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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" (figure 1). 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, call 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." 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 one of several devices.
●Holter monitor – This is a small, portable machine you wear that records all 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 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 14 days. You wear it all the time while you go about your usual activities.
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. 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 the speed or rhythm of your heartbeat
●A treatment called "cardioversion" – This involves applying an electrical current to the heart to fix its rhythm.
●Treatments called "ablation" – These treatments destroy the small part of the heart that is sending the abnormal electrical signals. They can use heat (called "radiofrequency ablation") or cold (called "cryoablation") to do this.
Patient education: Tachycardia (The Basics)
Patient education: ECG and stress test (The Basics)
Patient education: Vagal maneuvers and their responses (The Basics)
Patient education: Atrial fibrillation (The Basics)
