CONGENITAL HEART DEFECTS

Congenital heart defects are abnormalities in the heart's structure that are present at birth. Approximately 8 out of every 1,000 newborns have congenital heart defects, ranging from mild to severe.


Congenital heart defects happen because of incomplete or abnormal development of the fetus' heart during the very early weeks of pregnancy. Some are known to be associated with genetic disorders, such as Down syndrome, but the cause of most congenital heart defects is unknown. While they can't be prevented, there are many treatments for the defects and any related health problems

Types of Congenital Heart Defects

Congenital heart disease (CHD) can describe a number of different problems affecting the heart. It is the most common type of birth defect. Congenital heart disease is responsible for more deaths in the first year of life than any other birth defects. Many of these defects need to be followed carefully. Some heal over time, others will require treatment.

Congenital heart disease is often divided into two types: cyanotic (blue discoloration caused by a relative lack of oxygen) and non-cyanotic. The following lists cover the most common of the congenital heart diseases:



Cyanotic:

• Tetralogy of Fallot.Tetralogy of Fallot is actually a combination of four heart defects. It includes pulmonary stenosis, a thickened right ventricle (known as ventricular hypertrophy), a hole between the lower chambers (known as a ventricular septal defect), and an aorta that can receive blood from both the left and right ventricles, instead of draining just the left. Because deoxygenated (blue) blood can flow out to the body, children with this defect often appear bluish
• Transposition of the great vessels.In this condition, the pulmonary artery and the aorta (the major blood vessels leaving the heart) are switched so that the aorta arises from the right side of the heart and receives blue blood, which is sent right back out to the body without becoming oxygen-rich. The pulmonary artery arises from the left side of the heart, receives red blood and sends it back to the lungs again. The result is that babies with this condition often appear very blue and have low oxygen levels in the bloodstream. They usually come to medical attention within the first days of life
• Tricuspid atresia.Blood normally flows from the right atrium to the right ventricle through the tricuspid valve. In tricuspid atresia, the valve is replaced by a plate or membrane that does not open. The right ventricle therefore does not receive blood normally and is often small
• Total anomalous pulmonary venous return.The pulmonary veins normally are the blood vessels that deliver oxygenated blood from the lungs to the left atrium. Sometimes these vessels don't join the left atrium during development. Instead they deliver blood to the heart by other pathways, which may be narrowed. Pressure builds up in this pathway and in the pulmonary veins, pushing fluid into the lungs, decreasing the amount of oxygenated blood that reaches the body. These infants often have difficulty breathing and appear bluish
• Truncus arteriosus.In an embryo, the aorta and the pulmonary artery are initially a single vessel. During normal development, that vessel splits to form the two major arteries. If that split does not occur, the child is born with a single common great blood vessel called the truncus arteriosus. There is usually a hole between the ventricles associated with this defect
• Hypoplastic left heart.When the structures of the left side of the heart (the left ventricle, the mitral valve, and the aortic valve) are underdeveloped, they're unable to pump blood adequately to the entire body. This condition is usually diagnosed within the first few days of life, at which point the baby may be critically ill.
• Pulmonary atresia.In this defect the pulmonic valve does not open at all and may indeed be completely absent. The main blood vessel that runs between the right ventricle and the lungs also may be malformed and the right ventricle can be abnormally small.
• Some forms of total anomalous pulmonary venous return
• Ebstein's anomaly

Non-cyanotic:

