Tetralogy of Fallot: Information on Causes, Diagnosis & Treatments

Tetralogy of Fallot is a combination of four separate congenital heart defects, meaning that the condition developed while the child was in the womb. The defects affect the heart's function and structure that results in oxygen-depleted blood flowing out from the heart to the body. The condition is usually diagnosed in the days or weeks after the child is born. However, it can often go undetected until the patient reaches their teen years or adulthood, especially if the defects and associated symptoms are not severe.

Early diagnosis of tetralogy of Fallot usually necessitates a surgical repair to ensure that the child can live a relatively normal life involving routine medical care and restrictions on certain physical activities. Without treatment in severe cases, the condition is fatal. Surgical options can repair each of the four heart defects associated with the condition that includes:

1. A hole that developed between the left and right ventricles leading to VSD (ventricular septal defect)
2. A thickened right ventricle
3. A narrowing of the pulmonary outflow tract that connects the lungs to the heart
4. The shifted orientation of the aorta that developed over the ventricular septal defect

While the condition is rare, it is often easily identified within the first few hours or days after birth due to cyanosis, where the child's skin takes on a bluish gray tint due to the lack of oxygen circulating throughout the body.

• Who Is at Risk for Tetralogy of Fallot?
• Common Symptoms
• Diagnosing Tetralogy of Fallot
• Treating the Condition

Who Is at Risk for Tetralogy of Fallot?

Because the condition is congenital, meaning that children are born with the disease, any baby can develop tetralogy of Fallot. In fact, medical science has yet to determine the exact cause of the condition. However, there are likely certain risk factors associated with mothers birthing children with the condition. The risks might involve:

• Excessive alcohol consumption while pregnant


• Acquiring German measles (rubella) or other viral illness while pregnant


• The mother's poor nutrition while pregnant


• Family heredity where one or both parents were born with tetralogy of Fallot


• Pregnant mothers who are 40 years or older


• Babies who are born with other defects including DiGeorge syndrome and Down syndrome

Complications

If the child never received treatment for their tetralogy of Fallot condition, they will likely not develop or grow properly. In addition, these babies tend to develop serious complications including infectious endocarditis where the heart or heart valve becomes infected with harmful bacteria. In addition, cases of tetralogy of Fallot that go untreated often cause severe complications as the child ages that could result in significant disabilities or death.

Many children who are born with tetralogy of Fallot also develop other heart defects including a hole in the upper chambers of the heart (atrial septal defect).

Common Symptoms

The most common symptoms associated with tetralogy of Fallot will reveal themselves at birth or develop within a few days or weeks after the child is born. The severity of the symptoms is based on the extent of the restricted blood flow from the heart's right ventricle that leads out to the lungs. Common tetralogy of Fallot symptoms involve:

• Cyanosis where the baby's skin, lips or nails develop a bluish or grayish coloration


• Fainting caused by a loss of consciousness


• Rapid breathing or shortness of breath during physical movement or feeding


• Poor weight gain


• Abnormally rounded nail beds on the toes and fingers (clubbing)


• Prolonged crying


• Tiring easily with physical movement


• Heart murmur

Many of these conditions, especially cyanosis, develop within minutes of feeding or crying. The body typically experiences a rapid drop in oxygen levels in the bloodstream. Some children and toddlers develop an instinctive squat whenever experiencing a shortness of breath that allows an increased flow of blood into the lungs.

Some babies are sent home without ever being diagnosed with tetralogy of Fallot and will only begin revealing many of the common signs and symptoms associated with the condition after leaving the hospital. If the child experiences any of the symptoms listed below, the parent should seek out immediate medical attention by calling 911 or taking the child to the emergency room. The serious symptoms include:

• Difficulty in breathing


• Overall weakness


• Seizures or passing out


• Cyanosis where the skin takes on a bluish or grayish discoloration


• Unusual irritability

Placing the child on their side and pulling up on the knees to the chest helps increase the flow of blood to the lungs.

Diagnosing Tetralogy of Fallot

There may be suspicious indicators that the child was born with tetralogy of Fallot or another heart defect if their skin has a blue tint or the doctor hears a heart murmur during a physical examination. The murmur is usually the result of turbulent blood flow that causes an abnormally loud whooshing sound in the newborn's chest.

To validate a diagnosis of tetralogy of Fallot, the newborn's cardiologist will likely order various diagnostic tests that include:

• Echocardiogram – This machine uses sound ways to produce moving images of the heart muscle can be viewed on a monitor. In diagnosing the condition, the doctor can determine the location and severity of a ventricular septal defect in the structure of the pulmonary artery and pulmonary valve. This test can also identify the functioning of the right ventricle and reveal if the aorta is positioned in the proper location.


• Electrocardiogram – This machine records the heart a positive electrical activity while contracting. The doctor will use this information to determine if the child's right ventricle has become too enlarged causing right ventricle hypertrophy. This test can also reveal if the right atrium has become enlarged or identify and arrhythmias (abnormal heart rhythm).


• Chest X-Ray – Taking an x-ray of the chest can provide a still image of the child's lungs and heart. Usually, an indicator of tetralogy of Fallot in the x-ray image is revealed as a "boot shape" heart due to the enlargement of the right ventricle.


• Pulse Oximetry – The doctor can measure the oxygen level of the heart and lungs delivered throughout the body. A small sensor placed at the end of the tow her finger can measure oxygen levels in the bloodstream.


• Cardiac Catheterization – The doctor may feed a flexible, thin catheter (tube) in the vein or artery of the child's neck, growing, or arm that is spread into the heart muscle to measure oxygen and pressure levels and determine the function of the blood valves in the chambers of the heart.

Treating the Condition

Typically, surgery is the only effective solution for successfully treating tetralogy of Fallot. This might include a temporary repair involving a shunt before an intracardiac repair can be performed later in life. Extensive testing will need to be performed before the surgeon can make an accurate recommendation on the appropriate surgical procedures required to improve the child's condition.

Many complications can develop after surgery including chronic pulmonary regurgitation, arrhythmias (irregular heartbeats) and aortic group dilation that involves an enlargement of the ascending aorta. Nearly all children born with tetralogy of Fallot require lifelong care with a competent cardiologist who specializes in congenital heart diseases. Usually, the child will be restricted in their physical activities especially if they suffer from arrhythmias, pulmonary obstructions, or leakage.

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Sources:

http://www.mayoclinic.org/diseases-conditions/tetralogy-of-fallot/basics/definition/con-20043262

https://my.clevelandclinic.org/health/articles/pediatric-tetralogy-of-fallot

https://www.nhlbi.nih.gov/health/health-topics/topics/tof/causes

https://www.cdc.gov/ncbddd/heartdefects/tetralogyoffallot.html