Perioperative Management of Patients with Cardiac Implantable Electronic Devices

Definition and pathophysiology

Cardiac implantable electronic devices (CIEDs) include permanent pacemakers, implantable cardioverter-defibrillators (ICDs), and cardiac resynchronization therapy (CRT) devices. Implantable loop recorders are diagnostic devices rather than pacing or defibrillation systems, but their stored data may also be affected by perioperative electromagnetic interference (EMI).

The principal perioperative concern is interaction between the CIED and equipment used during surgery, particularly electrosurgery. EMI may produce inappropriate sensing, activation of rate-responsive functions, device resetting, inhibition of pacing, inappropriate ICD therapy, or, less commonly, device damage. Oversensing is more likely with unipolar leads. Electrocautery is the most frequent source of EMI, although radiofrequency procedures, nerve stimulators, and other electronic equipment may also interfere with device function.

The clinical consequences depend on the device, the patient's dependence on pacing, the presence of CRT, the type and location of surgery, and the anticipated current pathway. In a pacing-dependent patient, inhibition of pacemaker output may result in clinically important pauses. In an ICD patient, EMI may be interpreted as ventricular tachyarrhythmia and trigger inappropriate antitachycardia treatment unless detection and therapy are disabled. Conversely, asynchronous pacing may rarely result in pacing during ventricular repolarization and provoke ventricular tachycardia or ventricular fibrillation.

The likelihood of clinically significant EMI is generally low, particularly with bipolar electrocautery performed away from the device and with monopolar electrocautery below the umbilicus. Nevertheless, perioperative planning should be individualized according to the patient, device, procedure, and anticipated electrical environment.

Preoperative evaluation

Establish the nature and function of the device

The following should be determined before surgery:

• Device type: pacemaker, ICD, CRT pacemaker, or CRT-D.

• Manufacturer and model.

• Lead configuration and, where relevant, whether leads are unipolar or bipolar.

• Implantation history and current indication.

• Device function and battery status.

• Whether the patient is pacemaker-dependent.

• Whether the device has been recently interrogated and whether any malfunction has been identified.

Information should be obtained from the device identification card, the medical record, prior device interrogation, and, when necessary, chest radiography. A chest radiograph can help identify the device and lead configuration when records are incomplete.

A full device check should be available within the recommended interval before elective surgery. In the absence of malfunction, a pacemaker should have been checked within the preceding 12 months and an ICD within the preceding 6 months. Remote monitoring may be used for these assessments. More immediate interrogation and reprogramming are warranted in higher-risk circumstances, particularly for pacing-dependent patients, patients with CRT, and ICD recipients undergoing procedures likely to generate EMI.

Assess pacing dependence

Determining pacing dependence is central to planning. If EMI causes oversensing and pacing inhibition, a patient who has little or no reliable intrinsic rhythm may develop prolonged pauses. Pacing-dependent patients therefore require protection against inhibition during the period of anticipated EMI.

The perioperative strategy should also recognize that CRT patients may rely on continuous biventricular pacing for haemodynamic stability. In patients with resynchronization devices, maintaining CRT during surgery is recommended to provide better haemodynamic stability.

Define the operative electrical environment

The surgical team should establish:

• Whether electrosurgery or diathermy will be used.

• Whether monopolar or bipolar electrocautery is planned.

• The operative site in relation to the pulse generator and the umbilicus.

• Whether the operation is above or below the umbilicus.

• Whether the procedure is likely to expose the device or leads to substantial EMI.

• Whether the device or its leads could be mechanically damaged by the operation.

Procedures above the umbilicus, particularly those involving unipolar electrosurgery, carry greater concern for EMI. Thoracic surgery requires additional attention in patients with subcutaneous ICDs because the surgeon must avoid damaging the subcutaneous electrode, applying electrocautery directly to it, or placing sternal wires near the sensing electrodes.

