Which statement correctly describes the conduction pattern in Wolff-Parkinson-White syndrome?

• A. Atrial impulses bypass the AV node and activate the ventricular myocardium directly.
• B. Atrial impulses are delayed by the AV node.
• C. Conduction occurs exclusively through the AV node.
• D. There is no preexcitation pattern.

Answer: (A)

Wolff-Parkinson-White syndrome involves an accessory electrical pathway between the atria and ventricles that allows impulses to reach the ventricles without traveling through the AV node. This causes preexcitation of the ventricles, because part of the ventricular activation occurs earlier via the accessory pathway. On ECG this shows up as a shortened PR interval and a delta wave with a widened QRS complex. So the statement that atrial impulses bypass the AV node and activate the ventricular myocardium directly accurately describes the conduction pattern in WPW. The other descriptions either reflect normal AV nodal conduction, exclusive AV nodal conduction, or no preexcitation, none of which fit WPW.