Tachycardia is the medical term for a heart rate over 100 beats per minute. There are many heart rhythm disorders (arrhythmias) that can cause tachycardia.

Sometimes, it's normal for you to have a fast heartbeat. For instance, it's normal for your heart rate to rise during exercise or as a response to stress, trauma or illness. But in tachycardia (tak-ih-KAHR-dee-uh), the heart beats faster than normal due to conditions unrelated to normal physiological stress.

In some cases, tachycardia may cause no symptoms or complications. But if left untreated, tachycardia can disrupt normal heart function and lead to serious complications, including:

• Heart failure
• Stroke
• Sudden cardiac arrest or death

Treatments, such as drugs, medical procedures or surgery, may help control a rapid heartbeat or manage other conditions contributing to tachycardia.

Types of tachycardia

There are many different types of tachycardia. They're grouped according to the part of the heart responsible for the fast heart rate and cause of the abnormally fast heartbeat. Common types of tachycardia include:

• Atrial fibrillation. Atrial fibrillation is a rapid heart rate caused by chaotic, irregular electrical impulses in the upper chambers of the heart (atria). These signals result in rapid, uncoordinated, weak contractions of the atria.

  Atrial fibrillation may be temporary, but some episodes won't end unless treated. Atrial fibrillation is the most common type of tachycardia.

• Atrial flutter. In atrial flutter, the heart's atria beat very fast but at a regular rate. The fast rate results in weak contractions of the atria. Atrial flutter is caused by irregular circuitry within the atria.

  Episodes of atrial flutter may go away themselves or may require treatment. People who have atrial flutter also often have atrial fibrillation at other times.

• Supraventricular tachycardia (SVT). Supraventricular tachycardia is an abnormally fast heartbeat that starts somewhere above the lower chambers of the heart (ventricles). It's caused by abnormal circuitry in the heart that is usually present at birth and creates a loop of overlapping signals.

• Ventricular tachycardia. Ventricular tachycardia is a rapid heart rate that starts with abnormal electrical signals in the lower chambers of the heart (ventricles). The rapid heart rate doesn't allow the ventricles to fill and contract efficiently to pump enough blood to the body.

  Ventricular tachycardia episodes may be brief and last only a couple of seconds without causing harm. But episodes lasting more than a few seconds can become a life-threatening medical emergency.

• Ventricular fibrillation. Ventricular fibrillation occurs when rapid, chaotic electrical impulses cause the lower heart chambers (ventricles) to quiver instead of pumping necessary blood to the body. This can be deadly if the heart isn't restored to a normal rhythm within minutes with an electric shock to the heart (defibrillation).

  Ventricular fibrillation may occur during or after a heart attack. Most people who have ventricular fibrillation have an underlying heart disease or have experienced serious trauma, such as being struck by lightning.

When your heart is beating too fast, it may not pump enough blood to the rest of your body. This can starve your organs and tissues of oxygen and can cause the following tachycardia-related signs and symptoms:

• Shortness of breath
• Lightheadedness
• Rapid pulse rate
• Heart palpitations — a racing, uncomfortable or irregular heartbeat or a sensation of "flopping" in the chest
• Chest pain
• Fainting (syncope)

Some people with tachycardia have no symptoms, and the condition is only discovered during a physical examination or with a heart-monitoring test called an electrocardiogram.

When to see a doctor

A number of conditions can cause a rapid heart rate and tachycardia symptoms. It's important to get a prompt, accurate diagnosis and appropriate care. See your doctor if you or your child has any tachycardia symptoms.

If you faint, have difficulty breathing or have chest pain lasting more than a few minutes, get emergency care, or call 911 or your local emergency number. Seek emergency care for anyone experiencing these symptoms.

Tachycardia is caused by something that disrupts the normal electrical impulses that control the rate of your heart's pumping action. Many things can cause or contribute to a fast heart rate. These include:

• Anemia
• Drinking too many caffeinated beverages
• Drinking too much alcohol
• Exercise
• Fever
• High or low blood pressure
• Imbalance of electrolytes, mineral-related substances necessary for conducting electrical impulses
• Medication side effects
• Overactive thyroid (hyperthyroidism)
• Smoking
• Sudden stress, such as fright
• Use of stimulant drugs, such as cocaine or methamphetamine

In some cases, the exact cause of tachycardia can't be determined.

