Anaesthesia for Patients with Pacemakers and ICDs

Quick Answer

Patients with cardiac implantable electronic devices (CIEDs) including pacemakers and implantable cardioverter-defibrillators (ICDs) require systematic perioperative management to prevent device malfunction from electromagnetic interference (EMI). The 2011 HRS/ASA Expert Consensus Statement (PMID: 21167937) provides the cornerstone management framework. Key principles include: (1) preoperative device identification and interrogation (pacemakers within 12 months, ICDs within 6 months), (2) assessment of pacemaker dependency (absence of intrinsic rhythm), (3) EMI risk assessment based on surgical site (above umbilicus = high risk), (4) appropriate magnet application or reprogramming (pacemaker magnet = asynchronous pacing; ICD magnet = disables tachyarrhythmia therapies but NOT pacing function), (5) intraoperative peripheral pulse monitoring (SpO2 waveform or arterial line) since ECG is unreliable during electrocautery, and (6) postoperative device interrogation before discharge. For pacemaker-dependent patients, asynchronous pacing (VOO/DOO) must be ensured. External defibrillation pads and transcutaneous pacing equipment should be immediately available.

Clinical Overview

Definition and Epidemiology

Cardiac implantable electronic devices (CIEDs) encompass permanent pacemakers, implantable cardioverter-defibrillators (ICDs), and cardiac resynchronization therapy devices (CRT-P and CRT-D). An estimated 1.2 million pacemakers and 350,000 ICDs are implanted annually worldwide. In Australia, approximately 30,000 CIEDs are implanted each year, with an increasing proportion being ICDs and CRT devices due to expanding indications. The prevalence of patients presenting for surgery with CIEDs is rising as the population ages and device indications broaden. Approximately 25% of CIED patients will require noncardiac surgery within 5 years of implantation. [PMID: 21167937, PMID: 28502596]

Device Types and Classification

Permanent Pacemakers (PPM):

Single-chamber (AAI, VVI): Paces atrium or ventricle only; indicated for sick sinus syndrome (AAI) or chronic atrial fibrillation with slow ventricular response (VVI)
Dual-chamber (DDD): Paces and senses both chambers; maintains AV synchrony; most common type implanted
Biventricular/CRT-P: Paces both ventricles for cardiac resynchronization in heart failure with LBBB; improves symptoms and mortality in selected patients [PMID: 15152059, PMID: 15753115]

Implantable Cardioverter-Defibrillators (ICD):

Single-chamber ICD: Monitors and treats ventricular tachyarrhythmias
Dual-chamber ICD: Provides atrial and ventricular sensing for improved arrhythmia discrimination
CRT-D: Combines biventricular pacing with defibrillator function; indicated for heart failure patients meeting CRT criteria with high sudden cardiac death risk [PMID: 19723701, PMID: 21073365]

Leadless Pacemakers (e.g., Micra):

Self-contained intracardiac device; no transvenous leads
Lower infection and lead complication rates
Magnet response similar to traditional pacemakers but requires device-specific knowledge [PMID: 27053681]

Pathophysiology of Perioperative EMI

Electromagnetic interference (EMI) from surgical equipment, particularly monopolar electrocautery (diathermy), can be misinterpreted by CIEDs as cardiac electrical activity. EMI frequencies (300 kHz-5 MHz) overlap with cardiac signal detection ranges. Consequences include:

Pacemaker Effects:

Oversensing: Device interprets EMI as intrinsic cardiac activity and inhibits pacing output; catastrophic in pacemaker-dependent patients (asystole)
Undersensing: Noise reversion or "safety pacing" at fixed rate
Power-on reset: Device reverts to backup settings
Thermal injury: Rare; energy conducted down leads causing myocardial burns at electrode-tissue interface [PMID: 21167937, PMID: 23510771]

ICD Effects:

Inappropriate shock delivery: EMI interpreted as ventricular fibrillation triggers shock therapy
Inhibition of appropriate therapy: Rare; noise detection may paradoxically inhibit therapy
Pacing inhibition: Same oversensing mechanism as pacemakers (ICD magnet does NOT prevent this)

