Magnetic Resonance in the Assessment and Development of Surgical Strategies For Protecting the Brain During Cardiovascular Surgery

摘要

Summary. Neurological and neuropsychological impairments are important sequelae of cardiac surgery with cardiopulmonary bypass, particularly aortic arch surgery requiring circulatory arrest. The nature of the underlying brain injuries remains poorly understood. Hypothermic circulatory arrest is commonly used for brain protection during aortic arch surgery, but the safe duration of this technique is limited. Other techniques used for brain protection have been proposed and used clinically. However, none of the techniques is completely satisfactory. Precise, and preferably quantitative, definition of the localization and nature of the underlying injuries is a precondition for"rigorous evaluation of the efficacy of prophylactic measures. Magnetic resonance (MR) spectroscopy and imaging are unique, non-invasive tools that are amenable to repetitive monitoring of the anatomical, biochemical and physiological status of the brain. The ability of magnetic resonance spectroscopy and imaging to detect physiological and pathological changes in the brain is described. Results of serial experiments studying the biochemical and physiological sequelae of various selective brain perfusion techniques in an in vivo pig model are presented. MR imaging can provide non-invasive information on physiological and pathological changes and MR spectroscopy can follow changes in metabolism and intraceliular pH in the brain in various body perfusion situations. The combined information can help understand the nature of underlying brain injuries and develop better surgical strategies for protecting the brain during cardiovascular surgery.