On 29 January 2014, St. Jude Medical issued a "Dear Colleague" letter regarding their review of incident reports on older-model pacemakers (Affinity, Entity, Integrity, Identity, Sustain, Frontier, Victory and Zephyr models) that occasionally dropped their output voltage during surgical electrocautery. (Here’s a publication describing two such cases.)
Several issues regarding this advisory letter are troubling.
First of all, according to the St. Jude letter: "Placing a magnet over the device or programming to an asynchronous pacing mode will not prevent this temporary reduction in pacing output." Consequently, St. Jude advises that pacemaker-dependent patients with these older pacemakers consider undergoing surgery without the use of electrocautery or to "employ appropriate precautions to ensure that the heart rate will be supported in the presence of electrocautery. Consideration of placing a temporary transvenous pacemaker is appropriate. (Emphasis mine)"
Typically, placing a magnet over pacemakers causes them to pace at a default "magnet rate" and pace at the programmed output voltage. This is such a common feature among pacemakers that it formed one of the cornerstones of the 2011 guidelines for peri-operative pacemaker management. While electromagnetic interference on older pacemaker models has been seen due to the device being reset, it is unusual for pacemaker output voltage to drop briefly. Furthermore, the recommendation to place a temporary pacing wire before surgery where electrocautery use is anticipated in pacemaker-dependent patients suggests there is no programmable "work-around" for this problem.
Secondly, while it seems an effort has been made to notify physicians about this problem with certain older St. Jude pacemaker models, it is concerning that I could not find the notice on St. Jude’s Healthcare Professional website at the time of this writing, nearly three weeks after date of the original notification letter. Furthermore, it is concerning that such an unusual (and potentially fatal) failure mode of these older models of pacemakers has not been made more public to patients with these older St. Jude pacemakers so they can serve as their own advocates when surgery is in its planning stages.