What is a heart arrhythmia?
Also known as an irregular heartbeat, an
arrhythmia is any abnormality in the heart rate or rhythm.
Arrhythmias can be put into two main
categories; too fast a heart beat, or too slow. In a normal adult at rest, the
heart beats 60 — 100 times per minute. Bradycardia is when the heart beats at
less than 60 beats per minute. Tachycardia is when the heart beats at more than
100 beats per minute.
Arrhythmias can also be categorised
according to their origin. Ventricular arrhythmias originate in the ventricles
(the two lower chambers of the heart). Supraventricular arrhythmias originate
in an area above the ventricles, usually in the atria (the upper chambers of
Examples of heart arrhythmias are:
- Atrial fibrillation: a common type of
irregular heart rhythm, causing the heart to contract abnormally.
- Sinus node dysfunction: This usually
results in a bradycardia (too slow a heart beat). It can be caused by, for
example, hypothermia or severe liver disease.
- Ventricular fibrillation: This is a major
emergency and can be caused by such things as a heart attack (myocardial
infarction) or a drowning. With this type of arrhythmia, the ventricles quiver
ineffectively, producing no real heart beat, resulting in unconsciousness in
the person. Brain damage and death can occur within minutes.
What causes arrhythmias?
There are several different factors that
can cause an arrhythmia. These may include:
- Coronary artery disease
- Heart attack or other injury to the heart
- Congenital heart defects and other forms
of heart disease
- Lung conditions and other diseases
- Electrolyte imbalance in your blood (e.g.
levels of sodium or potassium)
- Medication – arrhythmia can sometimes
occur as a side-effect of some medications.
What are the symptoms of a heart
Symptoms of an abnormally fast heartbeat
(tachycardia) can include recurring heart palpitations (you may be able to feel
your heart ‘fluttering’), shortness of breath, light-headedness, fainting or
near-fainting spells, sweating and chest discomfort.
Symptoms of an abnormally slow heartbeat
(bradycardia) can include shortness of breath, fatigue and light-headedness and
fainting or near-fainting spells.
Symptoms can also depend on the different
types of arrhythmia. A sinus node dysfunction may prove asymptomatic (produces
no symptoms). If symptoms are present, they may include fatigue, fainting, or
How are arrhythmias treated?
In an emergency, electric shock therapy
may be necessary to stop the arrhythmia and restore a normal heart rate.
Other treatment may involve medication to
control the heart rate or reduce risk of blood clots, making lifestyle changes
or surgery. An implantable device called a pacemaker may be used to control an
irregular heart rate in the long-term. In some cases, no treatment at all may be
Your doctor will decide which treatment,
if any, is necessary.
Can heart arrhythmias be prevented?
Some can. For example, if your arrhythmia
is a side effect of the medication you are taking, your doctor can change
medication or lower your dose.
Some lifestyle measures can also be taken
to prevent or control an arrhythmia – including limiting your use of caffeine,
nicotine, alcohol and stimulant drugs, and reducing stress through exercise or
Unfortunately not all heart arrhythmias
can be prevented, however it is important to state that occasional, isolated
disturbances of the heartbeat are common and usually harmless.