Perioperative Management of People with Cardiac Implantable Electronic Devices

Overview

This specialist Guidelines summary outlines best practice for the perioperative management of the increasing number of people with cardiac implantable electronic devices. People who are pacing-dependent and those with implantable defibrillators may require device reprogramming or magnet application during their procedure.

This summary is intended for use in a secondary care setting by cardiologists. Refer to the full guideline for the complete set of recommendations.

Introduction

• The presence of cardiac implantable electronic devices (CIEDs) may present a problem when procedures are carried out in which the person may be exposed to electromagnetic interference (EMI), leading to inappropriate device function. Precautions therefore need to be considered before these procedures for the safe management of people with CIEDs
• Both pacemakers and implantable cardioverter defibrillators (ICDs) have been designed with a high degree of tolerance to electrical and magnetic interference fields, and special filtering components have been incorporated to minimise the effects of these
• However, if the energy level of a nearby field is very high, or has a frequency component that is close to that generated by the heart, this may have a variety of effects on the function of the CIED including: inhibition of pacing; induction of fixed-rate pacing; inappropriate rapid pacing; software reset; or triggering of shocks in an ICD
• Most types of EMI interfere only transiently with device function, and when the interference ceases the device returns to normal. Only very powerful fields are likely to have any permanent effects on device or lead function, for example, gamma radiation or very strong magnetic fields such as MRI scanners
• Potential sources of EMI in the surgical setting include: intraoperative MRI; diathermy/electrosurgery; nerve stimulators; transcutaneous electrical nerve stimulation machines; radiofrequency scanners for surgical instrument detection; magnetic guidance systems; and radiofrequency ablation devices
• Pacemaker sensing of EMI may inhibit appropriate pacing as the device wrongly interprets EMI as intrinsic cardiac rhythm. This is most concerning in people who are pacing-dependent and do not have any underlying rhythm
• Inappropriate shocks from an ICD are associated with increased mortality, and it is vital these are avoided, even if an anaesthetised person would be unaware of them. In addition, unanticipated movement associated with shock delivery may be harmful during surgery
• Implantable loop recorders and insertable cardiac monitors record cardiac signals and there is no risk to the patient with any surgical procedure. The device may interpret EMI as a rapid heart rhythm and record an episode of ‘tachycardia’, but this will be apparent when the device is interrogated. No additional precautions are needed for a patient with these devices.

Planned Surgical Procedures in People with CIEDs

Patient Screening

• Since the majority of surgical procedures are planned in advance, people with these devices should be identified through preoperative screening. Although the preoperative process may request patients to declare if they have a pacemaker/ICD, this should be independently verified and noted in the records. People with these devices are usually provided with a registration card recording details of the device and its manufacturer. An example flow chart is shown below.

Algorithm 1: Perioperative Cardiac Implantable Electronic Device Management Flowchart

Recording Pacemaker/ICD Details

• When a pacemaker/ICD is identified, it should be clearly recorded in the clinical notes by the surgical/procedural assessment staff and marked for the attention of key clinical staff. Before surgery, the anaesthetist and surgeon/operator involved should be aware of the implications of the patient having a CIED
• Where possible, the following key information should be noted for future reference (and will be available via the patient’s usual hospital pacing clinic):
  • type of device and manufacturer
  • implanting hospital
  • follow-up hospital
  • date of last follow-up
  • if the device is at or approaching battery depletion
  • if the device is part of a clinical investigation, where restrictions may apply
  • device location
• Device location is relevant when considering the implications of the procedure as CIEDs are usually implanted in the left or right pre-pectoral region; however, some devices may be located in the left lateral chest wall (subcutaneous ICDs) and, very rarely, the abdomen
• The person’s follow-up clinic will be able to confirm the correct functioning of the pacemaker/ICD and check the condition of the battery and leads before surgery
• Additional preoperative checks are not required providing regular follow-up is not overdue. The clinic undertaking follow-up of the device will be able to advise if the person is pacing-dependent and if adjustments to sensing/pacing parameters are required (the majority of devices will not require changes before or after surgery)
• If ICD deactivation is necessary, local follow-up centres should have a standard operating procedure that will detail the option of either temporary magnet deactivation or reprogramming the device to prevent shock therapy
• Many devices are now under remote follow up, and device interrogation may be possible without the need for the person to attend the clinic face to face. Remote threshold checks are equivalent to in-clinic tests; a person with stable lead parameters does not need an additional in-person check before surgery if the parameters are satisfactory on remote monitoring. If reprogramming is required, it is not possible to do this via the remote systems, and must be done face to face.

