An arrhythmia, or irregular heartbeat, is a problem with the rate or rhythm of your heartbeat. Your heart may beat too quickly, too slowly, or with an irregular rhythm.
It is normal for your heart rate to speed up during physical activity and to slow down while resting or sleeping. It is also normal to feel as if your heart skips a beat occasionally. But a frequent irregular rhythm may mean that your heart is not pumping enough blood to your body. You may feel dizzy, faint, or have other symptoms.
Arrhythmias are treatable with medicine or procedures to control the irregular rhythms. If not treated, arrhythmias can damage the heart, brain, or other organs. This can lead to life-threatening stroke, heart failure, or cardiac arrest. During cardiac arrest, the heart suddenly and unexpectedly stops beating, causing death if it is not treated within minutes.
There are many types of arrhythmias, depending on what part of the heart is affected and whether they cause a slow, fast, or irregular heart rate. Arrhythmias may happen in the atria (upper chambers of the heart) or the ventricles (lower chambers of the heart).
Arrhythmias that cause a slow, fast, or irregular heartbeat
- Bradycardia is a resting heart rate that is slower than 60 beats per minute. Some people, especially people who are young or physically fit, may normally have slower heart rates. If you have a slow heart rate, your doctor can find out whether this is normal for you.
- Tachycardia is a resting heart rate that is faster than 100 beats per minute. You may also have an irregular heartbeat.
- A premature or extra heartbeat happens when the signal to beat comes too early. This creates a pause, which is followed by a stronger beat when your heart returns to its regular rhythm. It can feel like your heart skipped a beat. This is a common type of arrhythmia, and it can cause other types of arrhythmias.
This type of arrhythmia starts in the atria or the gateway to the lower chambers.
- Atrial fibrillation is the most common type of arrhythmia. More than 2.5 million people in the United States have atrial fibrillation. This condition causes your heart to beat more than 400 beats per minute. Also, your heart’s upper and lower chambers do not work together as they should. When this happens, the lower chambers do not fill completely or pump enough blood to your lungs and body.
- Atrial flutter can cause the upper chambers of your heart to beat 250 to 350 times per minute. The signal that tells the atria to beat may be blocked by damaged or scar tissue. This may cause the upper chambers and lower chambers to beat at different rates.
- Paroxysmal supraventricular tachycardia (PSVT) causes extra heartbeats because of a problem with the electrical signals that begin in the upper chambers and travel to the lower chambers. This type of arrhythmia begins and ends suddenly. It can happen during vigorous physical activity. It is usually not dangerous and often happens in young people.
Ventricular arrhythmias start in your heart’s lower chambers, called the ventricles. These arrhythmias can be very dangerous and usually require medical care right away.
- Ventricular tachycardia is a fast, regular beating of your ventricles that may last for only a few seconds or for much longer. A few beats of ventricular tachycardia often do not cause problems. However, if this lasts for more than a few seconds, it can lead to more serious arrhythmias, such as ventricular fibrillation (v-fib).
- Ventricular fibrillation occurs if electrical signals make the ventricles quiver instead of pumping normally. Without the ventricles’ pumping blood to the body, cardiac arrest and death can happen within a few minutes.
How do you know if your heart beats too fast or too slow?
Most adults have a resting heart rate of between 60 and 100 beats per minute. Some smartwatches or smartphone apps can help you find out your resting heart rate. You can also find out your heart rate by feeling your pulse.
To find your pulse, gently place your index and middle fingers on the artery found on the inner wrist of either arm, below your thumb. You should feel a pulsing or tapping against your fingers. Watch the second hand or set the timer on your stopwatch or phone and count the number of beats you feel in 30 seconds. Double that number to find out your heart rate or pulse for 1 minute.
Causes and Triggers
Arrhythmias are often caused by a problem with the electrical signals within the heart. Often, an arrhythmia is set off by a trigger. Sometimes the cause of an arrhythmia is not known.
Problems with the heart’s electrical system: Your heart’s electrical signals control how fast your heart beats. A problem with these electrical signals can cause an irregular rhythm. This can happen when the nerve cells that produce electrical signals do not work properly or when the electrical signals do not travel normally through your heart. Also, another part of your heart could start to produce electrical signals, disrupting your normal heartbeat.
Conditions that cause a slowing of your heart’s electrical signals are called conduction disorders.
To understand arrhythmias, it helps to understand how your heart’s electrical system works.
What raises the risk of arrhythmia?
Age: As we age, changes in our heart such as scarring and the effects of other chronic conditions can raise the risk of arrhythmias. Older adults are also more likely to have health conditions, such as high blood pressure, heart failure, diabetes, and thyroid disease, that can lead to arrhythmias. Arrhythmias caused by congenital heart defects or inherited conditions are more common in children and young adults.
Family history and genetics: Arrhythmias can run in families. You may have an increased risk of some types of arrhythmias if a parent or other close relative has an arrhythmia.
