Information for patients: Facts about arrhythmias/rhythm disorders
What is an arrhythmia?
Does having an arrhythmia mean that a person has heart
What causes arrhythmias?
Are arrhythmias serious?
common are arrhythmias?
What are the symptoms of an
What happens in the heart during an arrhythmia?
What is a heart block?
What are the
different types of arrhythmias?
How does the doctor
know that I have an arrhythmia?
What tests can be
Tests for Detecting Arrhythmias
How are arrhythmias treated?
can arrhythmias be prevented
Is research on
arrhythmias being done?
Where can I find
publications about heart disease?
An arrhythmia is a change in the regular beat of the heart. The heart may seem to skip a beat or beat irregularly or very fast or very slowly.
Does having an arrhythmia mean that a
person has heart disease? No, not necessarily. Many arrhythmias occur in
people who do not have underlying heart disease.
What causes arrhythmias? Many
times, there is no recognizable cause of an arrhythmia. Heart disease may cause
arrhythmias. Other causes include: stress, caffeine, tobacco, alcohol, diet
pills, and cough and cold medicines.
Are arrhythmias serious? The
vast majority of people with arrhythmias have nothing to fear. They do not need
extensive exams or special treatments for their condition.
In some people, arrhythmias are associated with heart
disease. In these cases, heart disease, not the arrhythmia, poses the greatest
risk to the patient.
In a very small number of people with serious
symptoms, arrhythmias themselves are dangerous. These arrhythmias require
medical treatment to keep the heartbeat regular. For example, a few people have
a very slow heartbeat (bradycardia), causing them to feel lightheaded or faint.
If left untreated, the heart may stop beating and these people could die.
Arrhythmias occur commonly in middle-age adults. As
people get older, they are more likely to experience an arrhythmia.
Most people have felt their heart beat very fast,
experienced a fluttering in their chest, or noticed that their heart skipped a
beat. Almost everyone has also felt dizzy, faint, or out of breath or had chest
pains at one time or another. One of the most common arrhythmias is sinus
arrhythmia, the change in heart rate that can occur normally when we take a
breath. These experiences may cause anxiety, but for the majority of people,
they are completely harmless.
You should not panic if you experience a few flutters
or your heart races occasionally. But if you have questions about your heart
rhythm or symptoms, check with your doctor.
Originating in the Atria
- Sinus arrhythmia. Cyclic
changes in the heart rate during breathing. Common in children and often found
- Sinus tachycardia. The sinus
node sends out electrical signals faster than usual, speeding up the heart
- Sick sinus syndrome. The
sinus node does not fire its signals properly, so that the heart rate slows
down. Sometimes the rate changes back and forth between a slow (bradycardia)
and fast (tachycardia) rate.
- Premature supraventricular
contractions or premature atrial contractions (PAC). A beat occurs
early in the atria, causing the heart to beat before the next regular
- Supraventricular tachycardia (SVT),
paroxysmal atrial tachycardia (PAT). A series of early beats in the
atria speed up the heart rate (the number of times a heart beats per minute).
In paroxysmal tachycardia, repeated periods of very fast heartbeats begin and
- Atrial flutter. Rapidly
fired signals cause the muscles in the atria to contract quickly, leading to a
very fast, steady heartbeat.
- Atrial fibrillation.
Electrical signals in the atria are fired in a very fast and uncontrolled
manner. Electrical signals arrive in the ventricles in a completely irregular
fashion, so the heart beat is completely irregular.
syndrome. Abnormal pathways between the atria and ventricles cause the
electrical signal to arrive at the ventricles too soon and to be transmitted
back into the atria. Very fast heart rates may develop as the electrical signal
ricochets between the atria and ventricles.
Originating in the
- Premature ventricular complexes
(PVC). An electrical signal from the ventricles causes an early heart
beat that generally goes unnoticed. The heart then seems to pause until the
next beat of the ventricle occurs in a regular fashion.
- Ventricular tachycardia. The
heart beats fast due to electrical signals arising from the ventricles (rather
than from the atria).
- Ventricular fibrillation.
Electrical signals in the ventricles are fired in a very fast and uncontrolled
manner, causing the heart to quiver rather than beat and pump blood.
Describing how the heart beats normally helps to
explain what happens during an arrhythmia.
The heart is a muscular pump divided into four
chambers--two atria located on the top and two ventricles located on the
Normally each heartbeat starts in the right atrium.
Here, a specialized group of cells called the sinus node, or natural pacemaker,
sends an electrical signal. The signal spreads throughout the atria to the area
between the atria called the atrioventricular (AV) node.
The AV node connects to a group of special pathways
that conduct the signal to the ventricles below. As the signal travels through
the heart, the heart contracts. First the atria contract, pumping blood into
the ventricles. A fraction of a second later, the ventricles contract, sending
blood throughout the body.
Usually the whole heart contracts between 60 and 100
times per minute. Each contraction equals one heartbeat.
An arrhythmia may occur for one of several
- Instead of beginning in the sinus node, the
heartbeat begins in another part of the heart.
- The sinus node develops an abnormal rate or rhythm.
- A patient has a heart block.
Heart block is a condition in which the electrical
signal cannot travel normally down the special pathways to the ventricles. For
example, the signal from the atria to the ventricle may be (1) delayed, but
each one conducted; (2) delayed with only some getting through; or (3)
completely interrupted. If there is no conduction, the beat generally
originates from the ventricles and is very slow.
