Paroxysmal supraventricular tachycardia (svt, psvt)

[Justin Bieber]

Paroxysmal supraventricular tachycardia is a regular, fast (160 to 220 beats per minute) heart rate that begins and ends suddenly and originates in heart tissue other than that in the ventricles.

Most people have uncomfortable awareness of heartbeats (palpitations), shortness of breath, and chest pain.
Episodes can often be stopped by maneuvers that stimulate the vagus nerve, which slows the heart rate.
Sometimes, people are given drugs to stop the episode.

(See also Overview of Abnormal Heart Rhythms.)
Paroxysmal supraventricular tachycardia is most common among young people and is more unpleasant than dangerous. It may occur during vigorous exercise.
Paroxysmal supraventricular tachycardia may be triggered by a premature heartbeat that repeatedly activates the heart at a fast rate. This repeated, rapid activation may be caused by several abnormalities. There may be two electrical pathways in the atrioventricular node (an abnormal heart rhythm [arrhythmia] called atrioventricular nodal reentrant supraventricular tachycardia). There may be an abnormal electrical pathway between the atria and the ventricles (an arrhythmia called atrioventricular reciprocating supraventricular tachycardia). Much less commonly, the atria may generate abnormal rapid or circling impulses (an arrhythmia called true paroxysmal atrial tachycardia).
The fast heart rate tends to begin and end suddenly and may last from a few minutes to many hours. It is almost always experienced as an uncomfortable awareness of the heartbeat, such as feeling like the heart is pounding or racing (palpitations). It is often associated with other symptoms, such as weakness, light-headedness, shortness of breath, and chest pain. Usually, the heart is otherwise normal.
The doctor confirms the diagnosis by doing electrocardiography (ECG).