Which pattern on ECG is described by a delta wave and a wide QRS due to an accessory pathway?

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Multiple Choice

Which pattern on ECG is described by a delta wave and a wide QRS due to an accessory pathway?

Pre-excitation from an accessory pathway causes early ventricular activation, which is the main feature here. The delta wave is a slurred upstroke at the start of the QRS, reflecting impulse travel through an abnormal pathway (the bundle of Kent) that bypasses the AV node. Because part of the ventricle is activated early through this pathway and then via the normal His-Purkinje system, the PR interval shortens and the overall QRS becomes wider due to fusion of two activation wavefronts. This combination—delta wave with a widened QRS—is the Wolff-Parkinson-White pattern. It’s distinct from first-degree AV block (which has a prolonged PR with normal QRS), AVNRT (a narrow-complex tachycardia without pre-excitation), and atrial fibrillation (an irregular rhythm without a consistent delta wave pattern).

Pre-excitation from an accessory pathway causes early ventricular activation, which is the main feature here. The delta wave is a slurred upstroke at the start of the QRS, reflecting impulse travel through an abnormal pathway (the bundle of Kent) that bypasses the AV node. Because part of the ventricle is activated early through this pathway and then via the normal His-Purkinje system, the PR interval shortens and the overall QRS becomes wider due to fusion of two activation wavefronts. This combination—delta wave with a widened QRS—is the Wolff-Parkinson-White pattern. It’s distinct from first-degree AV block (which has a prolonged PR with normal QRS), AVNRT (a narrow-complex tachycardia without pre-excitation), and atrial fibrillation (an irregular rhythm without a consistent delta wave pattern).

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