A patient with a single‑chamber ventricular pacemaker (VVI) has a normal baseline heart rate, but during preparation for abdominal surgery in the operating room his heart rate increases and he becomes sweaty, preventing the operation. As a cardiologist, what management should be recommended?

Management of Intraoperative Tachycardia in a Patient with VVI Pacemaker

The pacemaker must be interrogated immediately to determine if rate-responsive features are causing inappropriate pacing, and if confirmed, these features should be disabled before proceeding with surgery. 1, 2

Immediate Assessment

The clinical picture—normal baseline rhythm but sudden tachycardia with diaphoresis in the operating room—strongly suggests inappropriate rate-responsive pacing triggered by the surgical environment. This is a recognized complication with single-chamber ventricular pacemakers (VVI-R) that have rate-modulation features enabled 1, 3, 4.

Key Diagnostic Steps:

1. Verify pacemaker dependency status - Review the ECG to determine if the patient has an adequate underlying rhythm 2
2. Identify the rate-response sensor type:
   • Motion-based (accelerometer) sensors can be triggered by surgical manipulation, patient positioning, or even external vibrations 4, 5
   • Temperature-based sensors (in newer leadless devices) can be triggered by warming blankets or temperature changes 3
3. Check for electromagnetic interference (EMI) - Though less likely to cause tachycardia, EMI from electrocautery can cause device malfunction 1, 2

Definitive Management Algorithm

Step 1: Immediate Stabilization

• Do NOT place a magnet - In VVI pacemakers, magnet application typically converts to asynchronous pacing (VOO) at a fixed rate but does NOT disable rate-responsive features 6
• Ensure hemodynamic stability with appropriate anesthetic management
• Have temporary pacing/defibrillation equipment immediately available 1

Step 2: Device Interrogation

Contact the pacemaker service or manufacturer representative urgently to:

• Interrogate the device to confirm rate-responsive pacing is the culprit 2
• Disable the rate-modulation feature (the "R" function) 1, 5
• If the patient is pacemaker-dependent, reprogram to asynchronous mode (VOO) to prevent pacing inhibition from EMI during surgery 2, 6, 2, 6

Step 3: Proceed with Surgery

Once rate-responsive features are disabled:

• Continue with continuous ECG and pulse monitoring (pulse oximetry plethysmography is essential as electrocautery may interfere with ECG) 2
• Use bipolar electrocautery if possible to minimize EMI 2, 7, 2
• If unipolar cautery is necessary, use short intermittent bursts at lowest energy and position the grounding pad to direct current away from the device 2

Step 4: Postoperative Management

• Restore original pacemaker settings before hospital discharge 2, 6, 2, 8
• Formal device interrogation to verify proper function and rule out any EMI-induced damage or reprogramming 1, 9

Critical Pitfalls to Avoid

Common Error #1: Assuming magnet placement will solve the problem. Magnets do not disable rate-responsive features in most pacemakers 6.

Common Error #2: Proceeding with surgery without addressing the underlying device issue. The tachycardia and sympathetic response (sweating) indicate the patient is experiencing inappropriate pacing that could lead to hemodynamic compromise 3, 4.

Common Error #3: Failing to have device expertise available. For abdominal surgery with anticipated electrocautery use, preoperative device evaluation and planning should have occurred 2, 8. This case represents a failure of preoperative preparation.

Why This Matters for Morbidity and Mortality

Inappropriate rate-responsive pacing can cause:

• Hemodynamic instability from inappropriately elevated heart rates 3, 10
• Increased myocardial oxygen demand in a potentially compromised patient
• Inability to proceed with necessary surgery
• Risk of device damage from uncontrolled EMI exposure 1, 9

The 2024 AHA/ACC guidelines specifically emphasize that patients with pacemakers undergoing surgery above the umbilicus with anticipated EMI require a preoperative management plan 8. This case highlights the consequences when such planning is inadequate.