Congenital Heart Defects

What are congenital heart defects?

Congenital heart defects (CHD) are problems with the heart’s structure that developed in the womb or early development and are present at birth or shortly thereafter.  Each year, about 1 percent or 30,000 babies are born with the defect, making it the most common birth defect in the U. S.  Congenital heart defects vary widely in structure and severity.  Some defects can be fatal, but thanks largely to new treatments, most affected individuals survive their childhood and live relatively normal lives.  Over 1,000,000 adults are currently living with a congenital heart disease.

How do congenital heart defects develop?

As a fetus’s heart develops from a simple tube to a four-chambered heart with associated veins and arteries, defects may develop.  Part of the heart may develop partially or not at all, a hole in the wall of the heart may form, or the heart arteries and veins may form abnormal connections with the heart.  Congenital heart defects are often thought to be genetic, but they can also be caused by illness or behavioral factors in the mother such as viral infections like German measles, certain prescription drugs and over-the-counter medicines, alcohol, or illegal drugs.  Some conditions like Down syndrome and Turner syndrome are associated with CHDs. 

What are the types of congenital heart defects?

Congenital heart defects vary widely in structure and severity.  CHDs usually involve one of the following: abnormal passages in the heart or between blood vessels, problems with the valves that control the emptying and filling of the heart chambers, mismatched or abnormally located or developed blood vessels near the heart, or structural or developmental malformations in the heart itself. 

What are the congenital heart defects that involve abnormal passages in the heart or between blood vessels?

When abnormal passages exist in the heart, oxygenated and deoxygenated blood can mix in the heart.  This depletes the oxygen in the blood and makes the heart work harder to deliver oxygen to the body.  A normal human heart has four chambers.  The two smaller, upper chambers are called atria; the two lower chambers are called ventricles.  The right atrium receives deoxygenated blood from the body and pumps it to the right ventricle, which, in turn, pumps it out to the lungs.  The left atrium receives oxygenated blood from the lungs and pumps it out to the left ventricle, which, in turn, pumps it out to the body.

Septal defects occur in the wall (septum) separating the right and left sides of the heart either between the two atria (atrial septal defect), the two ventricles (ventricular septal defect), or in the valves that control blood flow from atria to ventricles (atrioventricular septal defect). 

If a connection exists between the artery carrying oxygenated blood from the heart out to the body (the aorta) and the artery carrying deoxygenated blood to the lungs (the pulmonary artery), doctors call the defect a patent ductus arteriosus (PDA).  This blood flow anomaly is normally present before birth but should close shortly thereafter.

How do doctors treat septal defects and patent ductus arteriosus?

Surgeons can sew a patch in the septal wall of patients with atrial and ventricular septal defects to ensure normal blood flow in the heart.  A less invasive alternative to heart surgery is a catheter based procedure in which a doctor places a small, expandable disk in the hole through a small tube inserted through a blood vessel somewhere else in the body and threaded to the heart.  A small hole may not need treatment because it may heal itself or cause only an insignificant decrease in heart efficiency.  Sometimes, drug therapy can help to close the connection between the arteries in patent ductus arteriosus, but surgery may be necessary to fix the defect.

What are the congenital heart defects that involve the heart valves?

Any of the four heart valves can be narrowed, absent, or leaking. 

In aortic valve stenosis, the valve controlling blood flow between the left ventricle and the aorta is excessively narrow making it hard for the heart to pump blood out to the body.  This stenosis involves a malformed valve, which may have too few and/or stiffened leaflets.  A leaflet, or cusp, is a part of a heart valve resembling a flap.  When the aortic valve has two leaflets instead of three, it is called a bicuspid aortic valve.

In pulmonary valve stenosis, the right ventricle of the heart must work harder to pump blood to the lungs because the valve in between that ventricle and the pulmonary artery is narrowed. 

Patients with tricuspid valve atresia have a solid sheet of tissue instead of a tricuspid valve in between the right atrium and ventricle.  The heart of a patient without a tricuspid valve is unable to efficiently pump blood from the right atrium to the right ventricle and out to the lungs, and the right ventricle is often small and can be nonfunctional.  Holes in the septum allow a person with tricuspid valve atresia to survive, but his heart is inefficient. 

