed and recorded on an x-ray video as it moves through the heart. This imaging technique is called angiography. In some cases, blood vessel blockages or narrowed areas may be treated during the catheterization procedure using a specialized balloon tip or other device at the end of the catheter. When treatment is performed as part of a catheterization procedure, it is referred to as an interventional procedure.
Treatment
Treatment should be provided by a pediatric cardiologist, a specialist trained to diagnose and treat congenital cardiovascular defects.
Medications
Medications used to treat congenital cardiovascular defects include diuretics, which aid the child in excreting water and salts, and Digoxin, which strengthens the contraction of the heart, slows the heartbeat, and removes fluid from tissues. A potassium supplement may be prescribed along with diuretics, which remove potassium from the body along with excess fluid. Heart rate control drugs and antiarrhythmic drugs may be prescribed to treat irregular heart rhythms. Other medications may include anticoagulants (blood thinners) to reduce the risk of blood clots and stroke , ACE inhibitors to decrease artery constriction and improve blood flow, and inotropes to strengthen the heart's contractions.
Electrical therapy and implantable devices
If medications are not effective in controlling a child's heart rate, cardioversion may be required. In this procedure, an electrical shock is delivered to the chest wall to synchronize the heart and allow the normal rhythm to restart. A permanent pacemaker or implantable cardioverter defibrillator (ICD) is sometimes needed to regulate the child's heart rhythm. A pacemaker is a device that sends small electrical impulses to the heart muscle to maintain a suitable heart rate. An ICD is a device used primarily to treat ventricular tachycardia and ventricular fibrillation, two life-threatening heart rhythms. The ICD constantly monitors the heart rhythm. When a very rapid, abnormal heart rhythm is detected, the ICD delivers energy to the heart muscle to cause it to regain a normal rhythm.
Interventional procedures
Catheter-based procedures may be performed to open stenotic valves or vessels, widen the septal opening between the atria, or close abnormal vessels or certain septal defects. During catheterization, a long, slender tube called a catheter is inserted into a vein or artery and slowly directed to the heart, using x-ray guidance. Blood vessel blockages or stenotic valves may be treated during the catheterization procedure using a specialized balloon tip or other device at the end of the catheter. The balloon is rapidly inflated and deflated to open or widen the area. In older patients, a stent (metal mesh tube) can be positioned to act as a scaffold and hold the area open. Several closure devices such as coils, patches, or umbrella-like devices, have been developed that can be inserted through the catheter and are designed to close the defect.
Surgery
The goal of surgery is to repair the defect as much as possible, restore circulation to as close to normal as possible, reduce symptoms, improve survival, and improve quality of life. Sometimes, multiple surgical procedures are necessary. Surgery for most congenital cardiovascular defects has low risk of death (less than 2 percent), compared to 80–100 percent in the 1940s. Surgical procedures used to treat congenital cardiovascular defects include:
- arterial switch
- balloon atrial septostomy
- balloon valvuloplasty
- Damus-Kaye-Stansel procedure
- Fontan procedure
- pulmonary artery banding
- Ross procedure
- shunt procedure
- venous switch or intra-atrial baffle
Arterial switch, to correct transposition of the great arteries, involves connecting the aorta to the left ventricle and connecting the pulmonary artery to the right ventricle. Balloon atrial septostomy, also done to correct transposition of the great arteries, enlarges the atrial opening during heart catheterization. Balloon valvuloplasty uses a balloon-tipped catheter to open a narrowed heart valve, improving the flow of blood in pulmonary stenosis. It is sometimes used to treat aortic stenosis. Transposition of the great arteries also can be corrected by the Damus-Kaye-Stansel procedure, in which the pulmonary artery is cut in two and connected to the ascending aorta and the farthest section of the right ventricle.
For tricuspid atresia and pulmonary atresia, the Fontan procedure connects the right atrium to the pulmonary artery directly or with a conduit, and the atrial defect is closed. Pulmonary artery banding, narrowing the pulmonary artery with a band to reduce blood flow and pressure in the lungs, is used for ventricular septal defect, atrioventricular canal defect, and tricuspid atresia. The band can be removed at a later time, and the defect corrected with open-heart surgery.
To correct aortic stenosis, the Ross procedure grafts the pulmonary artery to the aorta. For tetralogy of Fallot, tricuspid atresia, or pulmonary atresia, the shunt procedure creates a passage between blood vessels, sending blood into parts of the body that need it. For transposition of the great arteries, venous switch creates a tunnel inside the atria to re-direct oxygen-rich blood to the right ventricle and aorta, and venous blood to the left ventricle and pulmonary artery.
When all other options fail, some patients may need a heart transplant. A heart transplant involves replacing the child's heart with a healthy heart from a donor who has died or been declared brain dead. The child's eligibility for a transplant depends on the results of blood tests and other factors related to his or her health and potential for survival.
Nutritional concerns
Infants and children with congenital cardiovascular defects tend to gain weight more slowly. An 8-oz to 1 lb (225–450 g) weight gain in a month may be acceptable. The physician will monitor the child's weight gain and advise the parents of the goal weight gain and any necessary dietary changes. The most common reason for poor growth among children with congenital cardiovascular defects is that they do not consume enough calories or nutrients. Some other factors that may interfere with growth include:
- rapid heart beat and increased breathing rate
- poor appetite
- decreased food intake due to rapid breathing and fatigue
- frequent respiratory infections
- poor absorption of nutrients from the digestive tract
- decreased oxygen in the blood
For infants with congenital cardiovascular defects, nutrition supplements may need to be added to regular formula or breast milk. Sometimes additional feedings are required with the aid of a nasogastric tube to provide enough calories and promote weight gain. The nasogastric tube is placed in the baby's nose and passes to the stomach. Formula or breast milk is delivered through the tube. Breastfeeding may not be possible right after birth, depending on the child's condition. A breast pump may be used to maintain the mother's milk supply during times when the baby cannot nurse.
