Which disorder is likely to produce a delta wave on the cardiac monitor?

• A. Lown-Ganong-Levine syndrome
• B. Atrioventricular nodal reentrant tachycardia
• C. Sinus tachycardia
• D. Wolff-Parkinson-White syndrome

Answer: (D)

Delta waves on an ECG reflect ventricular pre-excitation through an accessory pathway. In Wolff-Parkinson-White syndrome, an abnormal conduit (the Bundle of Kent) allows part of the ventricle to depolarize early, producing a slurred initial upstroke of the QRS complex—the delta wave. This pre-excitation shortens the PR interval and widens the QRS, creating the classic WPW pattern.

Other conditions may alter PR or QRS differently but do not produce this characteristic delta wave. For example, Lown-Ganong-Levine syndrome can show a short PR interval but lacks the delta wave pattern; AVNRT and sinus tachycardia produce normal pre-excitation patterns with no delta wave.

Thus, the presence of a delta wave points to Wolff-Parkinson-White as the disorder responsible for that ECG finding.