Artefacts mimicking ventricular fibrillation

ECG Quiz 60 – Discussion

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In most of the leads, the tracing looks like ventricular fibrillation. QRS complexes are seen very well in lead I where the artefacts are not obvious. Close scrutiny also shows the QRS complexes in leads aVR and aVL.  Artefacts are seen in between the QRS complexes in these leads. In other leads, it is difficult to make out the QRS complexes. Though interpreting this ECG may be sometimes difficult, in the clinical setting there will be no difficulty as the person will not be in cardiac arrest. Such artefacts seen on the monitor can lead to inadvertent defibrillation. As artifacts are not seen in lead I, we may presume that the source of the artefact is in the left foot electrode. Lead I does not have a connection to left foot. It has connections only to left and right upper limbs.

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