Signs of brain cell injury during open heart operations: past and present

Signs of brain cell injury have been studied during the evolution of open heart surgery in the last quarter century. At the beginning of the period, it was possible to elucidate signs of brain injury with rather crude psychometric tests and clinical observations in seemingly normal patients having routine operations. Over the next 5 years, a marked improvement in psychometric scores was observed. However, a biochemical cerebral cell injury marker (adenylate kinase) showed increased levels in the cerebrospinal fluid, a finding indicative of brain cell injury. There was a correlation between cerebrospinal fluid levels of adenylate kinase and psychometric test results as well as between the marker levels and clinical signs. Because of the relative insensitivity of the psychometric tests used and the increasing difficulty in receiving permission for spinal fluid taps, other methods were sought. Refined psychometric memory tests were used and showed that even in the 1990s, there are subtle signs of brain cell injury during open heart operations. This finding was corroborated by using a highly brain-specific and brain-sensitive biochemical cell injury marker (S-100 beta) that increased during extracorporeal circulation and showed a correlation with clinical cerebral complications.