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|Quick reference medical handouts used
by Pediatric offices
Normal and Abnormal Heart Rates
|About Heart Rhythms
|The heart rate is the number of times the heart beats
each minute. In an older child or teenager who's
resting, the heart beats about 70 times a minute. In a
newborn it beats about 140 times a minute. Usually the heart
rhythm is regular. This means the heart beats evenly (at
regular intervals). The heart rate changes easily. Exercise
makes the heart beat faster. During sleep it slows down. Click
here to view normal heart rates at different ages.
In a normal heart rhythm, the sinus node
generates an electrical impulse which travels through the right and left
atrial muscles producing electrical changes which is represented on the
electrocardiogram (ECG) by the p-wave. The electrical impulse then
continue to travel through specialized tissue known as the
atrioventricular node, which conducts electricity at a slower pace.
This will create a pause (PR interval)
before the ventricles are stimulated. This pause is helpful since
it allows blood to be emptied into the ventricles from the atria prior
to ventricular contraction to propel blood out into the body. The
ventricular contraction is represented electrically on the ECG by the
QRS complex of waves. This is followed by the T-wave which
represents the electrical changes in the ventricles as they are
relaxing. The cardiac cycle after a short pause repeats itself,
and so on.
An irregular heartbeat is an arrhythmia. The most
common irregularity occurs during breathing. When a child
breathes in, the heart rate normally speeds up for a few
beats. When the child breathes out, it slows down again.
This variation with breathing is called sinus
arrhythmia. It's completely normal.
|Knowing your Child's History
Arrhythmias (also called dysrhythmias) may occur at any
age. Many times they have no symptoms. Often parents and
children never suspect an arrhythmia and are surprised when
a doctor finds one during a routine physical exam. Rhythm
abnormalities are usually evaluated much like other health
problems. Your child's history — or what you and your
child report about the problem — is very important. You may
be asked questions like:
- Is your child aware of unusual heartbeats?
- Does anything bring on the arrhythmia? Is there anything
your child or the family can do to make it stop?
- If it's a fast rate, how fast?
- Does your child feel weak, lightheaded or dizzy?
- Has your child ever fainted?
Some medicines may make arrhythmias worse. Be sure to tell
your doctor about all the prescribed and over-the-counter
medications that your child takes. If your child has an
arrhythmia, discuss this with the doctor and ask what to
|Types of Arrhythmia in
|There are many different kinds of abnormal heart rhythms. If an abnormal rhythm occurs, it's important to find out what kind it is. Treatment recommendations depend on its type. Arrhythmias can cause the heart rate to be irregular, fast or slow. Fast rhythms are called tachycardia. Slow ones are called bradycardia.
- Premature atrial contraction (PAC) and premature ventricular contraction (PVC)
Premature beats or extra beats most often cause irregular heart rhythms. Those that start in the upper chambers
(atrium) are called premature atrial contractions or PACs. Premature ventricular contractions or PVCs start in the ventricles. If you've ever felt your heart "skip a beat," it was probably from this type of arrhythmia. The heart really doesn't skip a beat. Instead, an extra beat comes sooner than normal. Then there's a pause that causes the next beat to be more forceful. You felt this more-forceful beat.
Premature beats are very common in normal children and teenagers — most people have them at some time. Usually no cause can be found and no special treatment is needed. The premature beats may disappear later. Even if they continue, your child will stay well and won't need any restrictions. Occasionally premature beats may be caused by disease or injury to the heart. Your child's doctor may recommend more tests to make sure your child's heart is OK.
A fast heart rate is called tachycardia. The definition of "too fast" usually depends upon the person's age and physical activity. A newborn has tachycardia if the resting rate is more than 160 beats a minute. A teenager has it if the resting heart rate is more than 100 beats a minute. An exercising teenager may have a normal heart rate of up to 200 beats a minute.
Sinus tachycardia is a normal increase in the heart rate. It occurs with fever, excitement and exercise. No treatment is needed. Rarely, disease, such as anemia (low blood counts) or increased thyroid activity can cause this fast heart rate. In these cases, when the disease is treated, the tachycardia goes away.
Supraventricular tachycardia (SVT)
The most common abnormal tachycardia in children is supraventricular tachycardia (SVT). It's also called paroxysmal atrial tachycardia (PAT) or paroxysmal supraventricular tachycardia
(PSVT). The fast heart rate involves both the heart's upper and lower chambers. This isn't a life-threatening problem for most children and adolescents. Treatment is only considered if episodes are prolonged or frequent. For many infants, SVT is a time-limited problem. Treatment with medications often stops after six to twelve months.
- Wolff-Parkinson-White syndrome
If an abnormal conduction pathway runs between the atria and ventricles, the electrical signal may arrive at the ventricles sooner than normal. This condition is called Wolff-Parkinson-White syndrome
(WPW syndrome). It's named after the three people who first described it. WPW syndrome is recognized by certain changes on the
ECG. Many people with WPW syndrome don't have symptoms or episodes of
As a reminder, this information should not be relied on as
medical advice and is not intended to replace the advice of your childs pediatrician.
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