Babies with congenital cardiovascular defects tire quickly during feedings, making frequent feedings necessary. Feedings should be on-demand and may need to be as often as every two hours in the first few months. Some babies have difficulty feeding from a regular bottle nipple; parents may need to try different brands. If medications are prescribed, they should be given before a feeding. Medications should not be mixed in the formula or breast milk unless the doctor advises otherwise.
The pediatrician will advise when solid foods can be started, usually around six months of age. Fat should not be restricted in the diet, especially in the first two years. High-calorie foods and snacks can play an important role in providing good nutrition and helping the child grow at a healthy rate.
Follow-up care
Children with congenital cardiovascular defects require lifelong monitoring, even after successful surgery. Along with routine medical care and standard immunizations, periodic heart check-ups are necessary. Usually, heart check-up appointments are scheduled more frequently just after the diagnosis or after surgery. Additional immunizations, such as the influenza vaccine, may be recommended.
Medical identification
A medical identification bracelet or necklace should be worn to alert all health care providers of the child's heart condition in cases of emergency.
Prognosis
The outlook for children with congenital cardiovascular defects has improved markedly since the 1980s. Many types of congenital cardiovascular defects that were once fatal can be treated successfully. Most children with congenital cardiovascular defects grow up to be healthy adults. Children with complex heart disease may continue to need special medical attention throughout adolescence and into adulthood for survival and to maintain a good quality of life.
Research on diagnosing cardiovascular defects when the fetus is in the womb may lead to future treatment to correct these conditions before birth. Promising new prevention methods and treatments include genetic screening and the cultivation of cardiac tissue in the laboratory that could be used to repair congenital cardiovascular defects. As scientists continue to advance the study of genetics, they also will better understand the genetic causes of many congenital cardiovascular defects.
Prevention
Congenital cardiovascular defects cannot be prevented. However, to protect patients with congenital cardiovascular defects from heart infections (endocarditis), the American Heart Association recommends regular dental check-ups to prevent infections of the mouth as well as the preventive use of antibiotics . Preventive antibiotics should be taken before surgery, invasive tests or procedures, and dental work. A 2003 study reported that preventive antibiotics are underused in people with congenital cardiovascular defects, possibly because they do not understand their increased risk of developing bacterial endocarditis.
Parental concerns
If the child needs surgery, it is important for him or her to be as healthy as possible for the operation. If the child has a fever, cough , or cold, the parent should inform the surgical team to determine if the procedure should be delayed. The medical team can help parents prepare the child for surgery, and provide information on how to explain the procedure, based on the child's age, ability to understand, and emotions. The child usually stays in the hospital from five to seven days after surgery and returns to normal activities within four to six weeks.
KEY TERMS
Aneurysm —A weakened area in the wall of a blood vessel which causes an outpouching or bulge. Aneurysms may be fatal if these weak areas burst, resulting in uncontrollable bleeding.
Aorta —The main artery located above the heart that pumps oxygenated blood out into the body. The aorta is the largest artery in the body.
Arteriosclerosis —A chronic condition characterized by thickening, loss of leasticity, and hardening of the arteries and the build-up of plaque on the arterial walls. Arteriosclerosis can slow or impair blood circulation. It includes atherosclerosis, but the two terms are often used synonymously.
Artery —A blood vessel that carries blood away from the heart to the cells, tissues, and organs of the body.
Atrial —Referring to the upper chambers of the heart.
Bacterial endocarditis —An infection caused by bacteria that enter the bloodstream and settle in the heart lining, a heart valve, or a blood vessel. People with congenital cardiovascular defects have an increased risk of developing bacterial endocarditis, so preventive antibiotics are prescribed before surgery, invasive tests or procedures, and dental work to reduce this risk.
Coarctation of the aorta —A congenital defect in which severe narrowing or constriction of the aorta obstructs the flow of blood.
Congenital —Present at birth.
Cyanotic —Marked by a bluish tinge to the skin that occurs when the blood oxygen level drops too low. It is one of the types of congenital heart disease.
Ductus —The blood vessel that joins the pulmonary artery and the aorta. When the ductus does not close at birth, it causes a type of congenital heart disease called patent ductus arteriosus.
Echocardiogram —A record of the internal structures of the heart obtained from beams of ultrasonic waves directed through the wall of the chest.
Electrocardiagram (ECG, EKG) —A record of the electrical activity of the heart, with each wave being labeled as P, Q, R, S, and T waves. It is often used in the diagnosis of cases of abnormal cardiac rhythm and myocardial damage.
Hypertension —Abnormally high arterial blood pressure, which if left untreated can lead to heart disease and stroke.
Hypoplastic —Refers to incomplete or underdeveloped tissues or organs. Hypoplastic left heart syndrome is the most serious type of congenital heart disease.
Nuchal translucency —A pocket of fluid at the back of an embryo's neck, visible via ultrasound. When this pocket of fluid is thickened, it may indicate that the infant will be born with a congenital cardiovascular defect.
Renal artery stenosis —A disorder in which the arteries that supply blood to the kidneys are narrowed or constricted.
