Neuropathological features of profoundly hypothermic circulatory arrest: an experimental study in the pig.

Twenty-four neonatal pigs were exposed to periods of circulatory arrest of between 70 and 120 min under profound hypothermia at 15 degrees C. Brain tissue taken 6h after cardiopulmonary bypass was examined histologically and by electron microscopy for evidence of hypoxic damage. Specimens from control pigs and animals subjected to 70 min arrest showed no morphological changes in the cerebral or cerebellar neurones. The earliest changes were seen after 90-min arrest; these were highly significant after 120 min. The changes involved mainly the Purkinje cells of the cerebellum with vacuolation in the cytoplasm; the inferior half of the cerebellum was particularly affected. The frequency and pattern of selective vulnerability of the cerebellum may be related primarily to the nature of its blood supply.