The echo patterns on ultrasono-cardiotomogram were evaluated in relation to the histological changes of the myocardium. The ultrasono-cardiotomographic data were collected from 9 consecutive patients with transmural infarction (3 patients with antero-septal, 5 with postero-inferior, 1 with antero-lateral infarction) and also from 11 dogs with experimental myocardial infarction. Analyses of data obtained led to the following conclusion.
1) A decrement of the thickness and deformity of the wall echo: They were detected by a series of azimuthal angle and level ultrasono-cardiotomograms which were obtained by changing the direction and level of the ultrasonic beam through the heart along the long axis of the left ventricle.
2) An increment of echo-intensity of infarcted area: The intensity of abnormal echo of the infarcted area, when evaluated by using the intensity of the echo of normal pericardium as a reference of OdB, was +10 to +15dB more intense than that of the normal myocardium.
3) The study of the echo patterns in comparison with the histology of myocardium indicated that the echoes related to scar could be classified into 4 types: cord-like echo, scattered large nodular echoes, narrow band-like echo, and scattered small nodular echoes.
Types and indicated the formation of a transmural scar. Thus a possibility was suggested that histological characteristics of myocardial tissue could be estimated by a non-invasive method.