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Congenital heart disease

Atrial septal defect
An atrial septal defect (ASD) is a group of congenital heart diseases that involve the inter-atrial septum of the heart. The inter-atrial septum is the tissue that separates the right and left atria from each other. Without this septum, or if there is a defect in this septum, it is possible for blood to travel from the left side of the heart to the right side of the heart, or the other way around. There are many types of atrial septal defects. They are differentiated from each other by whether they involve other structures of the heart and how they are formed during the developmental process during early fetal development.
Ventricular septal defect
A ventricular septal defect is an opening in the ventricular septum, or dividing wall between the two lower chambers of the heart known as the right and left ventricles. VSD is a congenital (present at birth) heart defect. As the fetus is growing, something occurs to affect heart development during the first 8 weeks of pregnancy, resulting in a VSD. Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped out to the body through the aorta.
Patent ductus arteriosus
Patent ductus arteriosus (PDA) is a congenital heart defect wherein a child's ductus arteriosus fails to close after birth. Symptoms include shortness of breath and cardiac arrhythmia, and may progress to congestive heart failure if left uncorrected. In the developing fetus, the ductus arteriosus (DA) is a shunt connecting the pulmonary artery to the aortic arch that allows much of the blood from the right ventricle to bypass the fetus' fluid-filled lungs. During fetal development, this shunt protects the lungs from being overworked and allows the right ventricle to strengthen.
Bicuspid aortic valve
Bicuspid aortic valve is the most common type of aortic valve abnormality occurring in about two percent of the population. Instead of the normal three leaflets or cusps, the bicuspid aortic valve has only two. Bicuspid aortic valve is a condition that affects 1-2% of the population. It is more common in males than females. Usually, this defect does not produce problems, although there is the possibility that in later life it could begin to cause some symptoms of 'aortic stenosis'. About a third of people affected have quite normal function throughout their lives, while others suffer symptoms in varying degrees.
Tetralogy of Fallot
Tetralogy of Fallot is the most common form of cyanotic congenital heart disease. Cyanosis is the abnormal bluish discoloration of the skin that occurs because of low levels of circulating oxygen in the blood. Tetralogy of Fallot consists of the combination of four different heart defects: a ventricular septal defect (VSD); obstructed outflow of blood from the right ventricle to the lungs (pulmonary stenosis); a displaced aorta, which causes blood to flow into the aorta from both the right and left ventricles (dextroposition or overriding aorta); and abnormal enlargement of the right ventricle (right ventricular hypertrophy).
Transposition of the great vessels (TGV)
Transposition of the great vessels (TGV) is a form of congenital heart disease, in which the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle, with an associated intracardiac shunt. In normal individuals, oxygen-depleted blood from the right ventricle goes through the pulmonary artery to the lung to get oxygenated. The oxygen-rich blood goes to the left ventricle, from which it gets ejected to the aorta to the rest of the body. In individuals with TGV, the oxygen-depleted blood from the right ventricle goes directly to the aorta to supply the rest of the body. This is not compatible with life, since the body would never get oxygen-rich blood.
Congenital heart disease (CHD) is a broad term that can describe a number of different abnormalities affecting the heart. Congenital heart disease is, by definition, present at birth although its effects may not be obvious immediately. In some cases, such as coarctation of the aorta, it may not present itself for many years and a few lesions such as a small ventricular septal defect (VSD) may never cause any problems and are compatible with normal physical activity and a normal life span. Congenital heart disease is a defect of the heart that exists at birth. One percent of babies are born with a heart defect. Sometimes the defect improves without treatment. At other times the defect is small and does not require treatment.

There are many different birth defects that can affect the heart. For example, the valves of the heart may be missing or not work properly. In other cases, there may be holes in the walls of the heart or abnormal connections between blood vessels and the heart. The defects may be mild and cause no problems. Or they may be life threatening and require surgery hours after birth. Some common congenital heart defects include: • atrial septal defect, which is an abnormal opening between the two upper chambers of the heart • ventricular septal defect, which is an abnormal opening between the two lower chambers of the heart • tetralogy of Fallot, which is a set of four typical heart abnormalities • coarctation of the aorta, which is a narrowing of the aorta • pulmonary atresia, which is an abnormality of the opening between the heart and the arteries to the lungs • patent ductus arteriosus, which is an abnormal opening between the aorta and the artery to the lung • transposition of the great vessels, which is a switch in the normal positions of the aorta and the artery to the lung.

