Patient
Information
Supraventricular Tachycardia (SVT)
- General Information
Supraventricular tachycardia SVT is
a very common condition in which the heart suddenly goes very fast
(often over 200 beats per minute), and just as abruptly goes back
to a normal rate. The actual heart rate is usually the same for
each episode for a given person - If the heart rate was 210 the
first time, it will almost always be 210 every time. Depending on
how fast the rate is, and how long the episodes last, people with
SVT can experience a sensation of a racing heart, dizziness,
shortness of breath or chest pain. If SVT lasts a very long time
(days or more), the heart can be injured by the fast rate, but
usually SVT has no adverse effects on the heart.
Some people with SVT also have a
condition called Wolff-Parkinson-White Syndrome (WPW). Their SVT
is very much like anyone else's, but they have special issues that
bear on whether to proceed with radio frequency ablation (see
below).
SVT is usually triggered by a
premature heartbeat, not (as is commonly supposed) by activities
like exercise that make your heart go faster otherwise. Most
people have some premature heart beats over the course of a day,
most commonly at times when their heart is beating at a somewhat
slower rate (reading, watching TV) or when their heart is slowing
down (such as after exercise). Some people have more premature
beats, and more episodes of SVT, when they are excited, or if they
have a stimulant on board such as caffeine or certain stimulant
medications.
It is very hard to try to avoid SVT
by limiting a child's activities. First of all, it almost never
works, and can even backfire if a child becomes angry at being
told not to run or "get wild". Second, it sends a child
the message that they can't do things that other children can,
which may harm their self-esteem. Finally, it creates a lot of
tension between a child and his or her family, since children need
to assert some control over what they do as a natural part of
development.
The most useful measures for
controlling SVT in most children are vagal maneuvers, such as
bearing down (making your face red), hanging upside down, or ice
water pack to the forehead and bridge of the nose (for no more
than 30 seconds), etc. If SVT is interfering with a child's life,
or is thought to be a safety risk by their cardiologist, one can
consider eliminating the cause using catheter-delivered radio
frequency ablation. There are only a small number of centers with
a large experience with this procedure in children, but it is
probably important to seek one out if this procedure is necessary
for you or your child, and you don't happen to live near one.
Medications are a solution if the episodes are interfering with a
child's quality of life, or are concerning from a safety
perspective, particularly if RFA is not thought to be a good
solution or is not available.
Very often, people with SVT will
have episodes of tachycardia for a period of time (months to
years), followed by a period of time without any episodes. This is
particularly common in childhood, and many children with SVT in
infancy have no episodes later in life. Because of the tendency
for SVT to go away, it often makes sense to "live with
it" if the episodes are felt to be safe, and the symptoms are
controllable or bearable, rather than rush to RFA or medications.
Some Internet links that may be
helpful include:
American
Heart Association
About.com
A number of articles about SVT and WPW
Advocate Health Care
Health Square
Oxygen Thrive Online
EarthLink
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