Supraventricular Tachycardia

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Atrial fibrillation and ventricular tachycardia are types of fast heart rates that can be serious. If you have one of these heart problems, see the topic Atrial Fibrillation or Ventricular Tachycardia.

What is supraventricular tachycardia?

Supraventricular tachycardia (SVT) means that from time to time your heart beats very fast for a reason other than exercise, high fever, or stress. Types of SVT include:

• Atrioventricular nodal reentrant tachycardia (AVNRT).
• Atrioventricular reciprocating tachycardia (AVRT), including Wolff-Parkinson-White syndrome.

During an episode of SVT, the heart’s electrical system doesn't work right, causing the heart to beat very fast. The heart beats at least 100 beats per minute and may reach 300 beats per minute. After treatment or on its own, the heart usually returns to a normal rate of 60 to 100 beats a minute.

SVT may start and end quickly, and you may not have symptoms. SVT becomes a problem when it happens often, lasts a long time, or causes symptoms.

SVT also is called paroxysmal supraventricular tachycardia (PSVT) or paroxysmal atrial tachycardia (PAT).

What causes SVT?

Most episodes of SVT are caused by faulty electrical connections in the heart . What causes the electrical problem is not clear.

SVT also can be caused by very high levels of the heart medicine digoxin (such as Lanoxicaps or Lanoxin) or the lung medicine theophylline (such as Theochron or Uniphyl).

Some types of SVT may run in families, such as Wolff-Parkinson-White syndrome. Or they may be caused by a lung problem such as COPD or pneumonia.

What are the symptoms?

Some people with SVT have no symptoms. Others may have:

• Palpitations, a feeling that your heart is racing or pounding.
• A pounding pulse.
• A dizzy feeling or may feel lightheaded.

Other symptoms include, near-fainting or fainting (syncope), shortness of breath, chest pain, throat tightness, and sweating.

How is SVT diagnosed?

Your doctor will diagnose SVT by asking you questions about your health and symptoms, doing a physical exam, and perhaps giving you tests. Your doctor:

• Will ask if anything triggers the fast heart rate, how long it lasts, if it starts and stops suddenly, and if the beats are regular or irregular.
• May do a test called an electrocardiogram (EKG, ECG). This test measures the heart's electrical activity and can record SVT episodes.
• May do an electrophysiology (EP) study. This test finds out whether there is an extra electrical pathway inside your heart.

If you do not have an episode of SVT while you're at the doctor's office, your doctor probably will ask you to wear a portable EKG. When you have an episode, the device will record it.

Your doctor also may do tests to find the cause of the SVT. These may include blood tests, a chest X-ray, and an echocardiogram, which makes a picture of the heart.

How is it treated?

Some SVTs don't cause symptoms, and you may not need treatment. If you do have symptoms, your doctor probably will recommend treatment.

To treat sudden episodes of SVT, your doctor may:

• Prescribe a medicine to take when the SVT occurs.
• Show you how you can slow your heart rate on your own. You may be able to do this by coughing, gagging, or putting your face in ice-cold water. These are called vagal maneuvers.

If these treatments don't work, you may have to go to your doctor's office or the emergency room. You may get a fast-acting medicine such as adenosine or verapamil. If the SVT is serious, you may have electrical cardioversion, which uses an electrical current to reset the heart rhythm.

If you often have episodes of SVT, you may need to:

• Take medicine every day to prevent the episodes or slow your heart rate.
• Try catheter ablation. This procedure removes a tiny part of the heart that causes the problem.

What can you do at home to prevent SVT?

You can do a lot to prevent SVT by avoiding the things that trigger it.

• Limit alcohol to 2 drinks a day if you are a man and 1 drink a day if you are a woman.
• Limit caffeine. Even decaffeinated teas or coffee can cause SVT in some people.
• Don't smoke.
• Avoid over-the-counter decongestants, herbal remedies, diet pills, and "pep" pills.
• Don't use illegal drugs, such as cocaine, ecstasy, or methamphetamine.

To find your triggers, keep a diary of your heart rate and your symptoms. You might find, for example, that smoking or caffeine causes your SVT episodes.

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