细胞损伤严重时，可导致坏死。光镜下显示心肌纤维紊乱，许多细胞坏死以后，使心肌组织不能辨认。
许多细胞核发生了核浓缩，接着出现核碎裂和核溶解现象。细胞浆和细胞核的边缘分辨不清。
When there is marked cellular injury, there is cell death. This microscopic appearance of myocardium is a mess because so many cells have died that the tissue is not recognizable. Many nuclei have become pyknotic (shrunken and dark) and have then undergone karorrhexis (fragmentation) and karyolysis (dissolution). The cytoplasm and cell borders are not recognizable.