Perioperative management of pacemakers and ICDs

[1]

Why this is examined / the one-line answer

Almost every general list has a patient with a pacemaker or ICD. Examiners test whether you can decode the problem, not recite cardiology textbooks. The viva turns on four discriminators: what does the device do, is the patient pacing-dependent, what will diathermy do to it, and magnet versus reprogramming versus ICD therapy off.[1][2]

One-liner: I confirm device type and indication, assess pacing dependence, minimise EMI, use magnet or reprogramming as indicated, disable ICD shock therapies with external defibrillation ready, and restore/check the device after surgery. [1]

ASA 2020 Practice Advisory and HRS/ASA consensus provide the named frameworks examiners expect.[1][2]

Preoperative assessment and risk stratification

What you must know before induction

Pacing dependence (exam definition): absence of a reliable haemodynamically adequate intrinsic escape rhythm. Clues: underlying complete heart block, prior asystole when pacing suspended at clinic, 100% paced on ECG/device report, symptoms when rate falls. When unsure, treat as dependent until proven otherwise.[3]

Preoperative interrogation — when mandatory / strongly preferred

• Elective major surgery with significant EMI risk (monopolar above umbilicus, near generator)
• ICD patients when therapy will be suspended
• Unknown device function, recent shocks, battery alerts, or long interval since check
• Pacing-dependent patients
• Emergency: do not delay life-saving surgery for formal programming if magnet + pads + monitoring can temporise — document and arrange earliest interrogation.[1][2]

Ask the patient for their device card. If unavailable, CXR may show generator/leads; ECG may show pacing spikes. [1]

Investigations and optimisation

Recent electrolytes (especially K+ — hypo/hyperkalaemia alter capture thresholds), ECG, consider echo if heart failure/CRT, continue usual cardiac meds unless specific reason to hold. Document anticoagulation if recent lead revision (rare acute issue). [1]

Applied physiology / device logic (high-yield, not encyclopaedic)

NBG code — the letters you must decode

Pacemaker modes are classically three (or more) letters: [1]

1. Chamber paced: O = none, A = atrium, V = ventricle, D = dual (A+V)
2. Chamber sensed: O / A / V / D
3. Response to sensing: O = none, T = triggered, I = inhibited, D = dual (triggered + inhibited)
4. (Often) Rate modulation: R = rate-responsive
5. (Sometimes) Multisite pacing [1]

Exam workhorses: [1]

You do not need every obscure code. You need: sensing can be fooled by EMI; asynchronous modes ignore EMI for pacing decisions; ICDs add a shock layer on top. [1]

EMI mechanisms (theatre focus)

Monopolar diathermy is the classic source. Noise may be sensed as: [1]

• Intrinsic QRS → pacing inhibition (dangerous if dependent)
• Tachyarrhythmia → ICD charge/shock (inappropriate)
• Rate-response drive → inappropriate tachycardia
• Rare: reset/reprogram, or power-on reset to backup mode [1]

Bipolar diathermy has a short current path and is preferred when surgically acceptable. Ultrasonic scalpels have lower EMI risk than monopolar RF but are not zero-risk.[2][3]

Anaesthetic goals

1. Maintain capture and cardiac output — never leave a dependent patient without a pacing plan.
2. Minimise EMI or make the device ignore it (asynchronous pacing / ICD therapy off).
3. Keep external defibrillation/pacing immediately available when ICD therapies suspended.
4. Avoid extremes of K+, acid–base, and ischaemia that raise capture threshold.
5. Restore correct device function before unsupervised ward care. [1]

Technique options and decision matrix

Magnet vs reprogramming

Magnet teaching mantra: Pacemaker magnet → asynchronous pacing. ICD magnet → shock therapies off, pacing usually unchanged. Always state you will confirm magnet behaviour against manufacturer/device report because exceptions exist.[1][3]

When to reprogram (high-yield list)

• Pacing-dependent patient + monopolar EMI likely near generator/leads
• ICD + surgery with sustained EMI risk (suspend detection/therapies)
• Rate-response or minute-ventilation sensors that may malfunction with EMI/ventilation changes
• Unreliable magnet access (prone, generator site in field, sterile exclusion)
• Complex CRT or recent device issues [1]

Diathermy practical rules (say them cleanly)

1. Prefer bipolar or ultrasonic where possible.
2. If monopolar essential: place return pad so current path does not cross generator/heart (e.g. ipsilateral thigh for arm surgery away from generator path).
3. Keep active electrode away from generator (classic teaching distance often quoted around 15 cm — state principle, not magic number alone).
4. Short intermittent bursts (commonly taught <5 s), lowest effective power.
5. Full monitoring; watch for missing paced beats or VT/VF alarms.
6. Magnet immediately available; programmer if planned.[2][3]

ICD disable for surgery — the exam algorithm

1. Confirm ICD (transvenous or S-ICD).
2. Risk of EMI → suspend tachy therapies (reprogram preferred for planned major EMI; magnet if urgent/short).
3. Apply external multifunction pads in axis that avoids generator when possible; connect to defibrillator.
4. Continuous ECG (note: device magnet may alter pacing display).
5. After surgery: re-enable therapies and document; interrogate if any concern.
6. Until therapies restored, patient needs monitored environment with defibrillator access.[1][2]

[1]

Monitoring and equipment

• Standard ASA monitoring + attention to pulse oximeter / arterial waveform as mechanical pulse confirmation if ECG is noisy
• External pads on before incision when ICD therapies off or high EMI risk
• Magnet labelled and in theatre
• CIED team / cardiology contact number
• Emergency drugs for arrhythmia and support (adrenaline, amiodarone per ALS, isoprenaline rarely for brady if capture lost — but external pacing/defib first)
• Avoid placing central lines / subclavian wires blindly ipsilateral to fresh leads without indication awareness (lead injury risk) [1]

