A 62-year old man with carcinoma lung presented to emergency depament with respiratory distress. ECG showed electrical alternans. Most likely diagnosis is: (A) Pneumothorax, (B) Pleural effusion, (C) Cardiac tamponade, (D) Constrictive pericarditis
Answer is C. Electrical alterans-a beat-to-beat alternation in one or more components of the ECG signal-is a common type of nonlinear cardiovascular response to a a variety of hemodynamic and electro physiologic peurbations.Total electrical alterans with sinus tachycardia is a relatively specific sign of pericardial effusion,usually with cardiac tamponade.</p Ref:Harrison's med-18th edition,page no:1838