Skip to content

Quantitative measurement of the duration of the QRS complex in an electrocardiogram (ECG) waveform

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

This test evaluates how long the electrical impulses from your heart’s lower chambers (ventricles) take to spread through your heart muscle. It’s often measured as part of an ECG.

Quick summary

["A longer QRS duration may signal abnormal heart electrical activity, while a shorter duration may need further evaluation."]

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

Key facts at a glance

LOINC
9952-3
Short code
QRS dur L-I
Synonyms
QRS dur L-I
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 a QRS Complex?

The QRS complex is a key part of an ECG reading, representing the electrical signal that causes your heart’s ventricles to contract and pump blood. It typically appears as a sharp spike or peak on the ECG tracing.

Why Is This Test Done?

Your doctor may order this test to check for conditions affecting heart rhythm, such as bundle branch blocks (where electrical signals don’t travel normally through your heart’s lower chambers) or other structural heart issues.

How Is This Test Performed?

You’ll lie down on an exam table while electrodes are attached to your chest. A machine records your heart’s electrical activity over time. The test usually takes about 5 minutes.

What Do Results Mean?

Results are compared to a standard ECG pattern. A normal QRS duration is usually between 80–100 milliseconds (msec), but this can vary. Abnormal durations may require additional testing or evaluation by a specialist.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A prolonged QRS duration may indicate conditions like ventricular hypertrophy (thickened heart muscle), bundle branch blocks, or other cardiac conduction delays. A shortened duration may raise concerns about atrial issues or electrolyte imbalances. Always discuss results with your healthcare provider.

Short name

QRS Duration

Frequently asked questions

What causes a prolonged QRS duration?
Prolonged QRS duration can result from structural heart problems, such as heart muscle thickening, or from electrical conduction delays in the heart’s lower chambers. It may also be linked to certain medications or electrolyte imbalances.
What if my QRS duration is normal?
If your QRS duration is within the expected range, it generally means your heart’s electrical signals are traveling normally through the ventricles. However, your doctor may still recommend follow-up testing if you have symptoms like dizziness or irregular heartbeat.
How often should I get this test?
Your doctor will determine how often you need this test based on your health history, symptoms, and other risk factors. Regular check-ups or follow-up ECGs may be recommended if you have a history of heart conditions.
  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