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St Jude Medical implantable cardioverter defibrillators (ICDs):
St Jude Medical has informed the MHRA and all customers (Dear Doctor Letter dated 14 June 2005) that the above Atlas and Epic ICD models have the potential to experience either or both of
the following problems:
This problem is due to a software anomaly, which may occur as the battery approaches elective replacement indication (ERI). A prematurely terminated capacitor charging cycle (‘skipped
charge’) can result in a reduction in the number of shocks delivered per therapy episode; in a worst case scenario three shocks may be delivered instead of six. The problem may occur on
alternate capacitor charge cycles, but the first shock will always be delivered. The programmed energy per shock is not affected by this problem.
The anomaly affects all Atlas and Epic ICD models listed above having a serial number below 225000. There are 844 affected devices in the UK, all of which were distributed since January
2004. The anomaly can be corrected by a software upgrade (see below). Therefore St Jude Medical has not recalled unimplanted ICDs affected by this anomaly as they will be automatically
updated during programmer use at implantation.
No risk to patients implanted with affected devices is expected providing the downloading of the software upgrade to these devices is arranged well before their battery reaches ERI.
Inappropriate higher rate pacing may be initiated without being indicated by physiological need, when rate responsive pacing is programmed ‘on’ during automatic and clinician initiated
capacitor reformation. The problem does not occur during capacitor charging prior to therapy delivery since automatic rate response function is suspended during arrhythmia detection.
This anomaly is due to an out of specification component (hybrid circuit) and it is caused by electrical ‘noise’ being misinterpreted as a physiologically derived signal, during capacitor
reformation. This misinterpretation can cause the pacing rate to increase up to the maximum programmed sensor rate for up to 90 minutes.
The anomaly can occur in all Atlas and Epic ICD models listed above with serial numbers below 141000. This affects 609 implanted devices in the UK; St Jude Medical has informed the MHRA that
they have recalled and retrieved all UK unimplanted ICDs affected by this anomaly.
For implanted devices, a software upgrade (see below) will manage this anomaly in patients by suspending rate responsive pacing during capacitor charging and for up to 90 minutes afterwards.
If rate responsive pacing is already in progress when capacitor charging takes place, the rate response function will be suspended and the pacing rate will gradually reduce to the
programmed base rate for a period of up to 90 minutes.
St Jude Medical has released software version 4.8.5 for its 3510 and 3510+ programmers to manage both anomalies and plans to upgrade all programmers in the UK by 27 July 2005. When
performing ICD interrogation for the first time with an upgraded programmer, automatic downloading of the software upgrade from the programmer t the ICD will take approximately 45 seconds.
No adverse events regarding these anomalies have been reported to St Jude Medical or the MHRA.
by the end of December 2005, for all other affected implanted devices.
Please bring this notice to the attention of all who need to know or be aware of it. This will include distribution by:
Enquiries to the manufacturer/National Pacing and ICD Database should be addressed to:
Enquiries to the MHRA should quote reference number 2005/006/020/291/010 and be addressed to:
Change of address or removal from address list for the Healthcare Commission:
MDA/2005/045 - St Jude Medical implantable cardioverter defibrillators (ICDs).