An unusual pacing artifact

Cardiac implantable electronic devices (CIEDs) are widely used in current practice. Analyzing the electrocardiographic patterns of these devices and having knowledge of artifacts is crucial to appropriate CIED management. A 32-year-old female patient presented at the device clinic for a routine follow-up visit. A dual-chamber pacemaker had been implanted 12 years previously for sinus node dysfunction. An initial 12-lead electrocardiogram (ECG) prompted concern due to a cyclical pattern of multiple, rapid pacing stimulus artifacts. Device interrogation revealed normal overall pacemaker function. Turning the pace gain function of the ECG machine off failed to eliminate the artifact. On review of the past medical history, the patient was found to have a prior diagnosis of congenital central hypoventilation syndrome and pulmonary hypertension, for which she underwent insertion of a diaphragmatic pacemaker. Interrogation of the diaphragmatic pacemaker revealed that the programmed parameters correlated with the frequency of the artifact noted on the ECG. In cardiac pacing, a single stimulus artifact of sufficient threshold can enable myocardial capture. Capturing diaphragmatic pacing, however, requires a train of multiple stimuli above the threshold. Thus, an understanding of the pacing configurations of various electrical devices that can potentially interfere with CIEDs is crucial to appropriate patient management.