Interference of automated electroencephalographic processing by an endocardial pacemaker.

This article reports a patient with an endocardial pacemaker undergoing a carotid endarterectomy in whom cerebral function was monitored by using processed electroencephalography (EEG). The EEG was processed by means of aperiodic analysis. The pacemaker generated an artifact that was identified on the processed EEG display and on the raw EEG display. During the time of carotid cross-clamping, a loss of EEG activity was noted on careful examination of the processed EEG and confirmed by referring to the raw EEG. Nevertheless, because of the presence of the artifact, the activity edge remained essentially constant despite the change in underlying EEG activity. The cross-clamp was released based on the observed change in EEG activity, yielding a return to baseline EEG activity. The surgeon elected to shunt the patient. The patient awoke without neurologic sequelae. This case serves to demonstrate the importance of referring to the raw EEG signal and the limitations of the activity edge in the presence of artifact.