Also known as Dysrhythmia
An arrhythmia is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slowly, or with an irregular rhythm. When a heart beats too fast, the condition is called tachycardia. When a heart beats too slowly, the condition is called bradycardia.

Arrhythmia is caused by changes in heart tissue and activity or in the electrical signals that control your heartbeat. These changes can be caused by damage from disease, injury, or genetics. Often there are no symptoms, but some people feel an irregular heartbeat. You may feel faint or dizzy or have difficulty breathing.

The most common test used to diagnose an arrhythmia is an electrocardiogram (EKG or ECG). Your doctor will run other tests as needed. She or he may recommend medicines, placement of a device that can correct an irregular heartbeat, or surgery to repair nerves that are overstimulating the heart. If arrhythmia is left untreated, the heart may not be able to pump enough blood to the body. This can damage the heart, the brain, or other organs.

Explore this Health Topic to learn more about arrhythmia, our role in research and clinical trials to improve health, and where to find more information.

Types - Arrhythmia

Arrhythmias differ from normal heartbeats in speed or rhythm. Arrhythmias are also grouped by where they occur—in the upper chambers of the heart, in its lower chambers, or between the chambers. The main types of arrhythmia are bradyarrhythmias; premature, or extra, beats; supraventricular arrhythmias; and ventricular arrhythmias.

To understand arrhythmia, it helps to understand how your heart’s electrical system works. Arrhythmias known as conduction disorders are covered separately.

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Bradyarrhythmia is a slow heart rate—also called bradycardia. For adults, bradycardia is often defined as a heart rate that is slower than 60 beats per minute, although some studies use a heart rate of less than 50 beats per minute. Some people, especially people who are young or physically fit, may normally have slow heart rates. A doctor can determine whether a slow heart rate is appropriate for you.

Premature or extra heartbeat
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A premature heartbeat happens when the signal to beat comes early. It can feel like your heart skipped a beat. The premature, or extra, heartbeat creates a short pause, which is followed by a stronger beat when your heart returns to its regular rhythm. These extra heartbeats are the most common type of arrhythmia. They are called ectopic heartbeats and can trigger other arrhythmias.

Supraventricular arrhythmia
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Arrhythmias that start in the heart’s upper chambers, called the atrium, or at the gateway to the lower chambers are called supraventricular arrhythmias. Supraventricular arrhythmias are known by their fast heart rates, or tachycardia. Tachycardia occurs when the heart, at rest, goes above 100 beats per minute. The fast pace is sometimes paired with an uneven heart rhythm. Sometimes the upper and lower chambers beat at different rates.

Types of supraventricular arrhythmias include:

  • Atrial fibrillation. This is one of the most common types of arrhythmia. The heart can race at more than 400 beats per minute.
  • Atrial flutter. Atrial flutter can cause the upper chambers to beat 250 to 350 times per minute. The signal that tells the upper chambers to beat may be disrupted when it encounters damaged tissue, such as a scar. The signal may find an alternate path, creating a loop that causes the upper chamber to beat repeatedly. As with atrial fibrillation, some but not all of these signals travel to the lower chambers. As a result, the upper chambers and lower chambers beat at different rates.
  • Paroxysmal supraventricular tachycardia (PSVT). In PSVT, electrical signals that begin in the upper chambers and travel to the lower chambers cause extra heartbeats. This arrhythmia begins and ends suddenly. It can happen during vigorous physical activity. It is usually not dangerous and tends to occur in young people.

Ventricular arrhythmia
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These arrhythmias start in the heart’s lower chambers. They can be very dangerous and usually require medical care right away.

  • Ventricular tachycardia is a fast, regular beating of the 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, episodes that last for more than a few seconds can be dangerous. Ventricular tachycardia can turn into other more serious arrhythmias, such as ventricular fibrillation, or v-fibTorsades de pointes is a type of arrhythmia that causes a unique pattern on an EKG and often leads to v-fib.
  • Ventricular fibrillation occurs if disorganized electrical signals make the ventricles quiver instead of pumping normally. Without the ventricles pumping blood to the body, sudden cardiac arrest and death can occur within a few minutes.

