What is a congenital heart defect?
When the heart or blood vessels near the heart do not develop normally before birth, a condition called congenital heart defect occurs (congenital means "existing at birth").
Congenital heart defects occur in close to 1 percent of infants. Most young people with congenital heart defects are living into adulthood now.
In most cases, the cause is unknown. Sometimes a viral infection in the mother causes the condition. The condition can be genetic (hereditary). Some congenital heart defects are the result of alcohol or drug use during pregnancy.
Most heart defects either cause an abnormal blood flow through the heart, or obstruct blood flow in the heart or vessels (obstructions are called stenoses and can occur in heart valves, arteries, or veins). A hole between two chambers of the heart is an example of a very common type of congenital heart defect.
More rare defects include those in which:
- The right or left side of the heart is incompletely formed (hypoplastic)
- Only one ventricle is present.
- Both the pulmonary artery and aorta arise from the same ventricle.
- The pulmonary artery and aorta arise from the "wrong" ventricles.
Types of congenital heart defects
There are many disorders of the heart that require clinical care by a doctor or other health care professional. Listed below are some of the conditions, for which we have provided a brief overview.
- Aortic stenosis (AS). In this condition, the aortic valve between the left ventricle and the aorta did not form properly and is narrowed, making it difficult for the heart to pump blood to the body. A normal valve has three leaflets or cusps, but a stenotic valve may have only one cusp (unicuspid) or two cusps (bicuspid).
In some children, chest pain, unusual tiring, dizziness, or fainting may occur. Otherwise, most children with aortic stenosis have no symptoms. But, even mild stenosis may worsen over time, and a catheter-based procedure or surgery may be needed to correct the blockage or the valve may need to be replaced with an artificial one.
- Pulmonary stenosis (PS). The pulmonary, or pulmonic, valve, located between the right ventricle and the pulmonary artery, opens to allow blood to flow from the right ventricle to the lungs. When a defective pulmonary valve does not open properly, it causes the heart to pump harder than normal to overcome the obstruction. Usually, the obstruction can be corrected by a catheter-based procedure known as balloon valvuloplasty, although in some patients, open heart surgery may be needed.
- Bicuspid aortic valve. In this condition, an infant is born with a bicuspid valve which has only two flaps. (A normal aortic valve has three flaps that open and close). If the valve becomes narrowed, it is more difficult for the blood to flow through, and often the blood leaks backward. Symptoms usually do not develop during childhood, but are often detected during the adult years.
- Subaortic stenosis. This condition refers to a narrowing of the left ventricle just below the aortic valve. Normally, blood passes through it to go into the aorta. However, subaortic stenosis limits the blood flow out of the left ventricle, often resulting in an increased workload for the left ventricle. Subaortic stenosis may be congenital or caused by a form of cardiomyopathy.
- Coarctation of the aorta (coarct). In this condition, the aorta is narrowed or constricted, obstructing blood flow to the lower part of the body and increasing blood pressure above the constriction. Usually there are no symptoms at birth, but they can develop as early as the first week after birth. If severe symptoms of high blood pressure and congestive heart failure develop, surgery is necessary. Less severe cases may not be detected until a child is older but can result in long-term health problems if not corrected.
Some congenital heart defects allow blood to flow between the right and left chambers of the heart because an infant is born with an opening in the wall (or septum) that separates the right and left sides of the heart.
- Atrial septal defect (ASD). In this condition, there is an opening between the two upper chambers of the heart--the right and left atria--causing an abnormal blood flow through the heart. Children with ASD have few symptoms. The ASD may be closed by catheter-based techniques or open-heart surgery. Closing the atrial defect by open heart surgery in childhood can often prevent serious problems later in life.
- Ventricular septal defect (VSD). In this condition, a hole is present between the two lower chambers of the heart. Because of this hole, blood from the left ventricle flows back into the right ventricle, due to higher pressure in the left ventricle. This causes extra blood to be pumped into the lungs by the right ventricle, which can create congestion in the lungs. while some VSDs close on their own, others require surgery to repair the hole.
Cyanotic defects are defects in which blood pumped to the body contains less-than-normal amounts of oxygen. It causes a blue discoloration of the skin. Infants with cyanosis are often called "blue babies."
