This document discusses the perioperative management of patients with implanted cardiac devices such as pacemakers and implantable cardioverter-defibrillators. Key points include preoperative evaluation of the device and patient's cardiac condition, preparing the device for surgery by reprogramming or disabling functions to avoid interference from surgical equipment, monitoring the patient closely during surgery, and checking device function after surgery. The goal is to maintain pacing and therapeutic functions of the device while minimizing risks from electromagnetic or mechanical interference during the surgical procedure.

1. Perioperative anaesthetic management of a
patient with an implanted cardiac device
Types of CIED(Cardiac implantable electronic device)
1) Permanent pacemaker (PPM): for conduction system disturbances.
2) Artificial implantable cardioverter-defibrillator (AICD) for life threatening
arrhythmias.
3) Cardiac resynchronization therapy (CRT): for treatment of heart failure (HF).
4) Cardiac resynchronization therapy with defibrillator(CRTD): for treatment of
HF.
Indications for CIED :
Indications for pacemaker Indications for AICD:
• Symptomatic bradycardia from:
– Sinus node disease
– AV-node disease
• Long QT syndrome
• Hypertrophic obstructive cardiomyopathy
• Dilated cardiomyopathy Indications for CIED
• Prophylactic use in patients with ischemic
cardiomyopathy with: – EF ≤ 30% and NYHA class I
symptoms – EF ≤ 35% and NYHA class II-III
symptoms
• Non-ischemic cardiomyopathy with EF < 35% and
NYHA class II-III symptoms
• Ventricular fibrillation/VT from non-reversible
cause
• Brugada syndrome (RBBB with ST-elevation in V1
-V3
• Arrhythmogenic right ventricular dysplasia
• Long QT syndrome
• Hypertrophic cardiomyopathy
• Infiltrative cardiomyopathy.
Types of CIED Leads
Unipolar leads:
• Single electrode is present at the lead tip which serves as the cathode
• The pulse generator serves as the anode
• More susceptible to EMI than bipolar leads
Bipolar leads:
• Two electrodes are present at the distal end serving as cathode and anode
• Have a lower risk of EMI due to close spacing between electrodes

2. NASPE/BPEG Code for Pacemakers:
Position I
Pacing chamber
Position II
Sensing chamber
Position III
Response to
sensing
Position IV
Programmability
Position V
Multisite pacing
O = None O = None O = None O = None O = None
A = Atrium A = Atrium I = Inhibited R = Rate
modulation
A = Atrium
V = Ventricle V = Ventricle T = Triggered V = Ventricle
D = Dual (A+V) D = Dual (A+V) D = Dual (T + I) D = Dual (A+V)
NASPE/BPEG Generic Defibrillator Code:
Position I
Shock chamber
Position II
Anti-tachycardia
pacing chamber
Position III
Tachycardia detection
Position IV
Anti-bradycardia
pacing chamber
O = None O = None E = Electrogram O = None
A = Atrium A = Atrium H = Hemodynamic A = Atrium
V = Ventricle V = Ventricle V = Ventricle
D = Dual (A+V) D = Dual (A+V) D = Dual (A+V)
Sources of Interference with CIED:
A)Electromagnetic interference (EMI)with electrosurgery units (ESUs):
• Most common source of EMI
• Mono polar ESU causes EMI more often than bipolar electro cautery
• Coagulation mode (high-voltage) causes more EMI than cutting (low-voltage) mode
•Risk increases when ESU is used close to:
– Pulse generator
– Leads of ICD or pacemaker
B)EMI due to other operative equipment:
• Nerve stimulators for nerve blocks • Nerve stimulators for neuromuscular monitoring
• Evoked potential monitors (SSEP, MEP) • Transcutaneous electrical nerve stimulation
•Radiofrequency scanners used to find retained surgical instruments
• Magnetic resonance imaging • Radiofrequency ablation devices
• Extracorporeal shock wave lithotripsy • Electroconvulsive therapy
C) Mechanical interference:
• CVC guidewires may cause movement of CIED electrodes.
• Large tidal volumes. • Shivering/fasciculations.
• Vibrating bone saws during craniotomy may cause mechanical interference.

