Patient
Information
Tetralogy of Fallot
Tetralogy of Fallot (TOF) is one of the most common types of
heart disease in children requiring surgical repair. It consists
of a large hole between the two pumping chambers of the heart
(ventricular septal defect, or VSD) and a tightening of the area
leading out of the heart to the lungs (subvalvar pulmonary
stenosis). The rest of the tetralogy ("four findings")
don't make much sense to non-physicians as they are really
anatomic details: an overriding aorta, and thickening of the right
ventricle. Curiously, tetralogy of Fallot was not actually
discovered by Etienne-Louis Arthur Fallot, but it was named for
him because of a very good paper he wrote about it in 1888. It was
actually first described by a fellow named Stinson.
Although there are some more serious forms of TOF (including
TOF with pulmonary atresia, TOF with absent pulmonary valve and
TOF with other complex heart disease), most children with TOF do
not have very much pulmonary stenosis at birth, and may be
completely pink with no symptoms at all during the first few
months of life ("pink tetralogy"). However, the
pulmonary stenosis tends to gradually become worse over time, and
most children will eventually become somewhat blue (cyanotic), due
to blue (low oxygen) blood mixing with the pink (high oxygen)
blood within the heart. Children can be cyanotic from birth, or
can develop cyanosis gradually over time, usually within the first
year of life.
Because of the tendency for children to develop cyanosis,
tetralogy of Fallot is often classified as a type of
"cyanotic heart disease". There are many different types
of cyanotic heart disease, however, most of which are far more
severe than tetralogy of Fallot, so this is not a very useful
term.
Starting at about 6 months of age (occasionally sooner), a
child with the usual type of TOF may start to have "tetralogy
spells" ("tet spells" or "hypercyanotic
spells"). Tetralogy spells can be triggered by anger, pain,
feedings, a bath or even just waking up from a nap. During a
spell, a child becomes short of breath, deeply cyanotic (with very
low oxygen levels), irritable and even lethargic or unconscious.
The first step in treating a child having a tetralogy spell is to
place him or her in a fetal (knee-chest) position and keep them
calm and comfortable. Although children most often will come out
of a tetralogy spell on their own, tetralogy spells can be a real
medical emergency. Generally it's best to call an ambulance right
away unless a physician has specifically instructed otherwise.
There are medications that can reduce the risk of tetralogy
spells, but because of their side effects they are often not used
unless a child has spells at an earlier age than usual, or
develops spells before surgery is scheduled.
Prior to surgical repair, children with tetralogy of Fallot
must have a careful evaluation to outline all the details of their
condition. Some children may have an abnormal artery supplying the
heart itself with blood (conus coronary supplying the left
anterior descending artery), additional holes between the pumping
chambers, or abnormalities in the shape of the arteries to the
lungs, any of which might require a different type of surgery, or
surgery at a different age. Some centers obtain this information
by performing an echocardiogram (ultrasound of the heart) and a
cardiac catheterization, while others may perform only an
echocardiogram. In addition, a fraction of children with tetralogy
of Fallot also have a genetic condition known as DiGeorge syndrome
or velocardiofacial syndrome, related to a mutation on chromosome
22.
Surgical repair is required in every child with the usual type
of tetralogy of Fallot, unless such a procedure would carry too
high a risk for some reason. Because tetralogy spells can be
dangerous, most cardiologists would recommend surgical repair
within the first six months of life. In addition, there is
evidence that waiting for surgical repair until after a year of
age can increase the risk of serious cardiac complications,
including abnormal heart rhythms, later in life. For other types
of tetralogy of Fallot (listed above), surgery may be required
earlier or later, or may not be possible at all.
In the hands of a surgeon with a lot of experience in pediatric
heart surgery, the surgical repair of tetralogy of Fallot is
fairly low-risk, although of course all heart surgery entails some
risk. Following surgical repair, it is reasonable to expect that
children will have normal heart function and probably a normal
life expectancy. We really don't know this for certain, however,
as infant heart surgery has only been available for a few decades.
On the other hand, children with tetralogy of Fallot who do not
have surgical repair are very likely to have serious heart
problems by early adulthood, and in most cases probably would have
substantially reduced exercise tolerance, a low quality of life
with frequent hospitalizations, and a significantly shorter life
expectancy than other people. Approximately 40% of untreated
patients with TOF die within the first 4 years of life, 70% by 10
years, and 95% by 40 years. For this reason, given what we know,
surgical repair is the only sensible option.
For more information about tetralogy of Fallot, try some of
these web sites. I can't vouch for the quality of the material,
but I have reviewed each of them and haven't found any serious
problems with them.
Southern
Illinois University
Texas Heart Institute
eMedicine
University of
Michigan
PediHeart
DrKoop
American Heart Association
For more about DiGeorge syndrome:
NIH
GeneClinics
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