An autopsy case of cardiac tamponade caused by a ruptured ventricular aneurysm associated with acute myocarditis.

We report an autopsy case of hemopericardium caused by rupture of a ventricular aneurysm associated with acute myocarditis in an infant boy aged 2 years and 10 months. Three days before his death, the patient developed fever. On the day of death, he described an urge to defecate and attempted to do so in an upright position. While straining to defecate without success for a prolonged period, he stopped breathing and collapsed. On autopsy, his heart weighed 91.7 g and cardiac tamponade was evident, the pericardial cavity being filled with 140 mL of blood that had come from a 1.5-cm-long rupture in a 2.7×1.5 cm ventricular aneurysm in the posterior left ventricular wall. Patchy grayish-white discoloration was noted in the myocardium. Histologically, CD3-positive T lymphocytic infiltration accompanied by pronounced macrophage infiltration was observed in the myocardium. Hemorrhagic necrosis was detected in the area of the ventricular aneurysm. Staining for matrix metalloproteinase (MMP) expression revealed abundant MMP-2, MMP-7, and MMP-9. Polymerase chain reaction to detect viruses failed to identify any specific causative viruses in the myocardium. In this case of lymphocytic (viral) and histiocytic myocarditis with pronounced macrophage infiltration and upregulation of MMP expression, myocardial remodeling and associated wall weakening had resulted in formation and rupture of an aneurysm.