What is supraventricular tachycardia?
Supraventricular tachycardia (SVT) means that from time to time your
heart beats very fast for a reason other than exercise, high fever, or stress.
For most people who have SVT, the heart still works normally to pump blood through the body.
Types of SVT include:
- Atrioventricular nodal reentrant tachycardia
- Atrioventricular reciprocating tachycardia (AVRT),
During an episode of SVT, the heart's electrical system
doesn't work right, causing the heart to beat very fast. The heart beats at
least 100 beats a minute and may reach 300 beats a minute. After treatment
or on its own, the heart usually returns to a normal rate of 60 to 100 beats a
SVT may start and end quickly, and you may not have
symptoms. SVT becomes a problem when it happens often, lasts a long time, or
SVT also is called paroxysmal supraventricular
tachycardia (PSVT) or paroxysmal atrial tachycardia (PAT).
What causes SVT?
Most episodes of SVT are caused by
faulty electrical connections in the heart .
SVT also can be
caused by certain medicines. Examples include very high levels of the heart medicine digoxin or the lung medicine theophylline.
Some types of SVT may run in families, such as
Wolff-Parkinson-White syndrome. Other types of SVT may be caused by certain health problems, medicines, or surgery.
What are the symptoms?
Some people with SVT have no
symptoms. Others may have:
- Palpitations, a
feeling that the heart is racing or pounding.
- A pounding
- A dizzy feeling or may feel
Other symptoms include near-fainting or fainting (syncope), shortness of breath, chest pain, throat
tightness, and sweating.
How is SVT diagnosed?
Your doctor will diagnose
SVT by asking you questions about your health and symptoms, doing a physical
exam, and perhaps giving you tests. Your doctor:
- Will ask if anything triggers the fast heart
rate, how long it lasts, if it starts and stops suddenly, and if the beats are
regular or irregular.
- May do a test called an
electrocardiogram (EKG, ECG). This test measures the
heart's electrical activity and can record SVT episodes.
If you do not have an episode of SVT while you're at the
doctor's office, your doctor probably will ask you to wear a portable electrocardiogram (EKG), also called an ambulatory electrocardiogram. When
you have an episode, the device will record it.
Your doctor also
may do tests to find the cause of the SVT. These may include blood tests, a
X-ray, and an
echocardiogram, which shows the heart in motion.