BALTIMORE, MARYLAND. Coronary-artery bypass grafting (bypass surgery) is a very popular surgical procedure with more than 500,000 operations performed every year in the US alone. While the operation may improve heart performance it is now clear that it can seriously affect the brain. The risk of a stroke immediately following the procedure is 1.5 to 5.2 per cent; the risk of delirium (illusions, disorientation, hallucinations or extreme excitement) is 10 to 30 per cent and the risk of a significant cognitive decline is 33 to 83 per cent. Researchers at the Duke Medical Center now report that the cognitive decline persists for at least five years after the operation. This finding clearly supports common reports by patients that they are "just not the same" after the surgery. The observed cognitive changes involve loss of memory, problems with following directions, mental arithmetic, and planning complex actions. Mood swings, frustration, and short tempers are also common side effects of bypass surgery. The Duke researchers found a high (53 per cent) average decline in cognitive function at the time of discharge from the hospital when compared to the base level prior to the operation. The decline was reduced to 36 per cent after six weeks and to 24 per cent after six months. Surprisingly, after five years the decline had worsened to 42 per cent indicating that 42 per cent of patients had a cognitive performance significantly below their level before surgery. The researchers believe that after effects from anesthesia and the "showers" of blood clots released during bypass surgery are responsible for the adverse effects on the brain.
Newman, M.F., et al. Longitudinal assessment of neurocognitive function after coronary-artery bypass surgery. New England Journal of Medicine, Vol. 344, February 8, 2001, pp. 395-402
Selnes, Ola A. and McKhann, Guy M. Coronary-artery bypass surgery and the brain. New England Journal of Medicine, Vol. 344, February 8, 2001, pp. 451-52 (editorial)