Ramkumar a 70-year-old hypertensive male Was admitted in the intensive care unit with transmural anterolateral myocardial infarction. His condition was stable till the fifth day of admission When he developed a pericardial friction rub and pleuritic chest pain which persisted despite narcotic and steroid therapy. On the seventh morning, he suddenly developed marked hypotension. On examination there was marked a 'tension of the jugular veins, accompanied a with electromechanical dissociation, Most likely, the patient had developed