The heart's electrical system

To understand the causes of heart rate or rhythm problems such as tachycardia, it helps to understand how the heart's electrical system works.

Your heart is made up of four chambers — two upper chambers (atria) and two lower chambers (ventricles). Your heartbeat is normally controlled by a natural pacemaker called the sinus node, which is located in the right atrium. The sinus node produces electrical impulses that normally start each heartbeat.

From the sinus node, electrical impulses travel across the atria, causing the atrial muscles to contract and pump blood into the lower chambers of the heart (ventricles).

The electrical impulses then arrive at a cluster of cells called the atrioventricular (AV) node — usually the only pathway for signals to travel from the atria to the ventricles.

The AV node slows down the electrical signal before sending it to the ventricles. This slight delay allows the ventricles to fill with blood. When electrical impulses reach the muscles of the ventricles, they contract, causing them to pump blood either to the lungs or to the rest of the body.

When anything disrupts this complex system, it can cause the heart to beat too fast (tachycardia), too slow (bradycardia) or with an irregular rhythm.

Growing older or having a family history of tachycardia or other heart rhythm disorder makes you more likely to develop tachycardia.

Any condition that puts a strain on the heart or damages heart tissue can increase your risk of tachycardia. Such conditions include:

• Anemia
• Diabetes
• Heart disease
• Heavy alcohol use
• Heavy caffeine use
• High blood pressure
• Overactive or underactive thyroid
• Psychological stress or anxiety
• Sleep apnea
• Smoking
• Use of stimulant drugs

Lifestyle changes or medical treatment for related health conditions may decrease your risk of tachycardia.

Complications of tachycardia depend on the type of tachycardia, how fast the heart is beating, how long the rapid heart rate lasts and if you have any other heart conditions.

Possible complications include:

• Blood clots that can cause a stroke or heart attack
• Inability of the heart to pump enough blood (heart failure)
• Frequent fainting spells or unconsciousness
• Sudden death, usually only associated with ventricular tachycardia or ventricular fibrillation

The most effective way to prevent tachycardia is to maintain a healthy heart and reduce your risk of developing heart disease. If you already have heart disease, monitor it and follow your treatment plan to help prevent tachycardia.

Prevent heart disease

Treat or eliminate risk factors that may lead to heart disease. Take the following steps:

• Exercise and eat a healthy diet. Live a heart-healthy lifestyle by exercising regularly and eating a healthy, low-fat diet that's rich in fruits, vegetables and whole grains.
• Maintain a healthy weight. Being overweight increases your risk of developing heart disease.
• Keep blood pressure and cholesterol levels under control. Make lifestyle changes and take medications as prescribed to correct high blood pressure (hypertension) or high cholesterol.
• Stop smoking. If you smoke and can't quit on your own, talk to your doctor about strategies or programs to help you break a smoking habit.
• Drink in moderation. If you choose to drink alcohol, do so in moderation. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and up to two drinks a day for men. For some conditions, it's recommended that you completely avoid alcohol. Ask your doctor for advice specific to your condition.
• Don't use recreational drugs. Don't use stimulants, such as cocaine. Talk to your doctor about an appropriate program for you if you need help ending recreational drug use.
• Use over-the-counter medications with caution. Some cold and cough medications contain stimulants that may trigger a rapid heartbeat. Ask your doctor which medications you need to avoid.
• Limit caffeine. If you drink caffeinated beverages, do so in moderation (no more than one to two beverages daily).
• Control stress. Avoid unnecessary stress and learn coping techniques to handle normal stress in a healthy way.
• Go to scheduled checkups. Have regular physical exams and report any signs or symptoms to your doctor.

Monitor and treat existing heart disease

If you already have heart disease, you can take steps to help prevent tachycardia or another arrhythmia:

• Follow the plan. Be sure you understand your treatment plan, and take all medications as prescribed.
• Report changes immediately. If your symptoms change or get worse or you develop new symptoms, tell your doctor immediately.

To diagnose your condition and determine the specific type of tachycardia, your doctor will evaluate your symptoms, perform a physical examination, and ask you about your health habits and medical history.

Several heart tests also may be necessary to diagnose tachycardia.

Electrocardiogram (ECG)

An electrocardiogram, also called an ECG or EKG, is the most common tool used to diagnose tachycardia. It's a painless test that detects and records your heart's electrical activity using small sensors (electrodes) attached to your chest and arms.