Septal —Relating to the septum, the thin muscle wall dividing the right and left sides of the heart. Holes in the septum are called septal defects.
Stenosis —A condition in which an opening or passageway in the body is narrowed or constricted.
Ventricles —The lower pumping chambers of the heart. The ventricles push blood to the lungs and the rest of the body.
Most children with congenital cardiovascular defects can be fully active and are encouraged to exercise. A scientific statement by the American Heart Association advises children and teens with genetic heart disease to seek advice from their doctors about the types of physical activities that are safe. The statement was intended to help doctors counsel patients who have an increased risk of sudden cardiac death during physical activity. With some congenital cardiovascular defects, certain athletic activities such as competitive sports may be limited, depending on the child's diagnosis and medical condition. Since a child with congenital cardiovascular defects may tire easily, frequent breaks and rest periods should be encouraged, as needed, during activities. Parents should obtain a doctor's note to explain their child's specific exercise limitations. This information should be shared with all teachers and coaches.
Even though most children with congenital cardiovascular defects do not have any mental limitations, some children with congenital cardiovascular defects have developmental delays or other learning difficulties. Therefore, community and school-based resources are important for these children to achieve optimum functioning.
A child with a congenital cardiovascular defect has a greater adulthood risk of having a child with a cardiovascular defect. The frequency of disease increases from less than 1 percent in the general population to 2–20 percent when a parent is affected. Defects such as coarctation of the aorta and aortic valve stenosis have the greatest risk of occurring in the child's offspring. Genetic counseling and further testing, such as chromosome analysis before pregnancy or amniocentesis during pregnancy, may be recommended in adults with congenital cardiovascular defects.
Treatment and care for a child with congenital cardiovascular defects can be costly, and some health insurance plans may not cover all the expenses associated with a child's hospitalization or surgery. Help is available to cover medical expenses. The parents can discuss financial aid with the hospital. Some organizations, including The Heart of a Child Foundation and Little Hearts on the Mend Fund, provide financial assistance to children in need of heart surgery.
Caring for a child with congenital cardiovascular defects is demanding. Support groups are available to help parents and caregivers cope with these challenges. It is important for parents to take care of themselves, too, by eating properly, exercising regularly, taking care of personal hygiene, keeping in contact with friends and family members for support, and managing stress by practicing relaxation techniques.
See also Atrial septal defect.
Resources
BOOKS
Friedman, William F., and John S. Child. "Disorders of the Cardiovascular System." In Harrison's Principles of Internal Medicine. Dennis L. Kasper, et al. New York: McGraw Hill, July, 2004.
"If Your Child Has A Congenital Heart Defect." In Heart Diseases and Disorders Sourcebook., 2nd ed. Karen Bellenir and Peter D. Dresser, eds. Detroit: Omnigraphics, Inc., 2000.
McGoon, Michael D., ed. and Bernard J. Gersh, MD.Mayo Clinic Heart Book: The Ultimate Guide to Heart Health. 2nd ed. New York: William Morrow and Co., Inc., 2000.
Topol, Eric J., MD. "Pediatric and Congenital Heart Diseases." In Cleveland Clinic Heart Book: The Definitive Guide for the Entire Family from the Nation's Leading Heart Center. New York: Hyperion, 2000.
Trout, Darrell, and Ellen Welch.Surviving with Heart: Taking Charge of Your Heart Care. Colorado: Fulcrum Publishing, 2002.
Wild, C. L., and M. J. Neary. Heart Defects in Children: What Every Parent Should Know. Minneapolis, MN: Chronimed Publishing, 2000.
PERIODICALS
"AEP Underused for Congenital Heart Disease Patients." Heart Disease Weekly (Aug. 31, 2003): 23.
"New Insight Offered into the Genetics of Congenital Heart Disease." Heart Disease Weekly (Oct. 12, 2003): 3.
ORGANIZATIONS
Adult Congenital Heart Association (ACHA). 1500 Sunday Dr., Suite 102, Raleigh NC 27607-5151. (919) 861-4547. Web site: <www.achaheart.org>.
American College of Cardiology. Heart House. 9111 Old Georgetown Rd., Bethesda, MD 20814-1699. (800) 253-4636 ext. 694 or (301) 897-5400. Web site: <www.acc.org>.
American Heart Association. 7320 Greenville Ave., Dallas, TX 75231-4596. (214) 373-6300 or (800) 242-8721. Web site: <www.americanheart.org/children>.
Children's Heart Services. P.O. Box 8275, Bartlett, IL 60108-8275. (630) 415-0282. Web site: <www.childrensheartservices.org>.
The Cleveland Clinic Heart Center. The Cleveland Clinic Foundation, 9500 Euclid Ave., F25, Cleveland, Ohio, 44195. (800) 223-2273 ext. 46697 or (216) 444-6697. Web site: <www.clevelandclinic.org/heartcenter>.
Congenital Heart Disease Information and Resources. 1561 Clark Dr., Yardley, PA 19067. Web site: <www.tchin.org>.
The Heart of a Child Foundation and Little Hearts on the Mend Fund. Provides financial assistance to children in need of heart surgery. 26710 Fond Du Lac Rd., Rancho Palos Verdes, CA 90275. (310) 375-6617. Web sites: <www.heartofachild.org>and<www.littleheartsonthemend.org>.
Heart Support of America. 4873 N. Broadway, Knoxville, TN 37918. Web site: <www.heartsupport.com>.
International Children's Heart Foundation. 1750 Madison, Suite 100, Memphis, TN 38104. (877) 869-4243. Web site: <www.babyhearts.com>.
