Paroxysmal supraventricular tachycardia (paroxysmal SVT) is an episodic condition with an abrupt onset and termination. (See Etiology and Presentation.)
SVT in general is any tachyarrhythmia that requires atrial and/or atrioventricular (AV) nodal tissue for its initiation and maintenance. It is usually a narrow-complex tachycardia that has a regular, rapid rhythm; exceptions include atrial fibrillation (AF) and multifocal atrial tachycardia (MAT). Aberrant conduction during SVT results in a wide-complex tachycardia. (See Etiology and Workup.)
SVT is a common clinical condition that occurs in persons of all age groups, and treatment can be challenging. Electrophysiologic studies are often needed to determine the source of the conduction abnormalities. (See Epidemiology, Prognosis, Workup, Treatment, and Medication.)
Manifestations of SVT are quite variable; patients may be asymptomatic or they may present with minor palpitations or more severe symptoms. Results from electrophysiologic studies have helped to determine that the pathophysiology of SVT involves abnormalities in impulse formation and conduction pathways. The most common mechanism identified is reentry. (See Etiology, Prognosis, Presentation, and Workup.)
Rare complications of paroxysmal SVT include myocardial infarction, congestive heart failure, syncope, and sudden death. (See Prognosis and Presentation.)
The development of intracardiac electrophysiologic studies has dramatically changed the classification of SVT, with intracardiac recordings having identified the various mechanisms involved in the condition. Depending on the site of origin of the dysrhythmia, SVT may be classified as an atrial or AV tachyarrhythmia. Another way to separate the arrhythmias is to classify them into conditions having either regular or irregular rhythms.
Atrial tachyarrhythmias include the following:
Inappropriate sinus tachycardia (IST)
Sinus nodal reentrant tachycardia (SNRT)
Multifocal atrial tachycardia
AV tachyarrhythmias include the following:
AV nodal reentrant tachycardia (AVNRT)
AV reentrant tachycardia (AVRT)
Junctional ectopic tachycardia (JET)
Nonparoxysmal junctional tachycardia (NPJT)
For patient education information, see the Heart Health Center, as well as Supraventricular Tachycardia (SVT, PSVT), Atrial Fibrillation (AFib), Atrial Flutter, and Arrhythmias (Heart Rhythm Disorders).