Prospective evaluation of verbal memory performance after cardiopulmonary bypass surgery

One hundred and four patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) and a surgical control group undergoing major vascular or thoracic surgery (n = 18) were tested with the Auditory Verbal Learning Test (AVLT) at the following intervals: 1 day before, 1 week after, and 6 months after surgery. Early after surgery a significant decline in AVLT-performance was found, characterized by a smaller carry-over of learned words on subsequent acquisition trials. Six-month follow-up data revealed significant improvement in the delayed retention of words as compared to the preoperative assessment. No surgical group differences or time by group interaction effects were found. In the CPB group, deeper levels of hypothermia, reflecting longer and more extensive cardiac surgery, were associated with reduced improvement on retest.