Effects of flecainide on defibrillation threshold in pigs.

Flecainide has been reported to decrease defibrillation efficacy in pentobarbital-anesthetized dogs. Conversely, flecainide did not alter defibrillation energy requirements in halothane-anesthetized pigs. We wished to determine whether these discrepancies were related to defibrillation technique, interaction with the anesthetic regimen, or animal species. The effects of three doses of flecainide on defibrillation threshold (DFT) were determined using single- and sequential-pulse shocks in halothane-anesthetized open-chest pigs. Triplicate DFTs were obtained before and after three doses of flecainide (n = 34) or saline (n = 13) infusion. Similarly, the effects of the highest dose of flecainide were determined using barbiturate-anesthetized animals (n = 10). Flecainide did not alter DFT at any dose with either the single-pulse shock (control 17.7 +/- 2.1 J, highest dose of flecainide 19.1 +/- 3.2 J, p = NS) or sequential-pulse shock (control 9.2 +/- 1.0 J, highest dose of flecainide 8.4 +/- 1.4 J, p = NS) when halothane anesthesia was used. Similar results were obtained using barbiturate anesthesia either with sequential (control 8.7 +/- 0.9 vs. 8.2 +/- 0.6 J, p = NS) or single shocks (control 13.2 +/- 0.8 vs. 13.7 +/- 1.0 J, p = NS). Flecainide did not alter DFT in our model, regardless of defibrillation technique or anesthetic regimen.