Topic Overview

Your heart normally beats in a regular rhythm and rate that is just
right for the work your body is doing at any moment. The usual resting heart
rate for adults is between 50 to 100 beats per minute. Children have naturally
higher normal heart rates than adults.
The
heart
is a pump made up of
four
chambers
: two upper chambers (atria) and two lower chambers
(ventricles). It is powered by an
electrical system
that puts out pulses in a regular
rhythm. These pulses keep the heart pumping and keep blood flowing to the lungs
and body.
When the heart beats too fast, too slow, or with a skipping
(irregular) rhythm, a person is said to have an
arrhythmia. A change in the heart's rhythm may feel
like an extra-strong heartbeat (palpitation) or a fluttering in your
chest. A heartbeat that is occasionally irregular usually is not a concern if
it does not cause other symptoms, such as dizziness,
lightheadedness, or shortness of breath. It is not
uncommon for children to have extra heartbeats. In healthy children, an extra
heartbeat is not a cause for concern.
When heart rate or rhythm changes are minor
Many changes in heart rate or rhythm are minor and do not require
medical treatment if you do not have other symptoms or a history of heart
disease. Smoking, drinking alcohol or caffeine, or taking other stimulants such
as diet pills or cough and cold medicines may cause your heart to beat faster
or skip a beat. Your heart rate or rhythm can change when you are under stress
or having pain. Your heart may beat faster when you have an illness or a fever.
Hard physical exercise usually increases your heart rate, which can sometimes
cause changes in your heart rhythm.
Dietary supplements, such as goldenseal, oleander, motherwort, or
ephedra (also called ma huang), may cause irregular heartbeats. The U.S. Food
and Drug Administration (FDA) has banned the sale of ephedra, a stimulant sold
for weight loss and sports performance, because of concerns about safety.
Ephedra has been linked to
heart attacks,
strokes, and some sudden deaths.
It is not uncommon for pregnant women to have minor heart rate or
rhythm changes. These changes usually are not a cause for concern for women who
do not have a history of heart disease.
Well-trained athletes usually have slow heart rates with
occasional pauses in the normal rhythm. Evaluation is usually not needed unless
other symptoms are present, such as lightheadedness or fainting (syncope), or there is a family history of heart
problems.
When heart rate or rhythm changes are more serious
Irregular heartbeats change the amount of blood that flows to the
lungs and other parts of the body. The amount of blood that the heart pumps may
be decreased when the heart pumps too slow or too fast.
Changes such as
atrial fibrillation that start in the upper chambers
of the heart can be serious, because they increase your risk of forming blood
clots in your heart. This in turn can increase your risk for having a stroke or
a blood clot in your lungs (pulmonary embolism). People who have
heart disease,
heart failure, or a history of heart attack should be
more concerned with any changes in their usual heart rhythm or rate.
Fast heart rhythms that begin in the lower chambers of the heart
are called ventricular arrhythmias. They usually are fast and regular, such as
ventricular tachycardia, or fast and irregular, such as ventricular
fibrillation. These types of heart rhythms make it difficult for the heart to
pump enough blood to the brain or the rest of the body and can be
life-threatening. Ventricular arrhythmias may be caused by heart disease such
as heart valve problems, impaired blood flow to the heart muscle (ischemia or a
heart attack), a weakened heart muscle (cardiomyopathy), or heart
failure.
Ventricular tachycardia is a life-threatening arrhythmia that can
quickly lead to ventricular fibrillation, which causes death if not treated.
Both usually cause fainting (syncope) within seconds, and you may have
symptoms of a heart attack. Emergency medical
treatment is needed, such as medicines and electrical shock
(defibrillation).
When you have a change in your heart rhythm or rate, you also may
have other symptoms, such as chest pain, shortness of breath, lightheadedness,
fainting, confusion, or weakness. Changes in your heart rate or rhythm with
other symptoms can be caused by a serious heart problem.
Taking illegal drugs (such as stimulants, like cocaine) or
misusing prescription and nonprescription
medicines can cause serious heart rhythm or rate
changes and may be life-threatening.
Review the Emergencies and Check Your Symptoms sections to
determine if and when you need to see a health professional.