ZOLL Medical Corporation and the FDA notified healthcare professionals of a Class 1 recall of ZOLL AED Plus Defibrillators distributed from May, 2004 through February 9, 2009. The recall was initiated because the device may fail to deliver a defibrillation shock, which could result in failure to resuscitate a patient during treatment of sudden cardiac arrest. On February 12 and March 31, 2009, the company sent their distributors and customers recall letters with recommendations and instructions for customers on specific steps to mitigate the identified problems with this device.