Arrhythmia
What is it?
An arrhythmia is an abnormal heart rhythm.
There are many different types of arrhythmias that
range from harmless to life threatening. An
arrhythmia can be regular, meaning it occurs at
evenly spaced intervals, or irregular, meaning it
has no pattern.
Who gets it?
Heart arrhythmia can occur in adults and children,
males and females. This health topic
concerns arrhythmia in children.
What causes it?
To understand what causes arrhythmia, it's
important to understand how the heart works.
The heart has four chambersÑthe right and left
atria, and the right and left ventricles. In
simple terms, the muscular walls of the heart
contract with every heartbeat to circulate blood
through the heart's chambers and out to the body's
major organs. The heartbeat is triggered by
an electrical impulse that travels through the
chambers and makes them contract. The most
common cause of arrhythmia in children is
premature beats or extra beats. Premature
atrial contractions (PACs) start in the upper
chambers of the heart. Premature ventricular
contractions (PVCs) start in the ventricles.
Often, doctors find no cause for childhood
arrhythmia and the child eventually outgrows it.
However, arrhythmia can be caused by heart
disease, a congenital heart defect, injury to the
heart, anemia, or a thyroid disorder, and should
always be diagnosed and treated appropriately.
What are the symptoms?
The most obvious symptom of arrhythmia is the
heart rate. It can be too fast, called
tachycardia. In a newborn, that would be a
resting heart rate of more than 160 beats a
minute. A teenager has tachycardia if his or
her resting heart rate is more than 100 beats per
minute. An increase in heart rate with
fever, excitement, or exercise, however, is
normal. This is called sinus tachycardia.
A heart rate that is too slow is called
bradycardia. On average, a newborn's resting heart
rate shouldn't be lower than 80 beats a minute.
A physically fit adolescent will usually have a
resting heart rate of around 50 beats a minute.
When an arrhythmia affects the heart's ability to
pump blood, it can produce other symptoms,
including dizziness, light-headedness, and
fainting (called syncope). Infants with
arrhythmia may seem fussier or sleepier than
usual. Children may tire easily, complain of
upset stomach, and may actually be able to feel
abnormal heart palpitations.
How is it diagnosed?
Because many arrhythmias have no noticeable
symptoms, they are usually discovered during a
child's regular check-up. If your doctor
suspects an arrhythmia, he or she may use a
variety of tests to arrive at a definite
diagnosis. He will also refer you to a heart
specialist, called a cardiologist. The
commonly used test is an electrocardiogram (ECG or
EKG). In this painless test, the doctor
places small, sticky patches, called electrodes,
on the child's arms, legs, and chest. As the
heart beats, a machine connected to the electrodes
records the heart's rhythm and charts a picture of
it. The ECG records three major waves of
electric signals. The P wave shows the
electrical activity of the atria; the QRS wave
shows the electrical activity of the ventricles,
and the T wave shows the heart's return to the
resting state. The doctor can study the
shape and size of the waves, the time between
waves, and the heartbeat's rate and regularity.
However, the ECG shows the heart's rhythm only
over a short period of time. To get even
more information about the heart's rhythm, your
child may wear a Holter monitor over a period of
24 hours. With a holter monitor, electrodes
are again stuck to the chest. This time the
electrodes are connected to a portable,
battery-operated recorder that is carried in a
pouch with the child. Your child can go
about his or her normal activities. The data
on recorder is then analyzed to get a complete
picture of the heart's rhythms. If your
child is older and your doctor wants to see
whether the arrhythmia changes with exercise, he
or she may order a test where your child walks and
runs on a treadmill or rides a stationary bicycle.
Again, electrodes transmit data about the heart's
rate and rhythm. In cases where your child's
arrhythmia is very infrequent, the doctor may use
a transient event monitor. Over a period of
several months, you attach this monitor to your
child whenever he or she has symptoms, and the
data is recorded and stored. Another type of test
is called an echocardiogram. This test uses
sound waves to show the heart's size, structure,
and activity. If your child's symptoms have
included frequent fainting, a tilt test can show
how the child's heart and blood pressure react to
changes in position. Your child may have an
intravenous (IV) placed in a vein before this
test. If the tilt test causes dizziness and
fainting, medication can be given quickly through
the IV to stop the symptoms. In some cases
of tachycardia, your doctor may use more invasive
tests to pinpoint the type and cause of the
arrhythmia.
