###1: Electrocardiogram (ECG) QRS Duration
###3: QRS duration is a measurement taken from an electrocardiogram (ECG). It shows how long the electrical signal takes to travel through the heart’s ventricles, which pump blood to the lungs and the rest of the body.
["###4: A prolonged QRS duration may indicate delayed electrical conduction through the ventricles and should be interpreted by a healthcare professional."]
Key facts at a glance
- LOINC
- 8633-0
- Short code
- QRS dur
- Synonyms
- QRS dur
- 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
###5: What the QRS complex represents
###6: The QRS complex is the main spike on an ECG tracing. It reflects the electrical activation of the ventricles, the lower chambers of the heart that pump blood out of the heart.
###7: How QRS duration is measured
###8: The ECG machine measures the time from the beginning of the Q wave to the end of the S wave. Results are usually reported in milliseconds and are reviewed as part of the complete ECG.
###9: What a prolonged QRS duration can mean
###10: A prolonged QRS duration can occur when electrical conduction through the ventricles is slowed. Possible causes include a previous heart attack, certain heart rhythm or conduction disorders, bundle branch block, cardiomyopathy, or medication effects.
###11: Why interpretation and other ECG findings matter
###11: QRS duration should be interpreted with the rest of the ECG, your symptoms, medical history, and examination findings. A borderline or abnormal measurement does not by itself establish a diagnosis, and occasional variations may not be clinically important.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
###13: Clinical significance: An abnormally prolonged QRS duration may suggest ventricular conduction delay and can sometimes be associated with structural or electrical heart disease. However, it may also reflect benign variation or medication effects, so a clinician must interpret it in the context of the complete ECG and clinical situation.
Short name
###2: QRS duration
Frequently asked questions
###14: Is QRS duration the same as the QT interval?
###16: Can an abnormal QRS duration cause symptoms?
###18: Can medications affect QRS duration?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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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