WPW ‘A’ Conduction

Report:

Sinus rhythm

Right axis deviation[!xe "Right axis deviation :WPW" \b!]

WPW type ‘A’ conduction

Comment:

Subjects (rather than patients) with asymptomatic WPW conduction on routine ECG have normal life expectancy; there is no indication to subject them to electrophysiologic testing187.

The PR interval is shortened to 0.12” by the delta wave, best seen slurring the QRS upstroke in the inferior leads or V4. In type ‘A’ conduction there is a positive concordant precordial pattern; it indicates the bundle of Kent insertion into the left ventricular myocardium (hence a superficial resemblance to right bundle branch block). In lead V1, the QRS is positive, but its initial part is isoelectric, producing a spuriously normal PR interval: map the onset of the QRS upward from leads V2-3 to verify this.

An easy way to remember types ‘A’ and ‘B’ is that, in the all-important lead V1, the QRS is above in ‘A’ and below in ‘B’. That is, in V1, the QRS is predominantly positive in ‘A’ and predominantly negative in ‘B’.