Perioperative device preparation

Pacemakers

In pacing-dependent patients undergoing surgery with a meaningful risk of EMI, the pacemaker should be programmed to a non-sensing or asynchronous mode. Depending on the device, this may be achieved by programming or by applying a magnet over the generator.

Magnet use is not universally reliable. In modern pacemakers, magnet response is programmable, and application may not produce asynchronous pacing. Consequently, the response should be confirmed for the individual device. Leadless pacemakers require particular care: because they lack a Hall-effect sensor or reed switch, a magnet placed over the body cannot temporarily convert them to asynchronous pacing. A pacing-dependent patient with a leadless pacemaker therefore requires reprogramming when asynchronous pacing is needed.

Rate-responsive pacing should be disabled when appropriate, particularly if an active sensor could respond inappropriately to perioperative movement or electrical signals. In high-risk operations or when major metabolic shifts are anticipated, increasing pacing output may be considered.

ICDs and CRT-D devices

In ICD recipients undergoing surgery with anticipated EMI, ventricular arrhythmia detection and antitachycardia therapies should be disabled before the procedure. This can be achieved by reprogramming or, for modern ICDs, by applying a magnet over the device.

Magnet application to an ICD inhibits antitachycardia therapy while leaving bradycardia pacing intact. It does not convert ICD pacing to asynchronous pacing. Therefore, a pacing-dependent ICD patient may require separate programming to an asynchronous pacing mode in addition to disabling ventricular tachyarrhythmia therapies.

When therapies are disabled by programming, continuous ECG monitoring and immediate access to cardioversion, defibrillation, and cardiopulmonary resuscitation are required until the ICD has been reactivated. Programming may be impractical in some settings and also carries the risk that the patient could leave the procedural area before therapies are restored. A magnet may therefore be preferable when it can be securely positioned and the device is accessible. If the device cannot be reached by a magnet, reprogramming is mandatory.

ICD therapies should be restored and the device checked as soon as possible after surgery. Postoperative interrogation is particularly important after suspected malfunction or exposure to strong EMI.

CRT devices

CRT should generally be maintained during surgery because it may improve haemodynamic stability. If the device is also a defibrillator, tachyarrhythmia detection and therapy must nevertheless be addressed separately when EMI is anticipated.

Electrosurgery and reduction of electromagnetic interference

The risk of EMI can be reduced by modifying the surgical technique and current pathway.

Electrocautery technique

Bipolar electrocautery is preferred when feasible. It should be used:

• In short bursts, generally less than 5 seconds.

• At the lowest effective energy.

• With the instrument or stylus kept more than 15 cm from the device.

EMI is uncommon with bipolar electrocautery performed more than 5 cm from the CIED. If monopolar electrocautery is necessary, short pulses of less than 5 seconds should be used, with the lowest effective energy and appropriate placement of the dispersive electrode.

Dispersive grounding-pad placement

The return or dispersive pad should be positioned so that the current circuit does not pass near the generator or leads. It should be placed as far from the CIED as possible while keeping the surgical site between the device and the return electrode. Manufacturer recommendations should be followed; these commonly advise placement on the side opposite the CIED, close to the surgical site, on a well-vascularized muscular area.

For head and neck surgery, a practical example is placement of the dispersive pad on the shoulder contralateral to the generator. The exact position should be selected to minimize current flow through the device and its leads.

Monitoring during EMI exposure

In pacing-dependent patients, ECG monitoring alone may not reliably demonstrate effective mechanical cardiac activity. Plethysmography or an arterial line can be used to monitor the pulse and haemodynamic consequences of pacing inhibition. If pauses occur during ECG monitoring, electrocautery should be limited and the device strategy reassessed.

Intraoperative management

The operative team should ensure that the following are available when device therapies have been disabled or when clinically important EMI is anticipated:

• Continuous ECG monitoring.

• Reliable monitoring of mechanical pulse activity.

• Personnel capable of recognizing arrhythmias promptly.

