Abstract
Autopsy cases of myocardial infarction (MI) were divided into two groups, that is, the first attack group (FAG) consisting of 34 cases of transmural infarction and the reattack group (RAG) consisting of 24 cases. Pathomorphological changes of the hearts of RAG were studied in comparison with those of FAG. Roentgenological distribution of calcified foci of coronary arteries and sites of stenosis of those by angiography were all examined.
The results obtained were as follows.
1) As to the distribution of sites of MI in RAG, the recent MI were located in the same cardiac wall as before in 5 case, in the partially overlapped wall in 12 cases and in the different wall in 7 cases. The size of recent MI was larger than the old MI in 10 cases, about the same extent in 5 cases and smaller in 5 cases, while in 4 cases the comparison of the extent of MI was impossible.
2) The mean heart weight was 430 g in FAG and 448 g in RAG, respectively. In FAG the heart weight was above 400 g in 64.7 %, while in FAG it was so in 75.0 %. As to the pattern of cardiac hypertrophy, the concentric hypertrophy was more frequent than the dilatation hypertrophy in FAG, but the results were reserve in RAG.
3) The calcification of the coronary arteries was not revealed in 3 cases of under 60 years old in FAG, but it was present in all cases of RAG. The severity of calcification increased with age after the first attack and this changes may play innegligible role in the development of the reattack.
4) In FAG one branch stenosis was seen in 15 cases, two branches stenosis in 13 cases and three branches stenosis in 5 cases. In RAG all cases showed stenosis of above 75 % and one branch stenosis was in 3 cases, two branches stenosis in 12 cases and three branches stenosis in 9 cases. The majority of death cases within a month in FAG revealed one branch stenosis and widespread infarcted area with cardiorrhexis. In RAG the extent of freshly infarcted area was related with the anatomical distribution of stenosis of the coronary arteries.
5) The degree of injury of coronary arteries in FAG was the most marked in case of one branch stenosis and became less marked in cases of two and three branches stenosis. But in RAG the degree of arterial injury was all higher with no relation to the distribution of stenosis.
6) The sclerosis of small arteries in the myocardium was shown in about one third cases in FAG and in one half ones in RAG. The sclerosis seemed to be more related with the severity of injury of the coronary arteries than the anatomical distribution of stenosis.
7) Chronological changes such as necrosis of myocardial tissue, removal of necrotic tissue and replacement by granulation tissue and scarring in order were regularly discernible in FAG, while in RAG fresh changes of infarction were intermingled with dilatation of blood vessels, hemorrhage and ischemic change of neighboring muscles.
8) As to complication of MI, the incidence of cardiorrhexis war 15 cases among 34 cases in FAG, while only 4 cases among 24 cases in RAG. The cardiorrhexis was much more frequent in FAG and had the tendency to occure in cases of widespread MI.
