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Noninvasive Assessment of Brain Injury in a Canine Model of Hypothermic Circulatory Arrest Using Magnetic Resonance Spectroscopy
- Source :
- The Annals of Thoracic Surgery. 81:1593-1598
- Publication Year :
- 2006
- Publisher :
- Elsevier BV, 2006.
-
Abstract
- Background Studies have confirmed the neuroprotective effect of diazoxide in canines undergoing hypothermic circulatory arrest (HCA). A decreased N-acetyl-asparate:choline (NAA:Cho) ratio is believed to reflect the severity of neurologic injury. We demonstrated that noninvasive measurement of NAA:Cho with magnetic resonance spectroscopy facilitates assessment of neuronal injury after HCA and allows for evaluation of neuroprotective strategies. Methods Canines underwent 2 hours of HCA at 18°C and were observed for 24 hours. Animals were divided into three groups (n = 15 in each group): normal (unoperated), HCA (HCA only), and HCA+diazoxide (pharmacologic treatment before HCA). The NAA:Cho ratios were obtained 24 hours after HCA by spectroscopy. Brains were immediately harvested for fresh tissue NAA quantification by mass spectrometry. Separate cohorts of HCA (n = 16) and HCA+diazoxide (n = 23) animals were kept alive for 72 hours for daily neurologic assessment. Results Cortical NAA:Cho ratios were significantly decreased in HCA versus normal animals (1.01 ± 0.29 versus 1.31 ± 0.23; p = 0.004), consistent with severe neurologic injury. Diazoxide pretreatment limited neurologic injury versus HCA alone, reflected in a preserved NAA:Cho ratio (1.21 ± 0.27 versus 1.01 ± 0.29; p = 0.05). Data were substantiated with fresh tissue NAA extraction. A significant decrease in cortical NAA was observed in HCA versus normal (7.07 ± 1.9 versus 8.54 ± 2.1 μmol/g; p = 0.05), with maintenance of normal NAA levels after diazoxide pretreatment (9.49 ± 1.1 versus 7.07 ± 1.9 μmol/g; p = 0.0002). Clinical neurologic scores were significantly improved in the HCA+diazoxide group versus HCA at all time points. Conclusions Neurologic injury remains a significant complication of cardiac surgery and is most severe after HCA. Magnetic resonance spectroscopy assessment of NAA:Cho ratios offers an early, noninvasive means of potentially evaluating neurologic injury and the effect of neuroprotective agents.
- Subjects :
- Male
Pulmonary and Respiratory Medicine
Magnetic Resonance Spectroscopy
Vasodilator Agents
Neuropsychological Tests
Hippocampus
Neuroprotection
Choline
Lesion
chemistry.chemical_compound
Dogs
Cerebellum
medicine
Carnivora
Diazoxide
Animals
Hypoxia, Brain
Cerebral Cortex
Neurons
Aspartic Acid
Cardiopulmonary Bypass
biology
business.industry
Fissipedia
biology.organism_classification
Circulatory Arrest, Deep Hypothermia Induced
nervous system
chemistry
Anesthesia
Models, Animal
Circulatory system
Surgery
medicine.symptom
Cardiology and Cardiovascular Medicine
business
Complication
medicine.drug
Subjects
Details
- ISSN :
- 00034975
- Volume :
- 81
- Database :
- OpenAIRE
- Journal :
- The Annals of Thoracic Surgery
- Accession number :
- edsair.doi.dedup.....f183bbc5eac73343701c149dd5707f7c