3. Risks of EMI:
1) Inhibition of pacing due to ventricular over-sensing of EMI
2) Misinterpretation of EMI as tachyarrhythmia resulting in:
• Delivery of inappropriate shocks
• Anti-tachycardia pacing by AICD
3) Direct damage to CIED altering ability to treat ventricular arrhythmias
4) Myocardial burns
5) Activation of noise reversion mode/electrical reset of device
6) Total device failure with no output
Preoperative Evaluation:
A) Focused history:
• History of:
– HTN, DM, MI – Previous cardiac surgery
– Cardiomyopathy – Peripheral vascular disease
– Valvular heart disease – Congenital heart disease
• History suggestive of pacemaker dysfunction: battery failure—
– Vertigo – Syncopal attacks
B) Focused examination:
•Assess previous cardiac disease
• Assess pacemaker function:
– Type of pacemaker: ▪ Demand: synchronous ▪ Fixed: asynchronous ▪ AICD
– Determine pulse generator (PG) status:
▪ Indication for placement ▪ History of generator events
▪ Last PG test date and battery status ▪ Number and type of leads
– Time of insertion:
▪ Electrode displacement possible within 3 months of insertion
▪ Battery failure if long term
– Irregular heart rate: Competition of pacemaker with intrinsic heart rate
– Check if pacing pulses are present and create paced beats

4. • Device interrogation:
– Patients should be examined for:
▪ Underlying rhythm
▪ Appropriate functioning of CIED
– Device interrogation of CIED should be done:
▪ Within 6 months prior to surgery for ICD
▪ Within 12 months prior to surgery for conventional pacemaker
▪ Within 3–6 months for cardiac resynchronization therapy device
• Indications for CIED interrogation:
– To disable anti-tachycardia shocks in ICDs when EMI is expected
– Disable anti-tachycardia shocks when movement may be hazardous:
▪ Intraocular surgery ▪ Intracranial surgery
– Produce asynchronous pacing in pacing dependent patient
– Increase paced heart rate in patients with bradycardia to augment CO
– Disable mechanical sensor when surgery causes mechanical stimulation:
▪ Breast surgery ▪ Cardiac surgery
• CIED reprogramming using magnet:
– Magnets may be used for reprogramming if:
▪ Response to magnet is known and effect is desirable
▪ Patient is in supine position during surgery
▪ Access to magnet is adequate:
- Magnet may be observed
- Magnet may be easily removed in case of arrhythmias
– Responses to magnet application most commonly include:
▪ Asynchronous pacing at fixed rate with fixed AV-delay for PM
▪ Suspension of anti-tachycardia detection and therapy for ICDs
– Advantages: ▪ Changes in CIED function are reversible by removal of magnet
▪May not require placement of pacing/defibrillator pads

5. – Disadvantages:
▪ Does not result in asynchronous pacing with ICDs
▪ Might fail to elicit response in obese patients
▪ May be difficult to use in:
- Lateral position
- Prone position
▪ Encroaches on surgical field if incision is close to pulse generator
•Reprogramming using programming machine:
– Useful to suspend anti-tachycardia therapy in ICDs
– Advantages:
▪ Allows change in pacing mode of ICD to asynchronous mode
▪ Prevents intrusion of surgical field by magnet
– Disadvantages:
▪ Requires trained personnel
▪ Requires transcutaneous pacing/defibrillator pads post-reprogramming
▪ Changes in CIED function are not quickly reversible
C) Cardiologists opinion of pacemaker function
D) ™Investigations:
• ECG:
– For ischemia/previous MI – Confirm pacing capture: Pacing rate > intrinsic rate
– No intrinsic rhythm: patient is pacemaker dependent
– Only intrinsic rhythm: Test pacemaker function by converting to fixed mode with
magnet.
•Chest X-ray:
– Heart size, lung fields
– Continuity of pacing leads, distal tip to be within cardiac cavity
– Location of generator – Dual/single chamber
• Serum potassium: Hyperkalemia increases pacing threshold.
•Acid base balance: May affect pacing threshold.

