Quantitative Serum Amplitude of Forward Cardiac QRS Complex (Slope)
This test measures the electrical activity of your heart’s ventricles by analyzing the slope of the QRS wave on an ECG. It helps assess heart rhythm and conduction speed.
["This test may help diagnose or monitor heart conditions affecting electrical signals."]
Key facts at a glance
- LOINC
- 9968-9
- Short code
- QRS I-Amp L-V2
- Synonyms
- QRS I-Amp L-V2
- 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 Does This Test Measure?
The QRS wave is a key part of an electrocardiogram (ECG or EKG), representing the electrical depolarization of the heart’s ventricles. The slope of this wave reflects the rate at which the heart muscle contracts. This test specifically quantifies the forward slope of the QRS complex in serum, which can be linked to cardiac electrical activity when interpreted alongside ECG results.
Why Might You Need This Test?
While serum-based QRS slope measurements are less common than traditional ECG readings, they may be used in specialized settings to evaluate heart function indirectly. This could include research studies, advanced cardiac diagnostics, or when assessing conditions like arrhythmias or conduction disorders.
How Is This Test Performed?
This test is not a standalone blood draw but rather an analysis derived from ECG data. Your healthcare provider will record an ECG, which captures heart electrical activity. The slope of the QRS wave is then measured and reported. Serum samples are not directly tested for this measurement.
What Preparations Are Needed?
No special preparations are required for this test. However, you should follow standard ECG instructions: avoid caffeine or nicotine 1–2 hours before testing, and wear loose clothing for easy electrode placement.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
QRS Slope Measurement
Frequently asked questions
Will this test show heart disease?
How is the QRS slope measured in serum?
Can this test replace an ECG?
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