Pulmonary valve atresia involves a solid sheet of tissue in place of a valve between the right ventricle and pulmonary artery.  The right ventricle is often malformed, small, and nonfunctional in patients with this defect.  Blood must flow to the lungs through the patent ductus arteriosus connecting the aorta and pulmonary artery.  Mixing of oxygenated and deoxygenated blood makes a patient’s heart inefficient. 

Patients with Ebstein’s anomaly have a displaced and malformed tricuspid valve, which is leaky and located in the right ventricle.  The defect lets some of the blood, which should flow to the lungs to pick up oxygen, flow back down into the right atrium, decreasing the efficiency of the heart.

How do doctors treat congenital heart defects involving the valves?

Doctors can use a variety of techniques to treat problems with the heart’s valves.  They can replace or repair faulty valves with surgery or expand narrowed valves with balloons on catheters.  In patients with tricuspid or pulmonary valve atresia and only one functional ventricle, doctors can use a shunt to help blood flow to the lungs and/or the Fontan procedure to send blood coming back from the body directly to the lungs without first being pumped through the heart.  Prostaglandin E1 is a drug that doctors prescribe to try to keep the ductus arteriosus open so that it can help transfer blood from a functioning artery to the artery that is connected to the blocked valve.  Prostaglandin E1 may be a short term solution until a shunt is in place.

What are the congenital heart defects that involve mismatched blood vessels near the heart?

The location and formation of the blood vessels that connect with the heart are important, because the location determines the type of blood (oxygenated or deoxygenated) that a vessel receives.  If the body receives deoxygenated blood or the lungs receive oxygenated blood, the heart will be strained or unable to meet oxygen demands in the body. 

Transposition of the great arteries is a congenital heart disease in which the aorta and pulmonary artery have been mismatched in their connection to the heart.  Usually, the aorta receives oxygenated blood from the left ventricle and delivers it to the body.  But in a patient with transposition of the great arteries, the aorta receives blood that is poor in oxygen from the right ventricle and carries this blood to the body, and the pulmonary artery receives oxygen-rich blood from the left ventricle to be cycled again through the lungs.  Thus, without some sort of communication between the two sides, the same blood is continually pumped through the body and lungs.

The tetralogy of Fallot is a group of four defects including pulmonary valve stenosis, ventricular septal defect, overriding aorta, and right ventricular hypertrophy.  Patients with this disease have an unusually narrow pulmonary valve and an aorta that is located between the left and right ventricles and receives blood from a hole in the wall that separates the left and right ventricles.  Because the right side of the heart must work harder in patients with this defect, the muscle surrounding the right ventricle is abnormally thickened.  This structural setup for the heart is much more inefficient than a normal setup, and patients with this tetralogy may have inadequate blood flow to the lungs and an insufficient oxygen supply to the body.

Truncus arteriosus is a congenital defect in which the aorta and the pulmonary artery fail to form separately, but are joined permanently as they rise from the heart and separate as they branch into smaller arteries that deliver blood to the lungs and body.  This makes it impossible for the heart to segregate the oxygenated and deoxygenated blood that comes from the two sides of the heart.  Truncus arteriosus makes a patient’s heart inefficient because it delivers the same blood to the lungs and body. 

Coarctation of the aorta is a condition in which a patient’s aorta is constricted.  This constriction can obstruct blood flow as the heart pumps blood to the body.  High blood pressure is common in patients with this defect because the coarctation increases pressure before the constriction and causes inadequate blood flow to the body.  Patients with this defect are at risk for congestive heart failure and chronic high blood pressure. 

Some people are born with one or more of the veins that return blood to the heart from the lung returning blood to the wrong atrium.  Doctors call this condition anomalous pulmonary venous return.  All four of the pulmonary veins normally return their oxygenated blood to the left atrium, but patients born with this condition have at least one pulmonary vein attached to the right atrium.  This defect causes a mix of oxygenated and deoxygenated blood and decreases the heart’s efficiency.  Some people are born with all four pulmonary veins returning to the right atrium; they have total anomalous pulmonary venous return, a serious defect in which the only source of oxygenated blood for the body is through an atrial septal defect.  Most people with total anomalous pulmonary venous return can survive only if treated within their first year.

