Demonstration of the rate-dependent rather than mechanism-dependent nature of electrical alternans in supraventricular tachycardia

Transient electrical alternans in a patient with sinus tachycardia attributed to orphenadrine citrate ingestion

“…Tachyarrythmias are listed as a rare side-effect of this medication, 5 and are thought to be primarily because of anticholinergic effects. While case studies exist of EA patterns in patients presenting with other supraventricular tachyarrythmias, 6 we could not find any previous cases in the literature which described EA with a sinus tachycardia, in the absence of a mechanical or structural cause within the thorax.…”