Waveform analysis of electrocardiogram (ECG) parameters: R-wave amplitude and S-wave amplitude
This test measures the height of the R-wave (positive deflection) and S-wave (negative deflection) on an ECG, which can help assess heart electrical activity and potential abnormalities in conduction.
["Your ECG’s R-wave and S-wave amplitudes may indicate how well your heart’s electrical signals are traveling through your heart muscle."]
Key facts at a glance
- LOINC
- 76636-0
- Short code
- R wave Amp L-V5+S wave Amp L-V1
- Synonyms
- R wave Amp L-V5+S wave Amp L-V1
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ekg
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What Are R-Wave and S-Wave Amplitudes?
The R-wave and S-wave are key parts of the ECG waveform that represent electrical depolarization and repolarization of the heart’s ventricles. The R-wave is the upward deflection, while the S-wave is the downward deflection following it. Their amplitudes can vary depending on the heart’s position, size, and potential conduction issues.
Why Are These Measurements Taken?
Measuring R-wave and S-wave amplitudes helps doctors evaluate heart rhythm, detect abnormalities like bundle branch blocks (where signals take longer to travel through the heart), or assess changes in heart size or structure over time. These tests are often part of a broader ECG evaluation.
How Is This Test Performed?
This test is typically performed as part of a standard ECG, where electrodes are placed on your chest, arms, and legs. The machine records electrical activity over 10–30 seconds. The R-wave and S-wave amplitudes are measured from the recorded waveform and compared to standard references for your age, sex, and heart size.
What Do Results Mean?
Results may show normal amplitudes, indicating healthy electrical conduction, or abnormal amplitudes that could suggest conditions like myocardial infarction (heart attack), hypertrophy (enlarged heart), or other cardiac issues. Your doctor will interpret these findings in the context of your full ECG and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance of R-wave and S-wave amplitudes includes identifying conduction delays, assessing myocardial damage, or evaluating structural heart disease. These measurements are critical in diagnosing conditions like left or right bundle branch block, myocardial infarction, or cardiomyopathies.
Short name
ECG Waveform Amplitudes
Frequently asked questions
How often should I get this test?
What are the risks or side effects of this test?
Can I eat or drink before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy