The FDA advised consumers and first responders to monitor the readiness of some HeartStart automated external defibrillators (AEDs), which it warned may fail to deliver a shock in an emergency.

Philips Healthcare began recalling HeartStart FRx, HeartStart HS1 Home and HeartStart HS1 OnSite AEDs in September 2012 after an internal electrical component was found to fail. HeartStart FRx is used by emergency medical service and fire department personnel; the HeartStart HS1 Home by consumers; and the HeartStart HS1 OnSite by the public, who can find the devices in places such as airports, community centers, schools and government buildings.

The FDA classified the recall as a Class II recall. It recommended owners of devices made and distributed between 2005 and 2012 contact the company for a replacement AED unit. The recall was expected to involve 700,000 devices.

In November Philips released updated information about the failure that included a maintenance advisory. The FDA recommended that owners of HeartStart AEDs, or those unsure if they have a recalled or replaced device, contact Philips Healthcare for technical support. Owners should inspect and monitor their devices as well.

“Keep the recalled HeartStart AED in service until Philips Healthcare replaces the device or you can obtain another working AED,” the FDA wrote in a warning communication. “Despite current manufacturing and performance problems, the FDA considers the benefits of attempting to use an AED in a cardiac arrest emergency greater than the risk of not attempting to use the defibrillator.”