Overview of PSVT

Paroxysmal Supraventricular Tachycardia (PSVT) is the most common symptomatic tachyarrhythmia in childhood. It occurs in one out of every 250 to 1000 children. The initial onset of this arrhythmia may occur in utero, within the first few weeks of life, or may first occur in adolescence.

Ninety three percent of all infants diagnosed with PSVT will outgrow it by 10 months of age. Interestingly, approximately 35% of the children who "outgrow it" will have a recurrence between the ages of 5 and 8 years of age.

PSVT is a collective name for a group of arrhythmias with:

• similar EKG characteristics
• similar initiating stimuli or arrhythmias
• different mechanisms of conduction

Take a moment to see Rnceus Interactive's animated review of normal cardiac conduction.

Specific electrocardiogram (EKG) characteristics of pediatric PSVT are:

• heart rate of greater than 220 beats per minute (bpm) in infants
• heart rate of greater than 150-250 bpm in children or adolescents
• sudden onset and abrupt termination of the rhythm
• narrow QRS complex (<.08 - .12 seconds)
• rate is regular with no beat to beat variation in rhythm
• P wave may not be identifiable (if it is, however, the P wave axis is usually abnormal)
• a rate-related phenomenon of 1-8 mm. ST depression, which is not necessarily a sign of myocardial ischemia
• if PSVT persists, ST and T wave changes may be observed along with clinical signs of congestive heart failure (CHF), cardiovascular collapse, and clinical evidence of shock.

Instant Feedback:

About 1/3 of the children who outgrow PSVT have a recurrence at about 5 to 8 years of age.

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