心室中隔穿孔と右室自由壁破裂を合併した急性心筋梗塞症の一例—心破裂の機序に関する考察

A case of acute myocardial infarction complicated with interventricular septal perforation and right ventricular rupture

　近年Coronary Care Unit（CCU）の普及に伴い急性心筋梗塞症の不整脈死が減少し，かわって心破裂がポンプ失調に次ぐ急性心筋梗塞症の主要な死因の1つとなっている。急性心筋梗塞症の救命率を上げるために，その予知，予防対策がCCUの課題の1つといえる。

　心筋梗塞に合併する心破裂には，頻度として最も多い左心室自由壁の破裂（狭義の心臓破裂），心室中隔穿孔（IVSP），および乳頭筋断裂があり，その他稀に心房中隔破裂，右室自由壁破裂が報告されている。最近我々は，前壁中隔梗塞症に伴う右室前壁梗塞で，IVSPと右室自由壁破裂を合併して死亡した一剖検例を経験したので報告する。

A case of acute myocardial infarction complicat-ed with interventricular septal perforation (IVSP) and right ventricular rupture was experenced. A 75-year-old woman, diagnosed as acute anteroscp-tal myocardial infarction, manifested a sign of IVSP shortly after admission and fell into cardiogenic shock. Intraaortic balloon pumping was unsuccess-ful. Ten hours after admission, suddenly she lost her consciousness and electromechanical dissocia-tion was recognized. She died soon after.

Her autopsy revealed a transmural anteroseptal myocardial infarction with IVSP and transmural anterior right ventricular (RV) infarction with hemopericardium. Although the site of rupture could not be identified macroscopically, histologi-cal examination disclosed loss of normal myocar-dium and haemorrhage at the infarcted area of RV. It might be that cardiac rupture was occurred at the site. Intramyocardial venous congestion and ruptured vessel wall were recognized near by this area.

These findings indicated that there might be two different mechanisms of cardiac rupture in this case. One is the presence of RV infarction and increased RV volume and pressure overload due to IVSP. The other is primary intramyocardial venous con-gestion and vessel wall destruction which caused haemorrhage into myocardium. I nterraction of these different mechanisms of cardiac rupture should be investigated further.