title: Electrical alternans: a sign, not a diagnosis.
abstract: Electrical alternans is an electrocardiographic phenomenon defined as an alternating amplitude or axis of the QRS complexes in any or all leads. It is most commonly associated with a large pericardial effusion and impending threat of cardiac tamponade; however, a literature review showed that this electrocardiographic finding can be seen in a variety of other clinical scenarios with varying etiologies and prognoses. Several electrocardiogram examples are presented with a brief review of the potential mechanisms and clinical significance and demonstrate that electrical alternans is more correctly considered an electrocardiographic sign, rather than a diagnosis, with a broad differential for potential etiologies. For some causes, the clinical significance is well known, but for others, further research is needed.
authors.affiliation: Cardiology Service, Carl R. Darnall Army Medical Center, Fort Hood, TX 76544, USA. Manju.Goyal.mil@mail.mil
authors.forename: Manju
authors.initials: M
authors.lastname: Goyal
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Woods
authors.forename: John E
authors.initials: JE
authors.lastname: Atwood
mesh_terms: D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000209:etiology* / Q000628:therapy; D004562:Electrocardiography; D006801:Humans; D011379:Prognosis