When reviewing an ECG strip, the appearance of bunny ears is a descriptive pattern that often catches the eye of clinicians. This visual feature highlights specific components of the cardiac cycle and can support rapid interpretation when correlated with the clinical context.
This article explains what bunny ears on ECG typically represent, how to identify them on the tracing, and what clinical relevance they carry. The following sections include definitions, examples, practical guidance, and common questions to help you recognize and use this pattern effectively.
| Feature | Description | ECG Appearance | Clinical Note |
|---|---|---|---|
| Definition | Informal term for paired positive deflections after the QRS complex | Small upward bumps resembling rabbit ears | Most commonly associated with right bundle branch block |
| Typical Location | V1 to V3 leads | R and R' components visible | May extend into lateral leads in some patterns |
| Key Intervals | Prolonged QRS duration greater than 120 ms | Measured from first to last deflection | Indicates delayed ventricular activation |
| Clinical Associations | Right heart strain, pulmonary conditions | Cor pulmonale, pulmonary embolism | Requires correlation with symptoms and imaging |
Recognizing Rabbit Ears Morphology
Bunny ears on ECG are typically described as two or more small deflections immediately following the QRS complex, forming a pattern that resembles upright ears on a rabbit. This morphology is most easily seen in leads V1 to V3, where the transition from the QRS to the ST segment highlights the additional components clearly.
The hallmark of this pattern is a widened QRS with an RSR' or similar configuration, where the second peak or R' wave gives the visual impression of an ear. Understanding this shape helps clinicians quickly identify conduction abnormalities without misinterpreting them as artifact or ischemia.
By focusing on the timing, amplitude, and relationship between the initial and secondary deflections, you can determine whether the tracing reflects a benign variant or a condition requiring further evaluation. Careful lead selection and attention to baseline noise further improve recognition of this distinctive morphology.
Right Bundle Branch Block and Bunny Ears
Right bundle branch block (RBBB) is the most common cause of bunny ears on ECG, as delayed activation of the right ventricle produces the characteristic M- or W-shaped complexes in the right precordial leads. In RBBB, the QRS duration typically exceeds 120 ms, and the terminal portion of the deflection shows the secondary upward component that resembles an ear.
The initial downward deflection represents early depolarization of the left ventricle, while the subsequent R' reflects late activation of the right ventricle through alternative pathways. This sequence explains why the pattern is most prominent in V1 to V3, where electrical forces from the right heart are recorded most directly.
Clinicians use this morphology, in combination with other criteria, to confirm RBBB when it is newly discovered or associated with symptoms. Documenting the pattern accurately supports communication among team members and guides decisions about further testing or monitoring.
Clinical Relevance and Cor Pulmonale
When bunny ears on ECG appear in the setting of acute or chronic cardiopulmonary disease, they may signal underlying cor pulmonale, or right heart strain resulting from pulmonary hypertension. In these cases, the pattern reflects not only conduction delay but also increased mechanical load on the right ventricle.
Common associated conditions include chronic obstructive pulmonary disease, pulmonary embolism, and interstitial lung disease. Recognizing the ECG pattern in this context can prompt timely evaluation with echocardiography, biomarker testing, or imaging to assess severity and guide therapy.
Because many factors can influence QRS shape, the presence of bunny ears alone is not diagnostic. Instead, clinicians integrate the ECG findings with clinical history, physical examination, and objective measurements to reach a comprehensive interpretation.
Artifact Versus True Bunny Ear Patterns
Distinguishing true bunny ears from artifact is essential to avoid misdiagnosis, particularly when the pattern is subtle or appears intermittent. Muscle tremor, loose electrodes, or poor skin contact can create small deflections that mimic the morphology of right bundle branch block.
Reviewing the trace in multiple leads, checking for consistency across the recording, and ensuring proper filter and baseline settings help differentiate genuine conduction abnormalities from technical noise. Comparing current and prior ECGs is also valuable when evaluating a new pattern that could represent underlying structural heart disease.
Using standardized acquisition protocols, documenting calibration, and confirming patient stability when abnormalities are detected further supports accurate interpretation. These steps reduce uncertainty and ensure that bunny ear patterns are evaluated in context rather than in isolation.
Key Takeaways for Accurate ECG Interpretation
- Look for widened QRS with terminal positive deflections in V1 to V3 to identify bunny ear morphology.
- Correlate the pattern with clinical history, including cardiopulmonary conditions, to assess relevance.
- Rule out artifact by checking lead placement, signal quality, and consistency across multiple views.
- Use this pattern as a prompt for further testing when it appears new, symptomatic, or associated with right heart strain.
FAQ
Reader questions
What does it mean when I see rabbit ears on an ECG report?
It describes a pattern of small deflections after the QRS that resemble ears, most often caused by right bundle branch block, and indicates delayed right ventricular activation.
Are bunny ears on ECG dangerous or a sign of heart attack?
By themselves, they usually reflect a conduction issue rather than an acute heart attack, but new or changing patterns should prompt clinical evaluation to rule out underlying cardiac or pulmonary disease.
Can this pattern appear in healthy people during a routine ECG?
Yes, some otherwise healthy individuals may show a benign right bundle branch block pattern, so correlation with symptoms and other tests is important to determine clinical significance.
How is this pattern different from atrial flutter waves or paced spikes?
Atrial flutter waves are regular, smooth, and typically located between QRS complexes, while paced spikes are sharp, narrow, and precede a wide complex, whereas bunny ears are broader, notched deflections following the QRS.