What are the recommended drug regimens, dosages, preparation, and administration for acute control of peri‑operative arrhythmias in adult surgical patients?

Perioperative Arrhythmia Drug Management

Supraventricular Tachycardia (SVT) and Atrial Fibrillation

Beta-blockers and non-dihydropyridine calcium channel blockers (diltiazem, verapamil) are the first-line drugs for rate control in perioperative atrial fibrillation and SVT. 1

Initial Management Algorithm

For hemodynamically stable SVT:

• Attempt vagal maneuvers first 1
• Adenosine: 6 mg IV rapid push, followed by 12 mg if no response 1
• If adenosine fails, proceed to rate control agents 1

For atrial fibrillation/flutter rate control:

Beta-blockers (preferred):

• Metoprolol: 5 mg IV over 1-2 minutes, repeat every 5 minutes to maximum 15 mg 1
• Esmolol: 500 mcg/kg (0.5 mg/kg) loading dose over 1 minute, then 50 mcg/kg/min infusion; increase by 50 mcg/kg/min increments every 4 minutes to maximum 300 mcg/kg/min 1, 2
• Atenolol: 5 mg IV over 5 minutes, repeat 5 mg in 10 minutes if needed 1
• Propranolol: 0.5-1 mg over 1 minute, repeat to total 0.1 mg/kg 1

Calcium channel blockers (alternative):

• Diltiazem or verapamil: Use when beta-blockers are contraindicated or inadequate 1
• Avoid verapamil/diltiazem in wide-QRS tachycardia of unknown origin or pre-excited atrial fibrillation 1

Amiodarone (for heart failure or refractory cases):

• 150 mg IV over 10 minutes, may repeat if necessary 1
• Follow with 1 mg/min infusion for 6 hours, then 0.5 mg/min 1
• Maximum 2.2 g in 24 hours 1, 3
• Use as first-line in patients with heart failure, as digoxin is ineffective in high adrenergic states 1

Digoxin (limited role):

• 8-12 mcg/kg total loading dose: give half initially over 5 minutes, remaining as 25% fractions at 4-8 hour intervals 1
• Reserved for chronic heart failure patients only; slow onset renders it less useful acutely 1

Hemodynamically Unstable Patients

Immediate synchronized cardioversion starting at 100-200 J for sustained arrhythmias causing hemodynamic compromise 1

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Ventricular Arrhythmias

Stable Monomorphic Ventricular Tachycardia

Amiodarone is the preferred agent for hemodynamically stable monomorphic VT. 1

Dosing:

• 150 mg IV over 10 minutes, repeat if necessary 1
• Follow with 1 mg/min for 6 hours, then 0.5 mg/min 1
• Maximum 2.2 g in 24 hours 1, 3

Alternative agents:

• Procainamide: 20-50 mg/min until arrhythmia suppressed, hypotension occurs, QRS widens by 50%, or total dose 17 mg/kg reached; OR 100 mg every 5 minutes 1
  • Avoid in QT prolongation and heart failure 1
• Sotalol: 1.5 mg/kg infused over 5 minutes 1
  • Avoid in QT prolongation and heart failure 1
• Lidocaine: 1-1.5 mg/kg IV, repeat 0.5-0.75 mg/kg every 5 minutes if needed 1

Unstable Ventricular Tachycardia or Ventricular Fibrillation

Immediate defibrillation is required for pulseless VT or ventricular fibrillation. 1, 4

Algorithm:

• Shock 1: 200 J (monophasic) or equivalent biphasic 4
• Resume CPR immediately 4
• Shock 2: 200-300 J if VF/VT persists 4
• Shock 3: 360 J if VF/VT persists 4
• After third shock: Administer amiodarone 300 mg (5 mg/kg) IV bolus 3, 4
• Continue with additional shocks as needed 4
• Epinephrine 1 mg IV every 3-5 minutes 4

Alternative to amiodarone:

• Lidocaine 1.0-1.5 mg/kg IV bolus when amiodarone unavailable 4

Polymorphic Ventricular Tachycardia

With normal QT interval:

• Beta-blockers if ischemia suspected 1
• Amiodarone 150 mg IV over 10 minutes 1

Torsades de Pointes (with long QT):

• Withdraw all QT-prolonging drugs immediately 1
• Correct electrolyte abnormalities (potassium >4.0 mEq/L, magnesium >2.0 mg/dL) 1, 4
• Magnesium sulfate for patients with TdP and long QT syndrome 1
• Beta-blockade combined with temporary pacing for TdP with sinus bradycardia 1
• Isoproterenol for recurrent pause-dependent TdP without congenital long QT syndrome 1

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Amiodarone Preparation and Administration

Critical preparation requirements:

• Dilute only in 5% dextrose-in-water (D5W); normal saline causes precipitation 3
• Concentration ≤2 mg/mL for peripheral administration; higher concentrations require central access 3
• Central venous access strongly preferred for hemodynamic instability 3
• Use in-line filter during infusion 3

Monitoring requirements:

• Continuous ECG for bradycardia, AV block, QT/QRS prolongation 3
• Blood pressure monitoring (hypotension in ~16% of patients) 3
• Heart rate monitoring (bradycardia in ~5% of patients) 3

Management of adverse effects:

• Hypotension: Reduce or pause infusion, add vasopressor support, consider volume expansion 3
• Bradycardia/AV block: Lower infusion rate or discontinue; prepare for temporary pacing if high-grade block 3

Drug interactions:

• Digoxin: Reduce dose by 50% 3
• Warfarin: Reduce dose by one-third to one-half, monitor INR weekly 3
• Avoid co-administration with other QT-prolonging agents 3

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Bradyarrhythmias

Perioperative bradyarrhythmias usually respond to short-term pharmacological therapy; temporary pacing rarely required. 1

Indications for temporary pacing:

• Complete heart block 1
• Symptomatic asystolic episodes 1

Not indicated for temporary pacing:

• Asymptomatic bifascicular block with or without first-degree AV block 1
• External pacemaker for transcutaneous pacing should be available 1

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Critical Contraindications and Precautions

Beta-blockers:

• Avoid in asthma, obstructive airway disease, decompensated heart failure, pre-excited AF/flutter 1
• Mask hypoglycemic tachycardia in diabetics 2

Calcium channel blockers:

• Never use verapamil/diltiazem for wide-QRS tachycardia of unknown origin, especially with myocardial dysfunction 1
• Avoid in pre-excited SVT/AF 1

Amiodarone:

• Use extreme caution with heart rate <60 bpm, systolic BP <100 mmHg, or moderate-to-severe LV dysfunction 3

Procainamide:

• Avoid in QT prolongation and heart failure 1

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Common Pitfalls to Avoid

• Do not cardiovert minimally symptomatic AF until underlying problems corrected; spontaneous conversion is common 1, 5
• Do not treat asymptomatic premature ventricular contractions with antiarrhythmic drugs 5
• Avoid class IC antiarrhythmics in patients with prior myocardial infarction 5
• Balance anticoagulation benefits against postoperative bleeding risk in AF 1
• Correct electrolyte abnormalities immediately (potassium, magnesium) before initiating antiarrhythmics 1, 4, 5
• Optimize pain control to reduce sympathetic drive and tachycardia 5