When is monopolar diathermy (electrosurgery using a single active electrode) contraindicated in patients with medical conditions such as pacemakers (implantable cardioverter-defibrillators), metal implants, bleeding disorders, or those taking anticoagulant medications, or in pregnant women?

When Monopolar Diathermy Cannot Be Used

Monopolar diathermy is not absolutely contraindicated in any patient population, but requires specific device management protocols in patients with cardiac implantable electronic devices (CIEDs) when used above the umbilicus. 1

Critical Distance and Location Considerations

Electromagnetic interference (EMI) becomes a significant risk when monopolar electrosurgery is used within 15 cm of a CIED generator. 1 The key determinant is anatomical location relative to the device:

• Surgery above the umbilicus with anticipated EMI requires mandatory device management in all CIED patients 1
• Surgery below the umbilicus is unlikely to cause EMI with transvenous devices and may not require device intervention 1
• Surgery below the groin poses minimal risk even for subcutaneous ICDs 1

Situations Requiring Alternative Approaches or Device Management

Pacemaker-Dependent Patients with Transvenous Devices

For pacemaker-dependent patients undergoing surgery above the umbilicus, the device MUST be reprogrammed to asynchronous mode (VOO or DOO), or a magnet must be placed over the generator to prevent life-threatening pacing inhibition. 1 This is a Class I recommendation with B-NR level of evidence. 1

• Pacemaker dependency is determined by chart review and ECG examination showing no adequate intrinsic rhythm >60 bpm 1, 2
• EMI can cause transient inhibition of pacing, leading to asystole in dependent patients 1
• Reprogramming is preferred over magnet use because magnet effects vary by manufacturer and some devices have programmable magnet responses that may be disabled 1

Patients with Implantable Cardioverter-Defibrillators (ICDs)

ICDs require tachytherapy algorithms to be programmed OFF before any surgery above the umbilicus with anticipated EMI to prevent inappropriate shocks from misinterpreted electrical signals. 1 This is a Class I recommendation. 1

• A magnet will NOT force asynchronous pacing in an ICD - it only temporarily suspends shock therapy 1
• If the patient is also pacemaker-dependent, the device must be separately reprogrammed to asynchronous pacing mode 1, 3
• Continuous cardiac monitoring and immediately available external defibrillation equipment are mandatory throughout the entire period when tachytherapies are disabled 1, 3
• Critical pitfall: Systems must ensure ICDs are reprogrammed to active therapy before discharge - documented deaths have occurred from failure to restore tachytherapy function 1, 3

Leadless Pacemakers

Pacemaker-dependent patients with leadless pacemakers undergoing surgery above the umbilicus with anticipated EMI must have their devices reprogrammed to asynchronous mode. 1 This is a Class I recommendation with C-LD level of evidence. 1

• Leadless pacemakers may or may not be magnet responsive depending on manufacturer 1
• Correct magnet placement is difficult because these devices are fully intracardiac 1
• Reprogramming is the only reliable approach 1

Subcutaneous ICDs

For patients with subcutaneous ICDs having surgery above the groin with anticipated EMI, it is reasonable to reprogram the device or use a magnet to temporarily disable tachytherapies. 1 This is a Class IIa recommendation. 1

• Subcutaneous ICDs are more susceptible to EMI from electrosurgery above the groin due to their large surface area 1
• A magnet placed over the subcutaneous ICD will emit an R wave synchronous beep indicating correct positioning 1
• If the tone is not audible, reprogramming is necessary 1

Specific Surgical Scenarios Requiring Heightened Precautions

Intracranial, Intraspinal, or Intraocular Surgery

Even if EMI is not anticipated, monopolar diathermy may be problematic during these procedures because patient movement from an inappropriate CIED shock is unacceptable. 1 Consider:

• Prophylactic ICD tachytherapy deactivation even for remote surgical sites 1
• Alternative energy sources (bipolar, ultrasonic scalpel) 1

Major Abdominal or Thoracic Surgery

These procedures involving large amounts of electrocautery carry the highest risk of device interactions and mandate formal preoperative device evaluation within 3-6 months. 1, 3

Mandatory Risk Mitigation Strategies When Monopolar Diathermy Must Be Used

Technical Modifications

• Use intermittent, irregular bursts at the lowest feasible energy rather than continuous activation 1, 2
• Position the dispersive electrode as far as possible from the generator and heart 1
• Ensure the current path does not cross the generator or leads 1
• There is documented risk of EMI even with electrosurgery below the umbilicus when using underbody dispersive electrodes 1

Monitoring Requirements

All patients with CIEDs require BOTH continuous ECG monitoring AND continuous pulse monitoring (pulse oximetry or arterial line) during surgery. 1, 2 This dual monitoring is essential because:

• Electrocautery interference obscures ECG signals, making rhythm determination impossible 1, 2
• Pulse oximetry allows pulse detection even when the ECG is obscured 1, 2
• EMI may obscure pacing spikes and QRS complexes on the ECG 1

Preferred Alternatives to Monopolar Diathermy

Bipolar electrosurgery and ultrasonic scalpels are unlikely to cause EMI and should be used whenever technically feasible. 1, 2 This is the single most effective strategy to eliminate device interaction risk. 2

Common Pitfalls to Avoid

• Never rely on magnets without preoperative confirmation of their effects - some devices have programmable magnet responses disabled 1
• Magnets may not be effective in obese patients or when continuous generator contact cannot be ensured 1, 3
• Do not assume surgery below the umbilicus is always safe - underbody dispersive electrodes can still create EMI risk 1
• Rate-responsive functions can be triggered by EMI, causing undesirable tachycardia - deactivate during procedures 1
• Emergency cardioversion paddles must be positioned anterior-posterior and perpendicular to device leads if needed 1, 3

Postoperative Requirements

Patients who had devices reprogrammed must have functioning restored before hospital discharge, with formal interrogation confirming restoration of settings. 1 This is a Class I recommendation. 1 The device should not be considered safe until:

• Interrogated programmer printout verifies antitachycardia function is active (for ICDs) 1, 3
• Original or recommended settings are confirmed 1
• Patient is not discharged to an unmonitored setting until verification is complete 1