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: QT Interval, Lead aVR

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

: This test measures the QT interval, a portion of the heartbeat timing seen on an electrocardiogram (ECG), as viewed specifically in lead aVR.

Quick summary

[": The QT interval in lead aVR is one ECG measurement used to help assess the timing of the heart's electrical recovery."]

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

Key facts at a glance

LOINC
18534-8
Short code
Q-T interval L-AVR
Synonyms
Q-T interval L-AVR
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 Being Measured

: The QT interval reflects how long the heart's lower chambers take to electrically activate and then recover between beats. This test reports that interval as recorded from lead aVR, one of the standard views on an ECG.

: How the Test Is Done

: This is not a blood test. The information comes from an electrocardiogram, a painless recording made with electrodes placed on the skin while the heart's electrical activity is captured and the QT interval is measured.

: Why Lead aVR Matters

: Lead aVR is one of several leads in a standard ECG, and looking at the QT interval in different leads can give a fuller picture of the heart's electrical behavior. Results are interpreted together with other ECG findings rather than in isolation.

: What Results Can Mean

: A QT interval that is longer or shorter than expected may prompt further evaluation, but interpretation depends on many factors such as heart rate, medications, and other ECG measurements. Your clinician will consider the full ECG rather than this value alone.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

: Changes in QT interval can be associated with certain medications, electrolyte imbalances, and inherited heart conditions that affect the heart's electrical recovery. The QT interval in lead aVR is one piece of ECG information that clinicians use alongside other leads and clinical findings to assess electrical heart health.

Short name

: QT aVR

Frequently asked questions

: Is this a blood test?
: No. The QT interval is measured from an electrocardiogram (ECG) recording of the heart's electrical activity, not from a blood sample.
: Do I need to prepare for this test?
: Typically no special preparation is needed for a standard ECG. Tell your care team about any medications you take, since some can affect the QT interval.
: What does an abnormal result mean?
: It may suggest that the heart's electrical recovery is outside the expected range, but it is not a diagnosis on its own. Your clinician will interpret it together with the rest of your ECG and your medical history.
  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