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A 60-year-old man with a cardiac defibrillator implanted due to previous ventricular fibrillation arrest and ischaemic cardiomyopathy received a shock while cleaning his fish pond. At the time, his immersed arm was close to a submersed water pump, but the patient was asymptomatic. As a result of the shock he lost consciousness, but collapsed backwards, away from the pond. Interrogation of the device revealed a high-frequency artefact that was sensed by the device and triggered a shock. Device parameters were otherwise normal. Subsequently, the submersed water pump was found to be the source of an external alternating current leak and was identified as the likely cause of the inappropriate shock due to electromagnetic interference (EMI). Awareness of potential sources of EMI along with evaluation of data with a detailed clinical history is warranted in all cases.

Original publication




Journal article


BMJ Case Rep

Publication Date





Defibrillators, Implantable, Electrocardiography, Electromagnetic Phenomena, Humans, Male, Middle Aged, Ventricular Fibrillation