Shock Whilst Gardening-implantable Defibrillators & Lawn Mowers™

Electromagnetic interference with implantable cardioverter defibrillators (ICDs) can cause inappropriate shock delivery or temporary inhibition of ICD functions. We present a case of electromagnetic interference between a lawn mower and an ICD resulting in an inappropriate discharge of the device due to erroneous detection of ventricular fibrillation. Clinicians are continuously faced with curious implantable cardioverter defibrillator (ICD) findings including electromagnetic interference. They should be well-informed on potential sources of electromagnetic interference and their handling. 30 cm between combustion engines of this type in order to avoid electromagnetic interference. A 77-year-old patient with coronary artery disease and severely reduced left ventricular ejection fraction was supplied with an ICD 12 years ago, having survived ventricular fibrillation through successful cardiopulmonary resuscitation. Recently, he presented for a routine follow-up of his ICD without any specific complaints. Parenthetically, the patient mentioned experiencing an electric shock while bending over the engine of his 10-year-old lawn mower (HONDA lawn mower, combustion engine GCV 135, HONDA, Tokyo, Japan) a few months ago. Interrogation of the ICD showed normal lead values and did not point towards any device or lead malfunction. However, the ICD Holter revealed one episode husqvarna 450x residential robotic lawn mower of electromagnetic interference with erroneous detection of ventricular fibrillation and subsequent delivery of a 35 J shock (Figure 1). This coincided with the reported incident. After the shock, the patient immediately kept his distance from the engine. Normal bifocal stimulation was restored. Thus, the electric impulse striking the patient did not originate from the lawn mower but from the ICD. Episode stored in the ICD memory showing the atrial electrogram (first line), the ventricular electrocardiogram (middle line) and marker and interval annotations (bottom line). Intrinsic atrial rhythm and paced ventricular rhythm is overlapped by highly regular signals of the electromagnetic field of the lawn mower engine causing inappropriate detection of ventricular fibrillation and subsequent ICD discharge (arrow). The patient steps away from the lawn mower and no further interference is present thereafter. Episode stored in the ICD memory showing the atrial electrogram (first line), the ventricular electrocardiogram (middle line) and marker and interval annotations (bottom line). Intrinsic atrial rhythm and paced ventricular rhythm is overlapped by highly regular signals of the electromagnetic field of the lawn mower engine causing inappropriate detection of ventricular fibrillation and subsequent ICD discharge (arrow). The patient steps away from the lawn mower and no further interference is present thereafter. 30 cm between his chest and the engine. Without any apparent defect of the lawn mower, especially no short circuit, we advised the patient to continue using his lawn mower while keeping his habitual safe distance to the engine. During a follow-up of 6 months no further complications occurred. Given the current ICD implantation rates, every family and general practitioner in the United States will be faced with one new ICD recipient among his/her patients every 2 years. Any of these patients may present with the feeling of an ICD discharge while being exposed to an electromagnetically hostile environment. Although a detailed medical history may help with identifying the aetiology of the electric shock, device interrogation is the only way to differentiate between several possible scenarios: (i) Electric shock caused by defective household devices themselves as presumed by our patient.