St Jude implantable devices when used with the Merlin@home transmitter

Hazard alert update – additional issue that can result in an unintended device software reset

25 August 2015

Consumers and health professionals are advised that St Jude Medical, in consultation with the TGA, has issued a follow-up hazard alert for some of its implanted devices that have radio frequency (RF) capability.

Potentially affected devices include:

  • implantable cardioverter defibrillators (ICDs)
    • RF Ellipse
    • Fortify Assura
  • cardiac resynchronisation therapy defibrillators (CRT-Ds):
    • Unify Assura
    • Quadra Assura
  • pacemakers:
    • Assurity
    • Assurity+
  • Cardiac Resynchronisation Therapy Pacemakers (CRT-Ps)
    • Allure RF
    • Allure Quadra RF,
    • Quadra Allure MP RF.

ICDs/CRT-Ds and pacemakers are implantable medical devices that deliver electrical impulses to treat abnormal heart rhythms.

This information updates information provided in a previous hazard alert, for which the TGA published a statement on 24 December 2014. A software upgrade was undertaken to address that issue.

Since then, an additional software anomaly has been identified that, in rare cases, can also result in an unintended software reset, with the device entering back-up mode, if the patient is being actively monitored by a Merlin@home RF remote monitoring transmitter (model EX1150).

While this new issue and the one previously subject to a hazard alert are similar, investigations have found that the causes are different. An additional software update will be performed automatically over the telephone, broadband or mobile connection normally used by the device. No action is required by the patient.

If the implanted device enters back-up mode, an alert will be sent to the clinic where the patient is normally treated. Additionally, the ICDs/CRT-Ds will deliver a vibratory alert and the pacemakers will sound an audible alert.

In rare cases, only involving ICDs/CRT-Ds, the patient may experience inappropriate defibrillation therapy, with the primary symptom being pain. There will be no loss of pacing and/or defibrillation therapy, and in the vast majority of cases normal operation can be restored non-invasively. However, in rare cases device replacement may be necessary.

To date, there have been no reports of serious injuries resulting from this issue.

Information for consumers

If you or someone you care for has one of the potentially affected devices and use a Merlin@home remote monitoring transmitter, be alert for vibratory alerts (for ICDs/CRT-Ds) or audible alerts (pacemakers).

Please note that the above issue is rare and will be addressed by a software update to be performed automatically over the telephone, broadband or mobile connection normally used by the device.

If you have any ongoing questions or concerns regarding this issue, talk to your managing cardiologist.

Information for all health professionals

If you are treating a patient who has a potentially affected device and uses a Merlin@home remote monitoring transmitter, advise them of this issue but reassure them that it is rare and will be addressed by an automatic software update.

If your patients continue to have questions or concerns regarding this issue, refer them to their managing cardiologist.

Information for cardiologists

St Jude Medical has written to cardiologists who manage patients with the potentially affected device providing further information about this issue.

If you are treating a patient who has a potentially affected device and uses a Merlin@home remote monitoring transmitter, advise them of this issue but reassure them that it is rare and will be addressed by an automatic software update.

Advise patients to be alert for vibratory alerts (for ICDs/CRT-Ds) or audible alerts (pacemakers). If one is received, they should follow the normal procedures or contact you if they have any concerns.

No changes to patient management, including the patient's remote or in-clinic follow-up schedule, are required.

In the event that a St Jude ICD/CRT-D enters back-up mode, the nominal operational settings will be VVI pacing mode, 67 ppm, 5.0 V/0.6 ms with bipolar pacing output  and defibrillation settings of a VF detection rate of 146 bpm and 36 J high voltage therapy.

In the event that a St Jude pacemaker enters back-up mode, it will have output settings of VVI pacing mode, 67 ppm, 5.0 V/0.6 ms with unipolar pacing.

If a patient's device reverts to back-up mode, it is advised to call the patient back to the clinic to clear the condition and return the device to full functionality.

If you have any questions or concerns about this issue, contact St Jude Medical on 02 9936 1215.

Reporting problems

Consumers and health professionals are encouraged to report problems with medical devices. Your report will contribute to the TGA's monitoring of these products. For more information see the TGA Incident Reporting and Investigation Scheme (IRIS).

The TGA cannot give advice about an individual's medical condition. You are strongly encouraged to talk with a health professional if you are concerned about a possible adverse event associated with a medical device.