Histometrical estimation of scar tissue in hypertrophied human heart muscle.

Histometrical estimation of scar tissue was made on 28 hypertrophied human hearts obtained at autopsy in order to know the significance of scar tissue in the process of cardiac hypertrophy and in the development of cardiac failure. Estimation was made on histological specimens of the anterior wall of the left ventricle and the posteromedial papillary muscle, according to Chalkley's point counting method, and the amount of scar tissue was expressed by percentages. The mean percentages were 4.6, 8.5 and 18.3 in the epicardial, endocardial part of the left ventricle, and the papillary muscle. There were very significant differences between these 3 mean percentages. There was a very significant correlation between the percentages of scar tissue in the endocardial part of the left ventricle and heart weight. There were no definite correlations between the percentages of scar tissue in the epicardial part or in the papillary muscle and heart weight. From these results, possible causes of scar formation and significance of scar tissue to the development of cardiac failure were discussed.