Perioperative Management of Patients with Pacemakers

Overview

I. Basic Pacemaker Concepts Relevant to Perioperative Care

Pacemaker Types

Pacemaker Dependency

• AV nodal ablation (creates permanent complete heart block - always pacemaker-dependent)
• Complete heart block
• Severe sinus node dysfunction
• CRT devices (effectively always dependent because loss of biventricular pacing severely impairs cardiac output)

II. Preoperative Assessment

Key Determinations

1. Is the patient pacemaker-dependent? - Review history for syncope, bradyarrhythmia, or prior AV nodal ablation. Check percentage paced on interrogation report.
2. Device type and model - Pacemaker vs. ICD vs. CRT (different management strategies). Identify via:
   • Pacemaker ID card (many patients lack it)
   • Prior interrogation note from CIED team
   • Chest radiograph - ICDs show thicker shocking coil; CRT shows a coronary sinus lead
   • Direct manufacturer contact
3. Date of last interrogation - Should be within 6 months; if not, arrange pre-op interrogation.
4. Battery life - At least 3 months remaining is prudent. If battery is low and surgery is elective, refer to electrophysiologist for possible generator replacement first.
5. Will electrosurgery be used? - If yes, determine location relative to the CIED generator.
6. Presence of EMI sources - Electrocautery (especially monopolar), radiofrequency ablation, lithotripsy, MRI, radiation therapy, nerve stimulators.

Team Communication

Industry-employed allied professionals should not determine the perioperative plan - this is the responsibility of the clinical CIED team.

III. Electromagnetic Interference (EMI) - The Primary Intraoperative Risk

How EMI Causes Problems

• Oversensing - The pacemaker misinterprets EMI as intrinsic cardiac activity, inhibiting pacing. In a pacemaker-dependent patient this can cause asystole.
• Asynchronous pacing triggered - Pacing delivered without regard to intrinsic rhythm, potentially falling on T-wave (R-on-T phenomenon).
• Inappropriate shock delivery - ICDs may deliver shock for sensed EMI mimicking VF.
• Mode resetting - Device reverts to backup/reset mode (often VVI at 65-70 bpm).
• Permanent device damage - Rare but possible with high-energy sources.

Risk is greatest when:

• Surgical site is near the device or sensing leads
• Monopolar (vs. bipolar) cautery is used
• Long continuous bursts of cautery are applied

IV. Intraoperative Management Strategies

Magnet Application

• Pacemaker magnet behavior is manufacturer and model specific - always verify with the CIED team.
• In most pacemakers, magnet removal restores the original programmed mode.

Reprogramming (Alternative to Magnet)

• For pacemaker-dependent patients: reprogram to asynchronous mode (VOO or DOO).
• Disable rate-responsive pacing preoperatively (vibration sensors in rate-responsive devices can cause inappropriate rate increases with mechanical ventilation or patient movement).
• Consider increasing pacing output for high-risk surgery where metabolic shifts may alter pacing thresholds.
• For ICDs: reprogram to disable VT/VF detection for all procedures above the umbilicus involving electrocautery.

Dispersive Ground Pad Placement

• For monopolar cautery, the dispersive pad must be positioned so current does not flow through or near the generator/leads.
• Example: for head and neck surgery, place pad on the contralateral shoulder.

Practical Electrocautery Tips

• Use bipolar cautery whenever possible (minimal EMI).
• If monopolar must be used: use short bursts (<5 seconds), allow time between bursts.
• Keep the electrosurgical unit away from the pacemaker generator.

V. Monitoring

• Arterial pulse monitoring is mandatory (pulse oximeter plethysmography or arterial line) - do not rely solely on ECG since pacemaker spikes may be counted but may not be associated with mechanical contraction.
• Continuous ECG monitoring throughout.
• External transcutaneous pacing pads and defibrillator must be immediately available, especially for pacemaker-dependent patients.

VI. Specific Situations

Cardioversion / Defibrillation

• Preferred pad placement: anterior-posterior orientation, with anterior pad at least 8 cm from the CIED generator.
• With newer bipolar leads, cardioversion less commonly affects CIED function.
• If a magnet has been applied to an ICD disabling tachytherapy, remove the magnet first to re-enable ICD therapy before attempting external cardioversion.
• Post-cardioversion: interrogate device to verify function.

MRI

• MR-conditional devices (labeled 1.5T or 3T conditional): can undergo MRI under specific conditions per manufacturer.
• MR non-conditional devices: requires careful risk-benefit analysis; some centers perform with close monitoring and a pacing specialist present.
• 2020 ASA Practice Advisory: MR-conditional devices should follow manufacturer-specific MRI conditions.

Radiation Therapy

• Direct radiation to the generator can cause permanent malfunction.
• Device should be kept out of the radiation field.
• Cumulative dose >2 Gy to the generator is concerning.

Lithotripsy

• Shock wave can inhibit pacemakers if focused near the generator.
• Rate-responsive pacing should be disabled.
• Triggering lithotripsy to the R-wave is advisable.

Surgery Near the Device

• Chest procedures, shoulder/axillary surgery: risk of lead damage.
• Alert the surgical team; intraoperative device interrogation may be needed.

VII. Emergency Surgery - Decision Algorithm

1. Establish pulse plethysmography or arterial line; apply transcutaneous pacing/defibrillation pads.
2. Determine pacemaker dependency (12-lead ECG or rhythm strip).
3. If pacemaker-dependent: place magnet over generator + use only short bursts of electrocautery.
4. If ICD/CRT-D: magnet suspends tachytherapy; use short bursts of cautery until device can be formally reprogrammed.
5. Evaluate device prior to leaving telemetry area postoperatively.

VIII. Postoperative Management

• Restore all disabled functions (tachytherapy in ICDs, rate-responsive pacing) before leaving the recovery area.
• Any patient with disabled antitachycardia therapy must be continuously monitored until therapy is restored.
• Postoperative interrogation is required if:
  • Device was reprogrammed preoperatively
  • Any intraoperative CIED malfunction was suspected
  • Cardioversion/defibrillation was performed
• For "low-risk" procedures: ambulatory interrogation within 1 month postoperatively is acceptable (per HRS guidelines).
• Optimize heart rate and pacing parameters for the postoperative period (consider that opioids, beta-blockers, and calcium channel blockers commonly used postoperatively suppress SA/AV nodes and may increase pacing demand).

Summary Checklist