6. Factors Affecting Pacing Function Perioperatively
1) Electrolyte: Hypo/hyperkalemia
2) Acid base balance: Acidosis/alkalosis
3) Myocardial: Ischemia/acute infarction
4) Drugs: Digoxin toxicity, catecholamines, antiarrhythmics
5) Metabolic: Hypothermia, thyroid disturbances, hypoxia, hypoglycemia
6) Factors which increase the pacing threshold:
• Hyperkalemia • Acidosis, alkalosis • Hypoxia, hypoglycemia
•Hypothermia •Anti-arrhythmic drugs • Thyroid disturbances
Preoperative Preparation:
1) Informed consent
2) NPO orders
3) Premedication with benzodiazepines/opioids
4) Correct associated imbalances: potassium and acid base imbalances
5) If electromechanical interference (EMI) unlikely, no special precaution is needed
6) If EMI likely and CIED is a pacemaker:
• Reprogram to asynchronous mode especially when pacing-dependent:
– History of symptomatic bradycardia
– Inadequate escape rhythm
– History of AV-nodal ablation
•Suspend rate adaptive functions
•Reprogramming may be rarely done with a magnet placed over pulse generator
7) If EMI likely and CIED is an AICD:
• Suspend anti-tachyarrhythmia therapy function
• Pacing mode may be changed to asynchronous mode in pacing-dependent patients
• External pacing/defibrillator pads are placed prior to surgery

7. OT Preparation
1) Suction apparatus
2) Oxygen delivery apparatus
3) Anesthetic drugs
4) Monitors
5) Chronotropic drugs kept ready
•Atropine •Isoprenaline: 10–100 µg bolus or 0.05–0.2 µg/kg/min
• Ephedrine •Adrenaline
6) Temporary transcutaneous pacing should be made immediately available
7)External cardioverter- defibrillator kept ready
Monitoring:
1) Pulse oximetry:
•Continuous waveform display is important to detect mechanical systole
•May be used as source of heart rate as ECG may display double-sensed values
2) NIBP, urine output
3) Continuous ECG:
•Artifact filter is turned off to reduce highfrequency filtering
• Selection of diagnostic mode preferred over monitor or filter modes
• This allows display of high-frequency signals, including pacing spikes
• Pacing artifacts may be misinterpreted as QRS complexes by the ECG monitor
• This may result in display of erroneous heart rate
• This occurs more commonly with unipolar leads
4) Peripheral pulse to check cardiac output and pacemaker function
5) Invasive monitoring if indicated for surgery

8. 6) Central venous catheterization:
• Guidewire movement may cause: – Inhibition of pacemaker function– Delivery of
inappropriate shock
•Thus, CIED should be reprogrammed prior to CVC placement:
– Anti-tachycardia function suspended in ICDs
– Asynchronous mode activated for pacemakers
•Continuous monitoring of ECG and pulse oximetry is required during insertion
• Displacement of CIED lead is common during first 3 months post-insertion
• Coronary sinus lead is the most prone to displacement during CVC insertion
7) ABG for electrolytes
8) Nerve stimulator: may interfere with pacing
9) Beat to beat continuous CO monitor in HOCM
Choice of Anesthetic Technique:
A) Neuraxial blocks/regional anesthesia:
•Vasodilation may be poorly tolerated with fixed heart rate
• Avoid underhydration
• Caution during nerve blocks as nerve stimulator interferes with pacing
B) General anesthesia:
•Better preferred •TIVA is preferable when GA is used
•This is because:
– Volatile agents in general increase AV delay and pacing threshold – Sevoflurane/isoflurane cause
prolongation of QT interval
Considerations for GA in Patients with Pacemaker:
1)Placement of transcutaneous pacing/defibrillator pads:
• Placed before anti-tachycardia function of ICD has been disabled
• Allows treatment of malignant arrhythmias
•External defibrillator with pacing capability should be available
•Standard anterior-posterior location of pads preferred for left-sided CIEDs
•Anterolateral position may be used when AP position is not feasible

