Tetralogy of Fallot

Tetralogy of Fallot is a rare condition that is characterized by four related structural heart defects that are present at birth and often diagnosed in babies and toddlers. This group of defects cause oxygen-poor blood to flow out of the heart and to the rest of the body.

About Tetralogy of Fallot

During the first eight weeks of pregnancy, the heart’s four chambers develop from a hollow tube and the four structural heart problems that make up tetralogy of Fallot can develop at this time. Some babies have additional heart defects, such as atrial septal defect.

The four defects of tetralogy of Fallot include:

• Overriding Aorta: The aorta is attached slightly to the right of the left ventricle (where it is normally). An overriding aorta aligns with the ventricular septal defect and sends mixed blood to the body.
• Pulmonary Stenosis: A narrow pulmonary valve, which connects the right ventricle to the pulmonary artery and a narrow area before and after the valve. Pulmonary stenosis restricts blood flow from the heart to the lungs.
• Right Ventricular Hypertrophy: Because the heart cannot pump properly, the right ventricle can become enlarged from overwork. The muscular wall of the ventricle thickens and may eventually stiffen and weaken.
• Ventricular Septal Defect: An opening in the wall that separates the lower chambers (ventricles) of the heart. A ventricular septal defect allows oxygen-poor and oxygen-rich blood to mix potentially impeding the body from getting enough oxygen.
  

Children who have tetralogy of Fallot cannot deliver enough oxygenated blood to the body and as a result, the skin, lips, and nails may look blue (cyanosis). After feeding, crying, or becoming agitated, your child may suddenly experience severe cyanosis, known as tetralogy (or “tet”) spells. A tetralogy spell is triggered by a quick, substantial drop in the amount of oxygen in the blood. The decline may be caused by higher pressure in the lungs or a tighter passageway existing between the right ventricle and the pulmonary artery.

The exact cause of tetralogy of Fallot isn’t known; however, a baby may be at higher risk due a viral illness, a genetic condition, poor maternal nutrition, fetal alcohol syndrome, or the mother taking seizure medication during pregnancy. Diagnosis may be delayed if your child has mild tetralogy of Fallot and no symptoms. With early intervention, most children who have Tetralogy of Fallot can lead active lives.

Symptoms of Tetralogy of Fallot

Tetralogy of Fallot symptoms vary depending on the severity of the defects.

Tetralogy of Fallot symptoms may include:

• Blue-tinged skin, lips, and nails when the baby cries or feeds
• Cool, clammy skin
• Heart murmur
• Irritability
• Lethargy
• Pale, ashen skin
• Poor growth
• Tet spells
• Trouble breathing or feeding

Diagnosing Tetralogy of Fallot

Tetralogy of Fallot may be diagnosed soon after birth if your doctor notices a blue tinge to your baby’s skin or hears a heart murmur, which are extra sounds heard throughout the cardiac cycle due to increased blood flow.

Tests performed when diagnosing Tetralogy of Fallot may include:

• Cardiac Catheterization: During cardiac catheterization, a small catheter (thin tube) is inserted into a larger blood vessel, typically in the groin, and guided to the heart where blood pressure and oxygen measurements can be taken in the aorta and pulmonary artery as well as the four chambers of the heart. A dye can also be injected through the tube to make the heart’s structure more visible on an X-ray.
• Chest X-Ray: A chest X-ray produces an image of the tissue and bones in the heart and lungs and helps your provider assess the shape, size, and structure of the heart and lungs as well as the aeration of or any congestion in the lungs. Tetralogy of Fallot can make the right ventricle bigger than normal, giving the heart a characteristic boot shape.
• Echocardiogram: An echocardiogram uses ultrasound technology to create a moving image of the heart and its valves, allowing your provider to assess the structure and function of the heart. An echocardiogram also helps provide information about blood flow and how well the heart is pumping blood.
• Electrocardiogram (ECG or EKG): An electrocardiogram uses electrodes that are placed on the body to record the electrical activity taking place in the heart. An ECG/EKG test helps detect abnormal rhythms, such as cardiac arrhythmias, stress on the heart, and damage to the heart muscles.
• Pulse Oximetry: A pulse oximeter, or oxygen saturation test, is an electronic tool used to measure oxygen in the bloodstream. The oxygen level of patients with tetralogy of Fallot is frequently (but not always) lower than normal. A critical congenital heart disease (CCHD) screening, performed on all healthy newborns by checking the oxygen saturation prior to discharge from the hospital, will frequently demonstrate a problem with the oxygen level in the absence of other symptoms.

Treating Tetralogy of Fallot

Tetralogy of Fallot is treated with surgery, typically before your baby turns one year of age, to repair the defects. Your pediatric cardiologist may recommend performing the surgery at three to six months of age. A temporary shunt may be placed during an earlier procedure to improve oxygenation until your baby is old enough to undergo a more extensive surgery.

To repair tetralogy of Fallot, a pediatric heart surgeon places a patch over the ventricular septal defect, opens the pulmonary valve, or enlarges the pulmonary artery with a patch.

Most babies recover well after treatment for tetralogy of Fallot, but there can be lifelong complications, such as an irregular heartbeat, restricted blood flow, or a leaky heart valve. Your pediatric cardiologist may recommend restrictions on activity and follow-up care for the rest of your child’s life.

Care Team Approach

The Texas Center for Pediatric and Congenital Heart Disease, a clinical partnership between Dell Children’s Medical Center and UT Health Austin, takes a multidisciplinary approach to your child’s care. This means your child and your family will benefit from the expertise of multiple specialists across a variety of disciplines. Your care team will include pediatric cardiologists, cardiothoracic surgeons, interventional cardiologists, critical care specialists, hospitalists, anesthesiologists, perfusionists, nurses, advanced practice providers, social workers, psychologists, child life specialists, dietitians, physical and occupational therapists, pharmacists, and more, who work together to provide unparalleled care for patients every step of the way. We collaborate with our colleagues at the Dell Medical School and The University of Texas at Austin to utilize the latest research, diagnostic, and treatment techniques, allowing us to identify new therapies to improve treatment outcomes. We are committed to communicating and coordinating your child’s care with referring physicians and other partners in the community to ensure that we are providing comprehensive, whole-person care.

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