Causes - Arrhythmia

Arrhythmia is caused by changes to heart tissue. It can also occur suddenly as a result of exertion or stress, imbalances in the blood, medicines, or problems with electrical signals in the heart. Typically, an arrhythmia is set off by a trigger, and the irregular heartbeat can continue if there is a problem in the heart. Sometimes the cause of an arrhythmia is unknown.

Changes to the heart
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The following conditions may cause arrhythmia:

  • Changes to the heart’s anatomy
  • Reduced blood flow to the heart or damage to the heart’s electrical system
  • Restoring blood flow as part of treating a heart attack
  • Stiffening of the heart tissue, known as fibrosis, or scarring

Exertion or strain
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Strong emotional stress, anxiety, anger, pain, or a sudden surprise can make the heart work harder, raise blood pressure, and release stress hormones. Sometimes these reactions can lead to arrhythmias. If you have heart disease, physical activity can trigger arrhythmia due to an excess of hormones such as adrenaline. Sometimes vomiting or coughing can trigger arrhythmia.

Imbalances in the blood
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An excess or deficiency of electrolytes, hormones, or fluids can alter your heartbeat.

  • An excess of thyroid hormone can cause the heart to beat faster, and thyroid deficiency can slow your heart rate.
  • Dehydration can cause the heart to race.
  • Low blood sugar, from an eating disorder or insulin doses that are too high in someone who has diabetes, can lead to slow or extra heartbeats.
  • Low levels of potassium, magnesium, or calcium can trigger arrhythmia. These electrolyte disturbances can occur after a heart attack or surgery.

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Certain medicines can cause arrhythmia. These include medicines to treat high blood pressure and other conditions, including arrhythmia, depression, and psychosis. Some people also need to be careful about taking certain antibiotics and over-the-counter medicines, such as allergy and cold medicines.

Problems with the electrical signals in the heart
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An arrhythmia can occur if the electrical signals that control the heartbeat are delayed or blocked. 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 the heart. Another part of the heart could start to produce electrical signals, disrupting a normal heartbeat.

Disorders of electrical signaling in the heart are called conduction disorders.

Want to learn more about why arrhythmias occur?

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  • Treatment will discuss heart-healthy lifestyle changes that your doctors may recommend if you are diagnosed with arrhythmia.

Risk Factors - Arrhythmia

You may have an increased risk of arrhythmia because of your age, environment, family history and genetics, habits in your daily life, certain medical conditions, race or ethnicity, sex, or surgery.

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The chances of having arrhythmia grow as we age, in part because of changes in heart tissue and in how the heart works over time. Older people are also more likely to have health conditions, including heart disease, that raise the risk of arrhythmia.

Some types of arrhythmia happen more often in children and young adults, including arrhythmias due to congenital heart defects or inherited conduction disorders.

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Some research suggests that exposure to air pollutants, especially particulates and gases, is linked to a short-term risk of arrhythmia.

Family history and genetics
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You may have an increased risk of some types of arrhythmia if your parent or other close relative has had arrhythmia, too. Also, some inherited types of heart disease can raise your risk of arrhythmia. With some conduction disorders, genes mutations cause the ion channels that transmit signals through heart cells to work incorrectly or stop working.

Lifestyle habits
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Your risk for arrhythmia may be higher because of certain lifestyle habits, including:

  • Drinking alcohol
  • Smoking
  • Using illegal drugs, such as cocaine or amphetamines

Other medical conditions
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Arrhythmias are more common in people who have diseases or conditions that weaken the heart, but many conditions can raise the risk for arrhythmia. These include:

