Effects of Iontophoresis on St. Jude Medical Implantable Cardiac Rhythm Devices

Background

Iontophoresis delivers medication to localized tissue by applying electrical current to a topically applied medication, driving positively charged drug molecules into the tissue.

Potential effects

Pacemakers

Iontophoresis should not damage or reprogram pacemakers. Iontophoresis has not been reported to cause interference in pacemaker operation. If interference were to occur, temporary oversensing/inhibition may be possible.

ICDs

Interference in implantable cardioverter defibrillators (ICDs) has not been reported from the field. If interference should occur, the electric current may be interpreted ICDs as “electrical noise,” which could mask the underlying rhythm of the heart and cause a noise reversion. During a noise reversion, the device will not deliver therapy (therapy includes ATP pacing, cardioversion and defibrillation) and will revert to the programmed Noise Reversion Mode, which is programmable to Pacer Off or an asynchronous pacing mode. More importantly, the impulses may be misinterpreted as cardiac events, causing bradycardia pacing inhibition or resulting in inappropriate arrhythmia detection and therapy delivery.

A summary of potential effects is provided in the table below and is based on device testing at St. Jude Medical, clinical experience and/or a review of the scientific literature.

Potential Effect Estimated Frequency
  Pacemakers ICDs
Temporary inhibition of pacing Rare Rare
Asynchronous pacing/noise reversion Rare Rare
Inappropriate therapy delivery Not applicable Rare

 

Recommendations

  • Using the highest frequency available, such as 30 Hz, will help prevent inappropriate device inhibition and may force noise reversion in the device.
  • If inhibition should occur, discontinuing treatment will stop the interference and the pacemaker will automatically pace as usual. The patient should be alert for symptoms like those before the device was implanted (e.g. dizziness, light-headedness, etc.).
  • ECG monitoring may be useful if interference is suspected.

Pacemakers

  • A magnet can be placed over the pacemaker to force asynchronous pacing.

ICDs

  • A magnet can be placed over the ICD during iontophoresis to prevent inappropriate therapy for ICDs programmed to a normal magnet response. Once treatment is completed, the magnet should be removed. Magnet application will not affect the bradycardia pacing function of the device; therefore, the need for an asynchronous pacing mode should be considered. Alternatively, the ICD may be programmed to a non-tachyarrhythmia configuration using the appropriate St. Jude Medical programmer. Depending on the specific device, such programmable options are called “Tachy Therapy is Disabled” or “Zone Configuration Off.” When antitachyarrhythmia therapies are disabled, monitor the patient and ensure that external defibrillation capabilities are available.

If you have any questions on this topic, please contact St. Jude Medical Technical Services at 800-722-3774.

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Rev. 04/09