External monitoring-induced pacemaker-driven tachycardia: a case report

A 55-year-old African-American woman with a history of end-stage renal disease secondary to systemic lupus erythematosus, dual-chamber pacemaker placement secondary to sick sinus syndrome, and a previous subarachnoid hemorrhage presented via ambulance to our Emergency Department (ED) from an outside hospital with the report of altered mental status, hyperkalemia, and hypoglycemia. In the ED, the patient's initial physical examination revealed a stable, normal heart rate. Reassessment after placement of external monitoring devices found the patient to be tachycardic at approximately 132-135 beats/min, with minimal variation in rate. The patient was also tachypneic during this episode, up to a respiratory rate of 38 breaths/min. When misplaced external monitoring device leads were removed during pacemaker interrogation, the patient's heart rate dropped to the 70s. Reapplication of the external monitoring leads replicated the tachycardia. With permanent repositioning of the leads in the ED, the tachycardia did not return. The placement of the leads was determined to have caused a plethysmography-induced pacemaker-driven tachycardia.