Which pattern is commonly referred to as 'rabbit ears' on the ECG?

• A. Notched R waves
• B. Wide QRS
• C. Sinus tachycardia
• D. Peaked T waves

Answer: (A)

“Rabbit ears” on an ECG describe notching of the R wave—the R wave appears as two small upward deflections with a notch between them, giving a pair of peaks that look like ears. This notching is most noticeable in lateral leads (like I, aVL, V5–V6) and is classically seen with conditions that delay ventricular activation, such as left bundle branch block, where the QRS is wide and the R wave has that distinctive double-peak shape. So the pattern best described as notched R waves is the one that fits the “rabbit ears” idea. The other patterns don’t capture that double-peak R wave look: a wide QRS speaks to duration in general, sinus tachycardia is a fast rate, and peaked T waves are tall, pointed T waves seen in different problems.