Mended Little Hearts. Support program for parents of children with cardiovascular defects. (888)-HEART99. Web site: <www.mendedhearts.org/MLH/mlh.htm>.
National Heart, Lung and Blood Institute. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. Web site: <www.nhlbi.nih.gov>.
Texas Heart Institute. Heart Information Service. P.O. Box 20345, Houston, TX 77225-0345. Web site: <www.tmc.edu/thi>.
WEB SITES
HeartCenterOnline. Available online at: <www.heartcenteronline.com>.
The Heart: An Online Exploration. Developed by The Franklin Institute Science Museum with support from Unisys Corporation. The Franklin Institute Science Museum. 222 N. 20th St., Philadelphia, PA, 19103. (215) 448-1200. Available online at: <http://sln2.fi.edu/biosci/heart.html>.
Heart Information Network. Available online at: <www.heartinfo.org>.
Melissa Knopper Teresa G. Odle Angela M. Costello
Congenital Heart Disease
Congenital Heart Disease
Definition
Congenital heart disease, also called congenital heart defect, includes a variety of malformations of the heart or its major blood vessels that are present at birth.
Description
Congenital heart disease occurs when the heart or blood vessels near the heart do not develop properly before birth. Some infants are born with mild types of congenital heart disease, but most need surgery in order to survive. Patients who have had surgery are likely to experience other cardiac problems later in life.
Most types of congenital heart disease obstruct the flow of blood in the heart or the nearby vessels, or cause an abnormal flow of blood through the heart. Rarer types of congenital heart disease occur when the newborn has only one ventricle, or when the pulmonary artery and the aorta come out of the same ventricle, or when one side of the heart is not completely formed.
Patent ductus arteriosus
Patent ductus arteriosus refers to the opening of a passageway—or temporary blood vessel (ductus)—to carry the blood from the heart to the aorta before birth, allowing blood to bypass the lungs, which are not yet functional. The ductus should close spontaneously in the first few hours or days after birth. When it does not close in the newborn, some of the blood that should flow through the aorta then returns to the lungs. Patent ductus arteriosus is common in premature babies, but rare in full-term babies. It also has been associated with mothers who had German measles (rubella ) while pregnant.
Hypoplastic left heart syndrome
Hypoplastic left heart syndrome, a condition in which the left side of the heart is underdeveloped, is rare, but it is the most serious type of congenital heart disease. With this syndrome, blood reaches the aorta, which pumps blood to the entire body, only from the ductus, which then normally closes within a few days of birth. In hypoplastic left heart syndrome, the baby seems normal at birth, but as the ductus closes, blood cannot reach the aorta and circulation fails.
Obstruction defects
When heart valves, arteries, or veins are narrowed, they partly or completely block the flow of blood. The most common obstruction defects are pulmonary valve stenosis, aortic valve stenosis, and coarctation of the aorta. Bicuspid aortic valve and subaortic stenosis are less common.
Stenosis is a narrowing of the valves or arteries. In pulmonary stenosis, the pulmonary valve does not open properly, forcing the right ventricle to work harder. In aortic stenosis, the improperly formed aortic valve is narrowed. As the left ventricle works harder to pump blood through the body, it becomes enlarged. In coarctation of the aorta, the aorta is constricted, reducing the flow of blood to the lower part of the body and increasing blood pressure in the upper body.
A bicuspid aortic valve has only two flaps instead of three, which can lead to stenosis in adulthood. Subaortic stenosis is a narrowing of the left ventricle below the aortic valve that limits the flow of blood from the left ventricle.
Septal defects
When a baby is born with a hole in the septum (the wall separating the right and left sides of the heart), blood leaks from the left side of the heart to the right, or from a higher pressure zone to a lower pressure zone. A major leakage can lead to enlargement of the heart and failing circulation. The most common types of septal defects are atrial septal defect, an opening between the two upper heart chambers, and ventricular septal defect, an opening between the two lower heart chambers. Ventricular septal defect accounts for about 15% of all cases of congenital heart disease in the United States.
Cyanotic defects
Heart disorders that cause a decreased, inadequate amount of oxygen in blood pumped to the body are called cyanotic defects. Cyanotic defects, including truncus arteriosus, total anomalous pulmonary venous return, tetralogy of Fallot, transposition of the great arteries, and tricuspid atresia, result in a blue discoloration of the skin due to low oxygen levels. About 10% of cases of congenital heart disease in the United States are tetralogy of Fallot, which includes four defects. The major defects are a large hole between the ventricles, which allows oxygen-poor blood to mix with oxygen-rich blood, and narrowing at or beneath the pulmonary valve. The other defects are an overly muscular right ventricle and an aorta that lies over the ventricular hole.
In transposition (reversal of position) of the great arteries, the pulmonary artery and the aorta are reversed, causing oxygen-rich blood to re-circulate to the lungs while oxygen-poor blood goes to the rest of the body. In tricuspid atresia, the baby lacks a triscupid valve and blood cannot flow properly from the right atrium to the right ventricle.
Other defects
Ebstein's anomaly is a rare congenital syndrome that causes malformed tricuspid valve leaflets, which allow blood to leak between the right ventricle and the right atrium. It also may cause a hole in the wall between the left and right atrium. Treatment often involves repairing the tricuspid valve. Ebstein's anomaly may be associated with maternal use of the psychiatric drug lithium during pregnancy.
Brugada syndrome is another rare congenital heart defect that appears in adulthood and may cause sudden death if untreated. Symptoms, which include rapid, uneven heart beat, often appear at night. Scientists believe that Brugada syndrome is caused by mutations in the gene SCN5A, which involves cardiac sodium channels.
