The short-term effects of off-pump cardiopulmonary bypass graft surgery on cognitive performance

Master Thesis


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University of Cape Town

Postoperative neurocognitive impairment has been associated with coronary artery bypass graft surgery (CABG). This study investigates the short-term effects of off-pump cardiopulmonary bypass graft surgery (OPCAB) on cognitive performance, as a possible safer alternative in the treatment of coronary artery disease. This research forms part of a larger study in which, in addition to the OPCAB procedure, the cognitive effects of CABG surgery and percutaneous transluminal coronary angioplasty with intra-coronary stenting are assessed. 36 participants undergoing OPCAB surgery were included in the study, with a further 36 participants included as an age- and education- matched non-surgical control group. A standardized battery of neuropsychological tests, designed to assess seven cognitive domains, was administered on two occasions, preoperatively at 1-2 days prior to surgery, and postoperatively at 1 month after surgery, with control participant assessments at the same intervals. Emotional state scales assessing depression and anxiety levels were administered at each assessment. Data analysis included a two-way mixed analysis of variance conducted on each measure of cognitive function, and on the indicators of emotional state. In addition, standard multiple regression was conducted to assess whether change in emotional state is able to predict change in any of the cognitive domains. Results indicated no evidence of short-term cognitive decline, and highlighted an improvement in cognitive performance in both surgical and control groups in the domain of language, psychomotor speed, executive function and visual memory, with the control group demonstrating a consistently superior performance. This counter-intuitive finding could not be attributed to practice effects.

Includes bibliographical references (leaves 56-67).