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An ECG electrode is the conductor that touches the skin and picks up the heart’s electrical signal for an electrocardiograph. The wire or cable that carries that signal onward is a separate part, the lead wire. Searches such as “ecg electrodes and leads” and “electrodes in ecg” usually come down to keeping those two parts apart.
This page describes products and general use; it is not medical advice.
What ECG electrodes are
US federal regulation defines an electrocardiograph electrode as “the electrical conductor which is applied to the surface of the body” to transmit the body-surface electrical signal to a processor that produces an electrocardiogram or vectorcardiogram (21 CFR 870.2360, checked 2026-10-29). In plain terms, it is the skin-contact part of the chain. It records; it does not send electricity into the patient. For the machine that receives the signal, see what an ECG machine is.
Who uses them: clinic and hospital staff who set up ECG recordings and monitoring, biomedical and equipment teams who stock them, and students learning how an ECG is recorded.
ECG electrodes vs leads
The words are used loosely, and the many search variants (“leads and electrodes in ecg”, “ecg electrodes leads”, “electrodes ecg”) all circle the same distinction.
- Electrode: the physical sensor on the skin.
- Lead wire (cable): the wire that connects an electrode to the ECG monitor or machine. A catalogued FDA record for one disposable adult product describes “3-lead ECG monitoring” solid gel electrodes with pre-attached 39 inch (100 cm) non-shielded lead wires, so the two are sometimes supplied together (FDA AccessGUDID, checked 2026-10-29).
- “Lead” as a view of the heart: in clinical use a “lead” also means one recorded view of the heart’s electrical activity, calculated from signals between electrodes. This is why a standard 12-lead ECG uses 10 electrodes, as explained in our ECG machine guide.
What an ECG electrode is made of
A conventional disposable electrode of the kind used as the comparator in a peer-reviewed validation study was a round silver/silver chloride (Ag-AgCl) electrode with an electrolyte gel, 25 mm in diameter (Tsukada et al., Heart and Vessels, 2019; conventional gel-type comparator, Vitrode R). The study paired it with an adhesive pad. The example FDA record above describes a solid gel electrode with a silver/silver chloride sensor, rectangular, 30 mm x 45 mm, with pre-attached carbon lead wires.
Types of ECG electrodes
| Type | Typical use | Key difference | Source |
|---|---|---|---|
| Disposable solid-gel electrode with attached lead wire | Adult ECG monitoring | Catalogued as single-use, not packaged sterile, does not require sterilization before use (this one product) | FDA AccessGUDID record |
| Ag-AgCl electrode with wet electrolyte gel and adhesive | Conventional comparator in an ECG study | Round, 25 mm, with adhesive pad | Tsukada et al., 2019 |
| Textile (dry) electrode | Research, wearable ECG monitoring | No gel or adhesive; pad wetted with glycerol in the study | Tsukada et al., 2019 |
How FDA regulates ECG electrodes
Under 21 CFR 870.2360, ECG electrodes are Class II (special controls). The device is exempt from premarket notification (510(k)) subject to the limitations in 21 CFR 870.9, and the special control is the FDA guidance “Class II Special Controls Guidance Document: Electrocardiograph Electrodes”. FDA’s product code for the example record is DRX, “Electrode, electrocardiograph”. For how device classes work more generally, see what a medical device is.
Safe use and handling basics
- Follow the manufacturer’s instructions for use for the specific product. The example FDA record is flagged single-use; do not assume every electrode is, and do not assume one is reusable unless its labeling says so.
- Electrodes only record, and they are not a substitute for clinical judgement. Questions about placement and interpretation belong with trained clinical staff.
Common mistakes in understanding electrodes
- Treating “electrode” and “lead” as the same thing; they are the skin sensor and the connecting wire, and “lead” also names a recorded view.
- Assuming the number of leads equals the number of electrodes (12 leads come from 10 electrodes).
- Generalising one product record to all products: single-use status, latex labeling and attached lead wires vary by product and are stated in each product’s own labeling.
FAQ
What is the difference between ECG electrodes and leads?
An electrode is the conductor on the skin. A lead wire connects it to the monitor. A “lead” can also mean one recorded view of the heart’s activity.
How many electrodes are used for a 12-lead ECG?
Ten. See our ECG machine guide.
How does FDA classify ECG electrodes?
Class II with special controls, exempt from 510(k) subject to the limits in 21 CFR 870.9.
What are ECG electrodes made of?
One common conventional type is a round silver/silver chloride (Ag-AgCl) electrode with electrolyte gel and an adhesive pad. Textile (dry) electrodes with no gel or adhesive have been studied for wearable use.
Are ECG electrodes reusable?
It depends on the product’s labeling. The disposable example record above is marked single-use.
For the wider field, see what cardiology is. Related supplies are listed in the diagnostic, monitoring and imaging supplies category on lac.us.
Sources
- eCFR, 21 CFR 870.2360, Electrocardiograph electrode: https://www.ecfr.gov/current/title-21/section-870.2360 (checked 2026-10-29)
- FDA AccessGUDID device record: https://accessgudid.nlm.nih.gov/devices/20884838007882 (checked 2026-10-29)
- Tsukada YT et al., Validation of wearable textile electrodes for ECG monitoring, Heart and Vessels, 2019: https://pmc.ncbi.nlm.nih.gov/articles/PMC6556171/ (checked 2026-10-29)