How do doctors treat congenital heart defects that involve mismatched blood vessels near the heart?

Transposition of the great arteries requires immediate intervention to get adequate oxygen to the body for vital functions.  If the oxygenated and deoxygenated blood is kept completely separate, a person cannot survive long.  If, however, a septal defect or patent ductus exists in the heart or arteries, the two blood supplies will be able to communicate, and a patient may be able to retain vital functions.  Balloon atrial septostomy, or the Rashkind procedure, is a catheter-based procedure that doctors can use to widen a hole in the atrial or ventricular walls in order to allow better communication between the two bloods.  A surgeon may perform one of two procedures to correct transposition of the great arteries, venous switch or arterial switch.  Both of these procedures try to create a situation conducive to normal blood flow by switching the connections. 

Patients with the tetralogy of Fallot may need a procedure to allow blood to mix between the aorta and the pulmonary artery in order to survive infancy.  In early childhood, most patients with the tetralogy of Fallot will need open heart surgery to close the ventricular septal defect and widen the stenosis in the pulmonary valve. 

Most people born with truncus arteriosus will need a surgical procedure in which a surgeon separates the two arteries and makes connections between the pulmonary artery and the right ventricle.

Patients with coarctation of the aorta may or may not need serious treatment depending on the severity of the constriction in the aorta.  Many surgical options are available for a coarctation, and they all focus on removing, avoiding, or widening the obstruction in the aorta.  A catheter-based procedure called balloon dilation may be used with or without stent placement to open up the constriction in some patients.

Surgical repair for total anomalous pulmonary venous return is usually performed within the first six months of a person’s life.  The pulmonary veins are redirected to the left atrium and the atrial septal defect is closed.

What are the heart defects that involve structural or developmental malformations in the heart itself?

Single ventricle defects are conditions in which one of the ventricles is absent or undeveloped.  Hypoplastic left heart syndrome is a single ventricle defect affecting the left side of the heart and may be the hardest to manage of all the common congenital heart defects.  Mitral atresia, aortic atresia, an atrial septal defect, and a small, undeveloped left ventricle combine to make the syndrome.  This results in a situation where the right side of the heart must do all of the work; it must pump blood to and from the lungs and body.  The body’s only source of oxygenated blood, then, is the blood that passes through the patent ductus arteriosus, which, without treatment, will usually close within the first few days after birth.

How do doctors treat hypoplastic left heart syndrome?

Without treatment, hypoplastic left heart syndrome is almost always immediately fatal within the first few days of birth.  Treating the defect is an involved process.  Prostaglandin E1 will help keep the patent ductus open as doctors try to balance blood flow to the lungs and body with other drugs to allow the baby to survive.  Although heart transplantation is an option for children with this disorder, the most popular option is called “staged reconstruction.”  Staged reconstruction shows promising results and involves a series of three surgeries that are designed to make the patient’s heart as efficient as possible.  These surgeries, particularly the first, are dangerous and difficult, but the outlook for patients with this defect is improving.

What are the risk factors for congenital heart defects?

A person with a congenital defect is more likely to have a child with a defect than the average person.  Some factors increase a mother’s chance of having a child with a defect including viral infections, diabetes, certain legal and illegal drugs, some chemicals or x-rays, and alcohol consumption during pregnancy.

How do doctors identify congenital heart defects?

Some heart defects can be seen on prenatal tests and the doctor can order a fetal echocardiogram if he suspects a defect in the child.  Many defects, however, are identified shortly after birth by their signs and symptoms.  Some signs and symptoms of defects include a heart murmur; a bluish tint to skin, lips, and fingernails (cyanosis); shortness of breath; fast breathing; fatigue; and poor weight gain.  If a doctor suspects a heart defect in a newborn, he may order an echocardiogram, an EKG, a chest x-ray, or a pulse oximetry.  A pulse oximetry is a noninvasive test doctors use to see if oxygenated and deoxygenated blood is mixing in the heart and to observe lung function.  The test involves placing a sensor similar to a bandage on the child’s finger or toe.  A cardiac catheterization may be necessary to definitively see the arteries around the heart and observe heart function.