Intraoperative management

Induction: standard agents; avoid profound bradycardia/hypotension in low EF CRT patients. Succinylcholine fasciculations rarely discussed as EMI-like noise — usually not a practical issue with modern devices but beware in dependent patients if ECG noise appears. [1]

Maintenance: communicate with surgeon on diathermy timing. If inhibition occurs: stop diathermy, apply magnet (pacemaker), support circulation, call for help/programmer. [1]

Positioning: prone cases — magnet may not stay; prefer reprogramming. [1]

Lithotripsy / RF ablation / ECT / MRI: special protocols — generally disable ICD therapies, protect generator from shock wave focus, MRI only if conditional device + protocol (cross-link MRI topic). [1]

Crisis pivots

Asystole / severe bradycardia during diathermy

Stop EMI → 100% oxygen → magnet for pacemaker → external pacing/pads → CPR if needed → emergency reprogramming → correct reversible causes (K+, ischaemia, drugs). [1]

Inappropriate ICD shock under anaesthesia

Stop EMI → magnet to suspend further therapies if not already → treat any resultant arrhythmia → interrogate → continue only with therapies managed and pads on. [1]

Failure to capture

Check connections/ECG lead-off vs true failure; optimise electrolytes; increase external pacing output; urgent cardiology — possible lead issue or threshold rise. [1]

Power-on reset / unexpected mode

Assume backup mode (often VVI-like at fixed rate); arrange urgent interrogation; do not discharge to unmonitored ward. [1]

Postoperative / PACU plan

• Re-enable ICD therapies before leaving monitored care whenever suspended
• Re-interrogate after reprogramming, major EMI, shocks, or haemodynamic events
• Document mode, therapies status, and next cardiology follow-up
• Ward: continuous monitoring until device function confirmed if any doubt
• Analgesia standard; no special CIED interaction with most analgesics [1]

Special populations and devices

CRT-D: loss of LV pacing may drop output — haemodynamic vigilance. [1]

Leadless pacemaker: still EMI-aware; magnet/programmer specifics differ — check manufacturer pathway. [1]

S-ICD: no transvenous pacing (usually); magnet/therapy suspend still relevant for shocks; pads placement careful. [1]

Paediatric CIEDs: smaller generators, growth-related leads — same EMI principles, lower threshold for specialist involvement. [1]

Emergency surgery at night: magnet + pads + bipolar preference + earliest daytime interrogation is acceptable temporising strategy when programmer unavailable.[1]

SAQ answer scaffold

A 72-year-old with a dual-chamber pacemaker for complete heart block presents for laparoscopic hemicolectomy. How will you manage the CIED perioperatively? [1]

1. Assess (3): device card/interrogation, pacing dependence (likely high), battery/leads, ECG.
2. EMI plan (3): prefer bipolar; if monopolar, return pad path, short bursts, distance from generator.
3. Device strategy (4): asynchronous pacing via magnet or reprogramming; rate-response off if programmed; continuous monitoring + external pads available.
4. Post-op (2): restore original settings; re-interrogate; monitored recovery until safe.[1][2]

Viva stem bank and model phrases

Stem 1: “What does DDD mean?”
Model: “Dual chamber paced, dual chamber sensed, dual response — it paces and senses both atrium and ventricle with inhibition and tracking as programmed.” [1]

Stem 2: “Magnet on ICD?”
Model: “In most ICDs a magnet suspends tachyarrhythmia detection and therapies; it does not convert pacing to asynchronous mode the way a pacemaker magnet typically does.”[3]

Stem 3: “Patient is pacing-dependent — diathermy causes asystole.”
Model: “Stop diathermy, apply magnet for asynchronous pacing, external pace/defibrillate as needed, support ABC, arrange emergency programming.” [1]

Stem 4: “Surgery below the umbilicus — any issue?”
Model: “Lower EMI risk if current path remote, but monopolar can still affect devices; I still identify dependence and keep a magnet available.”[2]

Stem 5: “When must you reprogram?”
Model: “When magnet is impractical, when ICD therapies need reliable suspension for major EMI, when sensors are problematic, or when dependence plus high EMI risk demands a programmed asynchronous mode.” [1]

Stem 6: “Where do you put the diathermy plate?”
Model: “So the current path between active electrode and return pad does not cross the generator and heart.” [1]

Stem 7: “ICD therapies off — destination?”
Model: “Monitored bed with defibrillator until therapies re-enabled and device checked.” [1]

Common traps

• Treating ICD magnet like pacemaker magnet (assuming asynchronous pacing)
• Leaving ICD off on the ward
• No external pads when therapies suspended
• Long continuous monopolar bursts over the chest
• Ignoring pacing dependence
• Forgetting to restore settings after reprogramming
• Assuming “below umbilicus = no risk” without thinking [1]

[1] [1] [1]

Examiner mental map

1. Identify device and dependence.
2. Predict EMI.
3. Choose magnet vs reprogram.
4. Protect ICD patient with therapy suspend + external defib.
5. Mitigate diathermy.
6. Restore and document.
   Hit those six without waffle and you pass the CIED viva. [1]

References

1. [1]American Society of Anesthesiologists 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: Erratum Anesthesiology, 2020.PMID 32032098
2. [2]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 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.PMID 21722856
3. [3]Stone ME, Salter B, Fischer A Perioperative management of patients with cardiac implantable electronic devices Br J Anaesth, 2011.PMID 22156267