Last update:
25-Mar-2014

Cognitive decline is being diagnosed with increasing frequency as a complication of cardiac surgery, in both selective coronary artery bypass and various other types of cardiac surgery. Although cognitive decline may occur after general surgical operations, its frequency is much higher following cardiac surgery. Although the etiology of cognitive dysfunction after cardiac surgery remains unclear, many risk factors are identified, such as advanced age that restricts cognitive reserve and affects the ability to overcome brain damage, a low presurgical level of cognitive function, extensive atherosclerotic disease, diabetes mellitus, and increased concentrations of the protein S100 and neuron specific enolase, that are indicators of brain damage. The absence of a common and clear understanding of the etiology and natural history of cognitive decline following cardiac surgery is the product, to a great extent, of methodological limitations in the reported studies. These limitations are due to (a) the absence of consensus concerning the diagnostic criteria used for the detection of cognitive impairment, (b) the selection of inadequate control groups, (c) the unsuccessful and frequently limited selection of neuropsychological tests for the evaluation of cognitive function, and (d) the inadequate investigation of preexisting cognitive decline. Recent advances which make possible the accurate diagnosis of mild cognitive impairment and of dementia in older individuals by applying clinical, imaging, and biochemical markers provide, to a great extent, the ability to conduct studies free of the above limitations. Thus, it is now feasible to conduct appropriately designed research projects with the capacity to expand knowledge on the prevention, prognosis, and treatment options of cognitive decline following cardiac surgery.

Key words: Cognitive decline, Diffusion-weighted magnetic resonance imaging, Heart surgery, Ischemic lesions.