  • Aneurysms
  • autoimmune disorders, such as rheumatoid arthritis and lupus
  • Cardiomyopathy, which affects the heart muscle
  • Diabetes, which increases the risk of high blood pressure and coronary heart disease
  • Eating disorders, such as bulimia and anorexia, which cause electrolyte imbalance and severe malnutrition
  • Heart attack
  • Heart inflammation
  • Heart failure, which weakens the heart and changes the way electrical signals move through the heart
  • Heart tissue that is too thick or stiff or that has not formed normally. Arrhythmias can be more common among people who have had surgery to repair a congenital heart defect.
  • High blood pressure
  • Viral infections such as influenza (flu) or COVID-19.” Watch our video on how SARS-CoV-2, the virus responsible for COVID-19, may lead to or worsen an arrhythmia. Additionally, we offer information and resources on how we are working hard to support necessary COVID-19 research. 
  • Kidney disease
  • Heart valves. Leaking or narrowed heart valves make the heart work too hard and can lead to heart failure.
  • Low blood sugar
  • Lung diseases, such as chronic obstructive pulmonary disease (COPD)
  • Musculoskeletal disorders
  • Obesity
  • Overactive or underactive thyroid gland, caused by too much or too little thyroid hormone in the body. The most common cause of excess thyroid hormone is Graves’ disease.
  • Sepsis, a toxic immune response to infection
  • Sleep apnea, which can stress the heart by preventing it from getting enough oxygen

Race or ethnicity
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Studies suggest that white Americans may be more likely than African Americans to have some arrhythmias, such as atrial fibrillation, although African Americans have higher rates of high blood pressure and other arrhythmia risk factors.

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Some studies suggest that men are more likely to have atrial fibrillation than women. However, women taking certain medicines appear to be at a higher risk of a certain type of arrhythmia. Certain times of the menstrual cycle also appear to increase women’s risk of some arrhythmia events. If you are a pregnant woman, you may notice that an existing arrhythmia occurs more often. Benign extra beats are also more common during pregnancy. In some cases, the complications that can develop with arrhythmia also differ by sex.

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You may be at a higher risk of developing atrial flutter in the early days and weeks after surgery involving the heart, lungs, or esophagus.

Screening and Prevention - Arrhythmia

If you or your child is at increased risk of arrhythmia, the doctor may want to do a screening to assess the risk of a life-threatening event. Sometimes screening is required to participate in competitive sports. If your child carries a genetic risk of arrhythmia, your child’s doctor may recommend regular screening to monitor your child’s heart or other family members’ health. The doctor may also ask about risk factors and may suggest genetic testing if your child, parent, or other family member has a known or suspected arrhythmia or other heart condition. Heart-healthy lifestyle changes and other precautions can help decrease the risk of triggering arrhythmia.

Screening tests
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Your doctor may recommend screening tests based on your risk factors, such as age or family history.

  • An electrocardiogram (EKG or ECG) is the main test for detecting arrhythmia. An EKG records the heart’s electrical activity. Your doctor may do the test while you are at rest or may do a stress test, which records the heart’s activity when it is working hard. Your doctor may also give you a portable monitor to wear for a day or several days if no arrhythmia was detected during testing in the clinic. If you have a child who is at risk of arrhythmia because of a genetic condition, the doctor may recommend regular testing for your child and his or her siblings.
  • Genetic testing can help you understand your risk when a family member has been diagnosed with a genetic condition. Testing is especially important if your newborn or another close relative died suddenly and had a genetic risk. Your doctor may also suggest genetic testing if you have a history of fainting or have survived cardiac arrest or near drowning.
  • Imaging tests, such as cardiac magnetic resonance imaging (MRI), can help detect scarring or other problems that can increase your risk of arrhythmia.

Prevention strategies
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Learn about prevention strategies that your doctor may recommend, including:

  • Avoiding triggers, such as caffeine or stimulant medicines, that can cause arrhythmias or make them worse. Your doctor can also help if you are trying to avoid illegal drugs.
  • Getting an implantable or wearable cardioverter defibrillator to prevent sudden cardiac arrest from arrhythmia if you have heart disease. Defibrillators can correct arrhythmias by sending an electric shock to the heart.
  • Making heart-healthy lifestyle changes, such as heart-healthy eating, being physically active, aiming for a healthy weight, quitting smoking, and managing stress
  • Monitoring you after surgery, if you are having heart surgery. The surgical team may also use medicine and maintain or supplement electrolyte levels during or after the procedure to prevent arrhythmia.

If you are the parents of a child with an inherited condition that increases the risk of arrhythmia, discuss prevention strategies with your pediatrician as part of your child’s care.

  • If your child is a newborn, follow safe sleep recommendations to help reduce the risk of sudden infant death syndrome (SIDS).
  • Your doctor may recommend routine assessments of your child’s heart activity to detect patterns or symptoms of arrhythmia that emerge over time.

