CLINICS 2012;67(5):503-508 Cardiac changes following hypoxia Faa A et al. Figure 1 - Interstitial edema and wavy fibers. two-tailed. The statistical significance was set at 0.05, and the analysis was conducted using SPSS statistical software (version 17.0). RESULTS In total, 13 out of 40 piglets required chest compressions and the use of adrenaline. More specifically, five animals from group 1, two animals from group 2, three animals from group 3 and three animals from group 4 required more aggressive resuscitation. The histological examination of H&E-stained sections revealed pathological changes in all of the specimens. Interstitial edema was observed in 37/40 cases (92.5%); the degree of edema varied among the cases. In four cases (one in group 1, two in group 2 and one in group 3), the edema was severe and diffuse, leading to disarrangement of the myocardial architecture (Figure 1). In the majority of cases, the interstitial edema was mild and focal, primarily localized around small, dilated vessels. A wavy arrangement of cardiomyocytes was detected in all but nine cases (77.5%). In 19 hearts, the wavy fibers were focal, whereas in the remaining specimens, the wavy arrangement was diffuse (Figure 1). Cardiomyocyte hypereosinophilia was observed Figure 3 - Coagulative necrosis. in 28/40 cases (70%). This condition was characterized by cardiomyocyte cytoplasm with a homogeneous appearance, which was associated with an increase in the intensity of eosin staining (Figure 2). Hypereosinophilic fibers were mainly detected in small foci. Coagulative necrosis was detected in 26/40 hearts (65%). The degree of coagulative necrosis varied significantly among cases. In 13 hearts, this condition was mild and focal; in 12, it appeared in large foci; and in one case, coagulative necrosis diffused to large areas of the heart specimen examined (Figure 3). Apoptotic cells, characterized by the detachment of scattered cardiomyocytes from neighboring cells with the formation of roundish eosinophilic globules (Figure 4), were found in 3/40 cases (7.5%). This apoptotic cell death was mild and focal in five cases, whereas in one case, apoptotic globules were frequent and had diffused to all the heart regions sampled. Cytoplasmic vacuoles were found in 15/ 40 hearts (37.5%); vacuolization most often affected small groups of cardiomyocytes (Figure 5), whereas in one case, it was observed in the majority of cardiac cells. Contraction changes were rarely observed, and when present, the lesion was always focal. In contrast, nuclear lysis Figure 2 - Hypereosinophilia of cardiomyocytes. Figure 4 - Nuclear polymorphism and apoptosis. 505