Infants born with DiGeorge sequence can have heart defects such as a malformed aortic arch and tetralogy of Fallot. Researchers believe DiGeorge sequence most often is caused by mutations in genes in the region 22q11.
Marfan syndrome is a connective tissue disorder that causes tears in the aorta. Since the disease also causes excessive bone growth, most Marfan syndrome patients are over six feet tall. In athletes, and others, it can lead to sudden death. Researchers believe the defect responsible for Marfan's syndrome is found in gene FBN1, on chromosome 15.
About 32,000 infants are born every year with congenital heart disease, which is the most common birth defect. About half of these cases require medical treatment. More than one million people with heart defects are currently living in the United States.
Causes and symptoms
In most cases, the causes of congenital heart disease are unknown. Genetic and environmental factors and lifestyle habits can all be involved. The likelihood of having a child with a congenital heart disease increases if the mother or father, another child, or another relative had congenital heart disease or a family history of sudden death. In 2004, researchers identified a chromosome deletion that might explain some of the genetic causes of certain congenital heart diseases.
Viral infections, such as German measles, can produce congenital heart disease. Women with diabetes and phenylketonuria (an inherited liver condition also called PKU) also are at higher risk of having children with congenital heart defects. Many cases of congenital heart disease result from the mother's excessive use of alcohol or taking illegal drugs, such as cocaine, while pregnant. The mother's exposure to certain anticonvulsant and dermatologic drugs during pregnancy also can cause congenital heart disease. There are many genetic conditions, such as Down syndrome, which affect multiple organs and can cause congenital heart disease.
Symptoms of congenital heart disease in general include: shortness of breath, difficulty feeding in infancy, sweating, cyanosis (bluish discoloration of the skin), heart murmur, respiratory infections that recur excessively, stunted growth, and limbs and muscles that are underdeveloped.
Symptoms of specific types of congenital heart disease are as follows:
- Patent ductus arteriosus: quick tiring, slow growth, susceptibility to pneumonia, rapid breathing. If the ductus is small, there are no symptoms.
- Hypoplastic left heart syndrome: ashen color, rapid and difficult breathing, inability to eat.
- Obstruction defects: cyanosis (skin that is discolored blue), chest pain, tiring easily, dizziness or fainting, congestive heart failure, and high blood pressure.
- Septal defects: difficulty breathing, stunted growth. Sometimes there are no symptoms.
- Cyanotic defects: cyanosis, sudden rapid breathing or unconsciousness, and shortness of breath and fainting during exercise.
Diagnosis
Echocardiography and cardiac magnetic resonance imaging (MRI) are used to confirm congenital heart disease when it is suggested by the symptoms and physical examination. An echocardiograph will display an image of the heart that is formed by sound waves. It detects valve and other heart problems. Fetal echocardiography is used to diagnose congenital heart disease in utero, usually after 20 weeks of pregnancy. Between 10 and 14 weeks of pregnancy, physicians also may use an ultrasound to look for a thickness at the nuchal translucency, a pocket of fluid in back of the embryo's neck, which may indicate a cardiac defect in 55% of cases. Cardiac MRI, a scanning method that uses magnetic fields and radio waves, can help physicians evaluate congenital heart disease, but is not always necessary. Physicians also may use a chest x ray to look at the size and location of the heart and lungs, or an electrocardiograph (ECG), which measures electrical impulses to create a graph of the heart beat.
In children and adults, computed tomography (CT) and MRI are the preferred methods to visualize congenital heart disease. Contrast may be added to enhance the image for the radiologist.
Treatment
Congenital heart disease is treated with drugs and/or surgery. Drugs used include diuretics, which aid the baby in excreting water and salts, and digoxin, which strengthens the contraction of the heart, slows the heartbeat, and removes fluid from tissues.
Surgical procedures seek to repair the defect as much as possible and restore circulation to as close to normal as possible. Sometimes, multiple surgical procedures are necessary. Surgical procedures include: arterial switch, balloon atrial septostomy, balloon valvuloplasty, Damus-Kaye-Stansel procedure, Fontan procedure, pulmonary artery banding, Ross procedure, shunt procedure, and venous switch or intra-atrial baffle.
Arterial switch, to correct transposition of the great arteries, involves connecting the aorta to the left ventricle and connecting the pulmonary artery to the right ventricle. Balloon atrial septostomy, also done to correct transposition of the great arteries, enlarges the atrial opening during heart catheterization. Balloon valvuloplasty uses a balloon-tipped catheter to open a narrowed heart valve, improving the flow of blood in pulmonary stenosis. It is sometimes used in aortic stenosis. Transposition of the great arteries also can be corrected by the Damus-Kaye-Stansel procedure, in which the pulmonary artery is cut in two and connected to the ascending aorta and the farthest section of the right ventricle.
For tricuspid atresia and pulmonary atresia, the Fontan procedure connects the right atrium to the pulmonary artery directly or with a conduit, and the atrial defect is closed. Pulmonary artery banding, narrowing the pulmonary artery with a band to reduce blood flow and pressure in the lungs, is used for ventricular septal defect, atrioventricular canal defect, and tricuspid atresia. Later, the band can be removed and the defect corrected with open-heart surgery.
To correct aortic stenosis, the Ross procedure grafts the pulmonary artery to the aorta. For tetralogy of Fallot, tricuspid atresia, or pulmonary atresia, the shunt procedure creates a passage between blood vessels, sending blood into parts of the body that need it. For transposition of the great arteries, venous switch creates a tunnel inside the atria to redirect oxygenrich blood to the right ventricle and aorta and venous blood to the left ventricle and pulmonary artery.