• Ventricular septal defect (VSD).One of the most common congenital heart defects, VSD is a hole in the wall (septum) between the heart's left and right ventricles. These can occur at different locations and vary in size from very small to very large. Some of the smaller defects may gradually close on their own
• Atrial septal defect (ASD).ASD is a hole in the wall (called the septum) that separates the left atrium and the right atrium
• Patent ductus arteriosus (PDA).The ductus arteriosus (DA) is a normal blood vessel in the developing fetus that diverts circulation away from the lungs and sends it directly to the body. (The lungs are not used while the unborn fetus is in amniotic fluid — the fetus gets oxygen directly from the mother's placenta.) The DA usually closes on its own shortly after birth; it is no longer needed once a newborn breathes on his own. If the DA doesn't close, then a condition called patent ductus arteriosus (PDA) results, which can result in too much blood flow to a newborn's lungs. PDA is common in premature babies
• Aortic stenosis.In aortic stenosis, the aortic valve is stiffened and has a narrowed opening (a condition called stenosis). It does not open properly, which increases strain on the heart because the left ventricle has to pump harder to send blood out to the body. Sometimes the aortic valve also does not close properly, causing it to leak, a condition called aortic regurgitation
• Pulmonic stenosis.In pulmonary stenosis, the pulmonic valve is stiffened and has a narrowed opening (a condition called stenosis). It does not open properly, which increases strain on the right side of the heart because the right ventricle has to pump harder to send blood out to the lungs
• Coarctation of the aorta.COA is a narrowing of a portion of the aorta, and often seriously decreases the blood flow from the heart out to the lower portion of the body
• Atrioventricular canal (endocardial cushion defect).This defect — also known as endocardial cushion defect or atrioventricular septal defect — is caused by a poorly formed central area of the heart. Typically there is a large hole between the upper chambers of the heart (the atria) and, often, an additional hole between the lower chambers of the heart (the ventricles). Instead of two separate valves allowing flow into the heart (tricuspid on the right and mitral valve on the left), there is one large common valve, which may be quite malformed. Atrioventricular canal defect is commonly seen in children with Down syndrome.

Causes and Risk Factors.

These problems may occur alone or together. The majority of congenital heart diseases occurs as an isolated defect and is not associated with other diseases. However, they can also be a part of various genetic and chromosomal syndromes such as Down syndrome, trisomy 13, Turner syndrome, Marfan syndrome, Noonan syndrome, and DiGeorge syndrome.
No known cause can be identified for most congenital heart defects. Congenital heart diseases continue to be investigated and researched. Drugs such as retinoic acid for acne, chemicals, alcohol, and infections (such as rubella) during pregnancy can contribute to some congenital heart problems.

Signs and Symptoms of Heart Defects

Because congenital defects often compromise the heart's ability to pump blood and to deliver oxygen to the tissues of the body, they often produce telltale signs such as:

• a bluish tinge or color (cyanosis) to the lips, tongue and/or nailbeds
• an increased rate of breathing or difficulty breathing
• poor appetite or difficulty feeding (which may be associated with color change)
• failure to thrive (failure to gain weight or weight loss)
• abnormal heart murmur
• sweating, especially during feedings
• diminished strength of the baby's pulse

Diagnostic Tests

Several tests can show what kind of heart disease your baby has. Tests can also check on your baby's condition, to see how the heart is working. Here are some tests your baby might have:

• ECG -An ECG shows the heartbeat as a line tracing. It measures activity in different parts of the heart.
• Pulse oximetry--This test shows how much oxygen is in the baby's blood.
• Echocardiogram--This test gives the doctor an ultrasound "picture" of the baby's heart.
• Chest X-ray--This can show how well the heart is growing and if your baby's lungs have fluid in them.

Cardiac catheterization--This test uses dye in the heart to give the doctor a clear picture of the heart problem.

How are congenital heart defects treated?

Although many children with congenital heart defects don't need treatment, some do. Doctors treat congenital heart defects with:

• Procedures using catheters to repair the defect
  
• Surgery to repair the defect

The treatment your child receives depends on the type and severity of his or her heart defect. Other factors include your child's age, size, and general health. Treatment can be simple or very complex. Some children with complex congenital heart defects may need several catheter or surgical procedures over a period of years, or may need to take medicines for years.

Procedures Using Catheters

Catheter procedures are much easier than surgery on patients because they involve only a needle puncture in the skin where the catheter is inserted into a vein or an artery. Doctors don't have to surgically open the chest or operate directly on the heart to repair the defect. This means that recovery can be much easier and quicker.

The use of catheter procedures has grown a lot in the past 20 years. They have become the preferred way to repair many simple heart defects, such as:

• Atrial septal defect. The doctor inserts the catheter through a vein and threads it up into the heart to the septum. The catheter has a tiny umbrella‑like device folded up inside it. When the catheter reaches the septum, the device is pushed out of the catheter and positioned so that it plugs the hole between the atria. The device is secured in place and the catheter is then withdrawn from the body.
  
