Is deep hypothermia necessary for unilateral antegrade cerebral perfusion during circulatory arrest? A magnetic resonance study in a pig model

Objective: Localized P-31 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 hemisp heres of the brain during deep (15 degreesC) and moderate (28 degreesC) hyp othermic circulatory arrest (HCA). Methods: Eleven pigs were exposed to 120 min of U-ACP during HCA at 15 degr eesC (group I, n = 6) or 28 degreesC (group II, n = 5), followed by 60 min of cardiopulmonary bypass (CPB) at 37 degreesC. Localized P-31 MR spectra w ere acquired every 30 min. Histopathology was performed at the completion o f 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 w ere found in any of the energy metabolites or pHi between the left and righ t hemispheres. Histopathology showed no significant morphological changes i n the neurons. Conclusions: During either deep or moderate HCA, unilateral ACP through the right axillary artery prevents ischemic events in both hemispheres of norm al pig brains. Deep hypothermia may not be necessary when using U-ACP. Crow n Copyright (C) 2001 Published by Elsevier Science Ltd on behalf of The Int ernational Society for Cardiovascular Surgery. All rights reserved.