KEY TERMS
Aorta— The main artery located above the heart that pumps oxygenated blood out into the body. Many congenital heart defects affect the aorta.
Congenital— Refers to a disorder that is present at birth.
Cyanotic— Marked by bluish discoloration of the skin due to a lack of oxygen in the blood. It is one of the types of congenital heart disease.
Ductus— The blood vessel that joins the pulmonary artery and the aorta. When the ductus does not close at birth, it causes a type of congenital heart disease called patent ductus arteriosus.
Electrocardiograph (ECG, EKG)— A test used to measure electrical impulses coming from the heart in order to gain information about its structure or function.
Hypoplastic— Incomplete or underdevelopment of a tissue or organ. Hypoplastic left heart syndrome is the most serious type of congenital heart disease.
Neuchal translucency— A pocket of fluid at the back of an embryo's neck visible via ultrasound that, when thickened, may indicate the infant will be born with a congenital heart defect.
Septal— Relating to the septum, the thin muscle wall dividing the right and left sides of the heart. Holes in the septum are called septal defects.
Stenosis— The constricting or narrowing of an opening or passageway.
When all other options fail, some patients may need a heart transplant. Children with congenital heart disease require lifelong monitoring, even after successful surgery. The American Heart Association recommends regular dental check-ups and the preventive use of antibiotics to protect patients from heart infections, or endocarditis. However, a 2003 study reported that preventive antibiotics are underused in people with congenital heart disease. Many patients did not understand the risk of endocarditis. Since children with congenital heart disease have slower growth, nutrition is important. Physicians also may limit their athletic activity.
Prognosis
The outlook for children with congenital heart disease has improved markedly in the past two decades. Many types of congenital heart disease that would have been fatal now can be treated successfully. Because many children with these defects survive into adulthood, physicians and patients are reminded that the patients will require continued medical observation as they mature. Research on diagnosing heart defects when the fetus is in the womb may lead to future treatment to correct defects before birth. Promising new prevention methods and treatments include genetic screening and the cultivation of cardiac tissue in the laboratory that could be used to repair congenital heart defects. As scientists continue to advance the study of genetics, they also will better understand genetic causes of many congenital heart diseases. For example, scientists just discovered a potential cause of atrioventricular canal defects in the fall of 2003.
Resources
BOOKS
Mayo Clinic Heart Book. New York: William Morrow and Company, 2000.
Wild, C. L., and M. J. Neary. Heart Defects in Children: What Every Parent Should Know. Minneapolis: Chronimed Publishing, 2000.
Williams, R. A. The Athlete and Heart Disease. Philadelphia: Lippincott Williams & Wilkins, 1999.
PERIODICALS
"Adults With Congenital Heart Disease Need Continued Medical Observation." Cardiovascular Week August 23, 2004: 23.
"AEP Underused for Congenital Heart Disease Patients." Heart Disease Weekly August 31, 2003: 23.
"Coping with Congenital Heart Disease in Your Baby." American Family Physician 59 (April 1, 1999): 1867.
"Deletions on Chromosome 1q21.1 Are Related to Congenital Heart Disease." Heart Disease Weekly August 22, 2004: 50.
Hyett, Jon, et. al. "Using Fetal Nuchal Translucency to Screen for Major Congenital Cardiac Defects at 10-14 Weeks: Population Based Cohort Study." Lancet 318 (January 1999): 81-85.
"MRI and CT Can Visualize Congenital Heart Disease." Medical Devices & Surgical Technology Week August 22, 2004: 76.
"New Insight Offered into the Genetics of Congenital Heart Disease." Heart Disease Weekly October 12, 2003: 3.
ORGANIZATIONS
American Heart Association. 7320 Greenville Ave., Dallas, TX 75231-4596. (214) 373-6300 or (800) 242-8721. inquire@heart.org. 〈http://www.americanheart.org〉.
Congenital Heart Disease Information and Resources. 1561 Clark Dr., Yardley, PA 19067. 〈http://www.tchin.org〉.
Texas Heart Institute Heart Information Service. PO Box 20345, Houston, TX 77225-0345. (800) 292-2221. 〈http://www.tmc.edu/thi/his.html〉.
Congenital Heart Disease
Congenital heart disease
Definition
Congenital heart disease, also called congenital heart defect, includes a variety of malformations of the heart or its major blood vessels that are present at the birth of a child.
Description
Congenital heart disease occurs when the heart or blood vessels near the heart do not develop properly before birth. Some infants are born with mild types of congenital heart disease, but most need surgery in order to survive. Patients who have had surgery are likely to experience other cardiac problems later in life.
Most types of congenital heart disease obstruct the flow of blood in the heart or the nearby vessels, or cause an abnormal flow of blood through the heart. Rarer types of congenital heart disease occur when the newborn has only one ventricle, when the pulmonary artery and the aorta come out of the same ventricle, or when one side of the heart is not completely formed.
Patent ductus arteriosus
Patent ductus arteriosus refers to the opening of a passageway—or temporary blood vessel (ductus)—to carry the blood from the heart to the aorta before birth, allowing blood to bypass the lungs, which are not yet functional. The ductus should close spontaneously in the first few hours or days after birth. When it does not close in the newborn, some of the blood that should flow through the aorta then returns to the lungs. Patent ductus arteriosus is common in premature babies, but rare in full-term babies. It has also been associated with mothers who had German measles (rubella) while pregnant.
