Tachycardia (SVT)

Your heart rate is controlled carefully to ensure your heart’s activity matches your body’s need for blood. If your heart rate does not match your body’s needs, the result is an arrhythmia, which means the heart’s pace-making activity is altered. The heartbeat is an electrical current that originates in the atria, the heart tissue above the ventricles, which are the lower chambers that pump the blood.

Supraventricular tachycardia (SVT) is a condition where your heart beats quickly from time to time, at least 100 beats per minute (average heart rate is 60 beats per minute) and can increase to 300 beats per minute. Some situations, such as exercise, fever or stress, are commonly associated with tachycardia (rapid heartbeat), originating from the normal heart beat function. In SVT, however, all mechanisms relate to an abnormal heart rhythm function that should be inspected by a doctor. In many cases symptoms may not be apparent, but when SVT occurs more frequently, lasts for longer periods of time or causes symptoms, it can become a problem. SVT can also occur with a condition known as Wolff-Parkinson-White syndrome.

SVT is of concern like any type of arrhythmia and may be quite disturbing or uncomfortable to the person affected. Unlike some other arrhythmias, SVT is rarely immediately life threatening. The ventricles are programmed to ignore (at least partially) excessively rapid signals to contract. Alcohol, caffeine, drugs and smoking can increase the likelihood of SVT.

Symptoms of Supraventricular Tachycardia
SVT symptoms can last for a few minutes or several hours and may start and stop suddenly. The primary reported feeling is palpitations (noticeable and often uncomfortable) and a rapid pulse.

Some patients with SVT note one or more of the following symptoms: 

  • Chest discomfort or pain 
  • Dizziness 
  • Fainting 
  • Shortness of breath

Diagnosing SVT 
Because SVT comes and goes, a physical exam and office electrocardiogram (EKG) may not detect it, unless you are having SVT at that particular moment in time. A continuous recording of the heart’s rhythm (Holter monitor for 24 hours or longer) is more likely to detect SVT. The most accurate diagnostic test, however, is an electrophysiology study, in which your doctor would introduce catheters in the heart to induce SVT and delineate its mechanisms. These will help the physician find the best treatment and rule out other causes of arrhythmia. 

Treating SVT
If a person’s SVT requires treatment beyond lifestyle changes, medications may be prescribed to suppress or reduce SVT episodes.


Our physicians at Houston Methodist specialize in managing heart arrhythmias at the following convenient locations.