Wolff-Parkinson-White syndrome classification scheme

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]

EKG Classification

1. Type A:
   • Prominent R wave in lead V1 and V2.
   • It has been found at EP studies that these patients have early activation of the left ventricle.
   • Generally V1 shows either a notched R wave or RS or Rsr' deflection
   • Mimics a posterior MI, RVH
2. Type B:
   • Prominent S wave deflection in the right precordial leads, and upright R waves in the lateral precordial leads.
   • EP studies have showed that this form of WPW syndromes is due to early activation of the lateral aspect of the right ventricle
   • This form is more common.
   • May resemble an abnormal Q wave in the right precordial leads and be mistaken for an anterior MI
   • In both type A and B there may be abnormal q waves in leads 2, 3 and aVF.

Variants of WPW

Lown-Ganong-Levine Syndrome (LGL)

• There is a short PR interval, but no delta wave
• LGL is due to intranodal bypass tracts (i.e. there is conduction down the James fibers)
• Normal QRS duration
• PR less than 0.12 seconds
• Normal P wave

Mahaim Type Preexcitation

• Nodoventricular, nodofascicular or fasciculoventricular connections
• The impulse may travel through the AV node normally and this may then be followed by premature conduction to the basal ventricular myocardium
• There is a delta wave with a normal PR interval
• Rarer than WPW or LGL
• In older patients there can be a prolonged conduction down the accessory pathway resulting in a normal PR interval in the presence of WPW which is tough to distinguish from Mahaim fibers