Considering Additional Periprocedural Support

• Electrocardiogram monitoring should be started from the outset of the procedure. Some monitors may give inaccurate readings of paced beats, so if in doubt check the person’s pulse and/or use pulse oximetry
• External defibrillation equipment, external temporary pacing, and cardiopulmonary resuscitation equipment should be available. In people who have their ICD deactivated and where access to the anterior chest wall will interfere with surgery (or the sterile field), consider connecting the person to an external defibrillator using remote pads
• Defibrillator pads should be positioned as far away from a CIED as possible, and never directly over the device (pulse generator) itself. Where diathermy/electrocautery is unavoidable, limit its use to short bursts at the lowest feasible energy level and use bipolar diathermy if possible
• Surgical teams should ensure that the return electrode is anatomically positioned so that the current pathway between the diathermy electrode and return electrode is as far away from the pacemaker/ defibrillator (and leads) as possible. Underbody electrodes are not recommended
• If detectable pacemaker inhibition occurs, or there is evidence of ICD therapy being delivered, the surgeon should be informed immediately and diathermy either used intermittently for short bursts or discontinued
• Magnet application can be considered if this is not possible (see Magnets and CIEDs). If device programming has been altered for a surgical procedure, people need to have ECG monitoring until their device parameters have been restored to preoperative settings and/or the ICD is reactivated. This should be done as soon as practical and ideally in the post-anaesthesia care unit. Responsibility for arranging this remains with the treating surgical team.

Guidance for CIED Programming/Interrogation for Specific Procedures

Table 1: Suggested Guide for Required Actions in Different Clinical Situations

• There is evidence that EMI is more likely to affect device function if it is used near the pulse generator or leads. Typically, this occurs in surgery performed superior to the umbilicus, but is not likely during procedures below the umbilicus. Therefore, in procedures below the umbilicus, it is reasonable not to carry out ICD deactivation/pacemaker reprogramming. However, a magnet should be immediately available for emergency use. Postoperative checks are not usually required unless programming has been altered
• If ICDs are disabled for surgery, it is important to ensure they are re-enabled after surgery. Failure to re-enable tachycardia therapies after surgery will leave the person without protection from ventricular arrhythmias, which could result in their death
• If ICD function is to be suspended for surgery, surgical departments must have procedures in place to ensure the device is returned to normal operation as soon as practicable after procedures, and that checks are in place to ensure people will not be discharged to an unmonitored environment, or even home, without this having taken place. Responsibility for arranging this remains with the treating surgical team
• Suspension of ICD treatment can be achieved by deactivation of the device by a member of the cardiac team using a programmer or temporary application of a clinical magnet
• Centres should have a standard operating procedure in place to guide which approach for device deactivation is used and how this is accessed.

Surgical Magnetic Drapes

• Caution should be exercised when using magnetic drapes to hold surgical equipment as these may cause magnet effects in the CIED.

Magnetic Anchoring and Guidance Systems

• These systems require the use of a powerful external magnet. There are no direct data of the effect of these systems on CIEDs, but it is likely that device therapy would be affected by the magnet itself in addition to potential EMI. The system manufacturers state that the presence of a CIED is a contraindication to their use. In selected patients, it may be possible to program a device to mitigate some of this risk, but in general these magnetic systems are not recommended in people with CIEDs.

Emergency Procedures

• Wherever possible, the steps outlined above should be followed whenever emergency surgery is required. Temporary pacing in accordance with advanced life support guidance should be available.

Cardiac Arrest

• In the case of cardiac arrest, resuscitation should be carried out in the same way as if there were no device. This is regardless of the programmed functionality of the device at the time of the arrest. There is no significant risk to someone performing cardiopulmonary resuscitation or touching the person if a shock is delivered by an ICD. If an external shock is needed in a person with an implantable device, defibrillation pads should be positioned as far away as possible from the device, and ideally in the antero–posterior position. Energy from external defibrillation can damage an implantable device, so if the resuscitation attempt is successful then the device should be interrogated afterwards to confirm its function.

Magnets and CIEDs

• For the purposes of this guideline, a magnet refers to a specifically designed ring or block magnet, which should be available in all hospitals
• In the majority of clinical situations, a magnet placed directly over the ICD will be effective at withholding shock therapy. However, there a number of important considerations:
  • the use and function of the magnet must be fully understood and acknowledged
  • the inhibition of shock delivery will only be effective during correct magnet placement and that this should be secured to the patient for the duration of surgery using surgical tape. Magnets can easily shift position and need to be positioned correctly. If the surgical procedure is prolonged (>8 hours), Biotronik ICDs will revert to normal function, in which case the magnet needs to be removed and then reapplied
  • any subsequent ventricular arrhythmia will need to be treated using external defibrillation equipment. Consider attaching any person whose ICD has been deactivated to an external defibrillator using hands-free pads
  • an ICD may emit an audible alarm/beep/vibration when close to a strong magnetic field or when a magnet is applied over the generator.

Pacemaker Magnet Response

• Most pacemakers (simple and resynchronisation) respond with fixed-rate (asynchronous) pacing while a magnet is held over the generator. While this can be useful, in rare situations where pacing is inhibited by diathermy, leaving a magnet over the pacemaker is not generally recommended
• Leadless pacemakers do not respond to magnets with fixed-rate pacing and therefore any programming changes need to be carried out using the specific device programmer. If this is not possible, particularly in a pacing-dependent person, caution is advised.

Response of ICDs to Magnets

• For ICDs, placing a magnet over the device will inhibit the delivery of anti-tachycardia pacing and shock therapy but will have no effect on bradycardia pacing. Clinical magnets for this application will be available from the local cardiac pacing centre along with instructions for correct use. Magnets should also be available from coronary care units and local guidelines should be in place to detail their locations.