• Defibrillation and cardioversion equipment.

• Staff trained in cardiopulmonary resuscitation and advanced cardiac life support.

The patient should remain under these precautions from the point at which ICD therapies are disabled until they have been reactivated. Particular vigilance is necessary when the patient is pacing-dependent, has CRT, or undergoes surgery above the umbilicus with unipolar electrosurgery.

Most procedures do not require device intervention. The decision to use a magnet or reprogram should therefore be based on the anticipated EMI risk rather than on the mere presence of a CIED.

Postoperative management

The ICD should be interrogated and antitachycardia therapies restored as soon as possible after surgery. If programming rather than a magnet was used, continuous monitoring and resuscitation capability should continue until reactivation has been confirmed.

Postoperative CIED interrogation is recommended when malfunction is suspected or when the device has been exposed to strong EMI. A check is also appropriate when there have been unexplained pauses, arrhythmias, haemodynamic instability, inappropriate therapies, or concern about device reset or lead damage.

For implantable loop recorders, memory download should be considered before procedures involving possible EMI or surgery close to the device. This reduces the risk that electrical noise will be stored as arrhythmia or that clinically important recorded information will be overwritten.

Special situations

Leadless pacemakers

Leadless pacemakers should be managed with precautions similar to those used for conventional pacemakers, including avoidance of EMI and conversion to a non-sensing mode in pacing-dependent patients. Magnet application cannot provide temporary asynchronous pacing because these devices lack the sensing mechanism required for a magnet response.

Subcutaneous ICDs

A subcutaneous ICD may undergo surgery after antitachycardia therapy has been disabled or a magnet has been applied. Thoracic procedures, particularly median sternotomy, require the surgical team to identify the course of the subcutaneous electrode and avoid:

• Mechanical injury to the electrode.

• Direct electrocautery on the electrode.

• Placement of sternal wires close to the sensing electrodes.

Non-cardiac surgery in patients with CIEDs

Patients with CIEDs can undergo non-cardiac surgery when appropriate perioperative assessment and device management are performed. In high-risk patients—particularly those with ICDs or pacing dependence—undergoing procedures with a high probability of EMI, such as unipolar electrosurgery above the umbilicus, device interrogation and any necessary reprogramming should occur immediately before the operation.

Device implantation and infection prevention relevant to surgical planning

Although the principal perioperative issue is management of an existing device, implantation or revision may itself be part of the surgical context. Antibiotic prophylaxis should be administered within 1 hour before skin incision to reduce CIED infection risk. Chlorhexidine-alcohol is preferred for skin antisepsis over povidone-iodine-alcohol when appropriate.

The cephalic or axillary vein should be considered for venous access. Multiple fluoroscopic views may help confirm target ventricular lead position, and quadripolar leads should be considered first choice for coronary sinus implantation. Rinsing the device pocket with normal saline before wound closure may be considered.

In reintervention procedures, including pocket or lead revision, generator replacement, or system upgrade, an antibiotic-eluting envelope may be considered. Heparin bridging is not recommended because strategies that increase pocket haematoma formation increase infection risk.

Permanent pacemaker implantation should not be performed in a patient with fever. Implantation should be deferred until the patient has been afebrile for at least 24 hours.

Infection and the perioperative patient with a CIED

CIED infection may arise from contamination during implantation or from haematogenous seeding of the leads during bacteraemia. Relevant patient risk factors include corticosteroid use, diabetes, chronic kidney disease, previous device infection, and immunosuppression. Procedural risks include postoperative haematoma, lead reintervention, and prolonged procedures; revision procedures carry a two- to fivefold higher infection risk than first implantation. Multiple leads and device materials that promote bacterial adherence or biofilm formation may also contribute.

Pocket infection may present with cellulitis, erythema, pain, wound discharge, or erosion of the overlying skin. Lead or endocardial infection more often produces systemic manifestations such as fever and rigors and may coexist with a pocket infection.

