Timeline of myocardial infarction pathology
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|Time||Gross examination||Histopathology |
|0 - 0.5 hours||None[note 1]||None[note 1]|
|0.5 – 4 hours||None[note 2]||
|4 – 12 hours||
|12 – 24 hours||
|1 – 3 days||
|3 – 7 days||
|7 – 10 days||
|10 – 14 days||
|2 – 8 weeks||
|More than 2 months||Completed scarring[note 3]||Dense collagenous scar formed[note 3]|
|If not else specified in boxes, then reference is nr |
- For the first ~30 minutes no change at all can be seen by gross examination or by light microscopy in histopathology. However, in electron microscopy relaxed myofibrils, as well as glycogen loss and mitochondrial swelling can be observered.
- It is often possible, however, to highlight the area of necrosis that first becomes apparent after 2 to 3 hours by immersion of tissue slices in a solution of triphenyltetrazolium chloride. This dye imparts a brick-red color to intact, noninfarcted myocardium where the dehydrogenase activity is preserved. Because dehydrogenases are depleted in the area of ischemic necrosis (i.e., they leak out through the damaged cell membranes), an infarcted area is revealed as an unstained pale zone. Instead of a triphenyltetrazolium chloride dye, a LDH (lactate dehydrogenase) dye can also be used to visualize an area of necrosis.
- Once scarring is completed, there is yet no common method of discerning the actual age of the infarct, since e.g. a scar that is four months old looks identical to a scar that is ten years old.
- Bishop JE, Greenbaum R, Gibson DG, Yacoub M, Laurent GJ. Enhanced deposition of predominantly type I collagen in myocardial disease. J Mol Cell Cardiol. 1990;22:1157–1165
- Table 11-2 in: Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson. Robbins Basic Pathology. Philadelphia: Saunders. ISBN 1-4160-2973-7. 8th edition.