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Heart Rate Variability (RR Interval Analysis)

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

This test measures the natural variations in the time intervals between your heartbeats, which can reflect your autonomic nervous system’s health and stress response.

Quick summary

["Heart rate variability helps assess how well your heart adapts to changes and may indicate overall cardiovascular function and emotional well-being."]

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

Key facts at a glance

LOINC
8637-1
Short code
R-R interval
Synonyms
R-R interval
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?

RR interval analysis evaluates the time gaps between consecutive heartbeats. These intervals are recorded from an electrocardiogram (ECG or EKG) and analyzed to determine variability. Normal variability suggests a healthy balance between the sympathetic (stress) and parasympathetic (rest) nervous systems.

Why Is This Test Done?

Doctors may order this test to assess autonomic nervous system function, monitor conditions affecting heart rhythm (e.g., arrhythmias), evaluate recovery from stress or illness, or screen for conditions like autonomic neuropathy.

Common Uses and Conditions

Commonly used in research or specialized clinical settings to evaluate autonomic health, such as in patients with heart disease, diabetes, or those recovering from surgery. It may also be part of broader cardiovascular risk assessments.

Sample Collection and Preparation

This test typically requires an ECG, which involves attaching small electrodes to your chest. No special preparation is needed, but you may be asked to rest quietly for a few minutes to ensure accurate results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Heart Rate Variability (HRV) or RR Interval

Frequently asked questions

What Does a Low or High RR Interval Mean?
A low RR interval variability could suggest overstress, autonomic dysfunction, or conditions affecting heart rhythm. A high variability may reflect good autonomic balance but isn’t always abnormal—results depend on your overall health.
How Is This Test Different from a Standard Heart Rate?
Unlike a simple heart rate measurement, RR interval analysis looks at the *pattern* of your heartbeat intervals, not just the average number of beats per minute. It provides deeper insights into how your nervous system regulates your heart.
Can I Fast or Avoid Certain Foods Before This Test?
No special diet or fasting is required for an ECG-based RR interval test. However, avoid caffeine or nicotine for 30 minutes before testing if instructed by your provider, as they can temporarily affect heart rate.
  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