The Zoll LifeVest 4000, a wearable defibrillator, could fail to deliver a treatment shock after displaying the message “Call for service: Device has a problem that may require service. Call ZOLL for service, Message Code 102,” according to the FDA.

“Failure to contact Zoll and immediately replace the device after Message Code 102 appears on the device screen may result in serious patient harm or death of the patient because the device may fail to deliver therapy appropriately when needed” according to an FDA press release.

When functioning properly, the LifeVest is intended to deliver a shock to correct a patient’s heartbeat to a normal rhythm. However, when the error mentioned above occurs, LifeVest may not be able to function as intended and deliver the corrective shock because of an issue that prevents the device from charging its high-energy capacitors. To compound the malfunction of the device, the error message “Message Code 102” does not indicate that the device is not functioning properly and that the patient needs to contact Zoll immediately.

Only one death associated with “Message Code 102” malfunction of LifeVest has been reported, but about 0.1% of devices have displayed the “Message Code 102” error. According to Zoll, roughly 33,670 devices have been distributed as of Nov. 14, 2017, with nearly 75% of them distributed in the United States.

On Jan. 14, Zoll issued a voluntary recall of the LifeVest 4000 . The FDA has indicated that it will continue to work with Zoll to monitor adverse events associated with the “Message Code 102” error and work on finding a permanent solution to this problem. Recommendations for physicians, caregivers, and patients regarding how to respond to error messages can be found here .