| Abstrakt: |
Many of the antiarrhythmic drugs produce a rise in the ventricular defibrillation threshold (DFT). Although mexiletine has also been reported as the probable cause of a significant elevation of DFT, there has been no previous study; therefore, the effect of mexiletine on DFT was investigated in the present study. The experiments were performed on ten mongrel dogs in the open-chest state using general anesthesia. Mexiletine 1, 2, 4, 6, or 8 mg/kg was administered as the loading dose, followed by the same dose/kg per hour. In these five groups, fibrillation/defibrillation (F/D) trials were performed repeatedly every 10 minutes, until 60 minutes after starting the maintenance dose. F/D trials were also performed at 30, 45, and 60 minutes after the completion of mexiletine infusion. The heart was allowed to fibrillate for a total of 30 seconds. Applying internal paddles to the heart, energies of 2, 3, 5, 7, 10, 20, and 30 J maximum were used. The minimal energy shock that caused defibrillation was defined as the DFT. The mexiletine concentration in each group changed from 0 to 6.11 µg/mL, DFT ranged from 2-10 J, and no statistical correlation was found between mexiletine concentration and DFT. We conclude that mexiletine does not induce an increase in DFT in dogs. [ABSTRACT FROM AUTHOR] |
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