Rosh Internal Medicine Boost Practice Exam

What condition is characterized by a short PR interval, wide QRS complex, and delta wave on an ECG?

1. Atrial fibrillation

2. Wolff-Parkinson-White syndrome

3. Ventricular tachycardia

4. Second-degree AV block

The correct answer is: Wolff-Parkinson-White syndrome

The condition characterized by a short PR interval, wide QRS complex, and delta wave on an ECG is Wolff-Parkinson-White syndrome. This syndrome is a type of pre-excitation syndrome, which occurs due to the presence of an accessory pathway that allows electrical impulses to bypass the normal conduction system of the heart. The hallmark features on the ECG include a delta wave, which signifies early depolarization of the ventricles due to this accessory pathway, leading to the wide QRS complex. The short PR interval reflects the rapid transmission of electrical impulses from the atria to the ventricles via both the normal AV node and the accessory pathway. In contrast, other conditions do not present these specific features. For instance, atrial fibrillation often shows an irregularly irregular rhythm without distinct P waves and would not typically have a delta wave. Ventricular tachycardia is characterized by a wide QRS complex but presents with a regular rhythm and lacks the distinct delta wave seen in WPW. Second-degree AV block shows varying PR intervals and dropped QRS complexes, which do not match the characteristic findings of WPW. Thus, the combination of a short PR interval, wide QRS complex, and delta wave uniquely identifies Wolff-P