MAUDE Adverse Event Report: ZOLL MANUFACTURING CORPORATION LIFEVEST WCD 4000 SYSTEM; WEARABLE CARDIOVERTER DEFIBRILLATOR

Model Number WCD 4000

Device Problems High impedance (1291); Inappropriate/Inadequate Shock/Stimulation (1574)

Patient Problems Atrial Fibrillation (1729); Ventricular Tachycardia (2132); Shock from Patient Lead(s) (3162)

Event Date 02/15/2019

Event Type  Injury  

Manufacturer Narrative

There was no death associated with the inappropriate defibrillation event.Device evaluation summary: device evaluation of monitor sn (b)(4) has been completed.The reported problem (treatment) has been confirmed.Upon investigation the monitor was unable to power up.The cause for the failure was isolated to the defibrillator pca and computer/analog board.Insulated-gate bipolar transistor (igbt) q13 was shorted and there was contamination on the j1003aa and j1002aa connectors on the defibrillator pca.In addition, it was found that high voltage deviated to low voltage circuitry, thermally damaging multiple components on the computer/analog board.The cause of the short was high voltage deviated to low voltage circuitry.It is unknown when the monitor became unable to power on.The monitor was able to monitor the patient's rhythm and deliver treatment shocks during arrhythmia detections.The root cause of the voltage deviation cannot be positively identified.The cause for the contamination on the connectors was ingress of an unknown liquid.Lifevest patient training materials have been updated as a reminder not to expose lifevest electronic components to liquid.Electrode belt sn (b)(4) was returned and evaluated at the distributor, in accordance with procedures recommended by zoll manufacturing corporation.The evaluation included review of downloaded software flag files on the day of the event and incoming functional testing.The review of the software flags consisted of an analysis of the downloaded data to identify any fault flags or unusual patterns of software flags.The software flag files did not suggest a device malfunction that would contribute to the inappropriate treatment.During the incoming functional testing, a 1hz simulated normal sinus rhythm signal was applied to the ecg electrodes, followed by a 5hz simulated treatable arrhythmia signal which verified proper performance of the detection algorithm.The pulse delivery circuitry test verified proper delivery of a full energy 150j biphasic pulse.The functional testing confirmed proper ecg acquisition and pulse delivery functionality.Device manufacture date: monitor - 07/24/2015; belt - 09/28/2015.A cause and effect analysis was conducted using all of the available information which includes the incident report, device evaluation, software flag files, and ecg strips.The primary cause of the inappropriate shock event was improper response button use by the patient during the false detection, prior to shock delivery and throughout the treatment event.The ecg analysis, conducted by trained ecg technicians, identified the primary cause of the false detection was non-sustained ventricular tachycardia (nsvt).Inappropriate defibrillations are an anticipated risk associated with the use of the lifevest.Patients are instructed through alarms, voice messages, ifu, and training to press the response buttons to prevent an inappropriate defibrillation.(b)(4).A summary of the safety and effectiveness data (ssed), including the inappropriate defibrillation safety objective supporting fda's approval of the lifevest, can be found at http://www.Accessdata.Fda.Gov/cdrh_docs/pdf/p010030b.Pdf.The lifevest detection algorithm complies with iec 60601-2-4 performance requirements for sensitivity and specificity.

Event Description

A us distributor contacted zoll to report that a patient experienced an inappropriate defibrillation event consisting of five shocks.A doctor at the hospital where the patient was admitted reported that the patient had been treated several times.The patient reported that she was awake, asymptomatic and scratching ice off of her windows at the time of the event.The patient reported that she "tried to respond but it wouldn't respond".The patient's doctor reported that the patient had some dexterity issues and may have fumbled with the response buttons.The patient remained in the hospital and continued wearing the lifevest.Clinical review of the download data indicates that non-sustained ventricular tachycardia (nsvt) during atrial fibrillation (af) rhythm contributed to the false detection.The five shocks were all low energy pulses ranging from 71 to 98 joules.In the case of shocks 1 and 5, high impedance caused the low energy shocks.The cause of the high impedance is unknown.The device properly delivered conductive gel during the event.There is no indication that the high impedance was caused by a device malfunction.In the case of shocks 2, 3, and 4, an impedance of 0 ohms was observed.The low energy shocks were likely due to the pulse being delivered into an open load.This is consistent with zero ohm impedance.The cause of the open load and reported impedance was likely due to the therapy pads on the lifevest not making full contact with the patient at the time of the defibrillation event.The first three treatments were delivered while the patient was in a non-treatable rhythm.Treatment 4 was delivered while the patient was in ventricular tachycardia (vt) at 160 bpm.The post-shock rhythm was sinus rhythm at 130 bpm with nsvt.Treatment 5 was delivered while the patient was in vt at 150 bpm.The post-shock rhythm was sinus tachycardia at 115 bpm transitioning to af at 160 bpm.The response buttons were pressed intermittently earlier in the detection sequence but not immediately prior to the first treatment delivery.The response buttons were then pressed intermittently throughout the treatment event but not sufficiently to delay the treatment shocks.The response buttons functioned appropriately.There was no death associated with the inappropriate defibrillation event.

• Brand Name: LIFEVEST WCD 4000 SYSTEM
• Type of Device: WEARABLE CARDIOVERTER DEFIBRILLATOR
• Manufacturer (Section D): ZOLL MANUFACTURING CORPORATION; 121 gamma drive; pittsburgh PA 15238 3495
• Manufacturer (Section G): ZOLL MANUFACTURING CORPORATION; 121 gamma drive; pittsburgh PA 15238 3495
• Manufacturer Contact: manuela parra ; 121 gamma drive; pittsburgh, PA 15238-3495 ; 4129683333
• MDR Report Key: 8443405
• MDR Text Key: 139598277
• Report Number: 3008642652-2019-02091
• Device Sequence Number: 1
• Product Code: MVK
• UDI-Device Identifier: 00855778005005
• UDI-Public: 00855778005005
• Combination Product (y/n): N
• Reporter Country Code: US
• PMA/PMN Number: P010030
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: distributor
• Reporter Occupation: Other
• Type of Report: Initial
• Report Date: 03/21/2019

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Date FDA Received: 03/22/2019
• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: Yes
• Device Operator: Lay User/Patient
• Device Model Number: WCD 4000
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 02/27/2019
• Date Manufacturer Received: 02/21/2019
• Was Device Evaluated by Manufacturer?: Device Not Returned to Manufacturer
• Date Device Manufactured: 07/24/2015
• Is the Device Single Use?: No
• Is This a Reprocessed and Reused Single-Use Device?: No
• Type of Device Usage: Reuse
• Patient Sequence Number: 1
• Patient Outcome(s): Hospitalization; Other
• Patient Age: 72 YR