High-dose lidocaine does not affect defibrillation efficacy: implications for defibrillation mechanisms

Area of Science:

• Anesthesiology
• Pharmacology
• Cardiology

Background:

• Lidocaine is a local anesthetic and antiarrhythmic drug.
• Its effects on defibrillation energy requirements (DER) are not fully understood.
• Sodium-channel blockade is a key mechanism of lidocaine's action.

Purpose of the Study:

• To assess the dose-response effect of lidocaine on DER.
• To correlate changes in sodium-channel blockade with DER.
• To investigate the electrophysiological mechanisms involved.

Main Methods:

• A dose-response study was conducted in pigs.
• Defibrillation energy requirements (DER) were measured at baseline and during lidocaine infusion.
• Ventricular conduction velocity and fibrillation cycle length were assessed.

Main Results:

• Low-dose lidocaine significantly increased DER by 51%.
• Very high-dose lidocaine reduced DER back to near baseline levels.
• Lidocaine demonstrated an inverted U-shaped dose-response curve for DER.

Conclusions:

• Lidocaine exhibits an inverted U-shaped dose-response curve for DER.
• High-dose lidocaine may limit adverse effects on DER, possibly via increased refractoriness.
• Unidentified actions of lidocaine may also contribute to these findings.