Look for
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  • Diagnosis will explain tests and procedures that your doctor may use to diagnose types of arrhythmia.
  • Living With will discuss what your doctor may recommend to prevent your arrhythmia from recurring, getting worse, or causing complications.
  • Research for Your Health will discuss how we are using current research and advancing research to prevent arrhythmia.
  • Participate in NHLBI Clinical Trials will explain our open and enrolling clinical studies that are investigating prevention strategies for arrhythmia.

Signs, Symptoms, and Complications - Arrhythmia

An arrhythmia may not cause any obvious Signs or symptoms. You may notice something that occurs only occasionally, or your symptoms may become more frequent over time. Keep track of when and how often arrhythmia occurs, what you feel, and whether these things change over time. They are all important clues your doctor can use. If left untreated, arrhythmia can lead to life-threatening complications such as stroke, heart failure, or sudden cardiac arrest.

Signs and symptoms
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You may be able to feel a slow or irregular heartbeat or notice pauses between heartbeats. If you have palpitations, you may feel like your heart skipped a beat or may notice it pounding or racing. These are all symptoms of arrhythmia.

More serious signs and symptoms include:

  • Anxiety
  • Blurred vision
  • Chest pain
  • Difficulty breathing
  • Fainting or nearly fainting
  • Foggy thinking
  • Fatigue
  • Sweating
  • Weakness, dizziness, and light-headedness

What else will your doctor want to know about your symptoms?

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Arrhythmias that are unrecognized or left untreated can cause sometimes life-threatening complications affecting the heart and brain.

  • Cognitive impairment and dementia. Alzheimer’s disease and vascular dementia are more common in people who have arrhythmia. This may be due to reduced blood flow to the brain over time.
  • Heart failure. Repeat arrhythmias can lead to a rapid decline in the ability of the lower chambers to pump blood. Heart failure is especially likely to develop or to grow worse as a result of arrhythmia when you already have heart disease.
  • Stroke. This can occur in some patients who have atrial fibrillation. With arrhythmia, blood can pool in the atria, causing blood clots to form. If a clot breaks off and travels to the brain, it can cause a stroke.
  • Sudden cardiac arrest. The heart may suddenly and unexpectedly stop beating as a result of ventricular fibrillation.
  • Sudden infant death syndrome (SIDS). SIDS can be attributed to an inherited conduction disorder that causes arrhythmia.
  • Worsening arrhythmia. Some arrhythmias trigger another type of arrhythmia or get worse over time.

Look for
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  • Diagnosis will explain tests and procedures used to detect signs of arrhythmia and help rule our other conditions that may mimic arrhythmia.
  • Treatment will discuss treatment-related complications or side effects.

Diagnosis - Arrhythmia

To diagnose arrhythmia, your doctor will ask you about your symptoms, your medical history, and any signs of arrhythmia in your family. Your doctor may also do an EKG and a physical exam as part of your diagnosis. Additional tests may be necessary to rule out another cause or to help your doctor decide on treatment.

Medical history
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To diagnose an arrhythmia, your doctor will ask about your eating and physical activity habits, family history, and other risk factors for arrhythmia. Your doctor may ask whether you have any other signs or symptoms. This information can help your doctor determine whether you have complications or other conditions that may be causing you to have arrhythmia.

Physical exam
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During a physical exam, your doctor may take these steps:

  • Check for swelling in your legs or feet, which could be a sign of an enlarged heart or heart failure
  • Check your pulse to find out how fast your heart is beating
  • Listen to the rate and rhythm of your heartbeat
  • Listen to your heart for a heart murmur
  • Look for signs of other diseases, such as thyroid disease, that could be causing the arrhythmia

Diagnostic tests and procedures
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Your doctor may order some of the following tests to diagnose arrhythmia:

