The Consequences: Should this situation occur, it can be very serious. The following possible event could potentially occur:

	The device will no longer be able to pace the heart, shock the heart, sense abnormal rhythms or be interrogated by an external device programming computer.
	If the patient is pacemaker dependent then no pacemaker output will occur from the device after this failure; This may result in the patients death unless an "escape rhythm" occurs or external CPR is administered
	If a life threatening rhythm problem was the reason the device tried to shock the patient in the first place, then this rhythm will continue ultimately likely resulting in death to the patient (unless it self terminates or he/she is given advanced CPR externally).

The Risks: This failure is rare but obviously very serious when it occurs.  As of June 17, 2005, there have been 28 reported failures of this type out of 26,000 devices implanted.  The failures all have occurred in devices manufactured prior to April, 2002.  This includes approximately 14,000 devices currently implanted. Other failure may have occurred that have not been reported to the FDA with this device.  Remember, this failure can result in the death of the patient. Indeed, the recent news reports of the young patient with hypertrophic cardiomyopathy who died with this device illustrates such a tragic sequence of events. Unless, following a patients death an autopsy including device removal and forensic analysis is performed, then no one will ever know that the death was the result of a device failure and that patients device will assume to have been working normally.   If there have been 28 reported failures out of 14,000 the risk of failure is at least 1 in 500.  Since this failure tends to increase with the age of the device and since there is no question that deaths from this device failure could have occurred and never been discovered, the real risk of failure of this device is probably closer to 1% of all device implanted.  There is no way to discover by basic analysis of the device which device is likely to fail. Testing the devices ability to deliver high energy shocks appropriately may help uncover some of the devices that would otherwise ultimately fail. For many patients however, the first sign of failure of this device is at the time when it is needed to deliver therapies to treat otherwise life threatening rhythm problems. Guidant apparently was aware of this failure mechanism and did redesign the device (thus leading to no reported failures with the newer design after April, 2002).  Tragically however Guidant appears to have allowed previously manufactured devices to continue to be implanted until this older inventory was depleted.

	Replace the device if the patient is pacemaker dependent (i.e. the device is always working to maintain the heartbeat)
	Consider replacing devices is patients with this device are judge to be at very high risk for needing treatment for life threatening arrhythmias.  Such patients include those who have received appropriate therapies in the past for life threatening arrhythmias from the device and those who received the original device implant for aborted sudden death.
	Consider replacing the device in lower risk patients who would otherwise benefit from an upgraded device.  For example if since the device was implanted, the patient has developed congestive heart failure, then a new ICD with cardiac resynchronization pacing therapies for heart failure should be implanted.
	Consider annual or semi-annual testing of the devices high voltage subsystems by inducing an arrhythmia through the device (under safe controlled circumstances) and ensure that the device appropriately senses and delivers high voltage therapy for ventricular fibrillation.  This type of device check is an out-patient non-invasive test.  It is however done at the hospital after the patient is given a short acting sedative since the patient would feel the otherwise harmless shock the device delivers during this type of test.
	If the device is found to be beeping by the patient this can indicate a short circuit in the high voltage sub-system.  All beeping devices of this type need immediate analysis by a physician.
	Lower risk patients include those who have had their device implanted as a prophylactic measure because their ejection fraction or other factors places them in a group of patients who would benefit from having an ICD in place. In these patients, the risk of complications from immediate replacement of this device may exceed the long term benefits.  In many such patients all that is needed is careful routine follow-up and consideration for annual or semi-annual testing of the high voltage sub-systems of these devices. The majority of patients such as this will do well simply by following them without device replacement.  However, there is no way to guarantee that one of these devices wont fail when it is needed.  Thus, even in relatively low and moderate risk patients if the patient wants the assurance that there device will always work, then their device should be replaced for the patients peace of mind.