Capillary Dysfunction: Its Detection and Causative Role in Dementias and Stroke

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• 作者：Leif ?stergaard ; Sune N?rh?j Jespersen…
• 关键词：Capillary dysfunction ; Cardiovascular risk factors ; Stroke ; Reperfusion injury ; Vascular dementia ; