| Background and objective:Cardiopulmonary bypass (CPB) as a vital insurance is used in the most of cardiovascular surgery. Most of the complex congenital heart disease and great vessels are operated under the deep hypothermic circulation arrest. Due to cerebrum hypoxia-ischemia for long time, the metabolism chain was broken, adenosine triphosphate(ATP) stored was exhausted rapidly, glucose zymolysis was increased, and acidosis was occurred inside cerebral cell. The cerebrum energy metabolism and tissue structure was severe destroyed due to oxygen free radical and microcirculation dysfunction, when the brain was reperfused. Jonas believed that the patients could be have nervus system complications while the rectal temperature was 18℃, the time of circulation arrest longer than 40 minutes during CPB. Those patients could have symptom such as athetoid movements, transient convulsion in short time and retard of psychomotor development, difficult recognition in long term. So most of scholars believe that simple deep hypothermia reduce nervous system injury after hypoxia-ischemia for long time is not enough.Recently, deep hypothermic low flow (DHLF) is emphasised, it could ensure operation vision clear and reduce ischemia-reperfusion injury according to rectal temperature is 18℃, perfusion flow drop from 100 ml·kg-1·min-1 to 25 ml·kg-1·min-1 during CPB. It is infered that 25 ml·kg-1·min-1 of perfusion flow could be benefits to brain function recovery in short time.The amino acid derivative carnitine (3-hydroxy-4-Ntrimethylammonium-butyrate) is required for the maintenance of normal mitochondrial function. From the research of myocardium hypoxia-ischemia injury, Carnitine has three major functions: facilitating oxydation of hydrocarbon ; adjust the oxydation balance between glucose and fatty acid; eliminating oxygen free radial. The foreign scholars research mechanisms of Alzheimer's neurological dysfunction induced by injecting streptozo-tocin to cerebral ventricle in rats.
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