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P-wave amplitude in the left anterior fascicle (electrophysiology study)

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

This test measures the electrical activity of your heart’s conduction system, specifically the amplitude of the P-wave in the left anterior fascicle during an electrophysiology study.

Quick summary

["Assesses heart electrical conduction health in a specific pathway during a heart study."]

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

Key facts at a glance

LOINC
9913-5
Short code
P' wave Amp L-AVF
Synonyms
P' wave Amp L-AVF
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 This Test Used For?

Electrophysiology studies (EPS) are used to diagnose and evaluate heart rhythm disorders, such as arrhythmias. Measuring P-wave amplitude helps identify conduction delays or blockages in the heart’s electrical pathways, which may affect how well your heart beats normally.

How Is This Test Performed?

During an EPS, small electrodes are placed on your chest and inside your heart to record electrical signals. The test may involve pacing the heart to observe how electrical signals travel through different pathways, including the left anterior fascicle.

Why Might You Need This Test?

You may need this test if you have symptoms like palpitations, dizziness, or irregular heartbeat, or if your doctor suspects a conduction disorder affecting the heart’s electrical system.

Preparation and Risks

No special preparation is needed, but you may be given a mild sedative. Risks include temporary discomfort, bruising, or rare complications like heart rhythm changes or infection at the electrode sites.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Left Anterior Fascicle P-wave Amplitude

Frequently asked questions

What Does a Low or High P-wave Amplitude Mean?
A low amplitude may suggest delayed conduction through this pathway, while a high amplitude could indicate other conduction issues or artifacts. Your doctor will interpret results in the context of your symptoms and overall heart health.
Can This Test Be Done Without an Electrophysiology Study?
No, this specific measurement requires an electrophysiology study to record electrical signals accurately. Other heart tests, like an ECG, do not provide this detailed analysis.
How Long Does It Take to Get Results?
Results are typically reviewed by your cardiologist within a few days to a week, depending on follow-up needs. Immediate results may be discussed during the procedure if urgent decisions are required.
  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