Addition of R Wave Amplitude and S Wave Depth in Diagnosing Left Ventricular Hypertrophy
Yes, the addition of voltages, specifically the amplitude of the R wave and the depth of the S wave, is highly relevant in diagnosing left ventricular hypertrophy (LVH). Several established ECG criteria for LVH rely on this exact principle of voltage addition.
Key Voltage Addition Criteria for LVH
Cornell Criteria
- Combines R wave in aVL and S wave in V3
- Formula: R in aVL + S in V3
- Threshold: >28 mm in men, >20 mm in women 1
Sokolow-Lyon Criteria
- Combines S wave in V1 and R wave in V5 or V6
- Formula: S in V1 + R in V5 or V6
- Threshold: >35 mm 1
Other Combined Voltage Criteria
- SV2 + RV5 or RV6 (threshold >4 mV) 2
- SV2 + SV3 + RV5 + RV6 (threshold >4 mV) 2
- 12-lead sum of voltage 3
Scientific Rationale for Voltage Addition
The addition of voltages works because:
- Vector Summation: LVH increases electrical forces in multiple directions, which are captured by different leads
- Complementary Information: R waves and S waves in different leads reflect different aspects of ventricular depolarization
- Improved Diagnostic Performance: Research shows combined voltage criteria have superior sensitivity and specificity compared to single lead measurements 3
Special Considerations
Impact of Bundle Branch Blocks
- In left anterior fascicular block: R wave amplitude in leads I and aVL becomes less reliable, but criteria including S wave depth in left precordial leads improve LVH detection 1
- In RBBB: S wave amplitude in right precordial leads is reduced, requiring modified criteria 1
- In LBBB: LVH diagnosis is challenging and often not recommended unless specific criteria are met 4
Body Habitus Considerations
- Obesity reduces voltage amplitude, requiring correction
- Cornell voltage multiplied by body mass index (>604 mm·kg/m²) improves diagnostic accuracy 5
Practical Application
For optimal LVH detection:
- For standard patients: Use Cornell criteria or Sokolow-Lyon criteria
- For obese patients: Use BMI-adjusted Cornell criteria 5
- For patients with conduction disorders: Use criteria specific to the conduction abnormality 1
Recent Developments
Recent research suggests that RaVL alone may be a robust index for LVH screening:
- RaVL >1.0 mV has high specificity (98.3%) 6
- Below 0.5 mV and above 1.0 mV, RaVL alone may be sufficient to exclude or establish LVH 6
- Between 0.5-1.0 mV, composite indices like Cornell voltage should be used 6
Common Pitfalls
- Failing to account for conduction abnormalities when selecting criteria
- Not considering body habitus when interpreting voltage criteria
- Relying solely on voltage without considering other supportive findings (P-wave abnormalities, QRS duration, etc.)
- Using outdated terminology like "strain pattern" instead of more precise descriptions 1
Time-voltage area measurements (true area under the QRS complex) may provide superior accuracy compared to simple voltage or voltage-duration products, with reported sensitivity of 76% at 98% specificity 3.