When an implantable cardioverter defibrillator (ICD) battery nears replacement time, it reaches a stage called the “elective replacement indicator,” or ERI. When ERI is reached, ICDs may begin emitting a tone, which is meant to alert that the device has about 6 months of battery life remaining. At this point, the doctor and clinic will schedule a replacement procedure. Be sure to attend regular device check appointments.

If a device is not replaced, it will eventually reach another milestone called “end of service,” or EOS. This typically happens with about 3 months of battery life remaining and indicates a greater urgency to have replacement procedures done.