An ECG records the timing and strength of electrical signals as they travel through your heart. Your doctor can look for signal patterns to determine what kind of tachycardia you have and how problems in the heart may be causing a fast heart rate.

Your doctor may ask you to use a portable ECG device at home to provide more information about your heart rate. Portable, or remote, ECG devices include:

• Holter monitor. This portable ECG device is carried in your pocket or worn on a belt or shoulder strap. It records your heart's activity for an entire 24-hour period, which provides your doctor with a prolonged look at your heart rhythms.

  Your doctor will likely ask you to keep a diary during the same 24 hours. You'll describe any symptoms you experience and record the time they occur.

• Event monitor. This portable ECG device is intended to monitor your heart activity over a week to a few months. You wear it all day, but it records only at certain times for a few minutes at a time. With many event monitors, you activate them by pushing a button when you have symptoms of a fast heart rate.

  Other monitors automatically sense abnormal heart rhythms and then start recording. These monitors allow your doctor to look at your heart rhythm at the time of your symptoms.

• Other portable monitors. Some personal devices, such as smartwatches, offer electrocardiogram monitoring. Ask your doctor if this is an option for you.

Electrophysiological test

Your doctor may recommend an electrophysiological test to confirm the diagnosis or to pinpoint the location of problems in your heart's circuitry.

During this test, a doctor inserts thin, flexible tubes (catheters) tipped with electrodes into your groin, arm or neck and guides them through your blood vessels to various spots in your heart. Once in place, the electrodes can precisely map the spread of electrical impulses during each beat and identify abnormalities in your circuitry.

Cardiac imaging

Imaging of the heart may be performed to determine if structural abnormalities are affecting blood flow and contributing to tachycardia.

Cardiac imaging tests used to diagnose tachycardia include:

• Echocardiogram. An echocardiogram creates a moving picture of your heart using sound waves. It can identify areas of poor blood flow, abnormal heart valves and heart muscle that's not working normally.
• Magnetic resonance imaging (MRI). A cardiac MRI can provide still or moving pictures of how the blood is flowing through the heart and detect irregularities.
• Computerized tomography (CT). CT scans combine several X-ray images to provide a more detailed cross-sectional view of the heart.
• Coronary angiogram. To study the flow of blood through your heart and blood vessels, your doctor may use a coronary angiogram to reveal potential blockages or abnormalities. It uses a dye and special X-rays to show the inside of your coronary arteries.
• Chest X-ray. This test is used to take still pictures of your heart and lungs and can detect if your heart is enlarged.

Stress test

Your doctor may recommend a stress test to see how your heart functions while it is working hard during exercise or when medication is given to make it beat fast.

In an exercise stress test, electrodes are placed on your chest to monitor heart function while you exercise, usually by walking on a treadmill. Other heart tests may be done with a stress test.

Tilt table test

This test is sometimes used to help your doctor better understand how your tachycardia contributes to fainting spells. Under careful monitoring, you'll receive a medication that causes a tachycardia episode. You lie flat on a special table, and then the table is tilted as if you were standing up. Your doctor notes how your heart and nervous system respond to these changes in position.

Additional tests

Your doctor may order additional tests as needed to diagnose an underlying condition that is contributing to tachycardia and judge the condition of your heart.

The goal of tachycardia treatment is to:

• Slow the fast heart rate when it occurs
• Prevent future episodes
• Reduce complications
• Treat underlying disease that may contribute to tachycardia

Slowing a fast heart rate

A fast heart rate may correct itself. You also may be able to slow your heart rate using simple physical movements. However, medication or other medical treatments may be needed to slow down your heartbeat.

Ways to slow your heartbeat include:

• Vagal maneuvers. Your doctor may ask you to perform an action, called a vagal maneuver, during an episode of a fast heartbeat. The maneuvers include coughing, bearing down as if you're having a bowel movement and putting an ice pack on your face. Vagal maneuvers affect the vagus nerve, which helps control your heartbeat.
• Medications. If vagal maneuvers don't stop the fast heartbeat, you may need an injection of an anti-arrhythmic drug to restore a normal heart rate. An injection of this drug is given at a hospital. Anti-arrhythmic medicine is also available in pill form.
• Cardioversion. In this procedure, a shock is delivered to your heart through paddles, an automated external defibrillator (AED) or patches on your chest. The current affects the electrical impulses in your heart and restores a normal heartbeat. It's generally used when emergency care is needed or when maneuvers and medications don't work.

