Abstract
Eleven cardiac operations are reported in which there was electroencephalographic and/or clinical evidence of seizure activity during cardiopulmonary bypass (CPB). In four patients seizure activity appeared after acute episodes of cerebral ischaemia resulting from either hypotension or pump-generated emboli occurring at the beginning of CPB, or from air embolism occurring at the end of CPB when the myocardium was closed and defibrillated. In the remaining seven patients the seizures appeared to result from the synergistic action of a toxic substance in the perfusate with pre-existing or CPB-induced alterations in cerebral physiology.