II. Definition
- Form of Supraventricular Tachycardia (30% of cases) with an accessory pathway (outside the AV Node)
III. Epidemiology
- Most common in children (represents 60% of SVT cases in first decade of life)
- Decreasing Prevalence with age (represents 9% of SVT cases over age 70 years)
IV. Pathophysiology
- Accessory pathway between the atrium and the ventricle that bypasses the AV Node
V. Findings: General
- Heart Rate 160 to 240 (up to 256)
VI. Types: General
- Orthodromic, narrow complex (87% of cases)
- Antidromic, wide complex
- Signal passes retrograde up the AV Node and anterograde down the accessory path
- RP interval <100 msec
- Wide QRS Complex
VII. Types: Variants
-
Wolff-Parkinson-White Syndrome
- Anterograde conduction down the accessory path reaches the ventricle before the AV Nodal signal
- Results in preexcitation of the ventricle, forming a slurred upstroke of the QRS (delta wave)
- Permanent (or persistent) Junctional Reciprocating Tachycardia
- Slow retrograde conduction via the accessory pathway
- Results in sustained Supraventricular Tachycardia
- Risk of Tachycardia induced Cardiomyopathy and Congestive Heart Failure
VIII. Course
- May degenerate into Atrial Fibrillation
IX. References
- Joshi and Dermark (2016) Crit Dec Emerg Med 30(8):3-12
- Colucci (2010) Am Fam Physician 82(8): 942-52 [PubMed]
- Delacretaz (2006) N Engl J Med 354(10): 1039-51 [PubMed]
- Helton (2015) Am Fam Physician 92(9): 793-800 [PubMed]
- Kumar (2006) Cardiol Clin 24(3): 427-37 [PubMed]