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Serum or Plasma Impedance Measurement for Cardiac Electrical Activity (e.g., Electrical Impedance Cardiography-derived Index)

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

This test measures electrical properties in your blood or serum/plasma to assess heart function, often used alongside other cardiac tests.

Quick summary

["Helps evaluate heart performance and detect early signs of heart-related conditions."]

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

Key facts at a glance

LOINC
4465-1
Short code
SPA Smn-Imp
Synonyms
SPA Smn-Imp
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 This Test Measures

Impedance cardiography uses electrical signals to estimate blood flow and heart function. This test may be part of a broader cardiac assessment, including measurements of blood volume changes or cardiac output indirectly.

Common Uses

Doctors may order this test to monitor heart health during procedures, evaluate symptoms like shortness of breath or fatigue, or assess conditions such as heart failure or arrhythmias.

How the Test Works

Blood is drawn and analyzed using specialized equipment that measures resistance (impedance) to electrical currents passing through your bloodstream. This helps estimate how well your heart pumps blood.

Preparation

No special preparation is usually needed, but you may be asked to fast or avoid certain medications before the test. Follow your healthcare provider’s instructions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

This test can provide insights into how effectively your heart is pumping blood and may help identify issues like reduced cardiac output or fluid overload. It’s often used alongside other tests, such as echocardiograms or stress tests, for a fuller picture of heart health.
This test is not a standalone diagnostic for heart disease. It’s typically used in combination with other tests to support a comprehensive evaluation.
How long will I need to wait for results?
Results may be available within a few days to a week, depending on your lab and healthcare provider. Your doctor will discuss the findings with you during your follow-up visit.
Is this test painful?
A small needle is used to draw blood, which may cause a brief sting. Most people experience minimal discomfort afterward. If you have concerns, talk to your healthcare provider.
  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