Monday, January 21, 2008

St Jude Announces Defibrillator Update Needed

61 microseconds.

That's a tiny, tiny fraction of a second. 0.000061 second to be exact.

Heck, to put it in perspective, light travels a mile in a vacuum in a little over 5 microseconds.

But if an arrythmia occurs in that tiny window, patient's with St. Jude Epic or Atlas implantable cardiac defibrillators (ICDs) might undersense (not see) a life-threatening arrhythmia. So St. Jude began notifying doctors that a software fix is available to assure their devices work properly, even in this tiny vulnerable timing window.

There are estimated to be 143,000 of these defibrillators implanted worldwide and only 8 patients have been affected with this problem so far. Gratefully, no one has died. The risk of a specific patient being harmed by this defect is estimated to be on the order of one in a million (0.000001).

So what does it mean for defibrillator patients and doctors caring for them?

It is not thought at this time that an extra office visit is required due to the rarity of the problem, but during a patient's next regularly-scheduled device clinic visit, they'll receive a "software upgrade" to their Epic or Atlas ICD to correct the problem.

What I found amazing was the engineers' ability to figure out the root cause of this problem in the first place.


Reference: St. Jude's "Dear Doctor" letter dated 16 Jan 2008 (pdf) with the models affected.

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