Antibiotic prophylaxis before dental or other non-cardiac procedures is not warranted solely to prevent CIED-related infective endocarditis. A single positive blood culture without other clinical evidence of infection should not by itself lead to device removal. By contrast, confirmed infection involving a lead requires complete removal of the CIED system.

Management when infection is suspected or confirmed

Diagnosis integrates clinical examination, blood cultures, and echocardiography. Transoesophageal echocardiography is more sensitive and specific than transthoracic echocardiography for detecting lead vegetations. Echocardiographic masses are not always infectious, because sterile thrombi can also adhere to device leads. When echocardiography is inconclusive, radiolabelled leucocyte scintigraphy or 18FDG-PET/CT may provide additional information.

Definite CIED infection generally requires both antimicrobial treatment and complete extraction of the infected system, including the generator and all leads. Antibiotics without extraction are associated with a sevenfold higher 30-day mortality than treatment incorporating extraction. Extraction should therefore be undertaken without delay and ideally within 3 days.

The duration of antimicrobial treatment depends on the infection:

Reimplantation should be reconsidered rather than assumed. No component of the removed system should be reused, and the replacement device should be placed at a site distant from the original pocket. In the absence of vegetations, reimplantation should wait until local and systemic signs have resolved and blood cultures have remained negative for at least 72 hours after extraction. If vegetations are present, at least 2 weeks of negative blood cultures is recommended before reimplantation.

For patients at high risk of sudden cardiac death, a wearable defibrillator may bridge the period before reimplantation. A pacemaker-dependent patient may be supported temporarily with an active-fixation lead introduced through the internal jugular vein and connected to an external pacemaker for up to 4–6 weeks. Selected patients may instead be considered for a leadless pacemaker or a subcutaneous ICD when the risk of recurrent infection is high.

Guideline-based practical recommendations

The principal recommendations for perioperative management are summarized below.

Prognosis and follow-up

The perioperative prognosis is largely determined by the interaction between the patient's underlying cardiac condition, pacing dependence, device function, and the likelihood of EMI. Clinically significant EMI is uncommon when appropriate precautions are used, but the consequences can be serious in pacing-dependent patients and in ICD recipients whose tachyarrhythmia therapies have been disabled.

Follow-up should include confirmation that:

• The device is functioning normally.

• Any temporary programming changes have been reversed.

• ICD detection and antitachycardia therapies are active.

• No lead displacement, fracture, reset, or other malfunction has occurred when clinically suspected.

• Implantable loop-recorder data have been preserved or appropriately downloaded when relevant.

Remote monitoring can reduce the need for in-office visits in patients who have difficulty attending, and it is recommended when a device component has been recalled or is under advisory so that actionable events can be detected early, particularly in pacing-dependent patients.

Long-term management should also include reassessment of the continuing indication for the device. At ICD generator end of life, replacement should not be automatic. Life expectancy, quality of life, comorbidities, the current risk of fatal arrhythmia, the competing risk of non-arrhythmic death, and any improvement in left ventricular function should be reviewed with an experienced cardiologist. Shared decision-making should address generator replacement, potential device deactivation in terminal illness, and the implications of future procedures.

Patient-centred and psychosocial considerations

Patients should be informed about the purpose of the device, perioperative precautions, implantation-related complications, possible inappropriate shocks, driving implications, and the circumstances in which defibrillator therapy might later be deactivated or the system removed.

Anxiety and depression affect a substantial proportion of ICD recipients and are associated with increased mortality. Psychological distress commonly relates to fear of receiving a shock, even before a shock has occurred. Assessment of ICD-related concerns should therefore begin before shocks occur and may use structured questionnaires.

Communication should correct misconceptions about device function and address concerns about sexual activity, driving restrictions, and what to do after shock therapy. Patients with significant distress may require referral to mental health professionals. Cognitive behavioural therapy delivered by appropriately trained cardiac nurses and web-based interventions may also help selected patients.