Supraventricular Tachycardia

Cause

Two common types of supraventricular tachycardia—atrioventricular reciprocating tachycardia (AVRT) and atrioventricular nodal reentrant tachycardia (AVNRT)—are caused by an abnormal electrical pathway in the heart and often occur in people who do not have any other type of heart disease. What causes this abnormal pathway might not be clear.

Some experts believe that AVRT—specifically Wolff-Parkinson-White syndrome—may in some cases be inherited.

Other types of supraventricular tachycardia may be caused by:

• Overly high levels of the heart medicine digoxin (such as Lanoxin) or the bronchodilator theophylline .
• Other serious health problems, such as chronic obstructive pulmonary disease, heart failure, pneumonia, or metabolic problems.
• Heart surgery in the upper chambers of the heart, such as surgery for a congenital heart defect.

Symptoms

Symptoms of supraventricular tachycardia include:

• A racing or fluttering feeling in the chest (palpitations).
• Chest discomfort (pressure, tightness, pain).
• Lightheadedness or dizziness.
• Fainting (syncope).
• Shortness of breath.
• A pounding pulse. You may feel or see your pulse beating, especially at your neck, where large blood vessels are close to the skin.
• Sweating.
• Tightness or fullness in the throat.
• Tiredness (fatigue).
• Excessive urine production.

What Increases Your Risk

Some lifestyle factors can raise your risk of having an episode of supraventricular tachycardia (SVT), such as overuse of nicotine or alcohol, or use of illegal drugs, such as stimulants like cocaine or methamphetamine.

Decongestants that contain stimulants should also be avoided, including oxymetazoline (such as Afrin and other brands) and pseudoephedrine (such as Sudafed and other brands). Doctors also warn against using nonprescription diet pills or "pep" pills, because many contain ephedra, ephedrine, the herb ma huang, or other stimulants.

Congenital heart defects can raise the risk of having supraventricular tachycardia. Conditions that affect the lungs, such as chronic obstructive pulmonary disease (COPD), pneumonia, heart failure, and pulmonary embolism, can raise your risk for multifocal atrial tachycardia (MAT), a type of supraventricular tachycardia.

Many experts believe that Wolff-Parkinson-White syndrome may in some cases be inherited. If you have a first-degree relative, which is a parent, brother, or sister, with this disorder and he or she has symptoms, talk with your doctor about your risk for this abnormal heart rhythm.

When to Call a Doctor

Call 911 or seek emergency services immediately if you have a fast heart rate and you:

• Faint or feel as though you are going to faint.
• Have severe shortness of breath.
• Have chest pain.
• Have symptoms of a heart attack or stroke.

Call your doctor if you feel fluttering in your chest (palpitations) that persists and doesn't go away quickly or if you have frequent palpitations.

If you have a pacemaker

Call your doctor right away if you have symptoms that could mean your device is not working properly, such as:

• Your heartbeat is very fast or slow, skipping, or fluttering.
• You feel dizzy, lightheaded, or faint.
• You have shortness of breath that is new or getting worse.

Exams and Tests

An exact diagnosis is important because the treatment you receive depends on the type of tachycardia you have. Supraventricular tachycardia can sometimes be diagnosed simply on the basis of a medical history and physical exam and a few simple tests. Tests that may be done to monitor your heart and diagnose the type of fast heart rate that you have include:

• Electrocardiogram (EKG, ECG), which measures the electrical impulses in the heart. If an electrocardiogram is done while the fast heart rate is occurring, it often provides the most useful information.
• Ambulatory electrocardiogram. A portable EKG, such as a Holter monitor, can record your heart rhythm on a continuous basis, usually over a 24- to 48-hour period. If your symptoms are infrequent, your doctor may use another type of ambulatory electrocardiogram called a cardiac event monitor. When you have symptoms, you activate the monitor, which records your heart rhythm.
• Electrophysiology study. In this test, flexible wires are inserted into a vein, usually in the groin, and threaded into the heart. Electrodes at the end of the wires transmit information about the heart's electrical activity. Your doctor uses this information to see whether there is an extra electrical pathway inside the heart and, if so, where it is located. Catheter ablation can be done during this test to treat abnormal pathways and correct the supraventricular tachycardia.

After finding tachycardia, your doctor may need to search for its cause. The specific tests needed depend on the particular tachycardia. These tests may include:

• Blood tests to check thyroid function and electrolyte levels.
• Chest X-ray and/or pulmonary function tests to check for lung disease.
• Echocardiogram to see how well your heart is working.

Treatment Overview

Your treatment for supraventricular tachycardia (SVT) depends on a few things. They include what type of SVT, how often you have episodes, and how severe your symptoms are. The goals of treatment are to prevent episodes, relieve symptoms, and prevent problems. You and your doctor can decide what type of treatment is right for you.

Supraventricular tachycardia is usually treated if:

• You have symptoms such as dizziness, chest pain, or fainting (syncope) that are caused by your fast heart rate.
• Your episodes of fast heart rate are occurring more frequently or do not revert to normal on their own.