• Pulmonary valve stenosis. The doctor inserts the catheter through a vein and threads it into the heart to the pulmonary valve. A tiny balloon at the end of the catheter is quickly inflated to push apart the leaflets, or "doors," of the valve. The balloon is then deflated and the catheter is withdrawn. Procedures like this can be used to repair any narrowed valve in the heart.

Doctors often use an echocardiogram or a transesophageal echocardiogram (TEE) as well as an angiogram to guide them in threading the catheter and doing the repair. A TEE is a special type of echocardiogram that takes pictures of the back of the heart through the esophagus (the tube leading from the mouth to the stomach). TEE also is often used to define complex heart defects.
Catheter procedures also are sometimes used during surgery to help repair complex defects.

Surgery


A child may need open-heart surgery if his or her heart defect can't be fixed using a catheter procedure. Sometimes, one surgery can repair the defect completely. If that's not possible, a child may need more than one surgery over a period of months or years to fix the problem.

Open-heart surgery may be done to:

• Close holes in the heart with stitches or with a patch
  
• Repair or replace heart valves
  
• Widen arteries or openings to heart valves
  
• Repair complex defects, such as problems with where the blood vessels near the heart are located and how they develop

Rarely, babies are born with multiple defects that are too complex to repair. These babies may need a heart transplant. In this procedure, the child's heart is replaced with a healthy heart from a deceased child that has been donated by that child's family. 

Prevention

Avoid alcohol and other drugs during pregnancy.

 Doctors should be made aware that a woman is pregnant before prescribing any medications for her.

 A blood test should be done early in the pregnancy to see if the woman is immune to rubella. If the mother is not immune, she must avoid any possible exposure to rubella and should be immunized immediately following delivery.

Poorly controlled blood sugar levels in women who have diabetes during pregnancy are also associated with a high rate of congenital heart defects during pregnancy.

Experts believe that some prescription and over-the-counter medications and street drugs used during pregnancy increase the risk of heart defects.

There may be some hereditary factors that play a role in congenital heart disease. Genetics does appear to play a role in many diseases, and multiple family members may be affected. Talk to your doctor about screening.

Expectant mothers should receive good prenatal care. Many congenital defects can be discovered on routine ultrasound examinations performed by an obstetrician. The delivery can then be anticipated and the appropriate medical personnel (such as a pediatric cardiologist, a cardiothoracic surgeon, and a neonatologist) can be present, and ready to help as necessary. Such preparation can mean the difference between life and death for some babies.

Congenital Heart Disease At A Glance

• Congenital heart defects are problems with the heart's structure that are present at birth. Congenital heart defects change the normal flow of blood through the heart.
  
  
• Congenital heart defects are the most common type of birth defect, affecting 8 out of every 1,000 newborns. Each year, more than 35,000 babies are born with congenital heart defects.
  
  
• There are many types of congenital heart defects ranging from simple to very complex.
  
  
• Doctors don't know what causes most congenital heart defects. Heredity may play a role.
  
  
• Although many heart defects have few or no symptoms, some do. Severe defects can cause symptoms such as:
  
  
• Rapid breathing.
  
  
• A bluish tint to skin, lips, and fingernails. This is called cyanosis.
  
  
• Fatigue (tiredness).
  
  
• Poor blood circulation.
  

• Serious heart defects are usually diagnosed while a baby is still in the womb or soon after birth. Some defects aren't diagnosed until later in childhood, or even in adulthood.
  
  
• An echocardiogram is an important test for both diagnosing a heart problem and following the problem over time. This test helps diagnose problems with how the heart is formed and how well it's working. Other tests include EKG (electrocardiogram), chest x ray, pulse oximetry, and cardiac catheterization.
  
  
• Doctors treat congenital heart defects with catheter procedures and surgery.
  
  
• Treatment depends on the type and severity of the defect.
  
  
• With new advances in testing and treatment, most children with congenital heart defects grow into adulthood and can live healthy, productive lives. Some need special care all though their lives to maintain a good quality of life.