Electromechanical association: a subtle electrocardiogram artifact.

Artifacts on electrocardiogram (ECG) can simulate serious cardiac disorders. Although most common ECG artifacts can be easily recognized, in some exceptional situations, some patterns may hide pretty well even from experienced eyes. We recently reported an unusual ECG artifact caused by radial arterial impulse that closely imitates abnormal T wave. We now report 3 more examples and caught-in-the-act evidence of this subtle and dangerous artifact source.