The benefits of open-heart surgery as reflected in the EEG.

A one-year electroencephalographic (EEG) follow-up study was carried out on 65 cardiac valvular replacement patients with the main aim of investigating the nature and determinants of EEG disturbances related to cardiac valvular disease and surgery. The pre-operative incidence of abnormal EEG was high (49%, indicating the impairing effects of prolonged circulatory inadequacy. The brain proved highly sensitive to operative strains, as is reflected in the observed EEG changes: marked increase in slow wave abnormalities; increase in bilateral and continuous disturbances; slowing of the dominant activity. Generally, the postoperative disturbances were rapidly reversible. The long-term EEG outcome was favourable: one year after operation the incidence of abnormal EEG had decreased to 25%. Of the operative factors, age, cardiologic diagnosis and technical difficulties during operation were found the most significant determinants of cerebral dysfunction.