paroxysmal supraventricular tachycardia (PSVT)

Introduction

Regular narrow-complex tachycardia with an abrupt onset & termination.

Etiology

• AV nodal re-entrant tachycardia (most common in adults)
• orthodromic AV reciprocating tachycardia (most common in children)
• Wolf-Parkinson-White syndrome (WPW)

Clinical manifestations

• palpitations
• lightheadedness
• syncope or presyncope
• neck-pounding is associated with AV nodal re-entrant tachycardia

Diagnostic procedures

• electrocardiogram:
  • narrow-complex tachycardia* with rate of 130-240/min
  • a short R-P or P wave within ST segments suggests re-entry with
    • anterograde conduction through AV node
    • retrograde conduction through bypass tract
  • P wave after T wave: no accessory conduction
  • no P wave: re-entry simultaneously activates atria & ventricles
• event recorder better than HOLTER
• electrophysiologic testing

* QRS complexes may be wide if:

• bundle branch block
• aberrancy
• pacing
• anterograde accessory conduction pathway (WPW)

Management

• wide QRS complex: see wide complex tachycardia
  • do not treat wide-complex tachycardia with adenosine
• narrow QRS complex
  • generally a benign arrhythmia:
    • treatment indicated only for symptomatic patients
    • exception is patients with WPW
  • acute measures
    • consider vagal maneuvers
      • carotid sinus massage* is most common maneuver
      • modified valsalva maneuver
        • 15-second, 40-mm Hg strain while in a semirecumbent position
        • follow immediately by supine repositioning (recline head bed) & passive leg raise to 45 degrees
        • repeat maneuver if not successful
        • 43% success; NNT 3-4
      • facial immersion in cold water
    • adenosine 6 mg IV push, if no response in 1-2 min, 12 mg IV, push (may repeat once)
      • reduce dose in patients with history of cardiac transplantation
    • normal or elevated blood pressure, block AV node
      • verapamil 2.5-5 mg IV, then 5-10 mg IV or diltiazem
      • beta-blocker
      • digoxin
    • digoxin, amiodarone, diltiazem if LVEF < 40%
    • low or unstable blood pressure - synchronized cardioversion
  • electrophysiologic testing with catheter ablation
    • significant hemodynamic compromise during tachycardia
    • syncope or presyncope
    • PSVT with evidence of pre-excitation (WPW)
  • long-term pharmaco-therapy
    • beta-blocker
    • calcium channel blocker
    • short acting agents may be used at onset of tachycardia
      • propranolol 20 mg
      • verapamil 80 mg

* Contraindicated in:

• elderly
• patients with carotid bruits
• bilateral carotid sinus massage should never be performed

More general terms

• supraventricular tachycardia (SVT)

More specific terms

• AV nodal re-entrant tachycardia (AVNRT)
• orthodromic AV reciprocating tachycardia
• sinus node re-entrant tachycardia

Additional terms

• Wolff-Parkinson-White (WPW) syndrome