Lifestyle habits: Your risk of arrhythmias may be higher if you:
- Use illegal drugs, such as cocaine or amphetamines
- Drink alcohol more often and more than is recommended (no more than 2 drinks per day for men and 1 drink per day for women)
Medicines: Sometimes, medicines your doctor prescribes for other health conditions can cause an arrhythmia. Talk to your doctor about your risk of an arrhythmia if you are taking medicine to treat high blood pressure or for a mental health condition.
Certain antibiotics and over-the-counter allergy and cold medicines can also raise the risk of arrhythmias in some people.
Other health conditions
You may be more likely to have arrhythmias if you have:
- Heart and blood vessel diseases, such as cardiomyopathy, congenital heart defects, heart attack, and heart inflammation
- Kidney disease
- Lung diseases, such as chronic obstructive pulmonary disease (COPD)
- Sleep apnea, which can stress your heart by preventing it from getting enough oxygen
- Too much or too little thyroid hormone
- Viral infections such as influenza (flu) or COVID-19
Surgery: You may be at a higher risk of developing arrhythmias in the early days and weeks after surgery involving your heart, lungs, or throat.
What can trigger arrhythmias?
If you have any risk factors, certain situations may trigger an arrhythmia. These include any situations that make your heart work harder, raise your blood pressure, or cause your body to release stress hormone.
- Blood sugar levels that are too low or too high
- Caffeine, illegal drugs, and medicines that make you more alert or increase your energy
- Low levels of electrolyte, such as potassium, magnesium, or calcium
- Physical activity
- Strong emotional stress, anxiety, anger, pain, or a sudden surprise
- Vomiting or coughing
An arrhythmia may not cause any obvious symptoms. You may notice symptoms such as a slow or irregular heartbeat or notice pauses between heartbeats. You may also feel like your heart is skipping a beat, fluttering, pounding, or beating too hard or too fast. These are called heart palpitations.
Other symptoms of arrhythmias include:
- Chest pain or discomfort
- Difficulty breathing, or gasping during sleep
- Dizziness and fainting
- Tiredness or weakness
Keep track of when and how often you have symptoms, what you feel, what you were doing, and whether these things change over time. If your symptoms are very serious, such as difficulty breathing or chest pain, seek emergency medical care.
Sometimes, especially if you do not have any noticeable symptoms of an arrhythmia, your doctor may find out you have one during a routine screening or physical for a competitive sport.
To diagnose an arrhythmia, your doctor will ask you about any symptoms, lifestyle habits, and other risk factors of arrhythmias. Your doctor will also do a physical exam, which may include these steps:
- Checking for swelling in your legs or feet, which could be a sign of an enlarged heart or heart failure
- Checking your pulse to find out how fast your heart is beating
- Listening to the rate and rhythm of your heartbeat
- Listening to your heart for a heart murmur
- Looking for signs of other diseases, such as thyroid disease, that could be causing arrhythmias
If you or your child has a high risk of arrhythmias, your doctor may screen you regularly with heart tests. These tests, described in the next section, can help your doctor check whether your heartbeat is too fast, too slow, or irregular, even if you do not have any symptoms. Some of these tests may look at the heart’s structure and function or may determine if you have risk factors for developing an arrhythmia.
An electrocardiogram (EKG or ECG) is the most common test for diagnosing arrhythmias. An EKG records your heart’s electrical activity. Your doctor may do an EKG during a stress test, which records your heart’s activity when it is working hard and beating fast.
Your doctor may also do other tests to diagnose arrhythmias.
- Blood tests measure the level of certain substances in the blood, such as potassium or other electrolytes and thyroid hormone.
- Monitors for long-term recording include Holter monitors and implantable loop recorders. These record your heart rhythm while you do your normal activities. Holter monitors measure your heart rhythm using a device that is outside of your body and are usually used for short periods of time. For an implantable loop recorder, your doctor will place the device under your skin. The recorder transmits data to your doctor’s office. Implantable loop recorders may be worn for longer periods of time and may help your doctor figure out why you are having palpitations or fainting spells, especially if these symptoms do not happen very often.
- An electrophysiology study (EPS), which is performed by an EPS cardiologist, measures the electrical activity of your heart. The doctor threads a wire through a blood vessel to your heart. The wire electrically stimulates your heart and triggers any underlying arrhythmia if you have one. If you have another condition that may raise your risk, an EPS can help your doctor find out your risk of developing arrhythmias. An EPS also allows your doctor to test whether a treatment, such as medicine, will stop the problem.
- Tilt table testing may help find the cause of fainting spells. You lie on a table that moves from a lying-down position to an upright position. The change in position may cause you to faint. Your doctor watches your symptoms, heart rate, EKG reading, and blood pressure throughout the test.
- Genetic testing can check whether you have a type of arrhythmia that is caused by specific genes. This test is important when one or more of your close relatives has an arrhythmia caused by the same gene or had cardiac arrest.
- Heart imaging tests, such as computed tomography (CT) scans or cardiac magnetic resonance imaging (MRI), may check the structure of your heart chambers, show how well your heart is working, look for evidence of scar tissue in your heart muscle, or sometimes may look at your heart arteries.
How are arrhythmias treated?
