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Quantitative Serum/Plasma Amplitude of the QRS Complex (Electrocardiogram-derived)

Published: August 9, 2026Updated: August 16, 2026

This test measures the electrical amplitude (voltage) of the QRS complex in your blood sample, derived from an electrocardiogram (ECG). It helps assess the strength of electrical signals in your heart’s ventricles.

Quick summary

["This test supports heart health evaluation by measuring electrical activity amplitude in blood-derived ECG data."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
9969-7
Short code
QRS I-Amp L-V3
Synonyms
QRS I-Amp L-V3
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 Is the QRS Voltage Test Used For?

Doctors may use this test to evaluate heart function, especially in patients with suspected arrhythmias, heart enlargement, or other cardiac conditions. It can help determine if electrical signals in the heart are too weak or if there are structural issues affecting heart muscle strength.

How Is This Test Performed?

This test is not performed directly on blood. Instead, an ECG is taken to measure the electrical activity of your heart. The amplitude of the QRS complex (a specific part of the ECG waveform) is then analyzed and reported as a voltage measurement.

Why Might You Need This Test?

You might need this test if you have symptoms like chest pain, irregular heartbeat, or signs of heart disease. It may also be part of a broader cardiac evaluation, such as before surgery, for monitoring chronic heart conditions, or during diagnostic workups for unexplained symptoms.

What Does a Low or High QRS Voltage Mean?

A low QRS voltage may indicate conditions like pericardial effusion (fluid around the heart), heart tamponade, or other restrictive processes that limit heart muscle expansion. A high QRS voltage could suggest conditions like hypertrophic cardiomyopathy or other conditions that increase heart muscle thickness.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

QRS Voltage (Serum/Plasma)

Frequently asked questions

What Are the Normal Values for This Test?
There are no standard reference ranges for serum/plasma QRS amplitude alone, as it is derived from ECG data. Instead, interpretation depends on clinical context, ECG findings, and patient history.
Does This Test Require Special Preparation?
No special preparation is needed for this test. However, you may need to fast or avoid certain medications depending on the full diagnostic context, such as an ECG study.
How Long Does It Take to Get Results?
Results from this test are typically available within a few hours to a couple of days, depending on the lab and clinical workflow. Follow-up with your healthcare provider for interpretation.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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