Cardiac changes following hypoxia Faa A et al. Figure 5 - Cytoplasmic vacuolization of the cardiomyocytes. (30/40) and cytoplasmic homogenization (24/40) were observed in the majority of cases; the nuclear loss typically appeared as a focal lesion, although in four cases, it was diffuse. Neutrophilic infiltrate was detected in 16/40 cases (40%). The foci of neutrophils were always mild, mainly located around blood vessels and always in association with interstitial edema. Small foci of hemorrhage were observed in 3/40 cases (7.5%); these features were always very small and were detected in proximity to the dilated vessels. Perinuclear halos were detected in only one deceased animal. When histological findings were analyzed in the four groups of animals, based on the O2 concentration used for resuscitation, no significant differences were observed CLINICS 2012;67(5):503-508 among the four groups regarding the following features: a) interstitial edema; b) wavy arrangement; c) hypereosino- philia; d) vacuolization; or e) contraction. Marked inter- individual differences were observed within each group regarding the severity of the edema, which ranged from focal and mild to marked and diffuse. The wavy arrange- ment was found to be mild or moderate and always focal. The histological changes observed in the four groups were as follows: a) apoptotic bodies were observed in 30% of animals from groups 1 and 4, whereas they were not detected in groups 2 and 3 b) the percentage of positive cases for neutrophil infiltrate varied among the 4 groups, ranging from 20% in groups 2 and 3 up to 50% in groups 1 and 4. When histological changes were examined in the five groups (A-E) formed based on the time required for recovery, two histological changes exhibited a progressive enhance- ment associated with recovery time: coagulative necrosis and cytoplasmic vacuolization. Coagulative necrosis was present in 14.3% of the animals in group A, 57.1% of the animals in group B and 100% of the animals in groups C and D. Regarding cytoplasmic vacuoles in the tubular cells, they were absent in all of the animals in group A, with levels reaching 57% in the piglets in group B. Figure 6 elucidates the changes in cardiomyocytes with respect to recovery time. DISCUSSION Fetuses and newborns are very susceptible to hypoxia and have a number of immediate adaptive mechanisms, such as hyperventilation and blood redistribution, which serve Figure 6 - Changes in cardiomyocytes with respect to recovery time. 506