An arrhythmia is a
disorder of the heart that affects the rate or rhythm at which the heart beats.
An arrhythmia occurs when electrical impulses, which direct and regulate
heartbeats, don’t function properly. This causes the heart to beat too fast
(tachycardia), too slow (bradycardia), too early (premature contraction), or too
are very common and usually harmless. Nearly everyone will experience an
abnormal heart rhythm at least once. It may feel like your heart is racing or
fluttering. But some arrhythmias are problematic. When arrhythmia interferes
with the flow of blood to your body, it can cause damage to your brain, lungs,
and other vital organs. If not treated, this may be life threatening.
Your heart is
divided into four chambers. Each half of your heart consists of an upper
chamber (the atrium) and a lower chamber (the ventricle). The two halves create
two pumps, one on either side of the heart.
In a properly
beating heart, electrical impulses follow precise pathways through the heart to
each pump. These signals coordinate the activity of the heart muscle. Any
interruption in these pathways or impulses can cause the heart to beat
Blood enters the
heart, arriving first in the atria. After this happens, a single heartbeat
involves several steps:
sinus node—a group of cells in the right atrium—sends an electrical impulse
to both the right and left atria, telling them to contract.
contraction allows the ventricles to fill with blood.
the ventricles fill, the electrical impulse travels to the center of your
heart to the atrioventricular node—a group of cells between the atria and
impulse exits the node and then travels to your now blood-filled
ventricles, telling them to contract.
contraction pushes the blood out of the heart and into your body for
That is one
heartbeat. Then the process starts all over again. Under normal conditions, the
left and right sides of the heart beat one after the other. This keeps the blood
flow moving in one direction in a continuous pumping fashion.
A normal heart will
repeat this process about 100,000 times each day—that is 60 to 100 beats per
minute for the average healthy person’s heart while he or she is at rest.
named and categorized based on three points:
(too slow or too fast)
(whether it is in the ventricles or the atria)
Bradycardia is a
slow heartbeat. It is defined as a resting heart rate of fewer than 60 beats
per minute. Slow heart rate might mean your heart isn’t beating frequently
enough to ensure adequate blood flow throughout your body. Types of bradycardia
sinus node is responsible for setting the pace of your heart. If it isn’t
sending electrical impulses properly, your heart may be pumping too slowly
or irregularly. Scarring near the sinus node, from heart disease or a
heart attack, may also slow down or block the electrical impulses as they
try to travel through the heart.
block: If your heart’s electrical pathways are
blocked, the chambers of the heart may contract slowly or not at all. A
block can happen anywhere along the heart’s electrical pathways—between
the sinus node and atrioventricular (AV) node, or between the AV node and
the ventricles. These blocks may show no signs other than skipped or
Not all bradycardias are a problem. Athletes and people who are
physically fit often have bradycardias. Their resting heart rates may be less
than 60 beats per minute because their hearts are more efficient and can pump
adequate blood with fewer beats.
Tachycardia is a
fast heartbeat. It is defined as a resting heart rate of more than 100 beats
per minute. The two most common types of tachycardia are supraventricular
tachycardia and ventricular tachycardia.
tachycardia (SVT) is any arrhythmia that begins above the ventricle. SVTs are
usually identified by a burst of rapid heartbeats that can begin and end
suddenly or can be chronic. These bursts can last a few seconds or several
hours, and may cause your heart to beat more than 160 times per minute. The
most common SVTs include atrial fibrillation and atrial flutter.
If you have atrial fibrillation (AF), your atrium beats very
rapidly; as fast as 240 to 350 beats per minute. The atria are moving so
rapidly they aren’t able to contract completely. Instead, they quiver
(fibrillate). This can cause discomfort, but not a rapid pulse. Some of these
atrial beats can transfer to the ventricles and may cause a high pulse rate. AF
primarily affects older people. Your risk of developing this arrhythmia
increases past age 60, mostly due to the wear and aging an older heart
experiences. The chances of developing AF are also high if you have or have had
high blood pressure or other heart problems. AF can be dangerous. If left
untreated, it can lead to more serious conditions, such as stroke.
The heartbeats in atrial flutter are more rhythmic and constant
than the heartbeats in atrial fibrillation. Still, atrial flutter can come and
go in sudden bursts. It can be life threatening. This type of arrhythmia occurs
most often in people with heart disease. It also often shows up in the first
weeks after heart surgery.
tachycardia (VT) is an arrhythmia that begins in the ventricles of the heart.
Most VT occurs in people who have had heart disease or heart-related problems,
such as coronary artery disease or heart attack. VT is often caused by an
electrical impulse traveling around a scarred part of the heart’s muscle. It
can cause the ventricles to contract more than 200 times per minute. If left
untreated, VT may increase your risk of developing more serious ventricular
arrhythmias, such as ventricular fibrillation.
Sudden, rapid, irregular, and chaotic heartbeats in the
ventricle may be a sign of a dangerous arrhythmia called ventricular
fibrillation (VF). These erratic electrical impulses, sometimes triggered by a
heart attack, cause your heart’s ventricles to quiver (fibrillate). When you
have this kind of arrhythmia, your ventricles aren’t able to pump blood into
your body, and your heart rate drops quickly. This will make your blood
pressure fall, and the blood supply to your body and organs will be diminished.
VF is the number one cause of sudden cardiac arrest.
heartbeats may result in the feeling that your heart has skipped a beat. In
reality, your normal heart rhythm has been interrupted by a too-soon beat, and
you’re experiencing an extra beat between two normal heartbeats.
There are many
types of heart arrhythmias. Most arrhythmias are harmless. Virtually everyone
has an arrhythmia at one time or another. Frequently, it goes unnoticed. It’s
normal to have an increased heart speed during exercise, when your heart is
working hard to provide your tissues with oxygen-rich blood so you don’t
fatigue too quickly. Athletes and people who are physically fit may have slow
heart rates because their hearts work very efficiently and don’t require as
many beats as other less-fit people.
are not harmless. Your outlook depends on the type and severity of your
arrhythmia. If you believe you have an arrhythmia, you should see your doctor.
Even the most serious arrhythmias can often be successfully treated. Most
people with arrhythmia can live a normal life.