The ECG shows beat-to-beat alterations in the height of QRS complexes reflecting the swinging of the heart in the pericardial fluid(electrical alternans). This finding in combination with Hypotension suggest cardiac tamponade. other classic findings of tamponade including Low voltage complexes and tachycardia are not present
There is a narrow complex tachycardia at a rate of ~160 . each QRS complex is preceded by an abnormal p wave (inverted in the inferior leads, upright in aVR). occasional AV block is also present.