There are many types of arrhythmias. Arrhythmias are
identified by where they occur in the heart (atria or ventricles) and by what
happens to the heart's rhythm when they occur.
Arrhythmias arising in the atria are called atrial or
supraventricular (above the ventricles) arrhythmias. Ventricular arrhythmias
begin in the ventricles. In general, ventricular arrhythmias caused by heart
disease are the most serious.
Sometimes an arrhythmia can be detected by listening
to the heart with a stethoscope. However, the electrocardiogram is the most
precise method for diagnosing the arrhythmia.
An arrhythmia may not occur at the time of the exam
even though symptoms are present at other times. In such cases, tests will be
done if necessary to find out whether an arrhythmia is causing the
First the doctor will take a medical history and do a
thorough physical exam. Then one or more tests may be used to check for an
arrhythmia and to decide whether it is caused by heart disease.
- Electrocardiogram (ECG or
EKG). A record of the electrical activity of the heart. Disks are
placed on the chest and connected by wires to a recording machine. The heart's
electrical signals cause a pen to draw lines across a strip of graph paper in
the ECG machine. The doctor studies the shapes of these lines to check for any
changes in the normal rhythm. The types of ECGs are:
- Resting ECG. The patient lies down
for a few minutes while a record is made. In this type of ECG, disks are
attached to the patient's arms and legs as well as to the chest.
- Exercise ECG (stress test). The
patient exercises either on a treadmill machine or bicycle while connected to
the ECG machine. This test tells whether exercise causes arrhythmias or makes
them worse or whether there is evidence of inadequate blood flow to the heart
- 24-hour ECG (Holter) monitoring.
The patient goes about his or her usual daily activities while wearing a small,
portable tape recorder that connects to the disks on the patient's chest. Over
time, this test shows changes in rhythm (or "ischemia") that may not be
detected during a resting or exercise ECG.
- Transtelephonic monitoring. The
patient wears the tape recorder and disks over a period of a few days to
several weeks. When the patient feels an arrhythmia, he or she telephones a
monitoring station where the record is made. If access to a telephone is not
possible, the patient has the option of activating the monitor's memory
function. Later, when a telephone is accessible, the patient can transmit the
recorded information from the memory to the monitoring station. Transtelephonic
monitoring can reveal arrhythmias that occur only once every few days or weeks.
- Electrophysiologic study
(EPS). A test for arrhythmias that involves cardiac catheterization. Very thin,
flexible tubes (catheters) are placed in a vein of an arm or leg and advanced
to the right atrium and ventricle. This procedure allows doctors to find the
site and type of arrhythmia and how it responds to treatment.
Many arrhythmias require no treatment whatsoever.
Serious arrhythmias are treated in several ways
depending on what is causing the arrhythmia. Sometimes the heart disease is
treated to control the arrhythmia. Or, the arrhthmia itself may be treated
using one or more of the following treatments.
There are several kinds
of drugs used to treat arrhythmias. One or more drugs may be used.
Drugs are carefully chosen because they can cause
side effects. In some cases, they can cause arrhythmias or make arrhythmias
worse. For this reason, the benefits of the drug are carefully weighed against
any risks associated with taking it. It is important not to change the dose or
type of your medication unless you check with your doctor first.
If you are taking drugs for an arrhythmia, one of
the following tests will probably be used to see whether treatment is working:
a 24-hour electrocardiogram (ECG) while you are on drug therapy, an exercise
ECG, or a special technique to see how easily the arrhythmia can be caused.
Blood levels of antiarrhythmic drugs may also be checked.
restore a heart to its normal rhythm, the doctor may apply an electrical shock
to the chest wall. Called cardioversion, this treatment is most often used in
emergency situations. After cardioversion, drugs are usually prescribed to
prevent the arrhythmia from recurring.
- Automatic implantable
These devices are used to correct serious
ventricular arrhythmias that can lead to sudden death. The defibrillator is
surgically placed inside the patient's chest. There, it monitors the heart's
rhythm and quickly identifies serious arrhythmias. With an electrical shock, it
immediately disrupts a deadly arrhythmia.
- Artificial pacemaker
artificial pacemaker can take charge of sending electrical signals to make the
heart beat if the heart's natural pacemaker is not working properly or its
electrical pathway is blocked. During a simple operation, this electrical
device is placed under the skin. A lead extends from the device to the right
side of the heart, where it is permanently anchored.
When an arrhythmia
cannot be controlled by other treatments, doctors may perform surgery. After
locating the heart tissue that is causing the arrhythmia, the tissue is altered
or removed so that it will not produce the arrhythmia.
If heart disease is not causing the arrhythmia, the
doctor may suggest that you avoid what is causing it. For example, if caffeine
or alcohol is the cause, the doctor may ask you not to drink coffee, tea,
colas, or alcoholic beverages.
The National Heart, Lung, and Blood Institute (NHLBI)
supports basic research on normal and abnormal electrical activity in the heart
to understand how arrhythmias develop. Clinical studies with patients aim to
improve the diagnosis and management of different arrhythmias. These studies
will someday lead to better diagnostic and treatment strategies.
To obtain publications about heart disease, you may
want to contact your:
- local American Heart Association chapter.
- local or state health department.
The National Heart, Lung, and Blood Institute also has
publications about heart disease. For more information, contact:
- NHLBI Information Center
P.O. Box 30105
Bethesda, MD 20892-0105
Telephone: (301) 592-8573