Objective. Evaluating the presence of endothelial changes in myocardial
vessels in an experimental model of hypoxia and resuscitation in newborn
piglets. Methods. Fifty male Landrace/Large White neonatal piglets were
studied: ten of them were allocated in group A (control group,
SHAM-operated). In group B (forty animals, experimental group)
normocapnic hypoxia was induced by decreasing inspired concentration of
O-2 to 6%-8%. When the animals developed bradycardia or severe
hypotension, reoxygenation was initiated. The animals of group B were
allocated in 4 subgroups of 10, according to the concentration of O-2
they were resuscitated with (groups 1, 2, 3, and 4 received 18%, 21%,
40%, and 100% O-2, resp.). Results. Control group animals did not show
any significant endothelial lesions. Contrarily, endothelial lesions
were detected in all experimental group cases. When these lesions were
analyzed in the different heart zones, no significant difference in
their incidence was observed; analyzing the frequency in the animals of
the 4 subgroups, only microthrombosis showed a higher frequency in
animals in groups 4 and 3. Conclusions. Endothelial damage represents a
diffuse pathological feature in the myocardial vessels of piglets
subjected to normocapnic hypoxia and resuscitation suggesting a possible
role of hyperoxygenation in aggravating endothelial damage