Schneider Children's Hospital; Cardiology, Abnormalities of the Heart

CARDIOLOGY

Abnormalities of the Heart
Anatomic Abnormalities of the Heart (Congenital Heart Disease)
The majority of anatomic heart problems in children referred to the Children's Heart Center are congenital, that is present before birth. The incidence of such abnormalities in the general pediatric population varies but is estimated to at 6 to 8 per thousand live births (0.6 % to 0.8 %). The more serious forms of such problems requiring medical or surgical care in the first year of life occur in approximately 1 per thousand live births (0.1 %). The genetics and inheritance of congenital heart disease are not completely understood. Some forms of structural heart abnormalities are associated with chromosome abnormalities (trisomy 21 and 18 as well as deficiency of chromosome 22), however, the majority occur sporadically with limited predictability.
Congenital heart problems in the pediatric, adolescent and fetal age groups consist of abnormalities in the formation and development of the heart and blood vessels of the cardiovascular system (cardio=heart, vascular=blood vessels). Anatomic heart problems may also be due to persistence, after birth, of cardiovascular structures needed only during fetal life. The more common anatomic problems of the heart include:

persistence of heart structure or blood vessel needed only during fetal life, (patent foramen ovale), (patent ductus arteriosus)

defects in the walls separating the upper or lower chambers, interatrial septal defect (ASD), interventricular septal defect (VSD)

abnormal size or development of the lower pumping chambers

small right pumping chamber (hypoplastic right ventricle), small left pumping chamber (hypoplastic left ventricle)

size or function of a heart valve, narrowing (stenosis) of the tricuspid, pulmonary, mitral or aortic valve

absence (atresia) of the tricuspid, pulmonary, mitral or aortic valve leaking of a heart valve (tricuspid valve, pulmonary valve, mitral valve or aortic valve regurgitation)

size or connection of the veins returning blood to the heart, abnormal connection of the lung veins (pulmonary veins) to the heart (anomalous pulmonary venous return), abnormal connection of the body veins (vena cava) to the heart

size of the arteries connecting the heart to the lungs or the body, stenosis of the pulmonary artery or aorta (coarctation), absence (atresia) of the pulmonary artery or aorta, enlargement of the aorta (Marfan's syndrome)

connection of the arteries to the heart, transposition of the great vessels, double outlet right ventricle

combination of abnormalities, tetralogy of Fallot, complete common atrioventricular canal, hypoplastic left heart complex, hypoplastic right heart complex, Shone's complex
The effect of these structural problems on a patient varies. A minor abnormality may have no effect on the patient. If the abnormality is more severe, however, the patient may appear blue in color (cyanosis), or be limited in the ability to feed, as an infant or to exercise, as a child or adolescent.
Cyanosis occurs when blood from the right side of the heart goes to the body instead of the lungs. While this can be a temporary finding in the hands and feet of a normal infant (acrocyanosis), persistence of cyanosis beyond the first days of life often indicates obstruction to blood flow to the lungs or an abnormal connection of the arteries to the heart. Cyanosis is often apparent with simply looking at the patient's skin color. More subtle lowering of the oxygen level in arteries can be identified with the use of a simple painless device, a pulse oximeter. The pulse oximeter that is applied to a finger or toe to measure the oxygen level of the blood reaching the muscles and organs of the body..
It is important to remember that there is considerable variation in the severity of many anatomic heart problems in pediatric patients. Defects in the walls separating the upper or lower chamber may be present but too small to effect the ability of the heart to pump blood to the body. A valve may have mild narrowing or a minimal leak with neither effecting heart function.
A frequent finding in normal pediatric patients and those with structural (anatomic) heart abnormalities is the presence of an extra sound, a heart murmur, heard when listening with a stethoscope. A heart murmur indicates turbulence of blood flow. It may be present in a structurally normal (functional or innocent murmur) or abnormal heart (organic murmur). It is easiest to understand the difference between a functional and an organic murmur if one thinks of the flow of water in a stream or small river. Usually the water moves along almost silently. After a rain storm or with the melting of winter snow the rapidly moving water creates a sound, the functional murmur of the stream or river. There is nothing wrong with the stream or river; it is just moving more water, more quickly. This is often the situation in the normal child or adolescent where the heart pumps blood quickly at rest or when a fever is present. In contrast, if the banks of the stream or river are narrowed (stenosis of the stream or river), there is greater turbulence of the water and a harsher noise is heard, the organic murmur of the stream or river.
Electrical Abnormalities of the Heart (Arrhythmias)
The electrical system of the heart includes a site in the right upper chamber that is primarily responsible for setting the rate of the heart beat, the pulse rate. This area is the heart's natural pacemaker and is called the sinus node. It regularly sends out an electrical impulse that spreads first through the upper and then lower chambers of the heart to activate the pumping of the muscle. Between the upper and lower chambers is a small biologic junction box (atrioventricular node) that controls the spread of the electrical activity to the lower pumping chambers..
The heart rate normally varies with age, activity and quality of heart function. The normal pulse rate is highest in the fetus and gradually declines to adult levels through late childhood and early adolescents. Abnormalities in heart rate and rhythm may be encountered at any age. The importance of such abnormalities depend on the how much they increase or decrease the heart rate, if one abnormal beat follows another for a prolonged period of time or if the patient has symptoms that may include decreased ability to exercise, dizziness, loss of consciousness (syncope) or even seizures.
Abnormalities in heart rhythm (arrhythmia) may be found in the fetus. Rare or isolated extra heart beats in the fetus are usually not an important clinical issue. In certain situations, however, the fetal heart may beat too rapidly (tachycardia) or slowly (bradycardia. Either problem, when prolonged, may result in swelling of the tissues in the fetus (hydrops fetalis) and influence obstetrical care. When the fetal heart rate is excessively fast, medication may be given to the mother that will cross the placenta and control the rapid fetal rate. The presence of an excessively slow fetal heart rate (bradycardia) might actually alter the medical care of the mother. A persistent, very slow fetal heart rate may be due to failure of the electrical impulse to pass through the junction box (atrioventricular node) connecting the electrical pathways of the upper and lower fetal heart chambers (complete heart block or third degree heart block). This is a common problem in adult patients that is but due to a much different cause in the fetus. In the fetus, this abnormal slowing of the heart rate is due to damage of the biologic junction box of the heart caused by antibodies formed by the mother. These maternal antibodies cross the placenta and react with the tissues of the heart, damaging the conduction system and sometimes irritating the heart muscle itself. The antibodies are present in the mother's circulation when the illness of the immune system known as with Systemic Lupus Erythematosis (SLE) is present. The first sign of Systemic Lupus Erythematosis in a woman may be congenital complete heart block in her fetus or newborn.
Abnormalities in electrical activity of the heart (arrhythmias) occur throughout the pediatric age group. They include isolated extra beats originating in the upper or lower chamber (premature heart beats), sustained rapid heart beats (tachycardia) originating in the upper or lower chambers of the heart (supraventricular tachycardia, ventricular tachycardia), slowing of the heart beat due to a problem in the natural pacemaker of the heart (sick sinus syndrome) or abnormal conduction of the electrical activity between the upper and lower chambers of the heart (heart block or Wolf-Parkinson-White Syndrome). Problems in the electrical activity of the heart may be reported as abnormal sensations in the chest (pounding, jumping, pain) by the child or adolescent or may be associated with dizziness, loss of consciousness (syncope) or, particularly in the younger child, unusual seizures. Rarely electrical activities may occur with medications whose side effects include changes in heart rhythm or with viral infections that cause inflammatior of the heart muscle or lining of the heart.
Acquired Heart Disease
Acquired pediatric heart disease refers to heart abnormalities in structure or function that are not present at birth. These problems are most commonly due to inflammation or infection of the heart muscle, heart valves, arteries that provide blood to the heart muscle itself (coronary arteries), or the sac that surrounds the heart (pericardium).

