What are the preoperative considerations for a patient with bradycardia (abnormally slow heart rate) undergoing general surgery?

Preoperative Risk Assessment for Bradycardia in General Surgery

For patients with bradycardia undergoing general surgery, conduct a focused preoperative evaluation to determine if the patient has a cardiac rhythm management device (CRMD), assess pacemaker dependency, and stratify risk using patient-specific factors—then prepare transcutaneous pacing pads for high-risk patients rather than routine prophylactic transvenous pacing. 1, 2

Essential Preoperative Evaluation Components

The preoperative assessment must establish four critical elements 1:

• Device presence: Review patient interview, medical records, chest x-rays, ECG tracings, and perform physical examination checking for scars and palpable devices 1
• Device type identification: Obtain manufacturer's identification card, order chest x-ray if unavailable, or consult manufacturer databases and pacemaker clinic records 1
• Pacemaker dependency determination: Document history of syncope from bradyarrhythmia requiring CRMD implantation, prior AV nodal ablation, or CRMD evaluation showing no spontaneous ventricular activity at lowest programmable VVI rate 1
• Device function verification: Confirm current device programming and battery status 1

Risk Stratification Using the HEART Score

Apply the validated 5-point HEART score to predict intraoperative bradycardia or hypotension risk 2, 3:

• Heart rate <60 bpm at baseline 2, 3
• Elderly age >60-65 years 2, 3
• Angiotensin system blockade (ACE inhibitors, ARBs) or beta-blockers 2, 3
• Revised cardiac risk index ≥3 points or ASA Class III-IV 2, 3
• Type of surgery (major surgery) 2, 3

Each point increases odds of intraoperative bradycardia/hypotension by 2.51-fold, with maximum scores yielding a likelihood ratio of 3.64 3. Baseline blood pressure <110/60 mmHg represents an additional independent risk factor 2, 3.

Preoperative Management Algorithm for High-Risk Patients

For patients with elevated HEART scores or known conduction disease 2:

• Review and consider holding negative chronotropic medications (beta-blockers, calcium channel blockers, digoxin) in consultation with cardiology 2
• Place transcutaneous pacing pads before surgery begins (Class IIa recommendation) 1, 2
• Ensure atropine availability at the surgical field (0.5-1 mg IV, repeatable every 3-5 minutes up to 3 mg maximum) 2, 4
• Plan continuous heart rate monitoring throughout the procedure 2

Critical Pitfall: Avoid Routine Prophylactic Transvenous Pacing

Do not routinely place temporary transvenous pacing wires, even in patients with left bundle branch block requiring pulmonary artery catheterization 1, 2. The incidence of complete heart block during PA catheter insertion in LBBB patients is low, while prophylactic transvenous pacing carries increased risk of ventricular arrhythmias (Class III: Harm recommendation) 1, 2. Instead, be prepared to manage complete heart block with rapid transcutaneous pacing or emergent transvenous pacing if sustained rate support becomes necessary 1.

Procedure-Specific Considerations

Certain surgical procedures carry heightened bradycardia risk 1, 5:

• Carotid endarterectomy/stenting: High risk for angioplasty-related bradycardia requiring transcutaneous pacing readiness 1
• Laparoscopic procedures: Rapid peritoneal insufflation causes vagal-mediated bradycardia through peritoneal stretching—use low CO2 flow rates 5
• Procedures involving trigeminal nerve manipulation: Direct vagal stimulation risk 1

Mechanism Understanding

In noncardiac surgery, intraoperative bradycardia stems predominantly from sinus node dysfunction rather than worsening AV conduction 1, 2. This differs from cardiac surgery where direct surgical trauma to the conduction system plays a larger role 1. The bradycardia risk derives from patient factors and anesthetic management, not the surgical site itself 2.

Intraoperative Management Protocol

If bradycardia develops during surgery 2, 4:

1. Stop provocative maneuvers (insufflation, surgical manipulation) and allow patient recovery 2
2. Verify adequate oxygenation and ventilation 2
3. Identify reversible causes: medications, electrolyte disturbances, hypoxemia, myocardial ischemia, pain-induced vagal stimulation 4
4. Administer atropine 0.5-1 mg IV for persistent symptomatic bradycardia, repeatable every 3-5 minutes up to 3 mg maximum 2, 4
5. Consider aminophylline as alternative acute agent if atropine ineffective 4
6. Initiate transcutaneous pacing for hemodynamically unstable bradycardia unresponsive to pharmacologic therapy 1, 2

Postoperative Considerations

Approximately 20% of patients with compromising bradycardia require temporary emergency pacing for initial stabilization, while 50% ultimately need permanent pacemaker implantation 6. However, wait at least 72 hours before considering permanent pacing to avoid unnecessary implantation, as many conduction disturbances resolve spontaneously 4. After isolated CABG, permanent pacing is indicated before discharge only for new sinus node dysfunction or AV block with persistent symptoms or hemodynamic instability that does not resolve 1, 4.