A heart arrhythmia (uh-RITH-me-uh) is an irregular heartbeat. Heart rhythm problems (heart arrhythmias) occur when the electrical signals that coordinate the heart's beats don't work properly. The faulty signaling causes the heart to beat too fast (tachycardia), too slow (bradycardia) or irregularly.
Heart arrhythmias may feel like a fluttering or racing heart and may be harmless. However, some heart arrhythmias may cause bothersome — sometimes even life-threatening — signs and symptoms.
However, sometimes it's normal for a person to have a fast or slow heart rate. For example, the heart rate may increase with exercise or slow down during sleep.
Heart arrhythmia treatment may include medications, catheter procedures, implanted devices or surgery to control or eliminate fast, slow or irregular heartbeats. A heart-healthy lifestyle can help prevent heart damage that can trigger certain heart arrhythmias.
In general, heart arrhythmias are grouped by the speed of the heart rate. For example:
Tachycardia (tak-ih-KAHR-dee-uh) is a fast heart. The resting heart rate is greater than 100 beats a minute.
Bradycardia (brad-e-KAHR-dee-uh) is a slow heartbeat. The resting heart rate is less than 60 beats a minute.
Fast heartbeat (tachycardia)
Types of tachycardias include:
Atrial fibrillation (A-fib). Chaotic heart signaling causes a rapid, uncoordinated heart rate. The condition may be temporary, but some A-fib episodes may not stop unless treated. A-fib is associated with serious complications such as stroke.
Atrial flutter. Atrial flutter is similar to A-fib, but heartbeats are more organized. Atrial flutter is also linked to stroke.
Supraventricular tachycardia. Supraventricular tachycardia is a broad term that includes arrhythmias that start above the lower heart chambers (ventricles). Supraventricular tachycardia causes episodes of a pounding heartbeat (palpitations) that begin and end abruptly.
Ventricular fibrillation. This type of arrhythmia occurs when rapid, chaotic electrical signals cause the lower heart chambers (ventricles) to quiver instead of contacting in a coordinated way that pumps blood to the rest of the body. This serious problem can lead to death if a normal heart rhythm isn't restored within minutes. Most people who have ventricular fibrillation have an underlying heart disease or have experienced serious trauma.
Ventricular tachycardia. This rapid, regular heart rate starts with faulty electrical signals in the lower heart chambers (ventricles). The rapid heart rate doesn't allow the ventricles to properly fill with blood. As a result, the heart can't pump enough blood to the body. Ventricular tachycardia may not cause serious problems in people with an otherwise healthy heart. In those with heart disease, ventricular tachycardia can be a medical emergency that requires immediate medical treatment.
Slow heartbeat (bradycardia)
Although a heart rate below 60 beats a minute while at rest is considered bradycardia, a low resting heart rate doesn't always signal a problem. If you're physically fit, your heart may still be able to pump enough blood to the body with fewer than 60 beats a minute at rest.
If you have a slow heart rate and your heart isn't pumping enough blood, you may have a type of bradycardia. Types of bradycardias include:
Sick sinus syndrome. The sinus node is responsible for setting the pace of the heart. If it doesn't work properly, the heart rate may alternate between too slow (bradycardia) and too fast (tachycardia). Sick sinus syndrome can be caused by scarring near the sinus node that's slowing, disrupting or blocking the travel of impulses. Sick sinus syndrome is most common among older adults.
Conduction block. A block of the heart's electrical pathways can cause the signals that trigger the heartbeats to slow down or stop. Some blocks may cause no signs or symptoms, and others may cause skipped beats or bradycardia.
Premature heartbeats are extra beats that occur one at a time, sometimes in patterns that alternate with the normal heart beat. The extra beats may come from the top chamber of the heart (premature atrial contractions) or the bottom chamber (premature ventricular contractions).
A premature heartbeat may feel like your heart skipped a beat. These extra beats are generally not concerning, and they seldom mean you have a more serious condition. Still, a premature beat can trigger a longer-lasting arrhythmia, especially in people with heart disease. Occasionally, very frequent premature beats that last for several years may lead to a weak heart.
Premature heartbeats may occur when resting. Sometimes premature heartbeats are caused by stress, strenuous exercise or stimulants, such as caffeine or nicotine.