Atypical electrical alternans due to left pleural effusion

Abstract

Electrical alternans i.e., beat to beat of variation of QRS amplitude has been classically described in pericardial tamponade. Rarely, alternative causes are found in patients with QRS alternans. We report a case of atypical electrical alternans in a middle-aged female in the absence of pericardial effusion. A careful analysis of QRS complexes in our case suggested a unique pattern of alternans varying with respiratory movements instead. On evaluation, we found large left sided pleural effusion as the key underlying mechanism of the atypical alternans.