Hypoplastic left heart syndrome
Hypoplastic left heart syndrome, a condition in which the left side of the heart is underdeveloped, is rare, but it is the most serious type of congenital heart disease. With this syndrome, blood reaches the aorta, which pumps blood to the entire body, only from the ductus, which then normally closes within a few days of birth. In hypoplastic left heart syndrome, the baby seems normal at birth, but as the ductus closes, blood cannot reach the aorta and circulation fails.
Obstruction defects
When heart valves, arteries, or veins are narrowed, they partly or completely block the flow of blood. The most common obstruction defects are pulmonary valve stenosis, aortic valve stenosis, and coarctation of the aorta. Bicuspid aortic valve and subaortic stenosis are less common.
Stenosis is a narrowing of the valves or arteries. In pulmonary stenosis, the pulmonary valve does not open properly, forcing the right ventricle to work harder. In aortic stenosis, the improperly formed aortic valve is narrowed. As the left ventricle works harder to pump blood through the body, it becomes enlarged. In coarctation of the aorta, the aorta is constricted, reducing the flow of blood to the lower part of the body and increasing blood pressure in the upper body.
A bicuspid aortic valve has only two flaps instead of three, which can lead to stenosis in adulthood. Subaortic stenosis is a narrowing of the left ventricle below the aortic valve, which limits the flow of blood from the left ventricle.
Septal defects
When a baby is born with a hole in the septum (the wall separating the right and left sides of the heart),
blood leaks from the left side of the heart to the right, or from a higher pressure zone to a lower pressure zone. A major leakage can lead to enlargement of the heart and failing circulation. The most common types of septal defects are atrial septal defect, an opening between the two upper heart chambers, and ventricular septal defect, an opening between the two lower heart chambers. Ventricular septal defect accounts for about 15% of all cases of congenital heart disease in the United States.
Cyanotic defects
Heart disorders that cause a decreased, inadequate amount of oxygen in blood pumped to the body are called cyanotic defects. Cyanotic defects, including truncus arteriosus, total anomalous pulmonary venous return, tetralogy of Fallot, transposition of the great arteries, and tricuspid atresia, result in a blue discoloration of the skin due to low oxygen levels. About 10% of cases of congenital heart disease in the United States are tetralogy of Fallot, which includes four defects. The major defects are a large hole between the ventricles, which allows oxygen-poor blood to mix with oxygen-rich blood, and narrowing at or beneath the pulmonary valve. The other defects are an overly muscular right ventricle and an aorta that lies over the ventricular hole.
In transposition (reversal of position) of the great arteries, the pulmonary artery and the aorta are reversed, causing oxygen-rich blood to re-circulate to the lungs while oxygen-poor blood goes to the rest of the body. In tricuspid atresia, the baby lacks a triscupid valve and blood cannot flow properly from the right atrium to the right ventricle.
Other defects
Ebstein's anomaly is a rare congenital syndrome that causes malformed tricuspid valve leaflets, which allow blood to leak between the right ventricle and the right atrium. It also may cause a hole in the wall between the left and right atrium. Treatment often involves repairing the tricuspid valve. Ebstein's anomaly may be associated with maternal use of the psychiatric drug lithium during pregnancy.
Brugada syndrome is another rare congenital heart defect that appears in adulthood and may cause sudden death if untreated. Symptoms, which include rapid, uneven heart beat, often appear at night. Scientists believe that Brugada syndrome is caused by mutations in the gene SCN5A, which involves cardiac sodium channels.
Infants born with DiGeorge sequence can have heart defects such as a malformed aortic arch and tetralogy of Fallot. Researchers believe DiGeorge sequence is most often caused by mutations in genes in the region 22q11.
Marfan syndrome is a connective tissue disorder that causes tears in the aorta. Since the disease also causes excessive bone growth, most Marfan syndrome patients are over six-feet-tall. In athletes, and others, it can lead to sudden death. Researchers believe the defect responsible for Marfan syndrome is found in gene FBN1, on chromosome 15.
Genetic profile
Scientists have made much progress in identifying some of the genes that are responsible for congenital heart defects, but others remain a mystery. When possible, genetic testing can help families determine the risk that their child will be born with a heart defect.
Demographics
About 32,000 infants are born every year with congenital heart disease, which is the most common birth defect. About half of these patients require medical treatment. More than one million people with heart defects are currently living in the United States.
Signs and symptoms
In most cases, the causes of congenital heart disease are unknown. Genetic and environmental factors and lifestyle habits can all be involved. The likelihood of having a child with a congenital heart disease increases if the mother or father, another child, or another relative had congenital heart disease or a family history of sudden death. Viral infections, such as German measles, can produce congenital heart disease. Women with diabetes and phenylketonuria also are at higher risk of having children with congenital heart defects. Many cases of congenital heart disease result from the mother's excessive use of alcohol or illegal drugs, such as cocaine, while pregnant. The mother's exposure to certain anti-convulsant and dermatologic drugs during pregnancy can also cause congenital heart disease. There are many genetic conditions, such as Down syndrome , which affect multiple organs and can cause congenital heart disease.
Symptoms of congenital heart disease in general include: shortness of breath, difficulty feeding in infancy, sweating, cyanosis (bluish discoloration of the skin), heart murmur, respiratory infections that recur excessively, stunted growth, and limbs and muscles that are underdeveloped.
Symptoms of specific types of congenital heart disease are as follows:
- Patent ductus arteriosus: quick tiring, slow growth, susceptibility to pneumonia, rapid breathing. If the ductus is small, there are no symptoms.