Congenital heart defects occur while the fetus is developing in the uterus and affect 8-10 out of every 1,000 children. Congenital heart defects may produce symptoms at birth, during childhood and sometimes not until adulthood. Congenital heart defects are classified into two broad categories: acyanotic and cyanotic lesions. The most common acyanotic lesions are ventricular septal defect, atrial septal defect, atrioventricular canal, pulmonary stenosis, patent ductus arteriosus, aortic stenosis and coarctation of the aorta. Congestive heart failure is the primary concern in infants with acyanotic lesions. The most common cyanotic lesions are tetralogy of Fallot and transposition of the great arteries. In infants with cyanotic lesions, hypoxia is more of a problem than congestive heart failure. Suspicion of a congenital heart defect should be raised by the presence of feeding difficulties in association with tachypnea, sweating and subcostal recession, or severe growth impairment. Follow-up of infants with congenital heart disease should follow the schedule of routine care for healthy babies with some modifications, such as administration of influenza and pneumococcal vaccines. More frequent follow-up is required if congestive heart failure is present.

Congenital heart disease can have diverse causes. The causes include environmental factors (such as chemicals, drugs or infections), certain maternal diseases, chromosome abnormalities, genetic diseases, and unknown (idiopathic) factors.

The vast majority of congenital heart defects have no known cause. Mothers will often wonder if something they did during the pregnancy caused the heart problem. In most cases, nothing can be attributed to the heart defect. Some heart problems do occur more often in families, so there may be a genetic link to some heart defects. Some heart problems are likely to occur if the mother had a disease while pregnant and was taking medications, such as anti-seizure medicines. However, most of the time, there is no identifiable reason as to why the heart defect occurred.

Congenital heart problems range from simple to complex. Some heart problems can be watched by the baby's physician and managed with medicines, while others will require surgery, sometimes as soon as in the first few hours after birth. A baby may even "grow out" of some of the simpler heart problems, such as patent ductus arteriosus (PDA) or atrial septal defect (ASD), since these defects may simply close up on their own with growth. Other babies will have a combination of defects and require several operations throughout their lives.

Environmental factors sometimes are at fault. For example, if a mother catches German measles (rubella) during pregnancy, the infection can impair the development of her unborn baby's heart (and other organs). If the mother consumes alcohol during pregnancy, the fetus can suffer from fetal alcohol syndrome (FAS) including CHD.

Symptoms and signs of congenital heart disease are related to the type and severity of the heart defects. Some children have no symptoms or signs while others may develop shortness of breath, cyanosis (blue discoloration of skin due to decreased oxygen in the blood), chest pain, syncope (passing out), poor feeding, or poor growth. It is tremendously variable. Atrial septal defect (a hole in the wall between and left and right atria), for example, may cause few or no symptoms. The defect may go undetected for decades. Aortic stenosis (obstruction to blood flow across the aortic valve due to abnormal valve cusps) also commonly causes no symptoms, especially when the stenosis (norrowing) is mild. In the rare severe cases of aortic stenosis, symptoms can appear during infancy and childhood. These symptoms may include fainting spells, dizziness, chest pain, shortness of breath, and unusual tiring. Ventricular septal defect (VSD) is another example where symptoms are related to the severity of the defect. VSD is a hole in the wall between the two ventricles. When the defect is small, the children suffer no symptoms, and the only sign of VSD is a loud heart murmur. If the hole is large, the baby can develop heart failure, poor feeding and slow growth. In advanced cases with development of permanent pulmonary hypertension (severely elevated blood pressure in the arteries of the lungs), cyanosis can develop. Tetralogy of Fallot (TOF) is a heart defect where there is a combination of VSD and obstruction of blood flow out of the right ventricle. Cyanosis is common among babies and children with TOF. Cyanosis can appear soon after birth, with sudden episodes of severe cyanosis with rapid breathing, may even become unconscious. During exercise, older children with TOF may become short of breath and faint.

Treatment of congenital heart disease often involves open heart surgery to correct the heart defect. Sometimes more than one defect occurs at the same time and more than one operation is needed. With certain defects, medicine may be all that is needed. In others, no treatment other than observation is needed.

Topics in heart disease and cardiovascular disorders

Coronary circulation disorders
Myocardium disorders
Heart valve disorders
Arrhythmias (abnormal heart rhythms)
Heart inflammation and infection
Congenital heart disease
Valvular disease (blood vessels disorders)
Procedures done for coronary artery disease
Devices used in cardiology
Diagnostic tests and procedures for heart diseases
Heart transplant

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All information is intended for reference only. Please consult your physician for accurate medical advices and treatment. Copyright 2005,, all rights reserved. Last update: July 18, 2005