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Facts About
Arrhythmias/Rhythm Disorders
What is an arrhythmia?
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.
How common are arrhythmias?
Arrhythmias occur commonly in middle-age adults. As people get older, they are more likely
to experience an arrhythmia.
What are the symptoms of 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.
Arrhythmia Types:
Originating in the Atria—
- Sinus arrhythmia. Cyclic changes in the heart rate during breathing.
Common in children and often found in adults.
- Sinus tachycardia. The sinus node sends out electrical signals faster
than usual, speeding up the heart rate.
- 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
heartbeat.
- 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 end suddenly.
- 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.
- Wolff-Parkinson-White 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 Ventricles—
- 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.
What happens in the heart during an arrhythmia?
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 bottom.
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 reasons:
- 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.
What is 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.
What are the different types of an arrhythmias?
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.
How does the doctor know that I have an arrhythmia?
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 symptoms.
What tests can be done?
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.
Tests for Detecting Arrhythmias
- 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 recording
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 muscle ("ischemia").
- 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.
How are arrhythmias treated?
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
arrhythmia itself may be treated using one or more of the following treatments.
- Drugs
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 EPS to
see how easily the arrhythmia can be caused. Blood levels of antiarrhythmic drugs may also
be checked.
- Cardioversion
To quickly 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 defibrillators
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
An 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.
- Ablation
Much like an EPS small catheters are inserted into the heart from an artery or vein in the
leg. Mapping or locating abnormal tissue is performed and then the abnormal areas are
destoyed or ablated.
- Surgery
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.
How can arrhythmias be prevented?
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.
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