title: Reversible EOL-indicator: a new cause for low pacemaker rate.
abstract: A case is presented in which a new cause for decrease in pacemaker rate was encountered: six months after implantation of a Medtronic 5967 pacemaker, the first routine check-up revealed a rate of 62.5 ppm instead of 70 ppm. After application of a magnet, all measurements returned to normal. The cause for this phenomenon, which could not be attributed to battery depletion or oversensing, was probably a change of state of the flip-flop which is responsible for the sudden rate drop of 10% which serves as the end-of-life (EOL)-indicator in this pacemaker. This change of state may result from a very short decrease of power supply voltage during shipment or at the time of implant, and is fully and permanently reversible by performance of the magnet test. In order to prevent unnecessary pacemaker explants, future pacemaker circuits should be redesigned to eliminate the effect of very short voltage changes. Meanwhile, a routine magnet test should be performed immediately after implantation.
mesh_terms: D011211:Electric Power Supplies; D004560:Electricity; D004868:Equipment Failure; D005260:Female; D006339:Heart Rate; D006801:Humans; D008280:Magnetics; D010138:Pacemaker, Artificial / Q000592:standards*