What is supraventricular tachycardia (SVT)? — Supraventricular tachycardia, also called “SVT,” is a heartbeat that is faster than normal. It usually starts and stops suddenly, without warning. SVT is also called “paroxysmal supraventricular tachycardia” or PSVT. (Paroxysmal means a sudden attack.)

SVT happens because of a problem with the heart’s electrical system. It starts in the upper chambers of the heart, called the “atria” The fast heartbeat can last from a few minutes to hours, but usually lasts for 10 to 15 minutes. It often happens when you are at rest. But in some people, exercise triggers it.

The 3 main types of SVT are called:

��Atrioventricular nodal reentry tachycardia (AVNRT)

��Atrioventricular reentry tachycardia (AVRT)

��Atrial tachycardia

What are the symptoms of SVT? — You might not have symptoms. But you might feel that your heart is beating too fast, beating hard, or seems to skip a beat. These kinds of heartbeat changes are called “palpitations.”

You might also feel:

��Lightheaded

��Dizzy

��Very tired

If you also have coronary heart disease, you might also:

��Have trouble breathing

��Feel a tightness in your chest

Should I see a doctor or nurse? — If you have trouble breathing or have chest pain that lasts for more than a few minutes, call for an ambulance (in the US and Canada, dial 9-1-1).

If you do not have these problems, but you often feel your heart beating fast or irregularly, talk to your doctor or nurse.

Is there a test for supraventricular tachycardia? — Yes. Your doctor or nurse will do a test called an electrocardiogram, also known as an “ECG” or “EKG.”

Other possible tests include:

��Holter monitor - This is a small, portable machine you wear that records all the heart’s electrical activity over 1 or 2 days.

��Event or loop monitor – These are similar to Holter monitors but smaller, because they don’t record all the time. Instead, you start the monitor when you feel symptoms. Your doctor will likely have you wear one of these monitors every day for about a month.

How is supraventricular tachycardia treated? — The treatment depends on the cause of the tachycardia. When your heartbeat is very fast, your doctor might suggest ways to slow it down. He or she might have you cough, or bear down as if you’re having a bowel movement. He or she might also suggest that you put an ice pack on your face. Doing these things can affect the nerve that helps control your heartbeat.

Other treatments can include:

��Medicines to control the speed or rhythm of your heartbeat

��A treatment called “cardioversion” that involves applying a mild electrical current to the heart to fix its rhythm

��Treatments called “ablation.” Ablation treatments use heat (called “radiofrequency ablation”) or cold (called “cryoablation”) to destroy the small part of the heart that is sending the abnormal electrical signals.