Device Function and Codes

NBG Pacemaker Code

The NASPE/BPEG Generic (NBG) code is a 5-letter system describing pacemaker function:

Position	Category	Options
I	Chamber Paced	O (None), A (Atrium), V (Ventricle), D (Dual)
II	Chamber Sensed	O, A, V, D
III	Response to Sensing	O (None), I (Inhibited), T (Triggered), D (Dual)
IV	Rate Modulation	O (None), R (Rate-responsive)
V	Multisite Pacing	O (None), A, V, D

Common Pacing Modes:

VVI: Ventricular pacing, ventricular sensing, inhibited response; paces ventricle unless intrinsic ventricular activity detected
DDD: Dual pacing, dual sensing, dual response; most physiological mode maintaining AV synchrony
AAI: Atrial pacing only; for sick sinus syndrome with intact AV conduction
DOO/VOO/AOO: Asynchronous pacing (no sensing); used during EMI exposure to prevent inhibition [PMID: 18474815]

Rate-Responsive Pacing

Rate-responsive pacemakers (fourth letter "R") adjust pacing rate based on metabolic demand sensors:

Piezoelectric accelerometer: Detects body vibration/movement
Minute ventilation sensor: Measures transthoracic impedance changes with respiration
QT interval sensor: Detects catecholamine-mediated QT shortening

Perioperative Implications:

Accelerometer sensors may respond to surgical movement or external chest compressions
Minute ventilation sensors may be affected by electrocautery or positive pressure ventilation
Consider disabling rate response (programming to DDO/VVO) for major surgery [PMID: 21167937]

ICD Detection and Therapy

Detection Algorithms: ICDs detect ventricular tachyarrhythmias using:

Rate criteria: Ventricular rate exceeds programmed detection threshold (typically >170-200 bpm)
Duration criteria: Sustained tachycardia for programmed number of intervals
Morphology discrimination: Compares QRS morphology to stored template
Onset criteria: Distinguishes sinus tachycardia (gradual onset) from VT (sudden onset)
Stability criteria: VT typically has regular RR intervals; AF with rapid ventricular response is irregular

Therapy Delivery:

Anti-tachycardia pacing (ATP): Burst pacing to terminate monomorphic VT; painless and successful in 70-90% of VT episodes
Cardioversion: Synchronized shock (1-35 J) for VT
Defibrillation: Asynchronous shock (up to 40 J) for VF or hemodynamically unstable VT

ICDs typically have tiered therapy zones:

VT zone (170-200 bpm): ATP followed by cardioversion
VF zone (>200 bpm): High-energy defibrillation [PMID: 29097486, PMID: 36017540]

Preoperative Assessment

Device Identification

Information Required:

Device type (pacemaker, ICD, CRT)
Manufacturer and model number
Implantation date
Lead configuration (single, dual, biventricular)
Programming mode and settings
Battery status (elective replacement indicator)
Lead parameters (sensing, impedance, threshold)
Recent arrhythmia episodes (ICD memory)

Sources:

Patient device identification card
Manufacturer registration database
Chest X-ray (radiopaque codes identify manufacturer)
Device interrogation report [PMID: 21167937]

Interrogation Timing

Device Type	Recommended Interval	Emergency Surgery
Pacemaker	Within 12 months	CXR + assume pacemaker-dependent
ICD	Within 6 months	Disable tachyarrhythmia therapy
CRT-D/CRT-P	Within 6 months	Cardiology consultation if possible

Pacemaker Dependency Assessment

A patient is pacemaker-dependent if they lack an adequate intrinsic escape rhythm to maintain hemodynamic stability when pacing is inhibited.

