Epidemiology

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Physiology

• Type of supraventricular tachycardia (SVT) characterized by AV-nodal reentry
  • Both pathways reside within the AV node

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Clinical

• Narrow-Complex Regular Tachycardia: usual manifestation
  • Rate: usually >150
  • Typical abrupt onset and termination
  • Absence of readily identifiable p-waves
• Wide-Complex Regular Tachycardia: may be seen in cases with pre-existing bundle branch block or in cases with reta-related aberrant conduction

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Treatment

• Stable: agents that inhibit AV nodal conduction
  • Vagal Maneuvers (Carotid Massage, Valvsalva): when used alone, will terminate SVT’s in 25% of cases
  • Adenosine
    • Initial 6 mg via peripheral IV, followed by 20 ml flush
    • Subsequent 6 mg via peripheral IV, followed by 20 ml flush
    • Use initial dose 50% less if CVC, heart transplant, carbamazepine, dipyridamole
    • Antagonized by theophylline, theobromine, or caffeine
    • Side Effects: flushing, dyspnea/bronchospasm, chest discomfort
    • Contraindications: asthma
    • Pregnancy: safe
  • Beta Blockers
  • Calcium Channel Blockers
  • Digoxin: less desirable
  • Amiodarone
    • Slower effect than adenosine
    • Less desirable than AV nodal blockers in AVRT
• Unstable
  • Synchronized cardioversion 50-100 J

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References

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