Conduction Disorders: The Daily PANCE Blueprint

The answer is A. Right bundle branch block (RBBB)

The ECG findings described are characteristic of a right bundle branch block (RBBB). RBBB is identified by a wide QRS complex (>120 ms) and a “rabbit ear” pattern in V1, which represents a delayed right ventricular depolarization. The broad S wave in leads I and V6 is also typical of RBBB, reflecting the late activation of the right ventricle.

Explanation for Incorrect Answers:

• B. Left bundle branch block (LBBB): LBBB also presents with a wide QRS complex, but the ECG typically shows a broad, monophasic R wave in leads I, V5, and V6 and a deep S wave in V1, which is the opposite of the pattern seen in RBBB.
• C. Anterior myocardial infarction: While an anterior myocardial infarction can cause changes in the QRS complex, it typically presents with ST elevation and pathological Q waves in the anterior leads (V1-V4), not the typical pattern of RBBB.
• D. Wolff-Parkinson-White syndrome: This syndrome is characterized by a short PR interval and a delta wave on ECG, which represents pre-excitation of the ventricles. It does not typically present with a “rabbit ear” pattern in V1.
• E. Ventricular tachycardia: Ventricular tachycardia presents with a wide QRS complex and a rapid heart rate, usually greater than 100 beats per minute. The ECG pattern is different from the typical “rabbit ear” pattern seen in RBBB.