In a physician’s advisory dated October 6, 2005, St. Jude Medical Inc. announced that it has discovered that background levels of atmospheric ionizing cosmic radiation, more commonly known as cosmic rays, can affect a limited number of its older generation implantable cardioverter defibrillator (ICD) products.
The ICD products are within the Photon and Photon Micro device families and in certain Atlas devices.
They identified a particular vendor-supplied memory chip that can be affected at a low frequency rate by background cosmic radiation. Background cosmic radiation bombards the earth constantly. While the earth’s atmosphere acts as a shield and absorbs much of the cosmic radiation, some amount of high energy particles do arrive at the earth’s surface.
When the chip is exposed to background levels of cosmic radiation, it can trigger a high current drain condition, which will deplete the battery voltage rapidly. This can result in loss of output for a period of up to approximately 48 hours. During this period, a patient would be without pacing or defibrillation therapy.
The following St. Jude Medical ICDs are involved:
• Photon DR (Model V-230HV) (certain serial numbers)
• Photon Micro VR/DR (Models V-194/V-232)
• Atlas VR/DR (Models V-199/V-240)
Approximately 26,000 of these devices are in service. To date, the incidence rate is low and there have been no serious patient injuries or deaths reported to St. Jude Medical attributable to this anomaly.
St. Jude Medical began using a different vendor, who utilized a different memory chip design, in 2002. According to St. Jude Medical, laboratory testing and clinical experience indicate that the newer generation memory chip does not share the cosmic radiation problem.
St. Jude Medical notified the U.S. Food and Drug Administration (FDA) of the physician’s advisory, and the FDA may choose to recall the impacted devices.