What does the rabbit‑ears pattern in precordial leads V1 and V2 look like?

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Last updated: June 28, 2026 • View editorial policy

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The "Rabbit Ears" Pattern in V1 and V2

The "rabbit ears" pattern in leads V1 and V2 refers to the characteristic rsr', rsR', or rSR' morphology seen in right bundle branch block (RBBB), where two distinct R wave peaks create an appearance resembling rabbit ears—the second R wave (R' or r') is typically wider than the initial R wave. 1, 2

Morphological Features

The rabbit ears pattern specifically describes:

  • Two upright deflections (R waves) separated by a small S wave in the right precordial leads V1 or V2
  • The second R wave (R' or r') is characteristically wider than the first R wave
  • Common notations include: rsr', rsR', or rSR' patterns
  • The R' deflection represents delayed right ventricular activation

Complete RBBB Diagnostic Criteria

When you see this rabbit ears pattern, confirm complete RBBB by checking 1, 3, 4:

  1. QRS duration ≥120 ms in adults
  2. rsr', rsR', or rSR' pattern in V1 or V2 (the rabbit ears themselves)
  3. Wide S wave in leads I and V6 (S wave duration > R wave duration OR >40 ms)
  4. R peak time >50 ms in lead V1 but normal in V5 and V6

Important Variant Pattern

In a minority of patients, you may see a wide, often notched R wave pattern in V1 and/or V2 instead of the classic rsr' morphology—this still represents RBBB when other criteria are met. 1, 2 This variant can be confusing because it doesn't show the classic "two ears" but rather appears as a single broad, notched R wave.

Clinical Pitfall

The term "rabbit ears" is colloquial and not found in official guideline terminology. When documenting, use the precise morphological descriptors (rsr', rsR', rSR') rather than the metaphorical term to ensure clarity in medical records.

References

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.