  • Blood tests to check the level of certain substances in the blood, such as potassium and thyroid hormone, that can increase your risk of arrhythmia.
  • Cardiac catheterization to see whether you have complications from heart disease.
  • Chest X-ray to show whether your heart is larger than normal.
  • Echocardiography (echo) to provide information about the size and shape of your heart and how well it is working. Echocardiography may also be used to diagnose fetal arrhythmia in the womb.
  • EKG, or ECG, to see how fast the heart is beating and whether its rhythm is steady or irregular. This is the most common test used to diagnose arrhythmias.
  • Electrophysiology study (EPS) to look at the electrical activity of the heart. The study uses a wire to electrically stimulate your heart and trigger an arrhythmia. If your doctor has already detected another condition that raises your risk, an EPS can help him or her assess the possibility that an arrhythmia will develop. An EPS also allows your doctor to see whether a treatment, such as medicine, will stop the problem.
  • Holter or event monitor to record your heart’s electrical activity over long periods of time while you do your normal activities.
  • Implantable loop recorder to detect abnormal heart rhythms. It is placed under the skin and continuously records your heart’s electrical activity. The recorder can transmit data to the doctor’s office to help with monitoring. An implantable loop recorder helps doctors figure out why a person may be having palpitations or fainting spells, especially if these symptoms do not happen very often.
  • Sleep study to see whether sleep apnea is causing your arrhythmia.
  • Stress test or exercise stress test to detect arrhythmias that happen while the heart is working hard and beating fast. If you cannot exercise, you may be given medicine to make your heart work hard and beat fast.
  • Tilt table testing to 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.
  • Ultrasound to diagnose a suspected fetal arrhythmia in the womb.

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Treatment - Arrhythmia

Common arrhythmia treatments include heart-healthy lifestyle changes, medicines, surgically implanted devices that control the heartbeat, and other procedures that treat abnormal electrical signals in the heart.

Healthy lifestyle changes
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Your doctor may recommend that you adopt the following lifelong heart-healthy lifestyle changes to help lower your risk for conditions such as high blood pressure and heart disease, which can lead to arrhythmia.

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Your doctor may give you medicine for your arrhythmia. Some medicines are used in combination with each other or together with a procedure or a pacemaker. If the dose is too high, medicines to treat arrhythmia can cause an irregular rhythm. This happens more often in women.

  • Adenosine to slow a racing heart. Adenosine acts quickly to slow electrical signals. It can cause some chest pain, flushing, and shortness of breath, but any discomfort typically passes soon.
  • Atropine to treat a slow heart rate. This medicine may cause difficulty swallowing.
  • Beta blockers to treat high blood pressure or a fast heart rate or to prevent repeat episodes of arrhythmia. Beta blockers can cause digestive trouble, sleep problems, and sexual dysfunction and can make some conduction disorders worse.
  • Blood thinners to reduce the risk of blood clots forming. This helps prevent stroke. With blood-thinning medicines, there is a risk of bleeding.
  • Calcium channel blockers to slow a rapid heart rate or the speed at which signals travel. Typically, they are used to control arrhythmias of the upper chambers. In some cases, calcium channel blockers can trigger ventricular fibrillation. They can also cause digestive trouble, swollen feet, or low blood pressure.
  • Digitalis, or digoxin, to treat a fast heart rate. This medicine can cause nausea and may trigger arrhythmias.
  • Potassium channel blockers to slow the heart rate. They work by lengthening the time it takes for heart cells to recover after firing, so that they do not fire and squeeze as often. Potassium channel blockers can cause low blood pressure or another arrhythmia.
  • Sodium channel blockers to block transmission of electrical signals, lengthen cell recovery periods, and make cells less excitable. However, these drugs can increase risks of sudden cardiac arrest in people who have heart disease.

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If medicines do not treat your arrhythmia, your doctor may recommend one of these procedures or devices.

Other treatments
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Treatment may also include managing any underlying condition, such as an electrolyte imbalance, high blood pressure, heart disease, sleep apnea, or thyroid disease.

Your doctor may use supplements to treat magnesium or electrolyte deficiencies. Electrolytes can also be an alternative to medicines that treat arrhythmia if your doctor is concerned that those medicines might trigger an arrhythmia.

