Written and maintained by CASRAI Editorial Board
Published · Last updated
This page describes products and general use; it is not medical advice.
On this page
Defibrillator paddles are the hand-held or surgical electrodes that carry a defibrillator’s electrical shock to the heart. This guide is for clinic staff, biomedical and supply buyers, and students who need to tell internal paddles from external ones and understand how US regulators classify them. Paddles are used by trained clinicians with a manual defibrillator, not by lay rescuers.
What defibrillator paddles are
Under 21 CFR 870.5300, a DC-defibrillator is a device that delivers an electrical shock to restore normal heart rhythm in the atria or ventricles, and the regulation covers the device “including paddles”. It states that the device delivers the shock “through paddles placed either directly across the heart or on the surface of the body.” In plain terms, there are two placements and so two broad paddle types: internal paddles that touch the heart directly, and external paddles used on the chest surface. For the machine behind the paddles, see what a defibrillator is.
Internal vs external paddles
Internal defibrillator paddles
Internal paddles are used directly on the heart during open-chest surgery. One FDA-cleared example, the Philips Switched Internal Paddles (510(k) K203231), is indicated for treatment of ventricular fibrillation by manual defibrillation provided directly to the heart during open-chest surgical procedures, in adult and pediatric populations.
External paddles
External paddles are applied across the body surface, typically the chest wall, and are used with a manual defibrillator by trained clinicians.
| Feature | Internal paddles | External paddles | Source |
|---|---|---|---|
| Placement | Directly across the heart | On the surface of the body | 21 CFR 870.5300 |
| Setting named in the example clearance | Open-chest surgical procedures | Not covered by that clearance | FDA 510(k) K203231 |
Always follow the defibrillator manufacturer’s instructions for use.
Sizes: one manufacturer’s internal paddles
Internal paddles come in several sizes. The FDA 510(k) summary for the Philips Switched Internal Paddles lists four sizes, shown here as an example of one manufacturer’s range, not a universal standard.
| Size name | Size (cm) | Model | Compatible with |
|---|---|---|---|
| Extra large | 7.5 cm | M4741A | HeartStart MRx and HeartStart XL+ |
| Large | 6.0 cm | M4742A | HeartStart MRx and HeartStart XL+ |
| Medium | 4.5 cm | M4743A | HeartStart MRx and HeartStart XL+ |
| Small | 2.8 cm | M4744A | HeartStart MRx and HeartStart XL+ |
FDA classification of defibrillator paddles
FDA regulates paddles together with the defibrillator under 21 CFR 870.5300 (product code LDD in the FDA classification database):
- Low-energy DC-defibrillator: delivers up to 360 joules into a 50 ohm test load. The regulation says this includes units with lower output used in pediatric defibrillation or cardiac surgery. Class II (performance standards).
- High-energy DC-defibrillator: delivers more than 360 joules into a 50 ohm test load. Class III (premarket approval).
How to choose: what to check
- Intended setting: the example internal paddles are indicated for open-chest surgery, so the labeled indication is the first thing to read.
- Compatibility: the example paddles are listed for specific defibrillator models, so confirm that the paddles are listed for your device model.
- Size range: the example offers four sizes from 2.8 to 7.5 cm, listed by model number.
- Regulatory status: a cleared device appears in the FDA 510(k) database under its K number.
Safe use and handling basics
Paddle use is a trained-clinician activity under the manufacturer’s instructions for use and facility protocols. The 510(k) summary for the example internal paddles reports biocompatibility testing against ISO 10993-1 (cytotoxicity, sensitization, irritation, acute systemic toxicity, pyrogenicity). Check the instructions for use for cleaning, sterility and single-use or reuse details, since these differ by product.
Common mistakes
- Treating internal and external paddles as interchangeable; the regulation and the clearance describe different placements.
- Assuming paddles fit any defibrillator; compatibility is listed per model.
Frequently asked questions
What are internal defibrillator paddles?
They are paddles placed directly on the heart during open-chest surgery, as described in the FDA clearance for the Philips Switched Internal Paddles (K203231). 21 CFR 870.5300 describes paddles “placed either directly across the heart or on the surface of the body.”
Are defibrillator paddles regulated by FDA?
Yes. 21 CFR 870.5300 is titled “DC-defibrillator (including paddles)”. Low-energy devices (up to 360 J) are Class II and high-energy devices (above 360 J) are Class III.
How do paddles relate to an AED?
Paddles belong to the manual defibrillator context described in manual defibrillator vs AED. For related emergency equipment see what a crash cart is, AED trainers and AED wall mounts.
Where to find emergency equipment
Product categories for this area are listed under emergency and trauma response supplies.
Sources
- 21 CFR 870.5300, DC-defibrillator (including paddles), https://www.ecfr.gov/current/title-21/part-870/section-870.5300 (checked 2026-10-31).
- FDA 510(k) K203231, Philips Switched Internal Paddles, decision date 2021-01-11, product code LDD, FDA 510(k) database, https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K203231 (checked 2026-10-31 via https://api.fda.gov/device/510k.json?search=k_number:K203231).
