When is temporary pacing indicated in an adult patient with a history of cardiac disease undergoing cardiopulmonary resuscitation (CPR)?

Temporary Pacing in CPR

Temporary pacing is NOT recommended during cardiopulmonary resuscitation for asystolic cardiac arrest, as it does not improve survival and may delay effective chest compressions. 1

Pacing is Contraindicated in Asystolic Cardiac Arrest

• Pacing for patients in asystole during CPR is Class III (not recommended) with Level of Evidence B. 1
• Randomized controlled trials in both prehospital and hospital settings demonstrated no improvement in hospital admission rates or survival to discharge when pacing was attempted in asystolic patients. 1
• Even when electrical capture is achieved in asystolic patients, electromechanical dissociation typically follows and survival is not improved. 2
• Pacing attempts delay or interrupt chest compressions, which are the cornerstone of effective CPR. 1

When Pacing IS Indicated: Bradycardia Developing DURING CPR

If a patient develops acute symptomatic bradycardia or complete heart block DURING an ongoing resuscitation (not primary asystole), temporary pacing may be beneficial after atropine failure. 1

Treatment Algorithm for Bradycardia During CPR:

1. First-line: Atropine 0.5-1 mg IV every 3-5 minutes (maximum 3 mg total) 1, 3

   • Atropine is unlikely to be effective for type II second-degree or third-degree AV block with wide QRS complex. 3

2. Second-line if atropine fails:

   • Transcutaneous pacing (TCP) - Class IIa recommendation 1, 3
   • Dopamine infusion 5-20 mcg/kg/min IV 1, 3
   • Epinephrine infusion 2-10 mcg/min IV 1, 3

3. Third-line: Transvenous pacing if TCP and medications fail (Class IIa) 1

Evidence Supporting Selective Pacing Use:

• In patients who developed complete heart block or bradycardia DURING CPR (not primary asystole), transvenous pacing achieved electrical capture in 77% and successful resuscitation in one-third of cases. 2
• Prehospital external pacing for hemodynamically significant bradycardia (heart rate <60, blood pressure <90 mmHg, unresponsive to atropine) resulted in 100% resuscitation rate and 83% survival in one prospective trial. 4
• However, when bradycardia or asystole during cardiac arrest fails to respond to standard pharmacologic measures, it indicates severe myocardial damage and pacing rarely improves survival. 5

Critical Pitfalls to Avoid

• Never delay chest compressions to attempt pacing in asystolic arrest. 1
• Do not use synchronized cardioversion mode for asystole or pulseless VT—the device may not sense a QRS and fail to deliver a shock. 1
• Immediate pacing might be considered in unstable patients with high-degree AV block when IV access is not available (Class IIb). 1
• TCP serves only as a temporizing bridge and requires sedation/analgesia in conscious patients due to pain. 3

Special Circumstances in Cardiac Disease Patients

For patients with known cardiac disease undergoing CPR:

• Acute anterior MI with complete AV block: Immediate temporary pacing is indicated as His-Purkinje necrosis causes cardiogenic shock unresponsive to atropine. 6
• Post-cardiac surgery (aortic valve, tricuspid repair, VSD closure): Prophylactic temporary pacing may be warranted. 1, 6
• Bifascicular block with anterior MI: Consider prophylactic temporary pacing. 1, 6

The key distinction is that pacing has no role in PRIMARY asystolic arrest but may be lifesaving for acute bradyarrhythmias that develop as a complication during resuscitation efforts in patients with viable myocardium. 1, 2