Preventing episodes of a fast heart rate

With the following treatments, it may be possible to prevent or manage episodes of tachycardia.

• Catheter ablation. This procedure is often used when an extra electrical pathway is responsible for an increased heart rate.

In this procedure, a doctor inserts catheters into your groin, arm or neck and guides them through the blood vessels to your heart. Electrodes at the catheter tips can use extreme cold or radiofrequency energy to damage (ablate) the extra electrical pathway and prevent it from sending electrical signals.

Catheter ablation does not require surgery to access the heart, but it may also be performed in conjunction with other heart valve or artery repair surgeries.

• Medications. Anti-arrhythmic medications taken by mouth may prevent a fast heart rate when taken regularly.

  Other heart medications, such as calcium channel blockers and beta blockers, may be prescribed instead or in combination with anti-arrhythmic drugs.

• Pacemaker. Some types of tachycardias may be treated with a pacemaker. A pacemaker is a small device that's surgically implanted under your skin. When the device senses an abnormal heartbeat, it sends an electrical pulse that helps the heart resume a normal beat.
• Implantable cardioverter. If you're at risk of having a life-threatening tachycardia episode, your doctor may recommend an implantable cardioverter-defibrillator (ICD). The pager-sized device is surgically implanted in your chest. The ICD continuously monitors your heartbeat, detects an increase in heart rate and delivers precisely calibrated electrical shocks, if needed, to restore a normal heart rhythm.

• Surgery. Open-heart surgery may be needed in some cases to destroy an extra electrical pathway causing tachycardia.

  Tachycardia may also be treated with a maze procedure. During this procedure, a surgeon makes small incisions in heart tissue to create a pattern or maze of scar tissue. Because scar tissue doesn't conduct electricity, it interferes with stray electrical impulses that cause some types of tachycardia.

  Surgery is usually used only when other treatment options don't work or when surgery is needed to treat another heart disorder.

Preventing blood clots

Some people with tachycardia have an increased risk of developing a blood clot that could cause a stroke or heart attack. Your doctor may prescribe a blood-thinning medication to help lower your risk.

Treating an underlying disease

If another medical condition is contributing to tachycardia, such as some form of heart disease or hyperthyroidism, treating the underlying problem may prevent or minimize tachycardia episodes.

Exercise and weight loss can help limit some of the health risks associated with tachycardia by reducing the negative effects of high blood pressure and sleep apnea.

If you have a plan in place to deal with an episode of a fast heartbeat, you may feel calmer and more in control when one occurs. Talk to your doctor about:

• How to take your pulse and what a normal pulse rate is for you
• When and how to use vagal maneuvers if they are appropriate for you
• When to call your doctor
• When to seek emergency care

Seeking support from family and friends also can help you reduce stress and better manage your tachycardia.

Whether you first see your family doctor or get emergency care, you'll likely be referred to a doctor trained in heart conditions (cardiologist) for one or more appointments for a complete evaluation.

If possible, bring along a family member or friend who can give some moral support and help you keep track of new information. Because there may be a lot to discuss, it will be helpful to prepare as much as possible.

What you can do

Make a list ahead of time that you can share with your doctor. Your list should include:

• Symptoms you've experienced, including any that may seem unrelated to your heart
• Key personal information, including any major stresses or recent life changes
• Medications, including vitamins or supplements
• Questions to ask your doctor

List your questions from most important to least important in case time runs out. Basic questions to ask your doctor include:

• What is likely causing my fast heart rate?
• What kinds of tests do I need?
• What's the most appropriate treatment?
• What kind of risks does my heart condition create?
• How will we monitor my heart?
• How often will I need follow-up appointments?
• How will other conditions I have or medications I take affect my heart problem?
• Do I need to restrict my activities?
• Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask additional questions.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:

• When did you first begin experiencing symptoms?
• How often have you had episodes of a fast heartbeat?
• How long have the episodes lasted?
• Does anything, such as exercise, stress or caffeine, seem to trigger or worsen episodes?
• Does anyone in your family have heart disease or a history of arrhythmias?
• Has anyone in your family experienced cardiac arrest or died suddenly?
• Do you smoke?
• How much alcohol or caffeine do you use?
• Do you use recreational drugs?
• Are you being treated for high blood pressure, high cholesterol or other conditions that may affect your circulatory system?
• What medications do you take for these conditions, and do you take them as prescribed?