You may need one or more medicines to treat a slow, fast, or irregular heartbeat. Sometimes medicines are used together with other treatments. If your dose is too high, medicines to treat arrhythmias can make your arrhythmia worse. This happens more often in women than in men. Talk to your doctor if your symptoms get worse.
Medicine to treat a slow heartbeat (such as atropine) may be given by emergency medical services (EMS) or in the emergency room (ER). Atropine may cause difficulty swallowing.
Medicines to treat a fast heartbeat include:
- Adenosine, which can cause some chest pain, flushing, shortness of breath, and atrial fibrillation and may be given by EMS or in the ER
- Beta blockers, which can cause fatigue, stomach or sleep problems, and sexual dysfunction, and can make some conduction disorders worse
- Calcium channel blockers, which can cause digestive trouble, swollen feet, or low blood pressure
- Digoxin, which is used to treat atrial fibrillation, and can cause nausea, vomiting, and diarrhea
- Potassium channel blockers, which can cause low blood pressure, problems with your thyroid levels, lung conditions, or another type of arrhythmia
- Sodium channel blockers, which raise the risk of sudden cardiac arrest in people who have heart disease
Procedures and devices
If medicines do not treat your arrhythmia adequately, you may need one of the following procedures or devices.
Cardioversion is a procedure that uses external electric shocks to restore a normal heart rhythm.
Cardioversion is called defibrillation when it is done in an emergency to prevent death when irregular heartbeats in the lower chambers of your heart, the ventricles, threatens to, or actually causes, cardiac arrest. Your doctor may also schedule cardioversion as a way to treat arrhythmias in the upper chambers of your heart, called atrial fibrillation.
Scheduled cardioversion procedures may be done in a hospital or other healthcare facility by cardiologists, the doctors who specialize in the heart. While the procedure takes only a few minutes, it requires that you arrive a few hours before the procedure. To prepare, you will be given anesthesia through an intravenous (IV) line in your arm to make you fall asleep, and you will have electrodes placed on your chest and possibly your back. These electrodes will be attached to the cardioversion machine. The machine records your heart’s electrical activity and sends the needed electrical shocks to your heart. When ready, the doctor will send one or more brief, low-energy shocks to your heart to restore a normal rhythm. You will not feel any pain from the shocks.
You will need to stay for a few hours after your procedure. During this time, your healthcare team will monitor your heart rhythm and blood pressure closely and watch for complications. You will need a ride home because of the medicines or anesthesia you received. You may have some redness or soreness where the electrodes were placed. You also may have slight bruising where the IV line was inserted in your arm.
Although uncommon, cardioversion has some risks. It can cause or worsen life-threatening arrhythmias that will need to be treated. This procedure can cause blood clots to break away and travel from the heart to other tissues or organs and cause a stroke or other problems. Taking anticlotting medicines before and after cardioversion can reduce this risk.
Catheter ablation is a procedure to stop abnormal electrical signals from moving through your heart and causing an irregular heartbeat.
Doctors perform catheter ablation in a hospital. Ablation is done through a procedure called cardiac catheterization that passes flexible tubes, or catheters, through your blood vessels until they reach your heart. Some catheters have wire electrodes that record and locate the source of your abnormal heartbeats. Other catheters can deliver treatments. Your doctor will aim the tip of a special catheter at the small area of heart tissue. A machine will send either radiofrequency (RF) waves, extremely cold temperatures, or laser light through the catheter tip to create a scar on the heart. The scar prevents abnormal electrical signals from causing irregular heartbeat.
Catheter ablation has some risks both during the procedure and during recovery, including:
- Blood vessel damage
- Heart damage
- Blood clots
There also may be a very slight risk of cancer from radiation used during catheter ablation. Talk to your doctor and the technicians performing the ablation about whether you are or could be pregnant.
Implantable cardioverter defibrillators (ICDs)
Defibrillators are devices that restore a normal heartbeat by sending an electric pulse or shock to the heart. They are used to prevent or correct an arrhythmia, a heartbeat that is uneven or that is too slow or too fast. Defibrillators can also restore a heartbeat if the heart suddenly stops.
Different types of defibrillators work in different ways. ICDs can prevent sudden death among people who have a high risk of a life-threatening arrhythmia. They are surgically placed inside your body. It can take time and effort to get used to living with a defibrillator, and it is important to be aware of possible risks and complications.
A pacemaker is a small device that sends electrical pulses to help your heart beat at a normal rate and rhythm. Pacemakers can also be used to help your heart chambers beat together in sync so your heart can pump blood more efficiently to your body. You may need a temporary (short-term) or permanent (long-term) pacemaker.
Treating the cause of your arrhythmia
Your doctor may talk to you about steps to manage the cause of your arrhythmia, such as a problem with your electrolyte levels, high blood pressure, heart disease, sleep apnea, or thyroid disease. Your doctor may use supplements to treat low levels of magnesium or potassium.
Vagal maneuvers are relaxation techniques that may help slow your heart rate.
Techniques your healthcare team may guide you through include:
- Coughing or gagging
- Holding your breath and bearing down, which is called the Valsalva maneuver
- Lying down
- Placing a towel dipped in ice-cold water over your face