Indicators of Pacemaker Dependency:

100% ventricular pacing on interrogation
No intrinsic rhythm when pacing rate temporarily reduced during interrogation
History of complete heart block, post-AV node ablation, or symptomatic bradycardia without escape rhythm
Presenting rhythm shows continuous pacing without underlying activity

Clinical Significance: In pacemaker-dependent patients, EMI-induced oversensing leads to pacing inhibition and asystole. These patients MUST have either:

Magnet application (converts to asynchronous mode)
Device reprogramming to asynchronous mode (VOO/DOO) [PMID: 21167937, PMID: 30409863]

Indication Review

Understanding the original indication guides management:

Pacemaker Indications:

Sick sinus syndrome (sinus node dysfunction)
Complete (third-degree) AV block
Mobitz type II second-degree AV block
Symptomatic bradycardia
Post-cardiac surgery AV block
Carotid sinus hypersensitivity
Neurocardiogenic syncope [PMID: 30409863, PMID: 28847610]

ICD Indications:

Secondary prevention: Survived VT/VF arrest not due to reversible cause
Primary prevention: Ischemic cardiomyopathy (EF ≤30-35%) or non-ischemic cardiomyopathy (EF ≤35%, NYHA II-III) on optimal medical therapy
Landmark trials: MADIT-II, SCD-HeFT, AVID [PMID: 11907287, PMID: 15659722, PMID: 9374758]

EMI Risk Assessment

High EMI Risk (Surgery Above Umbilicus):

Cardiac, thoracic, upper abdominal surgery
Head and neck surgery
Shoulder and upper limb surgery
Monopolar electrocautery near device generator

Low EMI Risk (Surgery Below Umbilicus):

Lower abdominal, pelvic surgery
Lower extremity surgery
Use of bipolar electrocautery
Surgery distant from device [PMID: 21167937]

Perioperative Management

Magnet Application

Pacemaker Magnet Response:

Switches device to asynchronous pacing mode (VOO, DOO, AOO)
Paces at a fixed "magnet rate" (typically 85-100 bpm)
Ignores all sensing including EMI
Prevents inhibition of pacing output
Lower magnet rate may indicate battery depletion (elective replacement indicator)
Effect ceases immediately upon magnet removal

ICD Magnet Response:

SUSPENDS tachyarrhythmia detection and therapy (no shocks or ATP)
CRITICAL: Does NOT affect pacing function
In pacemaker-dependent ICD patients, magnet alone is INSUFFICIENT - pacing can still be inhibited by EMI
Continuous tone or beeps usually indicate magnet recognition
Effect persists only while magnet is in place [PMID: 21167937]

Important Caveats:

Magnet response is programmable; some devices may be programmed to ignore magnets
Verify expected magnet response from interrogation report
CRT devices: Magnet may affect biventricular synchrony; loss of LV pacing can cause hemodynamic deterioration in severe heart failure

Reprogramming Considerations

When to Reprogram (vs. Magnet Use):

Pacemaker-dependent patient with ICD (magnet alone insufficient)
Anticipated prolonged or repeated EMI exposure
Device programmed to ignore magnet
CRT-D patients where loss of biventricular pacing is undesirable
Patient discomfort from magnet positioning

Reprogramming Options:

Pacemaker: VOO or DOO mode at rate above intrinsic rhythm
ICD: Disable tachyarrhythmia detection/therapy; consider asynchronous pacing mode if pacemaker-dependent
CRT: Maintain biventricular pacing; disable tachyarrhythmia detection
Rate-response: Disable (program to DDO/VVO)

Electrocautery Precautions

Minimize EMI Exposure:

Use bipolar electrocautery whenever possible (current confined between forceps tips)
Short bursts (less than 5 seconds) if monopolar cautery required
Lowest effective power setting
Maximum distance between cautery and device (ideally >15 cm)
Return electrode (grounding pad) positioning: Place so current path does not cross device or leads (e.g., contralateral thigh for upper body surgery)
Avoid cautery near device generator - direct current flow through generator can cause permanent damage

Harmonic Scalpel/Ultrasonic Devices:

Generate minimal EMI
Generally safe alternative to electrocautery
Preferred when available for patients with CIEDs [PMID: 21167937, PMID: 23510771]

Other EMI Sources

Lithotripsy (ESWL):

