In their contribution “Is it Time to Embrace the Humble Magnet”,1 Som and colleagues review potential approaches to perioperative management of patients with implantable cardioverter-defibrillators (ICDs). Their discussion is highlighted by the case of a patient who experienced a delay to defibrillation and death from VF after having ICD therapies deactivated for an ocular procedure. They concluded that ICD deactivation can usually be safely done by magnet application rather than ICD reprogramming, and that magnet use should be more liberally applied.
We believe a global approach to magnet use may be unnecessary, and that doing nothing preoperatively to the ICD is often the best approach. We previously reported the results of the ICD-ON Protocol2 in which 201 consecutive patients with transvenous cardiovascular implantable electronic devices (CIEDs) underwent procedures requiring electrosurgery and were categorized into three groups: (1) Reprogram, (2) Magnet, or (3) No Change. Subjects with CIEDs within 6 inches of their surgical site were assigned to the Reprogram group, whereby all therapies were programmed off with asynchronous pacing if pacemaker dependent. Subjects with ICDs >6 inches from their surgical site but above the iliac crest were assigned to the Magnet group. All others were in the No Change group, including those with anticipated bipolar cautery. (Table 1)
Based on the ICD-ON Protocol, 73% of patients required no change to their CIED, 15% required reprogramming, and only 12% required magnet. Electrical magnetic interference (EMI) occurred in 37% of head/neck cases, 73% of thoracic cases, and 17% of upper extremity cases. There was no EMI in any abdominal procedures or procedures below the iliac crest. There were no inappropriate therapies or device reset in any subjects. These results are similar to prior studies that evaluated EMI by reviewing stored ICD event logs that correlated with the timing of surgery.3-7
Although there was no EMI in any abdominal procedures in this series, there has been EMI reported in two laparoscopic cholecystectomies and endoscopy.1,3,8 Given these findings, the ICD-ON Protocol calls for magnet application for ICDs in abdominal procedures above the iliac crest.
As noted by Som and colleagues, ICD magnet response could feasibly be programmed to ignore the magnet, since both Boston Scientific and St. Jude Medical devices have these options. We did not find this option programmed in any subjects in our two CIED perioperative management studies.2,3 Nevertheless, the programmed magnet response should be assessed preoperatively by review of remote monitoring or device clinic records.
Based on the ICD-ON Protocol and the HRS/ASA Consensus Statement,9 no change would have been required in the fatal case described by Som and colleagues, in which bipolar electrosurgery was used.
The goal of perioperative ICD management should be to minimize the sequelae of surgical EMI without increasing the risk of life-threatening dysrhythmias due to deactivated ICDs. It should be recognized that risks associated with EMI have not been reported when procedures are distant from the ICD, specifically below the iliac crest. We agree with Som and associates that the humble magnet has its place, but would add that for most surgeries, its place is on the shelf.
Disclosures: The ICD-ON Registry was funded by Medtronic, Boston Scientific, and St. Jude Medical through investigator-initiated research funding.
Ms. Gifford reports personal fees and grants from Medtronic, and grants from Boston Scientific and St. Jude Medical. Dr. Larimer and Ms. May report personal fees from the Edward Foundation. Ms. Thomas reports personal fees from the Edward Foundation as well as grants from Medtronic, St. Jude Medical, and Boston Scientific. Dr. Gami has no conflicts of interest to report regarding the content herein.
- Som S, Chawla P, Lam P. Is it Time to Embrace the Humble Magnet? EP Lab Digest. 2015;15(2):35-36.
- Gifford J, Larimer K, May P, et al. ICD-ON Protocol: perioperative management of CIEDs (abstract). Heart Rhythm. 2015:12:S157-S158.
- Gifford J, Larimer K, Thomas C, et al. Randomized controlled trial of perioperative ICD management: magnet application versus reprogramming. Pacing Clin Electrophysiol. 2014;37:1219-1224.
- Cheng A, Nazarian S, Spragg D, et al. Effects of surgical and endoscopic electrocautery on modern-day permanent pacemaker and implantable cardioverter-defibrillator systems. Pacing Clin Electrophysiol. 2008;31:344-350.
- Hoyt RH, Johnson WB, Leiserowitz A. Monopolar electrosurgery interactions with the implantable defibrillator (abstract). Heart Rhythm. 2010;7:S246-S247.
- Fiek M, Dorwarth U, Durchlaub I, et al. Application of radiofrequency energy in surgical and interventional procedures: are there interactions with ICDs? Pacing Clin Electrophysiol. 2004;27:293-298.
- Guertin D, Faheem O, Ling T, et al. Electromagnetic interference (EMI) and arrhythmic events in ICD patients undergoing gastrointestinal procedures. Pacing Clin Electrophysiol. 2007;30:734-739.
- Reif S, Tobias J, Landwehr P, et al. Risk of inappropriate ICD therapy due to new cauterization methods for endoscopic therapy (abstract). Heart Rhythm. 2015;12:S228.
- Crossley GH, Poole JE, Rozner MA, et al. The Heart Rhythm Society (HRS)/American Society of Anesthesiologists (ASA) Expert Consensus Statement on the perioperative management of patients with implantable defibrillators, pacemakers and arrhythmia monitors: facilities and patient management. Heart Rhythm. 2011;8:1114-1154.