Paroxysmal Supraventricular Tachycardia (PSVT) is a rapid heart rate, which begins and ends suddenly (paroxysmal). PSVT starts with events taking place above the ventricle. Normally, the chambers of the heart (atria and ventricles) contract in a coordinated manner. The contractions are caused by an electrical signal that begins in the sinoatrial node (also called the sinus node or SA node). The signal is conducted through the atria (the upper chambers) and stimulates the atria to contract.
Paroxysmal supraventricular tachycardia can be initiated in the SA node, in the atria or the atrial conduction pathways, or in the AV node. It occurs most often in young people and infants.