9. 2) Anesthetic agents:
•Anesthetic agents have minimal effect on CIED function
•Ketamine and etomidate cause myo-fasciculations which may interfere with pacing
•TIVA preferable as volatile anesthetics increase AV delay and pacing threshold
•N2O accumulates in pacemaker generator pockets
•High doses of anesthetics which exacerbate bradycardia are avoided such as:
– Dexmedetomidine – Opioids such as fentanyl
• In patients with prolonged QT-interval:
– Agents prolonging QT-interval are avoided:
▪ Haloperidol ▪ High dose sevoflurane and isoflurane ▪ Ondansetron
– This reduces the risk of polymorphic VT due to QT prolongation
•Desflurane and enflurane do not have any effect on QT interval
• Caution with succinylcholine as:
– Acute increase in potassium causes increase in pacing threshold
– Myopotentials during fasciculations may be abnormally sensed
3) Avoid underhydration as compensatory tachycardia to maintain CO is
absent
4) Considerations for diathermy/electrocautery interference:
• Risk of EMI with surgeries above the umbilicus are high
•Thus, anti-tachycardia therapy has to be suspended in above-umbilicus surgery
• Risk of EMI is negligible with surgeries below the umbilicus
•Unipolar cautery is the most common source of EMI
•Thus, it causes EMI especially in patients with unipolar CIED leads
•Therefore, use of bipolar cautery is recommended
•Ultrasonic/harmonic scalpel:
– Avoids EMI – Also facilitates coagulation of tissue with minimal EMI
• Position of return plate/electrode pad of ESU:
– Current path from ESU to pad should not cross CIED leads/generator
– Plane described by return plate and active electrode of electrocautery is perpendicular to plane
described by pacemaker and pacemaker electrode

10. • Similar considerations apply to pads of nerve stimulators and TENS
• Cutting mode (lower voltage) is used as it causes least EMI
•Smallest current intensity required for cutting is Used
•ESU is used in short bursts: one second for every 10 seconds
• Avoid using electrocautery within 15 cm of the device/lead
Considerations for GA in Patients with AICD
™
1) All ICDs have pacemakers incorporated intocircuitry
™
2) Preoperative assessment of cardiac condition
3) Cardiology opinion for:
• ICD interrogation
•Programming device to no-response mode
™
4) Preoperative preparation:
•Signals from electrocautery may be misinterpreted as dysrhythmias
•Convert AICD to no-response either by programming or using magnet
• Once converted, device will not deliver therapy secondary to misinterpretation
• Convert pacemaker to asynchronous mode sothat it is not inhibited by cautery
•Do not use electrocautery when AICD is programmed to sense and deliver therapy
•AICDs must be programmed to respond to a magnet
• Magnet will not change bradycardia related pacing parameters in the ICD
•Apply patches for external defibrillation when ICD is programmed to no response
•Ensure these pads are as far away as possible from device
• Pads not to be in same plane as device and electrodes
™
5) If PA catheter monitoring is required:
• Discuss with the cardiologist
•Document the need for PA catheter and discussion with cardiologist
• Discuss possibility of dislodgement of ICD electrodes with patient
• Maintain sterile technique, consider antibiotics before inserting lines
™
6) Continue antiarrhythmic drugs until time of surgery