Rheumatic fever

Kawasaki Disease

Myocarditis

Pericarditis

Bacterial endocarditis
Rheumatic fever is a classic form of acquired heart disease. It is an immune mediated illness associated with inflammation of the heart muscle, heart valves and the lining of the heart due to antibodies formed after streptococcal infection, typically of the throat. Despite the frequency of streptococcal infection of the throat in the pediatric population, rheumatic fever and its associated inflammation of the heart muscle and valves is uncommon. When rheumatic fever does occur, the inflammation it causes can effect the mechanical pump function of the heart. The effected heart muscle does not contract properly and the valves of the left side of the heart (aortic and mitral valves) leak.
Other forms of acquired heart disease in the pediatric population include Kawasaki disease, viral myocarditis, Pericarditis and bacterial endocarditis. Kawasaki disease is an illness of uncertain cause occurring most commonly in younger children. It is associated with inflammation of the mouth, eyes, skin and lymph nodes. The most important effect in some, not all patients, of this illness is the inflammation of the arteries supplying (coronary arteries) blood to the heart muscle. This inflammation weakens the walls of the coronary arteries. This weakening may result in changes in the coronary arteries (aneurysms) that can alter blood flow to the muscles of the heart.
Viral myocarditis, another form of acquired pediatric heart disease, is an infection of the heart due to a virus. Viruses associated with common upper respiratory tract illnesses may infect and inflame the heart muscle. This problem is extremely rare given the frequency with which children experience common, self-limiting respiratory illnesses. While viral myocarditis may be silent and have no effect on heart function (asymptomatic), severe forms of the illness can cause considerable muscle damage and result in heart failure.
Pericarditis is another form of viral infection of the heart. In this illness the heart muscle is minimally affected despite inflammation of the sac (pericardium) that surrounds the heart. Inflammation of the pericardium is often associated with chest pain that worsens when the patient tries to lay flat on their back. Viral pericarditis is most often a self limiting illness that resolves with medications that control inflammation. It is uncommon in infants and young children.
Bacterial endocarditis is an infection of the heart. In the majority of cases, it occurs in patients with known congenital heart disease. Endocarditis occurs when abnormal blood turbulence due to structural heart disease allows bacteria in the blood stream to attach to adjacent heart structures and multiply. The resultant infection and inflammation damages the underlying heart tissue and may result in leaking of involved valves or abscess in adjacent heart muscle. The source of the bacteria may be bacteria normally present in the mouth which enters the circulation during dental procedures and is transported to the heart. Antibiotic pre-treatment (SBE prophylaxis) one hour prior to dental procedures reduces the risk of bacterial endocarditis in most patients with structural heart disease.