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. For most people who have SVT, the heart still works normally to pump blood through the body.

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 a minute and may reach 250 beats a minute or more. After treatment or on its own, the heart usually returns to a normal rate of about 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.

Symptoms of SVT include:

• A racing or fluttering feeling in the chest (palpitations).
• Chest discomfort, such as pressure, tightness, or pain.
• Fainting, or feeling lightheaded or dizzy.
• 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.

Some people with SVT have no symptoms.

Your doctor will diagnose SVT based on your health and symptoms, a physical exam, and your test results. 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.
• Will do a test called an electrocardiogram (EKG, ECG). This test measures the heart's electrical activity and can record SVT episodes.

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 electrocardiogram (EKG), also called an ambulatory electrocardiogram. 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 shows the heart in motion.

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 with physical actions. These actions are called vagal maneuvers. They include bearing down or putting an ice-cold, wet towel on your face.

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 to slow your heart rate. If the SVT is serious, you may have a procedure called electrical cardioversion to reset the heart rhythm.

The goals of treatment are to prevent episodes, relieve symptoms, and prevent future problems. You and your doctor can decide what type of treatment is right for you. Your options may include medicines or a procedure called catheter ablation.

Catheter ablation might be done if you have symptoms that bother you a lot, you don't want to take heart rhythm medicine, or medicine has not worked for you. Ablation has risks, but they are rare. Many people decide to have ablation because they hope to feel much better afterward. That hope is worth the risks to them. But the risks may not be worth it for people who have few symptoms. Work with your doctor to decide what treatment is right for you.

• If you take medicine, take it exactly as prescribed. Call your doctor if you think you are having a problem with your medicine. You will get more details on the specific medicines your doctor prescribes.
• If your doctor showed you how to do vagal maneuvers, try them when you have an episode. These maneuvers include bearing down or putting an ice-cold, wet towel on your face.
• Monitor your condition by keeping a diary of your SVT episodes. Bring this to your doctor appointments.
  • Write down how fast or slow your heart was beating. To count your heart rate:
    • Gently place 2 fingers of your hand on the inside of your other wrist, below your thumb.
    • Count the beats for 30 seconds.
    • Then, double the result to get the number of beats per minute.
  • Write down if your heart rhythm was regular or irregular.
  • Write down the symptoms you had.
  • Write down the time of day your symptoms occurred.
  • Write down how long your symptoms lasted.
  • Write down what you were doing when your symptoms started.
  • Write down what may have helped your symptoms go away.
• If they trigger episodes, limit or avoid alcohol or drinks with caffeine.
• Do not use over-the-counter decongestants, herbal remedies, diet pills, or "pep" pills, which often contain stimulants.
• If you use stimulant drugs, quit or cut back as much as you can. These drugs include cocaine and methamphetamine. It's safest not to use them at all. Talk to your doctor if you need help decreasing your use.
• If you smoke, quit or cut back as much as you can. Smoking can make this condition worse. If you need help quitting, talk to your doctor about stop-smoking programs and medicines. These can increase your chances of quitting for good.
• Be alert for new or worse symptoms, such as shortness of breath, pounding of your heart, or unusual tiredness. If new symptoms develop or your symptoms become worse, call your doctor.