Summary

We present a case of a 59-year-old man with acute abdominal pain and progressive shortness of breath. A focused assessment with sonography for trauma scan showed free fluid in the hepatorenal recess and in the recto-uterine recess. Later, due to clinical deterioration and the differential possibility of a pulmonary embolism or aortic dissection, a CT scan was performed which revealed large pericardial effusion. This, together with a dilated vena cava inferior and portal system, raised the suspicion of cardiac tamponade. The diagnosis was confirmed by transthoracic echocardiography (TTE). In retrospect, the ECG at admission showed a sinus tachycardia, low-voltage QRS complexes and a total electrical alternans corresponding with the swinging heart seen on TTE. An electrical alternans on ECG is an important diagnostic clue but is often missed, causing an unnecessary delay to proper diagnostic and therapeutic measures.