Cosmic Rays May Affect Implantable Defibrillators (ICDs)

From the St. Jude Medical Website:

St. Jude Medical Inc. announced today 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.

Although the incidence rate is low, and there have been no serious patient injuries or deaths reported to St. Jude Medical attributable to this anomaly, the Company is taking a conservative approach in advising the medical community and regulatory agencies...

And from a letter sent to doctors:

This letter is written to provide you with important safety information regarding a memory chip component supplied to us and used in a limited number of St. Jude Medical ICD products within the Photon and Photon Micro device families and in certain Atlas devices.

Specifically, we have identified that a particular vendor-supplied memory chip can be affected at a low frequency rate by background levels of atmospheric ionizing cosmic radiation (background cosmic radiation). The anomaly can trigger a temporary loss of pacing function and permanent loss of defibrillation support. Our records indicate that you have implanted or are monitoring patients with impacted devices.

There have been no serious patient injuries or deaths reported to St. Jude Medical that are attributable to this low frequency anomaly found in the subject memory chip component. To date, an incidence of only 0.00167 of the devices at issue (60 out of 36,000) have been found to have been affected by background cosmic radiation. Although this incidence level is low, we are taking a conservative approach in advising you and the medical community about this issue...

The St. Jude Medical Website has more info.

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