MAUDE Adverse Event Report: ZOLL Manufacturing Corporation LifeVest WCD 4000 System; Wearable Cardioverter Defibrillator

Model Number	LifeVest WCD 4000 System
Medical Device Problem Code	Circuit Failure (1089)
Health Effect - Clinical Code	No Clinical Signs, Symptoms or Conditions (4582)
Date of Event	08/18/2026
Type of Reportable Event	Malfunction
Event or Problem Description
A us distributor returned a monitor and reported being unable to complete incoming functional testing.
Additional Manufacturer Narrative
Device evaluation of monitor has been completed.The reported problem (unable to baseline) has been confirmed.Upon investigation the monitor was not properly producing a driven ground signal.The cause for the failure was isolated to an open driven ground resistor on the computer/analog board.The root cause for the open resistor could not be positively identified.No adverse event resulted from the damaged monitor.

• Brand Name: LifeVest WCD 4000 System
• Common Device Name: Wearable Cardioverter Defibrillator
• Manufacturer (Section D): ZOLL Manufacturing Corporation; 121 gamma drive; pittsburgh PA 15238
• Manufacturer (Section G): ZOLL Manufacturing Corporation; 121 gamma drive; pittsburgh PA 15238
• Manufacturer Contact: zoll mfg corporation ; 121 gamma drive; pittsburgh, PA 15238
• MDR Report Key: 50945345
• Report Number: 3008642652-2026-09507
• Device Sequence Number: 9534233
• Product Code: MVK
• UDI-Device Identifier: 00855778005005
• UDI-Public: (01)00855778005005(11)200901
• Combination Product (Y/N): N
• Initial Reporter State: PA
• Initial Reporter Country: US
• PMA/510(K) Number: P010030
• Number of Events Summarized: 1
• Summary Report (Y/N): N
• Reporter Type: Manufacturer
• Report Source: Distributor
• Type of Report: Initial
• Report Date (Section B): 09/30/2026

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Is this an Adverse Event Report?: No
• Is this a Product Problem Report?: Yes
• Operator of Device: Lay User/Patient
• Device Model Number: LifeVest WCD 4000 System
• Is the Reporter a Health Professional?: No
• Type of Report(Section G): Thirty-Day
• Initial Date Received by Manufacturer: 09/28/2026
• Initial Report FDA Received Date: 09/30/2026
• Is the Device Labeled for Single Use? (Y/N): No
• Is This a Single-Use Device that was Reprocessed and Reused on a Patient? (Y/N): No
• Usage of Device: Reuse
• Patient Sequence Number: 1
• Patient Sex: Unknown