Cardiology, Congenital Disorders

A quick review of the basics…

Congenital heart disease refers to cardiac defects that are often present at birth.  These can include abnormalities of the blood vessels, poorly functioning heart valves or anatomic defects of the heart such as a septal defect.

These may be asymptomatic or life-threatening abnormalities.  Some defects can be familial.  They can also be related to maternal malnutrition, infections and use of drugs or alcohol.  Genetic diseases such as Marfan’s syndrome, Turner’s syndrome and Down’s syndrome which have recognized patterns of congenital heart defects.

In general, defects can be grouped into either cyanotic or noncyanotic heart defects.

In cyanotic congenital disorders unoxygenated blood is moved from the right heart to the left heart thereby skipping the lungs and is then pumped out to the body.  Consider that if there isn’t adequate oxygen in the blood your patient is going to be cyanotic.  In these cases, you should think about 5 T’s. They are:  Transposition of the great arteries, Tetralogy of Fallot, truncus arteriosus, tricuspid valve abnormalities, and total anomalous pulmonary venous connection.  And, if you want to thank of a 6th T, consider Tons of others.

In noncyanotic congenital disorders the blood that is moved from the left heart to the right heart has skipped the body.

In that case we think of ventral septal defect, which is most common, abbreviated as VSD.  Ventral septal defect is patency between the ventricles.  This allows blood to move from the left ventricle to the right ventricle.  If there is a particularly large defect this would allow increased pressures from the left ventricle to affect the pulmonary arteries and cause congestion.  It also requires the heart work much harder than an anatomically normal heart would.  Some small VSD will eventually heal on their own.  Others require open heart surgery for repair.

Atrial septal defect, or ASD, is similar.  This is a congenital heart defect where there is communication or a hole between the atria.  Here we’re thinking of a hole in the septum between the right and the left atria.  And again, the oxygen-rich blood from the left atria mixes with the blood returning from the body, which is low in oxygen.  This may result in lower oxygen saturation.  These patients may be entirely asymptomatic, especially while still young.  In the patients that are symptomatic, usually as adults, patients may report dyspnea, peripheral edema, or recurrent lung infections.  On clinical examination you may find atrial arrhythmias, especially atrial fibrillation, congestive failure, pulmonary hypertension, mitral valve regurgitation, syncope or stroke.  On auscultation, you may find mid-systolic ejection murmur loudest over the second left intercostal space.

The next noteworthy noncyanotic congenital disorder is patent ductus arteriosus, where the ductus arteriosus fails to close at birth.  The ductus arteriosus is a blood vessel which runs between the main pulmonary artery and the proximal descending aorta, essential for fetal blood circulation.  In the developing fetus, this allows blood flow to bypass the nonfunctioning lungs.  More commonly discovered in premature newborns.  Presence after birth allows for blood flow between the aorta and pulmonary artery causing congestive heart failure.  These children may remain entirely asymptomatic through the first year.  Clinically, there may be a subtle finding such as low weight or perhaps dyspnea, especially with exertion.  You may find the children tachycardic.  Their heart murmur is described as mechanical.  Some children are monitored over time if they’re asymptomatic.  Intervention can be surgical, percutaneous interventional and some children are treated successfully with nonsteroidal anti-inflammatory meds and such as indomethacin or ibuprofen.

Atrioventricular canal defect is sometimes known as endocardial cushion defect.  This is another very rare cardiac congenital disorder.  Atrioventricular canal defect occurs in less than one out of every 5000 live births and is seen frequently with Down syndrome.  Think of it as a loss of separation between the four chambers of the heart so that blood is mixing freely with each heartbeat.  It’s also not a single defect.  You can think of it as one valve or a single patency between the atria or ventricles.

One notable syndrome in this category is:  Tetralogy of Fallot, like the name implies, is a syndrome where four features are present, including: #1, a hole exists between the ventricles or lower chambers of the heart, known as a ventral septal defect.  2, there is obstruction from the right heart ventricle to the lungs, or stenotic pulmonary valve.  3, the aorta is positioned over the ventricular septal defect, so the aorta is receiving blood from both the right and left ventricles.  This means that blood going to the body is mixed with both oxygenated and un oxygenated blood.  And lastly, number 4, there is right ventricular hypertrophy. This is a condition that affects boys and girls equally.  It is rather rare, affecting about one in 2000 babies.

Patients may or may not be asymptomatic early in the disease.  As they age, most will eventually become cyanotic especially under stress.  Babies may have difficulty with feeding and suffer failure to thrive.  Children with tetralogy of Fallot are usually small for their age.  Parents may report a history of the child squatting for relief of symptoms.

While the exact mechanism of squatting isn’t clear, children Tetralogy of Fallot seem to get transient relief in the squatting position.  At least part of that relief comes from no longer exerting themselves.  It is also thought that some blood which has been desaturated become somewhat trapped in the lower extremities temporarily relieving some burden on the heart.

On your PE: You may be able to appreciate an impulse along the left sternal border.  Patients typically have a harsh systolic crescendo-decrescendo holosystolic ejection murmur over the left sternal border.  In addition to cyanosis you may see clubbing.