Mechanical shock waves can be sensed as cardiac activity
Acoustic energy can damage piezoelectric rate-response sensors
Focal point must be ≥15 cm from device generator
ECG-triggered lithotripters may malfunction with paced rhythms
Disable rate-responsive sensors [PMID: 21167937]

MRI:

Strong static magnetic field, radiofrequency pulses, gradient fields
Traditional CIEDs were absolute contraindication
MRI-conditional devices now available (approved for 1.5T, some for 3T)
Requires device-specific protocols, radiology and cardiology coordination
Non-MRI-conditional devices: alternative imaging (CT, ultrasound) preferred [PMID: 28502596]

Radiation Therapy:

Ionizing radiation can damage device circuitry
Cumulative dose threshold: generally less than 2-5 Gy to device
High-energy photon beams (>10 MV) produce neutrons causing unpredictable resets
Shield device from direct beam; frequent interrogation during treatment course [PMID: 28502596]

Radiofrequency Ablation:

High-frequency alternating current generates significant EMI
Can cause oversensing, inappropriate therapy, and power-on reset
Require device reprogramming and close monitoring
Grounding pad placement critical [PMID: 21167937]

Intraoperative Considerations

Monitoring Requirements

Essential Monitoring:

Continuous ECG: Detect arrhythmias (may be obscured by EMI during cautery)
Peripheral pulse monitoring: SpO2 plethysmograph waveform or invasive arterial pressure - CRITICAL as provides evidence of mechanical cardiac output when ECG unreliable
Invasive arterial pressure: Recommended for high-risk surgery or pacemaker-dependent patients; beat-to-beat blood pressure and confirmation of mechanical activity
Palpate pulse: If doubt about cardiac output during EMI, check femoral or radial pulse manually

Rationale for Peripheral Pulse Monitoring: During electrocautery, ECG display is obscured by artifact. If pacing inhibition occurs in a pacemaker-dependent patient, the SpO2 waveform will be lost. Arterial line tracing provides immediate evidence of cardiac output. This is the cornerstone of safe intraoperative monitoring. [PMID: 21167937]

External Pacing and Defibrillation Readiness

Transcutaneous Pacing:

External pacing/defibrillation pads should be applied preoperatively for all pacemaker-dependent patients
Position pads in anterior-posterior configuration to avoid device
Connect to defibrillator capable of pacing
Test capture settings if time permits (usually 50-100 mA)
Ensure sedation/analgesia available (transcutaneous pacing is painful) [PMID: 33081529, PMID: 21396559]

External Defibrillation:

Essential for ICD patients with tachyarrhythmia detection disabled
Pads positioned ≥8 cm from device generator
Anterior-posterior position preferred (avoids right pectoral device)
If shockable rhythm develops, provide external shock immediately
Do not delay defibrillation searching for device location
After successful resuscitation, device must be interrogated urgently [PMID: 33081529]

Anaesthetic Technique

Induction:

Standard induction agents acceptable
Avoid significant bradycardia (opioids, dexmedetomidine) in non-pacemaker-dependent patients
Succinylcholine-induced muscle fasciculations may cause transient oversensing
Ketamine increases sympathetic tone; may trigger tachyarrhythmias in ICD patients (theoretical)

Maintenance:

Volatile agents and propofol have minimal direct CIED effects
Maintain hemodynamic stability
Ensure adequate depth of anaesthesia to prevent catecholamine surges

Neuromuscular Monitoring:

Train-of-four monitoring may cause pacemaker inhibition (brief, clinically insignificant)
Use peripheral nerve stimulator distant from device if concerned

Intraoperative Problems

Pacing Inhibition:

Loss of SpO2 waveform/arterial trace during cautery
Stop cautery immediately
Apply magnet (pacemaker) or initiate transcutaneous pacing
If no response to magnet, consider device damage or non-responsive programming
Prepare for external pacing/CPR

Inappropriate ICD Shock:

Sudden patient movement, skeletal muscle contraction
Apply magnet immediately to suspend therapy
If VF/VT confirmed, remove magnet and allow ICD to deliver therapy
If artifact/EMI, maintain magnet application
External defibrillation available if ICD fails [PMID: 21167937]

Postoperative Device Check

Timing of Postoperative Interrogation

Immediate (Before Leaving Monitored Setting):

All ICDs must have tachyarrhythmia detection re-enabled
All devices that were reprogrammed preoperatively must be returned to original settings
Confirm appropriate pacing and sensing function

Before Discharge:

Formal interrogation recommended if:
- Significant EMI exposure occurred (cautery above umbilicus)
- Device was physically manipulated during surgery
- Hemodynamic instability occurred
- Cardiac arrest or resuscitation
Check battery status, lead parameters, threshold testing

Parameters to Assess:

Pacing thresholds (compare to baseline)
Sensing thresholds
Lead impedances (sudden increase may indicate lead damage)
Battery voltage
Arrhythmia logs (ICD: any appropriate/inappropriate therapies)
Reset to backup mode (indicates significant EMI exposure) [PMID: 21167937]

Postoperative Monitoring

All CIED Patients:

Continuous ECG monitoring in PACU
Confirm appropriate heart rate and rhythm
Document pacing function if pacing visible on ECG

ICD Patients:

External defibrillation pads remain in place until ICD re-enabled
Do not discharge from monitored setting until tachyarrhythmia therapy confirmed active
Telemetry monitoring until interrogation complete

Emergency Scenarios

Loss of Pacing

Recognition:

Bradycardia or asystole
Loss of pacing spikes on ECG
Loss of SpO2/arterial waveform
Hypotension, loss of consciousness

Immediate Management:

Stop EMI source (cease electrocautery)
Apply magnet over device (pacemaker → asynchronous pacing; ICD → does NOT restore pacing)
Initiate transcutaneous pacing if no immediate response
Pharmacologic support: Atropine 0.5-1 mg IV (limited efficacy in complete heart block), Isoprenaline infusion 1-10 mcg/min
CPR if pulseless
Prepare for transvenous pacing if external measures fail
Urgent cardiology/electrophysiology consultation

Causes:

EMI-induced oversensing (most common perioperatively)
Battery depletion
Lead dislodgement/fracture
Increased capture threshold (hyperkalemia, myocardial ischemia, antiarrhythmic drugs)
Device reset to backup mode [PMID: 21167937, PMID: 33081529]

Inappropriate ICD Shocks

Recognition:

Patient receiving shocks without VT/VF
Visible muscle contraction with shock delivery
Patient distress (conscious shocks are painful)
Monitor shows sinus rhythm or supraventricular arrhythmia

Causes:

EMI (most common perioperatively)
Supraventricular tachycardia with rapid ventricular rate
Atrial fibrillation with rapid ventricular response
T-wave oversensing
Lead fracture/failure
Device malfunction

Management:

Apply magnet immediately to suspend tachyarrhythmia detection
Assess rhythm: If patient in VT/VF, remove magnet and allow shock
If artifact/EMI: Maintain magnet, eliminate EMI source
External defibrillation pads applied (in case magnet removal needed for true VT/VF)
Sedation if patient conscious and distressed
Urgent device interrogation and reprogramming
Treat underlying cause: Correct electrolytes, treat SVT, consider beta-blocker/amiodarone for recurrent arrhythmias [PMID: 21167937, PMID: 10961951]

ICD Storm

Definition: Three or more sustained VT/VF episodes within 24 hours requiring ICD therapy

Management:

Sympathetic blockade: Beta-blocker - Propranolol (non-selective preferred), Esmolol infusion, Metoprolol
Antiarrhythmic therapy: Amiodarone 150 mg IV bolus, then 1 mg/min infusion
Sedation: Propofol, midazolam, or dexmedetomidine to reduce catecholamine surge
Correct precipitants: Electrolytes (K+ >4.0, Mg2+ >1.0), ischemia, hypoxia
Advanced options: Stellate ganglion block, catheter ablation (PMID: 27121327)
Consider general anaesthesia for refractory cases to completely suppress sympathetic activity
Cardiology/Electrophysiology emergency consultation [PMID: 10961951, PMID: 21545944, PMID: 36017540]

