A myocardial infarct (M.I.) can be followed chronologically by observing the morphological changes that occur in the myocardium. One hour after the onset of ischemia, stretching and waviness of the myocytes may be seen at the border of the infarct, as seen in this slide. Often, although not in this slide, large vacuoles are found within the injured myocytes. Coagulative necrosis is not visible at this time. After twelve hours, but within seventy-two hours, a typical pattern of coagulative necrosis is seen and there is a neutrophilic infiltrate. During days three to seven, macrophages remove the necrotic tissue. From day seven to day ten, collagen replaces the necrotic tissue and a dense scar begins to form. At day ten, most of the necrotic myocardium has been removed, but the fibrous scar tissue has not yet been substantially formed. It is at this time that rupture of the heart is most common.
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