What type of arrhythmia is propylene glycol most commonly associated with?

Propylene Glycol and Cardiac Arrhythmias

Propylene glycol is most commonly associated with ventricular arrhythmias, particularly ventricular tachycardia and ventricular fibrillation, though it can also cause bradyarrhythmias and conduction disturbances.

Mechanisms and Presentation

Propylene glycol is widely used as a solvent in many pharmaceutical preparations, including intravenous medications like lorazepam, phenobarbital, and phenytoin. While generally considered safe at normal doses, it can cause significant cardiac toxicity when administered in large amounts or in patients with risk factors.

The cardiac effects of propylene glycol include:

1. Ventricular arrhythmias:

   • Ventricular tachycardia
   • Ventricular fibrillation
   • Torsades de pointes (less common)

2. Conduction abnormalities:

   • Bradycardia
   • AV block
   • Conduction disturbances

3. Other cardiac effects:

   • Hypotension
   • Myocardial depression

Risk Factors for Propylene Glycol Cardiac Toxicity

The risk of propylene glycol-induced arrhythmias is significantly increased in:

• Patients with renal insufficiency 1
• Patients with hepatic dysfunction 1
• High cumulative doses of medications containing propylene glycol
• Rapid infusion rates
• Concurrent use of other cardiotoxic medications

Clinical Presentation and Diagnosis

Propylene glycol toxicity often presents with:

• High anion gap metabolic acidosis
• Increased osmolar gap
• Lactic acidosis
• Sepsis-like syndrome 2
• Cardiac arrhythmias

The challenge in diagnosing propylene glycol-induced arrhythmias is that many symptoms can mimic sepsis, which is common in critically ill patients 2.

Management of Propylene Glycol-Induced Arrhythmias

When propylene glycol toxicity is suspected as the cause of arrhythmias:

1. Immediate discontinuation of the offending agent containing propylene glycol 3

2. For ventricular tachycardia/fibrillation:

   • Standard ACLS protocols
   • Beta blockers may be considered 3
   • Sodium bolus may be effective for cardioversion-resistant VT 3

3. For conduction disturbances:

   • Temporary pacing may be required for severe bradyarrhythmias 3

4. For metabolic derangements:

   • Hemodialysis is effective for removing propylene glycol 1
   • Correction of electrolyte abnormalities

Prevention Strategies

To prevent propylene glycol-induced arrhythmias:

• Limit the dose of propylene glycol-containing medications, especially in high-risk patients 1
• Consider alternative formulations without propylene glycol when possible
• Regular monitoring of osmolar gap in at-risk patients 2
• Close cardiac monitoring in patients receiving high doses of propylene glycol-containing medications

Special Considerations

Interestingly, while high doses of propylene glycol can cause arrhythmias, some research suggests that at certain doses, propylene glycol may actually have antiarrhythmic properties 4. This paradoxical effect highlights the importance of appropriate dosing.

In patients with end-stage renal disease, the risk of propylene glycol toxicity is particularly high due to impaired clearance, and these patients should be monitored closely when receiving medications containing this solvent 2.