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Supraventricular Tachycardia

What is supraventricular tachycardia?

  • Supraventricular (soo-prah-ven-TRIK-u-lar) tachycardia (tak-ee-KAHR-dee-ah), or SVT, is a condition where your heart beats much faster than it should. A normal heart rate in a person at rest is about 70 to 80 beats every minute. With SVT, your heart may beat 140 to 250 beats a minute. Abnormal heart rhythms, including SVT, are called arrhythmias (ah-RITH-mee-ahs). SVT usually comes and goes, and may last a few seconds to several days. If your SVT comes and goes, it is called paroxysmal (par-ok-SIZ-mal) supraventricular tachycardia, or PSVT.

  • When your heart is beating too fast, your blood may not be able to move well through your body. This may cause you to feel dizzy, short of breath, or sick to your stomach during episodes of SVT. Some people feel fine during SVT episodes. Problems caused by your SVT may depend on many things. These include how long the SVT lasts, what is causing it, how fast your heart beats, and your general health.

What causes SVT?

  • Your heart has a special electrical system that controls your heartbeat. Your SVT may be caused by a problem with this electrical system in the heart muscle. You may have been born with this problem, or it may be caused by something else. Your SVT could be caused by a heart condition such as a valve problem or blocked arteries (blood vessels). The risk of SVT is increased after heart surgery. Thyroid disease or heart failure may also cause SVT. Low blood pressure from bleeding or dehydration (dee-heye-DRAY-shen), or having anemia (ah-NEE-mee-uh) may cause SVT. Using illegal drugs, such as "speed" or cocaine, can cause SVT and other heart problems.

  • Certain medicines, such as weight loss or cold and allergy medicines, may cause your SVT to start. Medicine used to treat certain thyroid problems may cause SVT if you take too much. Some herbs (such as ma huang) and diet supplements that have ephedra can cause SVT. Exercise, fever, stress, or being upset may also trigger an SVT episode. Other things that can trigger an SVT attack include smoking, drinking too much alcohol, and caffeine. Caffeine is found in coffee, chocolate, and some soft drinks and teas. You may notice that your SVT starts after sudden position changes, such as bending over too fast. Some women have SVT that starts or becomes worse during pregnancy.

What are the signs and symptoms of SVT?

Some people have no symptoms during an SVT episode. If you do have symptoms, they may include:

  • A heartbeat that you suddenly notice and that feels different than normal (heart palpitations). It may feel like a thumping in your chest. You may feel like your heart is fluttering, racing, or having extra beats.

  • Feeling more tired, weak, or short of breath than usual.

  • Feeling lightheaded or dizzy. You may feel like you have increased pressure in your head. You may even faint (pass out).

  • Having pain, pressure, or tightness in your chest, neck, jaw, arms, or upper back.

  • Feeling sick to your stomach (nauseated).

  • Feeling anxious, scared, or worried that something bad may happen.

How is SVT diagnosed?

It can be hard for your caregiver to find out what is causing your symptoms. Often, by the time you see a caregiver, your SVT may have stopped. Caregivers have a better chance of finding out what is wrong if you are seen when your SVT is happening. Your caregiver will review your medical history and any symptoms you have. Your caregiver will examine you, and listen to your heart and lungs with a stethoscope (STETH-oh-skohp). Other things that may be done include:

  • Tests on your blood and urine to look for possible causes of your SVT.

  • An EKG may be done to look for problems or damage in different areas of the heart. You may be asked to exercise while hooked up to an EKG machine. This is called an exercise stress test. You may need to wear a portable heart monitor at home for a short time.

  • A chest x-ray to check your heart and lungs.

  • An ultrasound of your heart called an echocardiogram (ek-o-KAHR-de-o-gram). An echocardiogram can find problems with your heart that do not show up on an EKG or in an x-ray.

  • If you have problems with fainting, you may need a tilt table test. This test checks to see what happens to your heart and your blood pressure when you change positions.

  • If your SVT is not helped by medicine, you may need an electrophysiology (ee-lek-troh-fiz-ee-OL-oh-jee) study. This test is used to "map out" the electrical pathways in your heart that control your heartbeat. Readings are taken through small wires that are fed through a blood vessel in your arm or groin to your heart. Your doctor can also use these wires to trigger your SVT and find the best way to treat it.

How is SVT treated?

How your SVT is treated may depend on what is causing it, your symptoms, and other health problems you may have. If your SVT causes few symptoms and you are healthy, you may not need any treatment. You may need to make lifestyle changes, such as decreasing stress and avoiding alcohol and caffeine. If your symptoms bother you or you have other health problems, your SVT may need further treatment. Treatments may include one of more of the following:

  • Vagal maneuvers: If caregivers are with you during your SVT episode, they may try vagal (VAY-gal) maneuvers. Vagal maneuvers use your own body to try and get your heart rate to slow down. Caregivers may have you cough, bear down like you are having a BM, or put your face in ice water. Caregivers may even teach you how to do vagal maneuvers so you can do them yourself at home.

  • Carotid sinus massage: Caregivers may massage your neck to try and slow your heart rate. This is called a carotid (kah-ROT-id) sinus massage. Never try to do a carotid sinus massage on yourself or anyone else.

  • Heart medicines: Long-term medicines may be given to keep your SVT from coming back, or to help symptoms.

  • Chemical cardioversion: Short-term medicines may be given to change your heart rate or rhythm. This is called a chemical cardioversion (KAHR-dee-oh-ver-zhun). You may need a chemical cardioversion more than once.

  • Electrical cardioversion: If you are having bad symptoms during an SVT episode, you may need an electrical cardioversion. This is a procedure where an electric shock is given to the heart. The shock is usually given through paddles or sticky patches placed on your chest or back. The shock helps your heart return to a normal beat. You may need this more than once.

  • Ablation: If your SVT causes problems and medicines do not help, you may need an ablation (ab-LAY-shun). This is a procedure where small wires are fed through a blood vessel in your arm or groin to your heart. Your doctor finds the area of the heart muscle causing the electrical impulse problem. Heat energy is applied to the area to stop the abnormal impulses. An ablation may keep your SVT from coming back forever.


In most people, SVT is not dangerous. However, it is important to be seen by a caregiver if you have new or worsening symptoms. Without treatment, you could have more SVT episodes. Some heart rhythms that are left untreated can increase your chance of heart failure or a heart attack. Rarely, SVT may be serious, even life threatening. Call your caregiver if you are worried or have questions about your medicine or care.

Coping with SVT:

You may feel scared, confused, or anxious because of your SVT. Call or write the following for more information about SVT and heart disease.

  • American Heart Association
    7272 Greenville Avenue
    Dallas , TX 75231-4596
    Phone: 1- 800 - 242-8721
    Web Address:
  • Heart Rhythm Society
    1400 K Street NW, Ste 500
    Washington , DC 20005
    Phone: 1- 202 - 464-3400
    Web Address:

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

© 2014 Truven Health Analytics Inc. Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes. All illustrations and images included in CareNotes® are the copyrighted property of A.D.A.M., Inc. or Truven Health Analytics.

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