Your doctor may also perform certain techniques to slow your heart rate. The exercises stimulate your body’s natural relaxation processes. They do this by affecting the vagus nerve, which helps control the heart rate. Techniques can include:

  • Having you cough or gag
  • Having you hold your breath and bear down, which is called the Valsalva maneuver
  • Having you lie down
  • Putting a towel dipped in ice-cold water over your face

Look for
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  • Living With will explain what your doctor may recommend including lifelong lifestyle changes and medical care to prevent your condition from recurring, getting worse, or causing complications.
  • Research for Your Health will explain how we are using current research and advancing research to treat people with arrhythmia.
  • Participate in NHLBI Clinical Trials will discuss our open and enrolling clinical studies that are investigating treatments for arrhythmia.

Living With - Arrhythmia

If you have been diagnosed and treated for arrhythmia, make sure to follow your treatment plan. Your ongoing care may focus on reducing the chance that you will have another episode or a complication. Keep your regular appointments with your doctor. Ask about heart-healthy lifestyle changes that you can make to keep your arrhythmia from happening again or getting worse.

Receive routine follow-up care
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How often you need to see your doctor for follow-up care will depend on your symptoms and treatment.

  • Get regular vaccinations, including a flu shot every year.
  • Follow your doctor's recommendations for adopting lifelong lifestyle changes, such as heart-healthy eating, being physically active, quitting smoking, managing stress, and aiming for a healthy weight. Your doctor may also recommend that you reduce or stop drinking alcohol and consuming coffee, tea, soda, chocolate, or other sources of caffeine, to avoid triggering arrhythmia.
  • Keep all of your medical appointments. Bring a list of all the medicines you take to every doctor and emergency room visit. This will help your doctors know exactly what medicines you are taking, which can help prevent medicine errors.
  • See your doctor for regular checkups if you are taking blood-thinning medicines. Your doctor may recommend blood thinners to prevent stroke, even if your heart rhythm has returned to normal. You may need routine blood tests to check how the medicines are working or the effect they are having on your organs.
  • Take your medicines as prescribed. Your doctor may also ask you to check your pulse regularly to monitor the effectiveness of the medicines.
  • Tell your doctor if you have side effects from your medicines, such as depression, light-headedness, or palpitations. Some of the medicines can cause low blood pressure or a slow heart rate or can make heart failure worse.
  • Tell your doctor if your symptoms are getting worse or if you have new symptoms. Over time, arrhythmias can become more common, last longer, or get worse. This can sometimes make arrhythmia resistant to medicines. Some arrhythmias can also make it more likely for other types of arrhythmia to develop.

Return to Treatment to review possible treatment options for arrhythmia.

Monitor your condition
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To monitor your condition, your doctor may recommend the following tests.

  • Blood tests to check the effects of medicines you are taking
  • Echocardiography (echo) to check your heart function if you have underlying heart disease
  • EKGs to monitor changes in heart rhythm
  • Holter or event monitors to record your heart’s electrical activity over several days
  • Smartphone-based monitors to record heart rhythms and detect when atrial fibrillation occurs. A band that can record a 30-second EKG has been approved by the U.S. Food and Drug Administration.

Learn the warning signs of serious complications and have a plan
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Arrhythmia can lead to serious complications, such as sudden cardiac arrest and severe bleeding in the brain. If you suspect any of the following in yourself or someone else, call 9-1-1 immediately:

  • Bleeding in the brain or digestive system. If you take too high a dose of blood-thinning medicines, it may cause bleeding in the brain or digestive system. Signs and symptoms may include bright red vomit; bright red blood in your stool or black, tarry stools; severe pain in the abdomen or head; sudden, severe changes in your vision or ability to move your arms or legs; or memory loss. A lot of bleeding after a fall or injury or easy bruising or bleeding may mean that your blood is too thin. Excessive bleeding is bleeding that will not stop after you apply pressure to a wound for 10 minutes. Call your doctor right away if you have any of these signs.
  • Heart attack. Signs of heart attack include mild or severe chest pain or discomfort in the center of the chest or upper abdomen that lasts for more than a few minutes or goes away and comes back. It can feel like pressure, squeezing, fullness, heartburn, or indigestion. There may also be pain down the left arm. Women may also have chest pain and pain down the left arm, but they are more likely to have other symptoms, such as shortness of breath, nausea, vomiting, unusual tiredness, and pain in the back, shoulders, or jaw. Read more about the signs and symptoms of a heart attack.
  • Stroke. If you think someone may be having a stroke, act F.A.S.T. and do the following simple test.

