RSR' Pattern in V1 and V2: Normal Variant Determination
An RSR' pattern in leads V1 and V2 is a normal variant in children when the QRS duration is normal (<110 ms in adults, age-adjusted thresholds in children), but requires careful evaluation in adults to exclude pathology. 1
Key Diagnostic Approach
QRS Duration is Critical
The distinction between normal variant and pathology hinges entirely on QRS duration:
- Normal QRS duration (<110 ms in adults): The RSR' pattern is considered a normal variant, particularly in children and young adults 1, 2
- Prolonged QRS (110-119 ms in adults): Suggests incomplete right bundle branch block (RBBB) 1
- Significantly prolonged QRS (≥120 ms in adults): Indicates complete RBBB 2, 3
Age-Specific Considerations
In children, the American College of Cardiology explicitly states that an RSR' pattern in V1 and V2 with normal QRS duration is a normal variant and requires no further workup 1, 2. The guideline specifically discourages using terms like "RSR'" or "normal RSR'" because they can be variously interpreted and cause confusion 2, 3.
In adults, while the pattern can still be benign with normal QRS duration, the differential diagnosis broadens significantly and includes potentially serious conditions 4.
When to Suspect Pathology
Even with normal QRS duration, consider further evaluation if:
- New onset in a previously normal ECG warrants echocardiography to assess for structural heart disease, right ventricular pressure/volume overload, or conduction system disease 2
- Associated symptoms such as syncope, cardiac arrest, or chest pain require exclusion of Brugada syndrome or arrhythmogenic right ventricular dysplasia 4
- Other ECG abnormalities are present, such as ST-segment elevation suggesting Brugada pattern 5
- Wide QRS (≥110 ms) with RSR' in left-sided leads (I, aVL, V5-V6) may indicate myocardial infarction scar with mural conduction delay 6
Critical Pitfall to Avoid
Lead misplacement is a common cause of false RSR' patterns. The American College of Cardiology notes that recording V1 too high or too far to the right can create an artifactual RSR' pattern 1, 2. If the pattern appears atypical, repeat the ECG with careful lead placement verification 5.
Clinical Management Algorithm
- Measure QRS duration accurately in multiple leads
- If QRS <110 ms (age-adjusted in children):
- In children/young adults: Reassure, no further workup needed 2
- In adults: Consider benign variant, but compare to prior ECGs if available
- If QRS 110-119 ms: Diagnose incomplete RBBB, consider echocardiography 1
- If QRS ≥120 ms: Diagnose complete RBBB, obtain echocardiography to assess for underlying structural disease 2, 3
- If any concerning features (symptoms, family history of sudden death, other ECG abnormalities): Pursue comprehensive cardiac evaluation including echocardiography and possibly stress testing 4
The American College of Cardiology's 2009 guidelines remain the authoritative source, emphasizing that context (age, QRS duration, associated findings) determines whether this pattern represents a benign normal variant or requires investigation 1, 2, 3.