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

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