What Is Tetralogy Of Fallot?

Tetralogy Fallot

As you might know by now, a baby’s organs start developing in the early weeks of pregnancy. Considering that babies grow into complex human beings after starting out as a couple of cells, it’s pretty amazing that perfectly healthy babies are born all the time.

Unfortunately, this isn’t always the case. Sometimes babies are born with congenital defects, or abnormalities in the way their organs form. One such abnormality of the heart is called “Tetralogy of Fallot.” Fortunately, it’s not common. According to the CDC, 1 in every 2518 babies born in the US each year have this condition.

What Is It?

The heart is a complicated organ, so what exactly does this mean? Tetralogy of Fallot is diagnosed when these 4 particular defects in the heart are found:

  1. A hole in the septum (wall) between the ventricles (lower chambers of the heart)
  2. Stenosis (narrowing) of the pulmonary valve and artery – this artery is the major blood vessel that goes from the heart to the lungs, and the valve connects the two
  3. Enlargement of the right ventricle walls
  4. Abnormal placement of the aorta – it normally leads from the left ventricle to the body, but in this case, it sits above the septum with the hole (see #1)

These defects can occur alone or accompany other heart problems or health conditions.

If you haven’t already, you can check out this blog post on heart murmurs, which nicely describes how the heart works. Due to the structural problems of Tetralogy of Fallot listed above, the baby’s heart is not able to get enough oxygenated blood to the rest of the body. That in itself is a major problem, but in addition, it also makes the heart work too hard.

How Is It Diagnosed?

Tetralogy of Fallot can be diagnosed during pregnancy with imaging. If certain characteristics are noted on ultrasound, the next step may be to get a fetal echocardiogram. An echocardiogram is an ultrasound test specifically for the heart that can evaluate the structure of the heart and blood flow patterns.

In many cases, this condition is not diagnosed until after birth. Infants with Tetralogy of Fallot often develop blue-tinged skin, nails, and/or lips, especially when feeding or crying. These episodes are called “tet spells” and are due to the lack of oxygen in the blood. Babies can also have shortness of breath, trouble gaining weight, fainting spells, irritability, or a heart murmur. Additionally, low oxygen levels can be detected in a baby with pulse oximetry, which uses a small, non-invasive device on the baby’s toe or finger.

If it’s less severe, Tetralogy of Fallot can go undetected into early childhood (or even adulthood!). Toddlers may frequently squat down while playing, which increases blood flow to the heart. When this condition is suspected, an echocardiogram or other tests can confirm the diagnosis.

What Causes It?

As mentioned previously, Tetralogy of Fallot occurs when the heart does not form properly in utero. Although genetic and environmental conditions are suspected, the exact cause is unknown. Some factors during pregnancy might increase a woman’s risk of having a baby with Tetralogy of Fallot, such as:

  • Viral illness (possibly mumps)
  • Age > 40 years
  • Poor nutrition
  • Alcohol use

A parent with Tetralogy of Fallot is also at higher risk of having a baby with it.

How Is It Treated?

Fortunately, the outlook for babies diagnose with Tetralogy of Fallot has improved greatly in recent decades. Currently, it is recommended that Tetralogy of Fallot be corrected with surgery in the first 6 months of life order to repair the structural problems in the heart. Throughout life, those affected should have regular follow-up with a cardiologist to monitor progress and watch for complications. These can include:

  • Infective endocarditis (infection of the inside of the heart)
  • Leaky valves
  • Narrowed valves or arteries
  • Arrhythmias (electrical abnormalities of the heart)

After surgery, some children may need to follow activity restrictions or avoid certain sports. Occasionally, additional surgery is needed later in life. But the good news is that with surgery and regular medical care, most infants can grow to lead healthy lives.

Mandy Armitage
Dr. Mandy Armitage is a board-certified physician and writer. She is passionate about education, for patients and clinicians alike. In her free time, she enjoys spending time with her family, reading, traveling, and attending live music events.

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