Cardiac Science is taking a voluntary field correction after it determined certain automated external defibrillators (AEDs) may not deliver therapy, according to a company statement. Electronic components in the defibrillators may fail, but the failure may not be detected by the device’s self-tests. The company has received 64 complaints concerning four resistors within certain AEDs and predicts the issue to occur in about one in 75,000 AEDs manufactured between August 2003 and August 2009.