Case report of life threatening EKG artifacts due to electrical interference between monitoring equipments

The electrical interference in electrocardiogram (EKG) caused by procedures like electroconvulsive therapy, extracorporeal roller pump, deep brain stimulation, crystalloid administration are well known in the literature and they varies from mild interferenceto life threatening arrhythmia. This may create unnecessary panic in operation theaters, cardiac catheterization laboratories or other setups while managing critical patients. We came across a case of 23-year-old male with rheumatic heart disease who was undergoing cardiac catheterization. He was being monitored simultaneously for ECG and intra-arterial pressure with a monitor (Seimens-elema-AB). The patient was showing normal sinus rhythm in EKG. After that he was put on COM machine for noninvasive cardiac output monitoring. After switching on the COM machine, the EKG waveform changed from normal sinus rhythm to one resembling to life threatening ventricular tachycardia EKG. That lead to panic in catheterization laboratory, but patient remained clinically and hemodynamically stable (as evidenced by no alteration in arterial pressure waveform) throughout this period.EKG waveform returned to normal on switching off the COM device. This finding was consistent and reproducible. The alteration did not occur on using a different EKG and pressure-monitoring device. The alteration in waveform was obviously due to electrical interference between two monitoring equipments. On closer examination of the waveform, true R-waves can be seen superimposed on an undergoing sinus wave pattern.