Cardiac Arrest in CIED Patient

Specific Considerations:

ICD in situ: If VF/VT, wait 30-60 seconds for ICD to attempt therapy; if no shock or unsuccessful, proceed with external defibrillation
External defibrillation: Position pads ≥8 cm from generator; anterior-posterior preferred
Pacemaker-dependent: If asystole/PEA, check for pacing output; if pacing spikes without capture, treat as failure to capture (hyperkalemia, ischemia)
Post-resuscitation: Urgent device interrogation; check for lead damage, generator damage, parameter changes
CPR: Standard chest compressions will not damage most devices; do not delay CPR to protect device [PMID: 33081529]

Indigenous Health Considerations

Aboriginal and Torres Strait Islander peoples experience cardiovascular disease at rates 1.3-2.0 times higher than non-Indigenous Australians, with onset at younger ages. Rheumatic heart disease remains prevalent, particularly in remote Northern Australian communities, with rates up to 2% compared to less than 0.02% in non-Indigenous populations. This burden translates to higher rates of bradyarrhythmias requiring pacemaker implantation and sudden cardiac death risk necessitating ICD therapy.

Access Barriers: Many Indigenous Australians live in remote and rural areas with limited access to cardiac electrophysiology services. Device implantation often requires travel to urban tertiary centres, creating significant barriers including cost, time away from community, and family separation. Follow-up device interrogation is challenging; remote monitoring technology is increasingly utilized but requires reliable telecommunications infrastructure and patient education. Coordination with Aboriginal Community Controlled Health Services, Rural Flying Doctor Service, and telehealth programs is essential.

Cultural Considerations: Family and community involvement in healthcare decisions is paramount. Extended family members may need to be included in preoperative discussions about device function, magnet use, and emergency scenarios. Cultural obligations may influence timing of elective surgery. Aboriginal Health Workers and Indigenous Liaison Officers should be engaged early to facilitate culturally safe communication. End-of-life discussions regarding ICD deactivation require particular sensitivity, with respect for traditional beliefs about death and dying. Ensuring informed consent in plain language, with interpreter services if needed, is critical given the technical complexity of CIED management.

Specific Clinical Factors: Higher prevalence of rheumatic heart disease means more patients with mechanical valve replacements requiring anticoagulation, adding complexity to device procedures. Diabetes, chronic kidney disease, and cardiomyopathy are more prevalent, affecting device indications and perioperative risk. Consideration of comorbidities when planning anaesthesia and postoperative monitoring is essential. [PMID: 23848353, PMID: 25176139, PMID: 29032654]

ANZCA Final Exam Focus

Common SAQ Patterns

Preoperative assessment of patient with pacemaker/ICD for noncardiac surgery
Comparison of magnet effects on pacemakers vs ICDs
Management of EMI from electrocautery
NBG pacemaker code interpretation
ICD detection algorithms and therapy delivery
Emergency management of loss of pacing or inappropriate shocks
Postoperative device check requirements

Clinical Viva Question Themes

Systematic approach to CIED patient presenting for urgent surgery
Intraoperative management when pacemaker dependency status unknown
Management of inappropriate ICD shock during surgery
CRT patient with severe heart failure requiring emergency surgery
Perioperative magnet use: when, why, and limitations
External pacing and defibrillation readiness

Management Algorithm Requirements

Preoperative:
- Identify device type and manufacturer
- Obtain recent interrogation report
- Assess pacemaker dependency
- Determine EMI risk based on surgical site
- Plan magnet use or reprogramming
- Arrange external pacing/defibrillation equipment
Intraoperative:
- Apply monitoring (ECG + peripheral pulse)
- Position external pacing pads
- Apply magnet or confirm reprogrammed mode
- Minimize EMI exposure (bipolar cautery, short bursts)
- Continuous vigilance for device malfunction
Postoperative:
- Re-enable ICD tachyarrhythmia therapy
- Restore original programming
- Formal interrogation if indicated
- Document management and outcome

