There are many types of SVT. Each type causes the abnormal fast heart rate in a slightly different way.
Treatment depends on the type of SVT and what is causing it, if known. Treatment might include medicines that slow the heart rate or a procedure called catheter ablation that stops the rhythm problem.
Atrial fibrillation or flutter
Atrial fibrillation is the most common type of SVT. It means that the heart's upper chambers (atria) beat irregularly.
Atrial flutter is like atrial fibrillation, because the electrical problem is in the atria. But with atrial flutter, the heart beats very fast in a regular rhythm. Atrial flutter is less common than atrial fibrillation.
Atrioventricular nodal reentrant tachycardia
Atrioventricular nodal reentrant tachycardia (AVNRT) is a common type of supraventricular tachycardia. It accounts for many of the fast heart rates that start in the upper part of the heart (excluding atrial fibrillation). Atrioventricular (AV) nodal reentrant tachycardia can cause symptoms at any age. It typically is not a result of other forms of heart disease.
AVNRT is caused by an abnormal or extra electrical pathway in the heart, a kind of "short circuit." Electrical pathways in the heart consist of microscopic muscle fibers that conduct electrical impulses. Normally, a single electrical pathway allows impulses to travel from the upper to the lower chambers. An extra electrical pathway in the AV node allows those impulses to travel backward at the same time, starting another heartbeat. During AVNRT the electrical impulses continuously go around the two pathways. This is known as "reentry" and can lead to a very fast heart rate.
Atrioventricular reciprocating tachycardia
Atrioventricular reciprocating tachycardia (AVRT) occurs when there is an extra electrical pathway linking the upper (atria) and lower (ventricles) chambers of the heart.
AVRT includes Wolff-Parkinson-White (WPW) syndrome.
Normally, the AV node is the only tissue that conducts electrical impulses between the upper and lower chambers of the heart. All electrical impulses must go through the AV node to reach the lower chambers of the heart. In an atrioventricular reciprocating tachycardia, electrical impulses travel one direction in the normal manner, down the AV node to the lower chambers (ventricles), but they then travel back up to the upper chambers (atria) through an abnormal, extra electrical pathway (accessory pathway) located outside the AV node.
Symptoms may start during the teen or young adult years.
Atrial tachycardia is a type of fast heart rate caused by rapid electrical signals that begin in the upper chambers of the heart. As a result, the heart can sometimes beat very rapidly.
Multifocal (chaotic) atrial tachycardia
During this rhythm, three or more different areas of the atrium initiate extra heartbeats. It is somewhat similar to having several different kinds of premature atrial contractions (PACs) occurring in the same person. These different areas of electrical activity can be seen on an electrocardiogram (EKG, ECG) and are used as the criteria for diagnosing this arrhythmia. People with this arrhythmia frequently complain of palpitations.
On EKG, multifocal atrial tachycardia may appear similar to atrial fibrillation. But it is a distinct condition. The problem with this rhythm is that it causes a persistently fast heart rate that may be difficult to control. If a lung disease is causing this rhythm problem, treating the lung disease might also control the rhythm problem.
Junctional tachycardia is a rare fast heart rate that starts in the area between the upper and lower chambers of the heart. This rhythm frequently affects adults who have heart disease and children who have had heart surgery.
Normal sinus tachycardia. Sinus tachycardia is present when a person's heart rate is over 100 beats per minute. This is normal if there is a clear reason for the fast heart rate, such as exercise, pain, or fever. With sinus tachycardia, the electrical system of the heart is working normally.
Abnormal (inappropriate) sinus tachycardia. Sinus tachycardia (heart rate over 100 beats per minute) is not normal if there is no apparent cause. In this rare condition, the electrical system of the heart is working normally.
Sinus node reentrant tachycardia
Sinus node reentrant tachycardia is a rare type of fast heart rate. This type is caused by abnormal conduction of electrical impulses within the sinus node.
Sinus node reentrant tachycardia begins and ends very suddenly.