Treatment for sudden-onset (acute) episodes

When episodes of supraventricular tachycardia (SVT) start suddenly and cause symptoms, you can try vagal maneuvers. Your doctor will teach you how to do vagal maneuvers safely. These are things such as bearing down or putting an ice-cold, wet towel on your face.

Your doctor may also prescribe a short-acting medicine that you can take by mouth if vagal maneuvers don't work. This allows some people to manage their SVT without having to visit the emergency room repeatedly.

If your heart rate cannot be slowed using vagal maneuvers, you may have to go to your doctor's office or the emergency room, where a fast-acting medicine can be given to slow your heart rate. If the arrhythmia does not stop and symptoms are severe, electrical cardioversion, which uses an electrical current to reset the heart rhythm, may be needed.

Ongoing treatment of recurring supraventricular tachycardia

If you have recurring episodes of supraventricular tachycardia, you may need to take medicines, either on an as-needed basis or daily. Medicine treatment may include beta-blockers, calcium channel blockers, or other antiarrhythmic medicines. In people who have frequent episodes, treatment with medicines can decrease recurrences. But these medicines may have side effects.

Many people with supraventricular tachycardia have a procedure called catheter ablation. This procedure can stop the rhythm problem in most people. Ablation is considered safe, but it has some rare, serious risks.

• Supraventricular Tachycardia: Should I Have Catheter Ablation?

Ongoing Concerns

If supraventricular tachycardia occurs in someone who has significant coronary artery disease, the heart may not receive enough blood to keep up with the demands of the increased heart rate. If this occurs, the heart may not get enough oxygen, potentially causing angina symptoms (such as chest pain or pressure) or a heart attack.

Mild supraventricular tachycardia, with short episodes that don't happen often, doesn't typically weaken the heart or lead to heart failure. But some people have a higher risk of getting heart failure, such as those who have a heart valve disease. If tachycardia is left untreated, repeated and long episodes of tachycardia can lead to heart failure (known as a tachycardia-mediated cardiomyopathy). But this heart failure might be stopped, or reversed, if the supraventricular tachycardia is stopped with treatment.

Prevention

You can reduce your risk of having episodes of supraventricular tachycardia by avoiding certain stimulants or stressors, such as nicotine, some medicines (for example, decongestants), illegal drugs (stimulants, like methamphetamines and cocaine), and excess alcohol.

If fast heart rates continue, long-term medicines may be used to help prevent a recurrence of the fast heart rate.

Living With Tachycardia

Home care includes monitoring your supraventricular tachycardia (SVT) and trying to slow your heart when a fast heart rate occurs. To monitor your condition, you may find it helpful to keep a diary of your heart rate and your symptoms.

Your doctor may suggest that you try vagal maneuvers—such as holding your breath and bearing down or putting an ice-cold, wet towel on your face—to slow your heart rate. Your doctor will help you learn these procedures so you can try them at home when your fast heart rate occurs.

Check your pulse when you have symptoms, and record the information in your diary. Be aware that if your heart is beating rapidly, it may be hard to feel your pulse and get an accurate count of your actual heart rate.

By keeping a diary of your heart rate and symptoms, you may be able to identify stressors—such as drinking alcohol or smoking—that trigger episodes.

Also, it's usually important to avoid overuse of nicotine or alcohol and the use of illegal drugs, such as stimulants like cocaine, ecstasy, or methamphetamine.

Decongestants that contain stimulants should also be avoided, including oxymetazoline (such as Afrin and other brands) and pseudoephedrine (such as Sudafed and other brands). Doctors also warn against using diet pills or "pep" pills, ephedrine, ephedra, the herb ma huang, or other stimulants.

For most people, moderate amounts of caffeine do not trigger SVT. So most people do not have to avoid chocolate, caffeinated coffee, tea, or soft drinks.

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Medications

If you have symptoms, medicines may be used to treat supraventricular tachycardia.

Medicine choices

For severe symptoms, such as chest pain, shortness of breath, or feeling faint, you may be given fast-acting antiarrhythmic medicines by health professionals in the hospital emergency department, where your heart can be monitored. Fast-acting antiarrhythmic medicines commonly used to slow the heart rate during an episode include:

• Adenosine.
• Calcium channel blockers.
• Beta-blockers.

Long-term use of an antiarrhythmic medicine may also be needed to reduce the chance of having more episodes of supraventricular tachycardia or to reduce the heart rate during these episodes. Common medicines used for this purpose include:

• Beta-blockers.
• Calcium channel blockers.
• Other antiarrhythmic medicines.

Surgery

Open-heart surgery is rarely done for supraventricular tachycardia. Surgery might be done if you cannot have catheter ablation or if you are having surgery for another heart condition.

Other Treatment

An electric shock to the heart (electrical cardioversion) may be needed if you are having severe symptoms of supraventricular tachycardia and your heart rate does not return to normal using vagal maneuvers or fast-acting medicines.

A procedure called catheter ablation may be done to try to stop SVT. During this procedure, the extra electrical pathway or cells in the heart that are causing the fast heart rate can often be identified and destroyed.

• Supraventricular Tachycardia: Should I Have Catheter Ablation?

Other treatment choices

• Electrical cardioversion
• Catheter ablation