[The "border zone" of a developing myocardial infarct]

The heart of 42 patients dying within 24 hours from acute myocardial infarction was studied by ordinary light and polarizing microscope. The interrelationship between the zone of irreversible ischemic damage and surrounding tissue was investigated. It is shown that during the time of the infarction formation the border zone which could be morphologically identified is absent. Altered cells with relaxated sarcomers are found to be in close neighbourhood with surviving cardiomyocytes or a relatively narrow zone of reperfusion changes also consisting of non-viable myocytes is present between them.