Patient education: Supraventricular tachycardia (SVT) (The Basics)

What is supraventricular tachycardia? — Supraventricular tachycardia ("SVT") is a heartbeat that is faster than normal. SVT that starts and stops suddenly is called "paroxysmal supraventricular tachycardia" ("PSVT"). (Paroxysmal means a sudden attack.)

SVT happens because of a problem with the heart's electrical system. The left and right ventricles are the main pumping chambers of the heart. SVT starts above the ventricles (figure 1).

With SVT, the fast heartbeat can last from seconds to hours. It can happen 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. Or you might feel like 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

Is there a test for SVT? — Yes. Your doctor or nurse will do a test called an electrocardiogram ("ECG"). This test measures the electrical activity in your heart (figure 2).

Other possible tests include various types of longer-term heart monitoring. This can be done using 1 of several devices:

●Holter monitor – This is a small, portable machine that you wear. It records all of your heart's electrical activity over 1 or 2 days (figure 3).

●Event or loop monitor – These are similar to Holter monitors but smaller, because they don't record all of the time. Instead, you start the monitor when you feel symptoms (figure 4). Your doctor will likely have you wear this type of monitor every day for about a month.

●Patch monitor – This is a newer type of monitor. It goes directly on the skin, without wires, and can be worn for up to 30 days. You wear it all of the time while you go about your usual activities.

How is SVT treated? — The treatment depends on the cause of the tachycardia.

For some types of heart rhythms, your doctor might suggest ways to slow it down. They might have you cough, or bear down as if you're having a bowel movement. Doing these things can affect the nerve that helps control your heartbeat.

Other treatments can include:

●Medicines to control your heart rhythm

●Cardioversion – This involves applying an electrical current to the heart to fix its rhythm.

If the tachycardia comes back often and causes symptoms, treatment can include:

●Medicines to prevent the abnormal rhythm

●Ablation – This is a treatment to destroy the small part of the heart that is sending the abnormal electrical signals. It uses energy such as heat (called "radiofrequency ablation") and cold (called "cryoablation").

Your doctor might suggest that you limit caffeine.

When should I call for help? — Call for an ambulance (in the US and Canada, call 9-1-1) if you have:

●Trouble breathing

●Chest pain that lasts for more than a few minutes

Call your doctor or nurse if you pass out or feel very dizzy.

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

More on this topic

Patient education: Overview of heart arrhythmias (The Basics)
Patient education: Tachycardia (The Basics)
Patient education: ECG and stress test (The Basics)
Patient education: Vagal maneuvers (The Basics)
Patient education: Atrial fibrillation (The Basics)
Patient education: Ambulatory heart monitoring (The Basics)
Patient education: Cardioversion (The Basics)

Patient education: Atrial fibrillation (Beyond the Basics)