Pseudo atrial flutter

Atrial flutter typically has a cycle length of 200 ms (300 cycles/min or 5 Hz); with 4:1 conduction through the AV node, this would lead to a ventricular rate of 75 bpm. We present a case of a patient with a Parkinsonian tremor at a frequency of 300 cycles/min that masqueraded as atrial flutter on the limb leads of a 12-lead ECG. He had presented with a respiratory tract infection and his bedside rhythm monitor appeared to show atrial flutter. This appeared consistent on a printed (lead II) rhythm strip. His intrinsic sinus rate was coincidentally 75 bpm, which added to the confusion in the initial assessment of his rhythm (mistaken to be atrial flutter with 4:1 AV conduction). Advice was sought regarding management of his atrial 'arrhythmia' and the appropriateness of anticoagulation and cardioversion. A 12-lead ECG was performed and assessment of this revealed normal sinus rhythm. He therefore avoided unnecessary therapy.