Congenital Heart Defects & Diseases

Continuing along the same lines of the fetal circulation transforming into post-natal circulation brings us to the topic congenital heart defects. Congenital heart defect means it is a problem with the structure of the heart and is present at birth. It is the most common type of defect at birth. The problem with the structure arises from the fetal circulation not correctly transitioning to a normal post-natal circulation.

The majority of the structural defects arise from a valve not shutting completely or at all. There are a variety of defects that can occur:

1. Atrial Septal Defect (ASD) also known as Patent Foramen Ovale

Remember the foramen ovale that connects the right atria and the left atria...while inside the mother, this should remain open to shunt blood away from the lungs. But after birth, this valve should shut. If the valve does not shut, blood can move from the left atria (oxygenated blood) to the right atria (deoxygenated blood), which causes too much pressure to build up in the lungs or from the right atria to the left atria. With a large shunt (large hole between the atria), a person will be significantly short of breath because blood can reverse directions. A small shunt may not even be discovered until later in life and generally does not cause any major problems. By itself, an ASD could have no symptoms but patients are at an increased risk for atrial fibrillation, heart failure, pulmonary hypertension, and stroke. Treatment is usually not necessary if the defect is minor; if the defect is large, a simple procedure done via a catheter can fix it.

2. Ventral Septal Defect (VSD)

During pregnancy, a fetus' heart does not have two separate ventricles. As the fetus grows, a ventral wall between the right and left ventricle will form to separate them. However, if the wall does not completely form, a hole remains and is called a ventral septal defect. A baby may have no symptoms but can be seen by an EKG; it also may close by itself. If the defect is too large, too much blood will be pumped to the lungs (from the left ventricle to the right and then to the lungs) and can lead to heart failure. If the defect is large, symptoms may arise, such as: shortness of breath, fast or hard breathing, paleness and fast heart rate. VSD is one of the most common congenital heart defects and often occurs with other heart defects. Treatment is usually not necessary if the defect is minor; if the defect is large, a simple procedure done via a catheter can fix it.

3. Coarctation of the Aorta

Coarctation means narrowing...thus coarctation of the aorta means narrowing of the aorta! This makes it difficult for blood and nutrients to pass to the rest of the body. It can be seen with other congenital heart defects and is more common in those with genetic disorders. There may be no symptoms but there may be symptoms of shortness of breath, chest pain, poor growth, nosebleed and dizziness. Coarctation of the aorta can be cured with surgery and the patient may need to be prescribed blood pressure medications.

4. Patent Ductus Arteriosus

Remember the ductus arteriosus artery that connects the pulmonary artery to the aorta in a fetus to shunt blood away from the lungs? Patent means open...patent ductus arteriosus means the ductus arteriosus has not closed completely after birth. The condition leads to abnormal blood flow between the aorta and pulmonary artery, two major blood vessels that carry blood from the heart. PDA affects girls more than boys and is common in premature infants and those born with other congenital heart defects. The usual goal of treating PDA is to close the valve. The exception is when other heart defects are present and the PDA is keeping the patient alive. Medications, catheter procedure or surgery are among the options to repair the PDA.

5. Pulmonary Atresia

Atresia means closed or blocked. Pulmonary atresia occurs when the pulmonary valve (from the right ventricle to the lung) does not form properly; thus, blood cannot flow to the lungs to become oxygenated. Someone with pulmonary atresia may also have a weak tricuspid valve (valve between the right atria and right ventricle) and may occur with VSD. Prostaglandins are usually given to move blood into the lungs to become oxygenated by keeping the ductus arteriosus open. Other treatments include heart catheterization or open heart surgery.

As you may have noticed, most of the congenital heart defects occur from valves that are inappropriately opened or closed or even the wrong size. I will list some of the diseases that may be commonly heard of and what exactly they entail:

1. Cyanotic Heart Disease

This is a congenital heart defect that results in low blood oxygen levels. Any abnormal blood flow through the heart can cause the blood to not be oxygenated to the appropriate level. This can cause the child's skin to appear blue on the lips, fingers and toes! Medications are often administered or may need surgery to repair the defect causing the oxygen levels to be low.