One such test is an intracardiac
electrophysiologic procedure. Intracardiac
means within the heart. With this procedure,
one or more long, thin tubes (catheters) are
placed into the large blood vessels in the legs,
arms, or both. The tips of the catheters are
moved into the heart where they record electrical
signals from the heart's electrical system.
The heart is then stimulated to beat rapidly or
irregularly. The doctor studies the way the
heart responds to the stimulus and the way
electricity moves around the heart during an
episode of tachycardia. Another way to
diagnose tachycardia is through an esophageal
electrophysiologic procedure. A thin, soft,
flexible plastic tube is inserted through the
child's nostril and positioned in the esophagus.
The esophagus connects the mouth and stomach.
The esophagus is close to the heart's upper
chambers, the atria, so the ECG recording there
gives more precise information than a regular ECG.
The doctor may use an electrical stimulator to
make the heart beat faster to try to restart your
child's arrhythmia. The doctor may try certain
medications during this procedure to find the most
effective one. There are many different types of
arrhythmia, so an accurate diagnosis is important
to determine what type of treatment is needed. The
most common abnormal tachycardia diagnosed in
children is supraventricular tachycardia (SVT),
also called paroxysmal atrial tachycardia (PAT) or
paroxysmal supraventricular tachycardia (PSVT).
This fast heart rate involves both the heart's
upper and lower chambers.
What is the treatment?
The treatment for arrhythmia depends upon the
diagnosis. This health topic provides an
overview of commonly used treatments. Your
child's doctor will determine what treatment is
best for the child's condition. Medications
are used when arrhythmia's cause significant
symptoms or pose a health risk. Because
there are so many possibilities, your doctor may
try several different medications to find the one
that is right for your child. These medications
can improve symptoms by preventing the episodes
from starting, decreasing the heart rate during
the episode, or shortening how long the episode
lasts. How often the child must take the
drug depends upon the frequency of the arrhythmia.
Some children are admitted to the hospital to
begin the medication so the doctor can monitor the
drug's effects. If your child is taking
medication, it's very important to follow the
instructions on the prescription. Children
on antiarrhythmic medications often require
periodic blood tests to monitor the amount of
medication in the bloodstream. Certain types
of tachycardia, like supraventricular tachycardia
(SVT), can be detected while a baby is still in
the womb. In these cases, the mother can
take medications to slow her baby's heart rate.
Children can also be taught techniques to slow
down their own heart rate during an episode of
tachycardia. This includes straining, for
example by holding the nose and mouth closed while
trying to breathe out. This is called a
Valsalva maneuver. Doctors can also stop an
abnormally fast heart rhythm by using the
esophageal electrophysiologic procedure explained
in the Diagnosis section of this health topic.
While rare with children, doctors may also use a
technique called countershock, or cardioversion,
to give a small electrical shock to the chest wall
to restore the normal heart rhythm. Your
child would receive a sedative or anesthetic
before this procedure. Sometimes, diseases
like anemia (low blood counts) or increased
thyroid activity can cause a fast heart rate.
Treating the disease also treats the arrhythmia.
In some cases, tachycardias require more permanent
treatment. One procedure is called radiofrequency
catheter ablation. Several long, thin tubes
called catheters are placed in the heart. The spot
that is causing the tachycardia is destroyed by
radiofrequency energy so the heart's natural
electrical current can no longer pass through that
tissue. The rest of the heart functions
normally. In severe cases, the rhythm
disorder may need to be controlled with an
artificial pacemaker. This type of
surgery is more commonly used for slow heart
rates, but may also be used to treat some fast
heart rates. An artificial pacemaker is a small
device that is implanted under the skin and is
connected to the heart with one or two thin wires.
The pacemaker is programmed to send small,
painless amounts of electricity to the heart to
make it beat normally. Some pacemakers can
even sense when your child is active and increase
the heart's beating to keep up with the activity.
New, improved pacemaker designs mean most
pacemakers last around 8 to 10 years.
However, it's extremely important that your child
has regular check-ups to make sure the pacemaker
is operating correctly. While most children
with pacemakers can participate in normal
activities, check with your doctor for advice on
contact-type sports.
Self-care tips
If your child has an arrhythmia, it's extremely
important to follow your doctor's orders for
treatment. Make sure all medications are
given at the correct times and according to the
label directions. Check your child's heart
rate as directed by your doctor, and help
your child use any techniques taught by your
doctor to stop episodes of tachycardia. If
your child has an artificial pacemaker, follow
your doctor's instructions for making sure it is
operating correctly. With the proper care,
your child will be able to enjoy a normal, active
lifestyle.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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