Postoperative electroencephalographic change in old patients with cardiac surgery

The purpose of this study was to evaluate cerebral dysfunction in aged patients associated with cardiac surgery using quantitative electroencephalograph (QEEG). Seventeen consecutive patients undergoing cardiac surgery were investigated. There were nine males and eight females whose ages ranged from 65 to 77 years (mean 70.6 years). The cardiac procedures consisted primarily of coronary artery bypass (eleven patients) and valve replacement (six patients). They had good postoperative course, no complications were recognized. Each patient had an EEG examination using digital EEG equipment in first day before operation. Follow up investigations were repeated three times (first day, fifth day and one month after operation). QEEG analysis consisted of fast Fourier transform method was performed in each record. A fall in the peak frequency at basic rhythm was seen in 1st and 5th postoperative day. A power spectra corresponding to slow wave showed an increase at parieto-occipital area in 1st and 5th postoperative day. Alpha activity at occipital area was increased in one month after operation. The EEG change in first or fifth postoperative day suggested the patients had cerebral dysfunction without clinical findings.