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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), prematurely, or with an irregular rhythm.
Heart arrhythmias are very common; nearly everyone will experience an abnormal heart rhythm at least once in their lifetime. In most cases, the arrhythmia will not be serious and will likely go undetected. But some arrhythmias are problematic; at the least, they can be bothersome, and at worst, 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 on either side of the heart.
In a properly beating heart, electrical charges or impulses follow precise pathways through the heart to each pump. These charges coordinate and direct all of the different functions inside the heart, and any interruption in these pathways or impulses can cause the heart to beat abnormally.
Blood enters the heart, arriving first in the atria. After this happens, a single heartbeat involves several steps.
That is one heartbeat, and 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.
Arrhythmias are named and categorized based on three points:
Bradycardia is a slow heartbeat—when the resting heart rate is less than 60 beats per minute. This weak pace might mean your heart isn’t beating frequently enough to ensure adequate blood flow throughout your body. Types of bradycardia include:
Not all bradycardias are a problem, however. Athletes or people who are physically fit often have bradycardias. Their resting heart rates may be less than 60 per minute because their hearts are more efficient and can pump adequate blood with fewer beats.
Tachycardia is a fast heartbeat—the resting heart rate is greater than 100 beats per minute. The two most common types of tachycardia are supraventricular tachycardia and ventricular tachycardia.
Supraventricular tachycardia (SVT) encompasses any arrhythmia that begins above the ventricle. SVTs are usually identified by a burst of rapid heartbeats that begin and end suddenly. These bursts can last a few seconds or several hours and may cause your heart to beat greater than 160 times per minute. The most common SVTs include:
Ventricular tachycardia (VT) is an arrhythmia that begins in the ventricles of the heart. Most VT occurs in people who have had a 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, including:
Premature 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.
Not all tachycardias, bradycardias, or premature heartbeats are unhealthy or a sign of a problem. Again, athletes or people who are physically fit may have bradycardia because their hearts work very efficiently and don’t require as many beats as other less-fit people. Also, it’s normal to have an increased heart speed during exercise; your heart is working hard to provide your tissues with oxygen-rich blood so you don’t fatigue too quickly.
Written by: the Healthline Editorial Team
Medically reviewed by Jennifer Monti, MD
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