- Hypoplastic left heart syndrome: ashen color, rapid and difficult breathing, inability to eat.
- Obstruction defects: cyanosis (skin that is discolored blue), chest pain, tiring easily, dizziness or fainting, congestive heart failure, and high blood pressure.
- Septal defects: difficulty breathing, stunted growth. Sometimes there are no symptoms.
- Cyanotic defects: cyanosis, sudden rapid breathing or unconsciousness, and shortness of breath and fainting during exercise.
Diagnosis
Echocardiography and cardiac magnetic resonance imaging are used to confirm congenital heart disease when it is suggested by the symptoms and physical examination. An echocardiograph will display an image of the heart that is formed by sound waves. It detects valve and other heart problems. Fetal echocardiography is used to diagnose congenital heart disease in utero, usually after 20 weeks of pregnancy. Between 10 and 14 weeks of pregnancy, physicians also may use an ultra-sound to look for a thickness at the nuchal translucency, a pocket of fluid in back of the embryo's neck, which may indicate a cardiac defect in 55% of cases. Cardiac magnetic resonance imaging, a scanning method that uses magnetic fields and radio waves, can help physicians evaluate congenital heart disease, but is not always necessary. Physicians may also use a chest x ray, to look at the size and location of the heart and lungs, or an electrocardiograph (ECG), which measures electrical impulses to create a graph of the heart beat.
Treatment and management
Congenital heart disease is treated with drugs and/or surgery. Drugs used include diuretics, which aid the baby in excreting water and salts, and digoxin, which strengthens the contraction of the heart, slows the heartbeat, and removes fluid from tissues.
Surgical procedures seek to repair the defect as much as possible and restore circulation to as close to normal as possible. Sometimes, multiple surgical procedures are necessary. Surgical procedures include: arterial switch, balloon atrial septostomy, balloon valvuloplasty, Damus-Kaye-Stansel procedure, Fontan procedure, pulmonary artery banding, Ross procedure, shunt procedure, and venous switch or intra-atrial baffle.
Arterial switch, to correct transposition of the great arteries, involves connecting the aorta to the left ventricle and connecting the pulmonary artery to the right ventricle. Balloon atrial septostomy, also done to correct transposition of the great arteries, enlarges the atrial opening during heart catheterization. Balloon valvuloplasty uses a balloon-tipped catheter to open a narrowed heart valve, improving the flow of blood in pulmonary stenosis. It is sometimes used in aortic stenosis. Transposition of the great arteries can also be corrected by the Damus-Kaye-Stansel procedure, in which the pulmonary artery is cut in two and connected to the ascending aorta and the farthest section of the right ventricle.
For tricuspid atresia and pulmonary atresia, the Fontan procedure connects the right atrium to the pulmonary artery directly or with a conduit, and the atrial defect is closed. Pulmonary artery banding, narrowing the pulmonary artery with a band to reduce blood flow and pressure in the lungs, is used for ventricular septal defect, atrioventricular canal defect, and tricuspid atresia. Later, the band can be removed and the defect corrected with open-heart surgery.
To correct aortic stenosis, the Ross procedure grafts the pulmonary artery to the aorta. For tetralogy of Fallot, tricuspid atresia, or pulmonary atresia, the shunt procedure creates a passage between blood vessels, sending blood into parts of the body that need it. For transposition of the great arteries, venous switch creates a tunnel inside the atria to re-direct oxygen-rich blood to the right ventricle and aorta and venous blood to the left ventricle and pulmonary artery.
When all other options fail, some patients may need a heart transplant. Children with congenital heart disease require lifelong monitoring, even after successful surgery. The American Heart Association recommends regular dental check-ups and the preventive use of antibiotics to protect patients from heart infections, or endocarditis. Since children with congenital heart disease have slower growth, nutrition is important. Physicians may also limit their athletic activity.
Prognosis
The outlook for children with congenital heart disease has improved markedly in the past two decades. Many types of congenital heart disease that would have been fatal can now be treated successfully. Research on diagnosing heart defects when the fetus is in the womb may lead to future treatment to correct defects before birth. Promising new prevention methods and treatments include genetic screening and the cultivation of cardiac tissue in the laboratory that could be used to repair congenital heart defects.
Resources
BOOKS
Mayo Clinic Heart Book. New York: William Morrow and Company, 2000.
Wild, C. L., and M. J. Neary. Heart Defects in Children: What Every Parent Should Know. Chronimed Publishing, Minneapolis, 2000.
Williams, R. A. The Athlete and Heart Disease. Lippincott Williams & Wilkins, Philadelphia, 1999.
PERIODICALS
"Coping with Congenital Heart Disease in Your Baby." American Family Physician 59 (April 1, 1999): 1867.
Hyett, Jon, et. al. "Using fetal nuchal translucency to screen for major congenital cardiac defects at 10-14 weeks: population based cohort study." Lancet 318 (January 1999): 81-85.
ORGANIZATIONS
American Heart Association. 7272 Greenville Ave., Dallas, TX 75231-4596. (214) 373-6300 or (800) 242-8721. inquire@heart.org. <http://www.americanheart.org>.
Congenital Heart Disease Information and Resources. 1561 Clark Dr., Yardley, PA 19067. <http://www.tchin.org>.
Texas Heart Institute Heart Information Service. PO Box 20345, Houston, TX 77225-0345. (800) 292-2221. <http://www.tmc.edu/thi/his.html>.
Melissa Knopper