Elevation of defibrillation thresholds with propofol during implantable cardioverter-defibrillator testing

A 26-year-old man with severe dilated cardiomyopathy and frequent ventricul ar tachycardia treated with propafenone plus mexiletine underwent implantab le cardioverter-defibrillator testing one day after dual chamber defibrilla tor implantation. There were no significant changes in the R-wave and lead position on chest x-ray, Routine defibrillator threshold (DFT) testing afte r 320 mg intravenous propofol demonstrated high DFTs (greater than 31 Joule s and requiring 360 Joules externally for termination). Change in polarity failed to improve DFTs, After about 20 minutes of washout, conscious sedati on was performed with 20 mg of midazolam and repeat DFTs were equal to 21 J oules, This case demonstrates the potential for an acute dose dependent ris e in DFT with propofol.