Electromagnetic Interference with an Underbody Dispersive Electrode in Patients with Implantable Cardioverter Defibrillators Undergoing Surgery

Peter Schulman, MDPeter Schulman, MD
Professor of Anesthesiology, Oregon Health & Science University

Dr. Schulman’s project is entitled: “Electromagnetic Interference with an Underbody Dispersive Electrode in Patients with Implantable Cardioverter Defibrillators Undergoing Surgery.”

Background: During a surgical procedure, the function of a cardiac implantable electronic device (CIED) may be disrupted by electromagnetic interference (EMI).1 The consequences of EMI include hemodynamically significant bradycardia or asystole in the pacing-dependent patient, inappropriate shocks or antitachycardia pacing, direct damage to the CIED, and other less common sequelae.1 Failure to prevent or mitigate these effects might lead to patient injury and increased mortality2. Intraoperative EMI most often results from the use of monopolar electrosurgery (i.e., “cautery”). Monopolar electrosurgery requires a dispersive electrode to complete the electrical circuit. While a conventional dispersive electrode is applied directly to the patient’s skin, an alternative “underbody” dispersive electrode is now being used with increasing frequency that is incorporated into a gel pad and placed directly on the operating table.3 Because the surface area of the underbody electrode is substantially larger than a conventional electrode, some reports suggest that the use of an underbody dispersive electrode might be associated with an increased risk of EMI, but conclusive evidence is lacking.3,4 As the use of underbody electrodes becomes more ubiquitous it is imperative to better understand and quantify their associated risks for patients with CIEDs undergoing surgery.

Aims: This study will evaluate the risks of underbody dispersive electrode use in patients with implantable cardioverter defibrillators (ICDs) undergoing non-cardiac surgery. Specifically, we will determine the risk of any EMI, and the risk of clinically meaningful EMI, from monopolar electrosurgery with use of an underbody dispersive electrode for patients with ICDs undergoing non-cardiac surgery superior or inferior to the umbilicus. We will then use data from a prior study that we conducted5 to determine if these risks are higher than with the use of an appropriately positioned conventional dispersive electrode.

Implications: A substantial number of patients with CIEDs undergo surgical procedures. Monopolar electrosurgery is required for most operations, and underbody dispersive electrode use is rapidly increasing. Determining the risk of EMI with underbody dispersive electrode use and comparing this risk to that of conventional dispersive electrode use will inform future practice recommendations, prevent adverse events, and improve perioperative care. If the risk of EMI is significantly higher with an underbody electrode, using a conventional, appropriately positioned dispersive electrode rather than an underbody electrode might obviate the need for CIED reprogramming in certain circumstances. Conversely, if the risk of EMI with an underbody electrode is not actually increased, this information could be used to assuage concerns about underbody electrode use for patients with CIEDs and to bolster the case that CIED reprogramming is typically not needed for inferior to the umbilicus surgery.


  1. Practice Advisory for the Perioperative Management of Patients with Cardiac Implantable Electronic Devices: Pacemakers and Implantable Cardioverter–Defibrillators 2020: An Updated Report by the American Society of Anesthesiologists Task Force on Perioperative Management of Patients with Cardiac Implantable Electronic Devices*. Anesthesiology 2020;132:225-52.
  2. Rozner MA, Kahl EA, Schulman PM. Inappropriate Implantable Cardioverter-Defibrillator Therapy During Surgery: An Important and Preventable Complication. J Cardiothorac Vasc Anesth 2017;31:1037-41.
  3. Tully BW, Gerstein NS, Schulman PM. Electromagnetic Interference With an Underbody Dispersive Electrode in a Patient With an Implantable Cardioverter-Defibrillator Undergoing Noncardiac Surgery: A Case Report. A A Pract 2020;14:e01285.
  4. Singleton MJ, Fernando RJ, Bhave P, et al. Inappropriate Implantable Cardioverter-Defibrillator Therapy With the Use of an Underbody Electrosurgery Dispersive Electrode. J Cardiothorac Vasc Anesth 2021.
  5. Schulman PM, Treggiari MM, Yanez ND, et al. Electromagnetic Interference with Protocolized Electrosurgery Dispersive Electrode Positioning in Patients with Implantable Cardioverter Defibrillators. Anesthesiology 2019;130:530-40.

Funding: $150,00 (January 1, 2023-December 31, 2024). This grant was designated as the APSF/Medtronic Research Award, and was also designated as the APSF Ellison C. Pierce, Jr. MD Merit Award with $5000 unrestricted research support.