11. ™
7) No clear preferences of anesthetic technique between regional/general
anesthesia
™
8) If intraoperative arrhythmias occur:
•Treat intraoperative causes to prevent recurrence
•If dysrhythmia continues and magnet has been used to create no response mode:
– Remove magnet from ICD – Allow ICD to charge and deliver a response
• If dysrhythmia continues and ICD has been programmed to no response mode:
– Reprogram ICD to deliver a response – Alternatively, use external defibrillation directly
– Place external defibrillation paddles in antero-posterior location – Deliver sufficient shock
– External pacing may be required if ICD is damaged with the shock
™
9) While transporting the patient from OR:
• Monitor patients ECG •Be prepared to deliver external defibrillation
• Interrogate and reprogram ICD when patient has entered PACU
Postoperative Care
™
A) Immediate postoperative period:
• Check pacemaker functions, if procedure involved cardioversion and diathermy
•Monitor cardiac rate and rhythm continuously •Back up pacing and cardioversion/defibrillation
capability
™
B) Postoperative restoration of CIED function:
• Use cardiologist help • Interrogate to assess function
• Reprogram appropriate setting •If CIED is AICD, restore all anti-tachycardia therapy
Treatment of Pacemaker Failure
Rate Response
Adequate to maintain BP Oxygen, airway control
Place magnet over pacemaker
Atropine, if sinus bradycardia
Severe bradycardia and hypotension Oxygen, airway control
Place magnet over pacemaker
Transcutaneous/transvenous pacing if magnet fails
Atropine if sinus bradycardia
Isoproterenol to increase ventricular rate
No escape rhythm Cardiopulmonary resuscitation Place magnet over
pacemaker
Transcutaneous/transvenous pacing if magnet fails
Isoproterenol to increase ventricular rate

12. Emergency Cardioversion/Defibrillation
™
1) Terminate all EMI sources
™
2) Remove magnet to enable defibrillation pads
™
3) Minimize current flow through pulse generator/leads
™
4) Defibrillation pads placed as far away from pulse generator as possible
™
5) Defibrillation pads placed perpendicular to major axis pulse generator/leads
™6) To extent possible, pads placed in anterior-posterior location
™
7) Use clinically appropriate energies
Complications:
™
- Failure to fire - Failure to capture
™
- Pacemaker syndrome seen with VVI mode - Pacemaker tachycardia
Special Considerations:
™TURP:
• Use harmonic scalpel • Cutting mode may cause electromagnetic interference
• Use cautery in short bursts
• Coagulation mode does not interfere • May have to convert to fixed mode if diathermy plate placed
around chest
• Possibility of random reprogramming due to EMI ™
Direct current electrical cardioversion:
• Use lowest possible energy • Paddles placed as far away from generator as possible (> 10 cm)
• Paddles placed perpendicular to line between generator and lead tip
• Follow up with formal pacemaker interrogation • Modern CIEDs are fitted with Zener diodes to
prevent damage from DC shocks
™MRI:
• During MRI a large radiofrequency signal 30–3000 Hz is generated
• This may induce lead heating of CIED up to 89°C leading to: – Myocardial thermal injury
– Changes in pacing properties: ▪ Inhibition of pacing ▪ Rapid pacing induced by radiofrequency signal
• For majority of older CIEDs, MRI is unsafe
• Many modern CIEDs have been designed to be MRI conditional
• MRI is contraindicated in pacing dependent patients
• When MRI performed: – Imaging must be performed in 1.5 Tesla magnet – CIED is interrogated
before and after the MRI
™Radiotherapy:
• Ionizing radiation used in radiation therapy may result in pacemaker damage:
– Temporary change resulting in oversensing – Reset to factory settings – Complete device failure
• ≥ 1000 rads causes pacemaker damage
• Non-neutron producing treatment is preferred to reduce risk of device reset
• Pulse generator and leads should be outside radiotherapy field
• Surgical relocation of pulse generator should be considered if EMI is inevitable
• Verify pulse generator function before and after therapy
• CIED is evaluated at weekly intervals in case of recurrent therapy
™

13. Extracorporeal shock wave lithotripsy:
• Used to treat upper urinary tract calculi
• Piezoelectric crystals for rate-adaptive pacing may be damaged by ESWL waves
• < 16 KV shock energy to be used • Do not focus lithotripsy beam near pulse generator
• Pacing mode is changed to VOO or DOO to prevent EMI from ESWL waves