Critical Points Examiners Look For

Understanding that ICD magnet does NOT affect pacing function
Recognition that pacemaker-dependent ICD patients need both magnet AND asynchronous pacing
Importance of peripheral pulse monitoring (not just ECG)
Systematic approach to emergency scenarios
Knowledge of NBG code and rate-responsive pacing implications
Appreciation of EMI sources beyond electrocautery
Cultural considerations for Indigenous patients

Assessment Content

SAQ Practice Question (20 marks)

Clinical Scenario:

A 72-year-old man with an ICD (dual-chamber, CRT-D) implanted 3 years ago for ischemic cardiomyopathy (EF 25%) is scheduled for urgent laparoscopic cholecystectomy for acute cholecystitis. His device was interrogated 8 months ago showing normal function. He reports no recent ICD shocks. His current medications include bisoprolol 5 mg daily, ramipril 5 mg daily, and spironolactone 25 mg daily. He is ambulant with NYHA Class II symptoms.

Question:

Outline your perioperative management plan for this patient, addressing preoperative assessment, intraoperative management including device programming and monitoring, and postoperative care. (20 marks)

Model Answer:

Preoperative Assessment (5 marks):

Device Evaluation:

Identify device: CRT-D (biventricular pacing + ICD function)
Interrogation was 8 months ago (exceeds 6-month recommendation for ICDs)
Ideally obtain urgent pre-procedure interrogation to assess:
- Battery status and lead parameters
- Percentage of biventricular pacing (should be >90% for optimal CRT benefit)
- Any recent arrhythmia episodes
- Current programming and magnet response settings
If interrogation not available due to urgency, proceed with heightened vigilance

Patient Assessment:

Severe LV dysfunction (EF 25%): high perioperative cardiac risk
CRT indicates heart failure with conduction delay
NYHA Class II: moderate functional limitation
Assess fluid status, electrolytes (K+, Mg2+ - arrhythmia risk)
Recent symptoms: any palpitations, syncope, ICD shocks
Indication for ICD: primary prevention vs secondary (affects arrhythmia risk)

Pacemaker Dependency:

CRT patients are often pacemaker-dependent for hemodynamic optimization
Loss of biventricular pacing can cause acute decompensation
Assume pacemaker-dependent unless proven otherwise

Intraoperative Management (10 marks):

Device Programming Strategy:

Laparoscopic surgery involves monopolar electrocautery above umbilicus: HIGH EMI RISK
Options:
1. Magnet application during cautery:
  - Suspends ICD tachyarrhythmia detection (prevents inappropriate shocks)
  - Does NOT affect pacing; if patient pacemaker-dependent, EMI can still inhibit pacing
2. Reprogramming (preferred if available):
  - Disable tachyarrhythmia detection
  - Program to asynchronous biventricular pacing (DOO) to prevent inhibition
  - Maintains CRT synchrony for hemodynamic benefit
For this patient: request electrophysiology team to reprogram preoperatively if time permits; alternatively, use magnet with transcutaneous pacing backup

Monitoring Requirements:

Standard ASA monitors plus:
Invasive arterial pressure monitoring (essential for EF 25%)
Peripheral pulse confirmation: SpO2 waveform visible during cautery proves mechanical output
Continuous ECG with ST-segment analysis
Central venous access for inotrope/vasopressor administration
Consider TOE availability for volume/contractility assessment

External Pacing/Defibrillation:

External pacing/defibrillation pads applied in anterior-posterior position (avoid right pectoral generator)
Transcutaneous pacer ready to deliver 50-100 mA if pacing lost
Defibrillator charged and ready; if ICD detection disabled and VF occurs, external shock required immediately

Electrocautery Precautions:

Use bipolar cautery preferentially
If monopolar required: short bursts (<5 seconds), lowest effective power
Grounding pad on contralateral thigh (current path away from device)
Surgeon aware of CIED: minimize cautery near upper abdomen

