Tetralogy of Fallot (ToF)
What is Tetralogy of Fallot?
Tetralogy of Fallot (ToF) is a rare but serious congenital heart defect that is made up of four different defects.
When a baby is born with ToF, they have these four defects:
Ventricular septal defect: A hole in the wall between the two lower chambers (ventricles) of the heart.
Pulmonary stenosis: A narrowing of the pulmonary valve and main pulmonary artery.
Ventricular hypertrophy: The muscular wall of the lower right chamber of the heart (right ventricle) is thicker than normal.
Overriding aorta: Occurs when the aortic valve, which opens to the aorta, is enlarged and seems to open from both ventricles, rather than from the left ventricle only, as in a normal heart. In this defect, the aortic valve sits directly on top of the ventricular septal defect.
ToF affects the structure of the heart, and alters the way blood flows through the heart to the rest of the body.
Tetralogy of Fallot is usually diagnosed during pregnancy or soon after a baby is born. However, if defects and symptoms are mild, ToF may not be noticed or diagnosed until adulthood.
What are the symptoms of Tetralogy of Fallot?
ToF symptoms will vary depending on how much blood flow is blocked from the heart to the lungs, but symptoms may include:
- Blue or gray skin
- Shortness of breath and rapid breathing, especially during feeding or exercise
- Trouble gaining weight
- Getting tired easily during play or exercise
- Irritability
- Crying for long periods of time
- Fainting
Some babies experience something called ‘tet spells’, where they suddenly develop blue or gray skin, nails and lips – usually when the baby is crying, eating or upset.
Tet spells (also known as cyanotic episodes, hypercyanotic spells or hypoxic spells) are caused by a rapid drop in the amount of oxygen in the blood.
Tet spells most commonly occur in babies aged 2-6 months.
What treatment options are there?
Surgery to treat Tetralogy of Fallot can include a temporary repair and a complete repair.Â
Temporary repair: Some infants with ToF may need a temporary repair, to improve blood flow to the lungs while waiting for open-heart surgery. A surgeon places a tube called a shunt between a large artery that comes off from the aorta and the lung artery, creating a new path for blood to go to the lungs. This surgery may be done if a baby is born early or if the lung arteries aren’t fully developed.
Complete repair: A person with Tetralogy of Fallot will need open-heart surgery to completely fix the heart.
A complete repair is usually done in the first year of life, though in rare occasions, a person may not have surgery in childhood if the condition goes undiagnosed or if surgery is not available.
A complete repair is done in several steps, The surgeon patches the hole between the lower heart chambers and repairs or replaces the pulmonary valve. The surgeon may remove thickened muscle below the pulmonary valve or widen the smaller lung arteries.
