"Supraventricular tachycardia (SVT) means that from time to time your heart beats very fast for a reason other than exercise, high fever, or stress. Types of SVT include:
Atrioventricular nodal reentrant tachycardia (AVNRT).
Atrioventricular reciprocating tachycardia (AVRT), including Wolff-Parkinson-White syndrome.
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 per minute and may reach 300 beats per minute. After treatment or on its own, the heart usually returns to a normal rate of 60 to 100 beats a minute.
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 causes symptoms.
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 . What causes the electrical problem is not clear.
SVT also can be caused by very high levels of the heart medicine digoxin (such as Lanoxicaps or Lanoxin) or the lung medicine theophylline (such as Theochron or Uniphyl).
Some types of SVT may run in families, such as Wolff-Parkinson-White syndrome. Or they may be caused by a lung problem such as COPD or pneumonia".
I hope this helps. Take care, Ally
Very basically SVT or supraventricular tachycardia is:
supra = above
ventricular = concerning the lower two chambers of the heart
tachy = rapid (over 100/min but not into the 200-300 range - that has different names)
cardia = heart
So it's a heart rate above 100 that originates or occurs in the top part of the heart (the artia). Since the ventricles don't always receive or respond to such rapid electrical signals, it is possible to have the atria and ventricles beating at different rates. It is possible for this to be going on without you even being aware of it. Other times symptoms like palpitations or chest pain or faintness are experienced.