II. Definition

  1. Form of Supraventricular Tachycardia (30% of cases) with an accessory pathway (outside the AV Node)

III. Epidemiology

  1. Most common in children (represents 60% of SVT cases in first decade of life)
  2. Decreasing Prevalence with age (represents 9% of SVT cases over age 70 years)

IV. Pathophysiology

  1. Accessory pathway between the atrium and the ventricle that bypasses the AV Node

V. Findings: General

  1. Heart Rate 160 to 240 (up to 256)

VI. Types: General

  1. Orthodromic, narrow complex (87% of cases)
    1. Signal passes anterograde down the AV Node and retrograde up the accesory path
    2. Represents up to 87% of AVRT cases
    3. Retrograde P Waves appear after the QRS in I, II, III, aVF, V1 (may be obscured by T Wave)
  2. Antidromic, wide complex
    1. Signal passes retrograde up the AV Node and anterograde down the accessory path
    2. RP interval <100 msec
    3. Wide QRS Complex

VII. Types: Variants

  1. Wolff-Parkinson-White Syndrome
    1. Anterograde conduction down the accessory path reaches the ventricle before the AV Nodal signal
    2. Results in preexcitation of the ventricle, forming a slurred upstroke of the QRS (delta wave)
  2. Permanent (or persistent) Junctional Reciprocating Tachycardia
    1. Slow retrograde conduction via the accessory pathway
    2. Results in sustained Supraventricular Tachycardia
    3. Risk of Tachycardia induced Cardiomyopathy and Congestive Heart Failure

VIII. Course

  1. May degenerate into Atrial Fibrillation

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