    F—Face: Ask the person to smile. Does one side of the face droop?

    A—Arms: Ask the person to raise both arms. Does one arm drift downward?

    S—Speech: Ask the person to repeat a simple phrase. Is their speech slurred or strange?

    T—Time: If you observe any of these signs, call 9-1-1 immediately. Every minute matters.

    Read more about the signs and symptoms of a stroke.

  • Sudden cardiac arrest. Usually, the first sign of sudden cardiac arrest is fainting. At the same time, no heartbeat can be felt. Some people may have a racing heartbeat or feel dizzy or light-headed just before they faint. Within an hour before cardiac arrest, some people have chest pain, shortness of breath, nausea, or vomiting. Call 9-1-1 right away if someone has signs or symptoms of sudden cardiac arrest. Look for a defibrillator nearby and follow the instructions.

Learn about other precautions to help you stay safe
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If you have arrhythmia, you will need to learn ways to care for your condition at home. You will also need to avoid activities that may trigger your arrhythmia.

  • Ask your doctor whether you can continue your daily activities without any changes. Your doctor may recommend low or moderate activity; avoiding competitive sports; eliminating activities that might trigger an arrhythmia, such as swimming or diving; or participating in activities with a partner.
  • Carry a medical device ID card with information about your defibrillator or pacemaker and contact information for the health care provider who oversees your care. Medical bracelets with information about your condition can also be helpful in the event of an emergency.
  • Check with your doctor before taking over-the-counter medicines, nutritional supplements, or cold and allergy medicines. Some of these products can trigger rapid heart rhythms or interact poorly with heart rhythm medicines.
  • Learn how to take your pulse. Discuss with your doctor what pulse rate is normal for you. Keep a record of changes in your pulse rate, and share this information with your doctor.
  • Lie down if you feel dizzy or faint or if you feel palpitations. Do not try to walk or drive. Let your doctor know about these symptoms.
  • Talk to your doctor about techniques that you can do at home if you notice your heart racing. These include breathing out without letting your breath escape or putting a cold, wet towel over your face.

Research for Your Health

The NHLBI is part of the U.S. Department of Health and Human Services’ National Institutes of Health (NIH)—the Nation’s biomedical research agency that makes important scientific discovery to improve health and save lives. We are committed to advancing science and translating discoveries into clinical practice to promote the prevention and treatment of heart, lung, blood, and sleep disorders, including arrhythmia. Learn about the current and future NHLBI efforts to improve health through research and scientific discovery.

Improving health with current research
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Learn about the following ways the NHLBI continues to translate current research into improved health for people with arrhythmia. Research on this topic is part of the NHLBI’s broader commitment to advancing heart and vascular disease scientific discovery.

  • Studying innovations to improve heart and vascular disease outcomes. The Cardiothoracic Surgical Trials Network (CTSN) is an international network that studies heart valve disease, arrhythmias, heart failure, coronary heart disease, and the complications of surgery. CTSN researchers have studied the success of treatments for people who have atrial fibrillation and need heart valve surgery and compared rate control and rhythm control as a first treatment after surgery.
  • Testing varied approaches to treatment. The Catheter Ablation versus Antiarrhythmic Drug Therapy for Atrial Fibrillation Trial (CABANA) compared catheter ablation with medicine and found that catheter ablation was no better than medicines at treating atrial fibrillation.
  • Building evidence to support guidelines for care. The NHLBI convenes experts to help identify research questions that can shape future clinical practice. For example, a 2010 working group on screening for sudden cardiac death in the young aimed to help determine whether screening can help prevent deaths from arrhythmia reliably and economically.
  • Supporting heart failure research collaboration. The Heart Failure Clinical Research Network (HFN) conducts clinical trials to evaluate treatments for acute and chronic heart failure. The HFN brings together nine Regional Coordinating Centers and additional clinical sites in the United States to research strategies that address the increasing public health burden of heart failure, including the impact of the arrhythmias that heart failure can cause.
  • Using new technologies to improve clinical care. The New Approaches to Arrhythmia Detection and Treatment initiative aimed to improve the ability to detect, prevent, and treat all forms of cardiac arrhythmias. It encouraged small business firms to seek recent technological or scientific breakthroughs and develop new diagnostic and therapeutic tools, devices, or products from them. Efforts included new technologies to help reduce errors in screening infants for arrhythmia risk or make it easier to record fetal heart rhythms, a blood test to detect heart failure patients with an increased genetic risk of sudden cardiac arrest, a reliable EKG monitoring device that patients can wear over their clothes, fluorescent dyes doctors can use to better see the heart’s abnormal electrical activity, and a tool to improve placement of pacemakers and ICDs.
  • Funding advances in emergency response. The Resuscitation Outcomes Consortium (ROC) is a clinical trial network that tested treatments to address high rates of illness and death from out-of-hospital cardiac arrest and severe traumatic injury. For example, consortium researchers confirmed that certain heart rhythm medicines improved patients’ likelihood of surviving transport to the hospital after experiencing sudden out-of-hospital cardiac arrest and failing electrical shock treatment. Arrhythmia triggered the patients’ sudden cardiac arrest.
  • Promoting a clinical trial network to address emergency medicine. The trans-NIH Network for Emergency Care Clinical Trials: Strategies to Innovate EmeRgENcy Care Clinical Trials Network (SIREN), in partnership with the Department of Defense, will conduct clinical trials to improve outcomes in emergency departments and pre-hospital settings.

