Muscle-tremor artefact is a potential cause of misdiagnosis of atrial arrhythmias on electrocardiography (ECG) monitoring. Such errors may lead to inappropriate and potentially dangerous therapies in some patients. We present a case of a patient with uncontrolled seizures whose bedside electrocardiogram monitor analysis appeared to demonstrate atrial flutter with 4:1 conduction through the AV node. The ECG monitor and ECG rhythm strip additionally showed a regular ventricular rate of 94 bpm with an underlying regular `saw-tooth` baseline. We applied cardioversion to convert to sinus rhythm. Amiodarone was loaded and added to the patients therapy who had atrial flutter after cardioversion. Echocardiogram was performed by a pediatric cardiologist and they noted that the atrial rate and ventricular rate were equal. After this, we began to suspect this situation might be a pseudoflutter due to his muscle contractions. We applied rocuronium to the patient to understand whether this was a pseudo-flutter or not. We saw that the ECG returned to normal sinus rhythm. Physicians especially working in intensive care units should be aware of artifact to avoid unnecessary therapeutic procedures. As Hippocrates said centuries ago `First, do no harm.`.

Keywords: atrial flutter, cardioversion, electrocardiogram