Single event upsets in implantable cardioverter defibrillators

Single event upsets (SEU) have been observed in implantable cardiac defibri llators. The incidence of SEUs is well modeled by upset rate calculations a ttributable to the secondary cosmic ray neutron flux. The effect of recent interpretations of the shape of the heavy ion cross-section curve on neutro n burst generation rate calculations is discussed. The model correlates wel l with clinical experience and is consistent with the expected geographical variation of the secondary cosmic ray neutron flux. The observed SER was 9 .3 x 10(-12) upsets/bit-hr from 22 upsets collected over a total of 284672 device days. This is the first clinical data set obtained indicating the ef fects of cosmic radiation on implantable devices. Importantly, it may be us ed to predict the susceptibility of future implantable device designs to co smic radiation. The significance of cosmic radiation effects relative to ot her radiation sources applicable to implantable devices is discussed.