Learn about some of the pioneering research contributions we have made over the years that have improved clinical care.

Advancing research for improved health
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In support of our mission, we are committed to advancing arrhythmia research in part through the following ways.

Learn about exciting research areas the NHLBI is exploring about arrhythmia.

Participate in NHLBI Clinical Trials

We lead or sponsor many studies on arrhythmia. See whether you or someone you know is eligible to participate in our clinical trials.

Did you develop atrial fibrillation after coronary artery bypass graft (CABG) surgery?

This study will examine whether adding oral anti-blood clotting medicines to anti-platelet medicines (such as aspirin) helps prevent stroke and other complications in people who develop atrial fibrillation after CABG surgery. To participate in this study, you must be at least 18 years old and have been diagnosed with atrial fibrillation after having CABG surgery. The study is located in 63 places in 22 states, the District of Columbia, Canada, and Germany.

Do you know someone who will be having heart surgery?

This study aims to identify what genetic patterns might cause atrial fibrillation and other adverse events that happen after heart surgery. To participate in this study, you must be between 20 and 90 years old. The study is in three locations in Massachusetts and Texas.

Do you have heart disease that requires an ICD to prevent sudden cardiac arrest?

This study aims to learn what signs distinguish patients who have a higher risk of an arrhythmia that leads to sudden cardiac arrest. Researchers plan to track patients with a recent ICD replacement for 10 years. To participate in this study, you must be between 18 and 85 years old. This study is located in Washington, D.C.; Baltimore, Maryland; and Richmond, Virginia.

Are you a Minnesota resident with hypertrophic cardiomyopathy?

This study aims to find out how common it is for people with hypertrophic cardiomyopathy to also have sleep apnea. Hypertrophic cardiomyopathy is a disease that causes the heart muscle to thicken. Participants will also wear a heart rhythm monitor to help researchers learn whether sleep apnea is linked to arrhythmia. The study seeks healthy volunteers as well as participants in the Hypertrophic Cardiomyopathy Registry. To participate in this study, you must not have had a catheter ablation procedure to treat atrial fibrillation, had surgery to replace your heart valves, or been treated for sleep apnea. The study is located in Rochester, Minnesota.

Are you being treated for atrial fibrillation?

This study aims to compare two types of ablation treatment for patients who continue to have symptoms of atrial fibrillation despite treatment with medicines. The two ablation procedures treat different areas of tissue. To participate in this study, you must be at least 21 years old. The study is located in Palo Alto and San Diego, California.

Do you have a ventricular arrhythmia?

This study aims to evaluate the safety and effectiveness of low-energy shocks for the treatment of ventricular tachycardia and ventricular fibrillation. This approach will be tested during a catheter ablation or placement of an implantable cardioverter defibrillator (ICD). To participate in this study, you must be between 18 and 75 years old. This study is located in Minneapolis, Minnesota, and Austin, Texas.

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