Anaesthetic Considerations:

Avoid bradycardia-inducing agents in excess (high-dose opioids, dexmedetomidine)
Maintain euvolemia (preload-dependent with reduced EF)
Avoid myocardial depression (titrate propofol carefully)
Maintain normal K+ and Mg2+ (reduces arrhythmia risk)
Consider low-dose inotrope (dobutamine) if evidence of low cardiac output

Postoperative Care (5 marks):

Immediate:

Continuous ECG monitoring in PACU/HDU
Maintain external defibrillation pads until ICD re-enabled
Do not discharge from monitored area until device interrogated and reprogrammed

Device Interrogation:

Formal interrogation before discharge (mandatory)
Check:
- Battery voltage unchanged
- Lead impedances normal (no evidence of damage)
- Pacing and sensing thresholds unchanged
- Arrhythmia logs (any oversensing events, inappropriate detections)
- No power-on reset occurred
Re-enable tachyarrhythmia detection
Restore biventricular pacing parameters

General Postoperative Care:

HDU/ICU admission for 24-48 hours (EF 25%, intermediate-risk surgery)
Multimodal analgesia (regional techniques if not contraindicated)
Maintain euvolemia
Serial troponin for MINS detection (high-risk patient)
Continue cardiac medications (beta-blocker, ACE inhibitor)
VTE prophylaxis when appropriate

Total: 20 marks

Viva Scenario (20 marks)

Clinical Scenario:

You are called to theatre for a 65-year-old woman undergoing emergency repair of a fractured neck of femur. She has a permanent dual-chamber pacemaker (DDD) implanted 5 years ago for complete heart block. No device identification card is available, and the last interrogation was 18 months ago. She is conscious and reports "the pacemaker keeps my heart beating."

Examiner Questions and Model Answers:

Examiner: What is your immediate concern about this patient?

Candidate: My immediate concern is that she is highly likely to be pacemaker-dependent. Her indication was complete heart block, meaning she has no reliable intrinsic escape rhythm. Her statement that "the pacemaker keeps my heart beating" confirms pacemaker dependency. If pacing is inhibited during surgery - most likely from electrocautery EMI - she could become asystolic. This is a potentially life-threatening situation that requires careful planning.

Examiner: The last interrogation was 18 months ago. How does this affect your management?

Candidate: The recommended interval for pacemaker interrogation is within 12 months of elective surgery. Her device is overdue for assessment. I would be concerned about:

Battery status (may be approaching elective replacement)
Lead integrity (sensing, impedance, thresholds)
Current programming (rate, mode, magnet response)

However, this is emergency surgery for fractured NOF - delay risks fat embolism, increased morbidity and mortality. I would attempt to contact the cardiology/pacing service for urgent telephone advice and arrange bedside interrogation if a technician is rapidly available. If neither is possible, I would proceed with surgery using a "safe" approach:

Assume pacemaker-dependent
Have magnet available and apply during EMI exposure
External transcutaneous pacing as backup
Arterial line for continuous pulse monitoring

Examiner: How will you identify this device and its manufacturer?

Candidate: Several approaches:

Contact patient's GP or cardiologist for records
Check hospital databases for implant records
Patient may know the name or have paperwork at home (contact family)
Chest X-ray: The generator has a radiopaque manufacturer identification code visible on X-ray
Online databases: Some manufacturers have patient lookup services
If device identified, contact manufacturer for programming information

For this emergency, I would obtain a CXR, identify the manufacturer, and call their 24-hour technical support line for device information.

Examiner: Surgery will involve monopolar diathermy for femoral approach. What is your intraoperative plan?

Candidate: This is a high EMI risk situation. My plan:

Pre-induction:

Apply external pacing/defibrillation pads in anterior-posterior configuration
Connect to defibrillator with pacing capability
Test transcutaneous pacing threshold if possible
Arterial line placement for beat-to-beat pulse monitoring
Magnet immediately available (taped to patient's chest near device)