- Tetralogy of Fallot. This condition is characterized by four defects, including the following:
- An abnormal opening, or ventricular septal defect, that allows blood to pass from the right ventricle to the left ventricle without going through the lungs
- A narrowing (stenosis) at or just beneath the pulmonary valve that partially blocks the flow of blood from the right side of the heart to the lungs
- The right ventricle is more muscular than normal
- The aorta lies directly over the ventricular septal defect
Tetralogy of Fallot is the most common defect causing cyanosis in people beyond 2 years of age. Most children with tetralogy of Fallot have open-heart surgery before school age (frequently in infancy) to close the ventricular septal defect and remove the obstructing muscle. Lifelong medical follow-up is needed.
- Tricuspid atresia. In this condition, there is no tricuspid valve, therefore, no blood flows from the right atrium to the right ventricle. Tricuspid atresia is characterized by the following:
- A small right ventricle
- A large left ventricle
- Diminished pulmonary circulation
A surgical shunting procedure is often necessary to increase the blood flow to the lungs.
- Transposition of the great arteries. In this embryologic defect, the positions of the pulmonary artery and the aorta are reversed, thus:
- The aorta originates from the right ventricle, so most of the blood returning to the heart from the body is pumped back out without first going to the lungs.
- The pulmonary artery originates from the left ventricle, so that most of the blood returning from the lungs goes back to the lungs again.
Immediate medical intervention is necessary to correct this condition.
- Hypoplastic left heart syndrome (HLHS). In this condition, the left side of the heart, including the aorta, aortic valve, left ventricle, and mitral valve, is underdeveloped. Blood reaches the aorta through a patent ductus arteriosus, and if this ductus closes, as is normal, the baby will die. The baby often seems normal at birth, but the condition will become noticeable within a few days of birth, as the ductus closes. Babies with this syndrome become ashen (gray), have diminished or absent pulses in the legs, have difficulty breathing, and are unable to feed. Treatment is surgical and typically requires three operations.
- Patent ductus arteriosus (PDA). This condition results from failure of the PDA to close normally after birth, allowing blood to mix between the pulmonary artery and the aorta. When it does not close, extra blood may flood the lungs and cause pulmonary congestion. Patent ductus arteriosus is often seen in premature infants.
- Ebstein's anomaly. In this defect, there is a downward displacement of the tricuspid valve (located between the upper and lower chambers on the right side of the heart) into the right bottom chamber of the heart (or right ventricle). This means the atrium is larger than normal and the ventricle is smaller than normal, which can lead to rhythm abnormalities and heart failure. It is usually associated with an atrial septal defect.
Who treats congenital heart defects?
Babies with congenital heart problems are followed by specialists called pediatric cardiologists. These doctors diagnose heart defects and help manage the health of children before and after surgical repair of the heart problem. Specialists who correct heart problems in the operating room are known as pediatric cardiovascular or cardiothoracic surgeons.
A new subspecialty within cardiology is emerging as the number of adults with congenital heart disease (CHD) is now greater than the number of babies born with CHD, as a result of the advances in diagnostic procedures and treatment interventions that have been made since 1945. These doctors care for adults with heart problems that began in infancy or childhood, as opposed to the types of heart conditions that develop in adults as they age.
In order to achieve and maintain the highest possible level of wellness, it is imperative that those individuals born with CHD who have reached adulthood transition to the appropriate type of cardiac care. The type of care required is based on the type of CHD a person has. Those people with simple CHD can often be cared for by a community adult cardiologist. Those with more complex types of CHD will need to be cared for at a center that specializes in adult CHD. For adults with CHD, guidance is necessary for planning key life issues such as college, career, employment, insurance, activity, lifestyle, inheritance, family planning, pregnancy, chronic care, disability, and end of life. Knowledge about specific congenital heart conditions and expectations for long-term outcomes and potential complications, and risks must be reviewed as part of the successful transition from pediatric care to adult care. Parents should help pass on the responsibility for this knowledge and accountability for ongoing care to their young adult children to help ensure the transition to adult specialty care and optimize the health status of the young adult with CHD.