Electromagnetic interference (EMI) can cause malfunction of pacemakers and internal cardiac defibrilators (ICDs). The most common cause of EMI is monopolar electrocautery, especially if it is within 6 inches of the pulse generator. It can inhibit pacing, damage pulse generator, and cause inappropriate tachycardia therapy. In the event of surgery above the umbilicus, reprogramming or magnet applicaiton is necessary.
Pacemakers can interpret EMI as intrinsic cardiac activity and will not trigger a paced rhythm (oversensing). It is therefore important to determine if the patient is pacemaker dependent (does not have a perfusing rhythm without pacing). In these patients, an additional method of pacing is required and magnet application or reprogramming to convert the pacer to asynchronous mode is needed. If not, consider reporgramming or magnet application if the source is < 15 cm from the generator.
In the event of an ICD, the tachycardia response must be deactivated to avoid inappropirate pacing or shocks due to EMI. In the event of a biventricular ICD (cardiac resynchronization devices), pacing optimizes cardiac output. In this scenario, allowing the device to pace will improve hemodynamic stability vs. turning off the device.
Magnets can be applied to convert pacemakers into asynchronous mode, to protect from EMI, but the response to magnet application is variable. The response can be programed, therefore some pacemakers will have no response and some will pace asynchronously. The magnet effect must be confirmed prior to any operative procedure when possible.
Battery life can affect the response to magnet application. If the battery is low, the pacemaker will pace at lower rates and may be inadequate. Battery life should be documented greater than 3 months prior to surgery.
George H Crossley, Jeanne E Poole, Marc A Rozner, Samuel J Asirvatham, Alan Cheng, Mina K Chung, T Bruce Ferguson, John D Gallagher, Michael R Gold, Robert H Hoyt, Samuel Irefin, Fred M Kusumoto, Liza Prudente Moorman, Annemarie Thompson 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 this document was developed as a joint project with the American Society of Anesthesiologists (ASA), and in collaboration with the American Heart Association (AHA), and the Society of Thoracic Surgeons (STS). Heart Rhythm: 2011, 8(7);1114-54