Patients whose mean arterial blood pressure drops during bypass surgery may be at risk for early difficulties in thinking, learning and memory, according to an article in the August 2007 print issue of Archives of Neurology.
"Many patients who undergo a coronary artery bypass graft (CABG) operation have pre-existing vascular disease, and a subset have pre-existing cognitive dysfunction," the authors write as background information in the article. "Although recent prospective controlled trials have suggested that CABG may not cause long-term cognitive dysfunction, there may be a subset of patients who experience short-term cognitive problems."
Rebecca F. Gottesman, M.D., of the Johns Hopkins University School of Medicine, Baltimore, and colleagues assessed 15 patients age 57 to 81 years undergoing CABG operations who were believed to be at high risk for having a stroke following surgery. All 15 patients were given cognitive (thinking, learning and memory) tests before and three to five days after surgery. Their blood pressure was taken before and during the operation and the mean arterial blood pressure (MAP) was measured. The MAP is calculated as the diastolic (bottom number) blood pressure plus one-third times the difference between the systolic (top number) blood pressure and the diastolic blood pressure and provides an estimate of the pressure that perfuses the various organs in the body. Thirteen of the patients also underwent magnetic resonance imaging (MRI) of the brain following surgery.