Supraventricular Tachycardia

The heart muscle is responsible for circulating blood throughout the body, which uses electrical signals from within the heart to manage the heartbeat. When the electrical system of the heart does not operate as it is supposed to, an abnormal heart rhythm can develop.

A tachycardia is a type of heart rhythm disorder in which the heart beats faster than normal (more than 100 beats per minute). "Supra" means "above," so a supraventricular tachycardia (SVT) is an abnormally fast heartbeat that originates in the atria, the upper chambers of the heart.

When the condition happens irregularly or from time to time, it is known as paroxysmal supraventricular tachycardia.


The rapid heart rate of SVT usually starts and ends abruptly. It can last anywhere from a few minutes to several hours. It is usually felt as an uncomfortable palpitation of the heart but can also include other symptoms that result from the heart not beating efficiently and an inadequate supply of blood reaching the body. These symptoms can include:

  • Chest pain
  • Lightheadedness
  • Shortness of breath
  • Weakness
  • Palpitations
  • Loss of consciousness

Typically, the heart is otherwise normal.

Causes and Risk Factors

Supraventricular tachycardia may be caused by an abnormality, such as:

  • Rapid impulses generated in the atria, called paroxysmal atrial tachycardia
  • An abnormal electrical pathway between the heart's upper and lower chambers, called an accessory pathway or bypass tract
  • Two electrical pathways in the atrioventricular node

Young people are more likely than older people to experience supraventricular tachycardia.


Diagnosis of an atrial fibrillation and flutter will generally begin with the physician taking a medical history and performing a physical exam. During the physical exam, the physician will listen to the patient’s heart to detect if there is an abnormal heart rate, and ask the patient for a detailed description of their symptoms.

After the physical exam, the physician may order tests to examine the heart muscle, the blood flow through the heart, and any potential leaking within the heart valves. An electrocardiogram (EKG) is a painless procedure that provides a picture of the electrical activity of the heart and how the heart is working. A similar test is an echocardiogram, a noninvasive procedure that uses ultrasound to create a moving picture of the heart as it works.

If the abnormal heart rhythm is intermittent, the patient may need to wear a Holter monitor. This portable device allows the medical team to observe the patient’s heart activity over a longer period of time and helps diagnose the condition if the abnormal rhythm happens while the patient is not at the hospital.

Other diagnostic tests may include electrophysiology studies to look at the electrical system of the heart.


Several things can be done to stop supraventricular tachycardia:

  • Stimulate the vagus nerve, which is responsible for controlling the heart rate
  • Move food through the intestinal tract (gastrointestinal peristalsis)
  • Sweat
  • Make several muscle movements in the mouth.

By stimulating the vagus nerve the heart rate can be slowed. That stimulation is usually performed by or under a doctor's supervision, but people who frequently have this problem can learn to do it themselves. Methods include:

  • Plunging the face into a bowl of ice-cold water
  • Rubbing the neck just below the angle of the jaw to stimulate an area on the carotid artery
  • Straining as if having a difficult bowel movement

These methods are most effective when done soon after the irregular heartbeats or arrhythmia start.

Medical intervention to control arrhythmia is needed if:

  • The above methods are ineffective
  • An episode lasts more than 20 minutes
  • Symptoms are severe

A physician can usually stop an episode by giving an injection of a drug. If the arrhythmia does not stop and symptoms are severe, electrical cardioversion may be necessary. This procedure uses an electrical current to reset the heart's rhythm and is performed under sedation.

Medication such as beta blockers (Propranolol or Atenolol) or calcium channel blockers (Verapamil or Diltiazem), which work to prevent arrhythmias, may be prescribed in the short term to help prevent future episodes. However, catheter ablation is often performed to destroy the tissues where supraventricular tachycardia starts, as this is highly curative.

The knowledgeable and highly trained staff at the Cedars-Sinai Heart Institute will work with each patient to determine the best treatment option.