Paroxysmal supraventricular tachycardia

SVT terminology can be confusing, as some references consider SVT to be any rhythm originating above the ventricles (i.e. sinus tachycardia, MAT, atrial flutter, atrial fibrillation, PSVT, etc). As these entities have their own specific articles and treatment, only paroxysmal supraventricular tachycardia links here as used in normal clinical parlance.

Background

• Also known as PSVT and frequently referred to just as SVT
• AV nodal reentrant tachycardia (AVNRT) and AV reentrant tachycardia (AVRT) are subtypes of PSVT
• most common dysrhythmia in children
• infants: poor feeding, tachypnea, and irritability

Diagnosis

Sx	Sinus Tach	SVT
Hx	volume loss	sudden onset
PE	dehydated	CHF-like
*HR	<180	>180
Variability	Yes	No

*In infants HR cuttoff = 220

DDX

1. WPW
2. Lown-Ganong-Levine Syndrome‎
3. Mitral disease
4. Digitalis toxicity
5. Acute MI
6. Pericarditis
7. Hyperthyroidism
8. Drugs (alcohol, tobacco, caffeine)

Treatment

1. Unstable
   1. Synchronized cardioversion 0.5-1.0 J/kg
   2. Pediatrics: cardioversion at 0.5-1 J/kg. If unsuccessful, increase to 2 J/kg
2. Stable
   1. Vagal maneuvers
      1. Pediatrics: often successful with ice application to face
      2. Carotid sinus massage (ideal duration of 15 seconds)
      3. Valsalva manoeuvre
   2. Adenosine
      1. 6mg IVP; 12mg IVP (if initial dose failed)
   3. Calcium-channel blockers
      1. Diltiazem 15–20mg IV over 2min
         1. May give 25mg IV if inadequate response after 15min
         2. If IV bolus worked start IV infusion at 5–20mg/hr
         3. Contraindications: Hypotension, CHF, any suspicion of VT
      2. Beta-blockers
         1. Metoprolol 5mg IV q5min x 3; give 50mg PO if IVP effective
         2. Esmolol 500mcg/kg IV over 60sec
            1. May give repeat bolus if inadequate response after 2-5min
            2. If effective start infusion at 50mcg/kg/min (titrate up to 300mcg/kg/min)
         3. Contraindications: asthmatics

See Also

• V Tach vs. SVT
• Tachycardia (Narrow)
• ACLS: Tachycardia
• PALS: Tachycardia

Source

• Rosen's
• UpToDate
• Inaba AS, Horeczko T: Cardiac Disorders, in Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine Concepts and Clinical Practice, ed 7. St. Louis, Mosby, Inc., 2010, (Ch) 169:p2155-2156.