Supraventricular tachycardia (SVT) in children is a common disturbance of cardiac rhythm that is usually managed without difficulty by using a methodical approach. Technically, the term SVT refers to any rapid rhythm originating in or involving the atria or atrioventricular (AV) node. The most common type of SVT treated in the pediatric clinic is a reentrant rhythm involving the AV node or a bypass tract (paroxysmal SVT [PSVT]). This type of SVT is characterized by sudden onset and cessation, very little beat-to-beat variability, and rates usually well beyond 220 beats/minute. Reentrant rhythms are susceptible to vagal maneuvers, pharmacologic intervention, and electrical cardioversion. Other types of SVT include atrial flutter (rare in children) and automatic tachycardias, which tend to vary in rate over time and start and stop more gradually. It is important to distinguish automatic tachycardias from PSVT because they do not resolve with vagal maneuvers or electrical cardioversion and because they are notoriously difficult to manage with medications. The automatic tachycardia most frequently confused with PSVT is sinus tachycardia, which usually requires no treatment.
The first step in evaluation is to check the hemodynamic status. A small proportion of children who have PSVT may present with shock. If the child is hypotensive or has poor capillary refill, one must start immediate measures to restore effective perfusion, including securing reliable intravenous (IV) access and supine positioning.
Supraventricular Tachycardia by Concealed Bypass Tract
