<prompt> Electrical alternans is seen in -Cardiac tamponadeRestrictive cardiomyopathyConstrictive pericarditisRight Ventricular MI RVMT  <response>: Electrical alternans is an electrocardiac phenomenon of alternation of QRS complex amplitude or axis between beats and a possible wandering base-line. It is seen in cardiac tamponade and severe pericardial effusion and is thought to be related to changes in the ventricular electrical axis due to fluid in the pericardium , as the hea essentially wobbles in the fluid filled pericardial sac . Ref Harrison 20,th edition pg 1543 