Arrhythmia, 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.

Types of 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.

Bradyarrhythmia

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

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

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

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-fib. Torsades 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 of 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

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

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

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.

Medicines

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

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.

Risk Factors for 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.

Age

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.

Environment

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

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, gene mutations cause the ion channels that transmit signals through heart cells to work incorrectly or stop working.

Lifestyle habits

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

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
• Influenza, or flu
• 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

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.

Sex

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.

Surgery

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.

Signs, Symptoms, and Complications of 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

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

Complications

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.

Diagnosing 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

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

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

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, tosee 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 monitorto 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 studyto 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 testingto 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.

Treatment for 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

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.

• Aiming for a healthy weight
• Being physically active
• Heart-healthy eating
• Managing stress
• Quitting smoking

Medicines

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 toslow 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.

Procedures

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

• Cardioversion
• Catheter ablation
• Implantable cardioverter defibrillators (ICDs)
• Pacemakers

Other treatments

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