2. Dextrocardia

Strangley enough, someone's heart can be tilted incorrectly! The heart is pointed toward the right side of the chest rather than the left. Most types of dextrocardia also occur with other abdomen or heart problems. In a rare case, the heart and other organs can mirror what they normally look like. In this case, no treatment is needed. In addition, the abdominal and chest organs in babies with dextrocardia may be abnormal and may not work correctly. If heart defects are present along with dextrocardia, surgery and medications may be necessary.

3. Hypoplastic Left Heart Syndrome

Hypoplastic Left Heart Syndrome occurs when the left heart (ventricle, mitral valve, aortic valve and aorta) do not develop completely. This is very rare and occurs in males more often than females. It causes the ventricle and aorta to be smaller than normal, which leads to the heart being unable to send enough blood to the rest of the body and overloads the right ventricle by forcing it to fulfill the duties of supplying the lungs and the rest of the body with blood. This eventually leads the right heart into heart failure. If it is known that the baby has hypoplastic heart syndrome before birth, medication will be given to keep the ductus arteriosus open in order for the baby to stay alive. If the ductus arteriosus is allowed to close, the patient could quickly die. The baby may seem normal when born but could have symptoms of blue skin, cold extremities, lethargy, poor pulse or rapid breathing. A ventilator may be necessary to help the baby breathe and will soon need surgeries to fix the hypoplastic left heart syndrome.

4. Transposition of the Great Vessels

A congenital heart defect in which the two major vessels that carry blood away from the heart (the aorta and pulmonary artery) are switched....a major problem. In transposition of the great vessels, the blood goes to the lungs, picks up oxygen, and then goes right back to the lungs without going to the body. Blood from the body returns to the heart and goes back to the body without ever picking up oxygen in the lungs. The patient will most likely be blue, feed poorly, be short of breath and have clubbing of the fingers or toes. The infant will immediately receive prostaglandins, which keep the ductus arteriosus open, allowing some mixing of the oxygenated and deoxygenated blood. A cardiac catheterization and a surgery called arterial switch procedure will be needed to permanently correct the problem. This must be done within the first week of the baby's life.

5. Tricuspid Atresia

The tricuspid heart valve is the valve between the right atria and ventricle. Atresia means blocked or closed. In tricuspid atresia, the tricuspid heart valve is missing or is not completely developed. While rare, 20% of the patients with this condition will have other heart problems. Blood ultimately cannot enter the lungs to pick up oxygen; thus, the infant's skin will be blue (cyanotic). Being extremely short of breath, the baby will need to be put on a ventilator to help it breathe and prostaglandin is used to maintain circulation of blood to the lungs. This condition always requires surgery within the first few days of life. Three surgeries may be necessary, two of which are called the Glenn shunt and Fontan procedure.

6. Tetralogy of Fallot

Tetra=4....4 related defects of the heart and its major blood vessels:
a. VSD (hole between left and right ventricle)
b. Narrowing of the pulmonary outflow tract (the valve and artery that connect the heart with the lungs)
c. Overriding aorta that is shifter over the right ventricle and VSD, instead of only coming out from the left ventricle
d. Thickened muscular wall of the right ventricle (hypertrophy=larger than normal)

Cyanosis (blue skin), difficulty feeding, failure to gain weight, passing out, clubbing of fingers, and poor development are all symptoms of tetralogy of fallot. Surgery is always required to correct the heart's 4 defects, and usually multiple surgeries. Most cases can be corrected with surgery and the patient can live an active, healthy life.

Clearly, medications and surgeries are the answers to correcting the majority of the congential heart defects. And even more obvious, the tranformation of the heart from fetal circulation to post-natal circulation is of utmost importance for a normal, heart-healthy baby.