Objective: Localized (31)P magnetic resonance spectroscopy (MRS) was used to investigate whether unilateral antegrade cerebral perfusion (U-ACP) could maintain normal energy metabolism and intracellular pH (pHi) in both hemispheres of the brain during deep (15 degrees C) and moderate (28 degrees C) hypothermic circulatory arrest (HCA).
Methods: Eleven pigs were exposed to 120 min of U-ACP during HCA at 15 degrees C (group I, n=6) or 28 degrees C (group II, n=5), followed by 60 min of cardiopulmonary bypass (CPB) at 37 degrees C. Localized (31)P MR spectra were acquired every 30 min. Histopathology was performed at the completion of each experiment.
Results: MR recorded no changes in energy metabolites (phosphocreatine and ATP), or pHi during U-ACP in either group, and no significant differences were found in any of the energy metabolites or pHi between the left and right hemispheres. Histopathology showed no significant morphological changes in the neurons.
Conclusions: During either deep or moderate HCA, unilateral ACP through the right axillary artery prevents ischemic events in both hemispheres of normal pig brains. Deep hypothermia may not be necessary when using U-ACP.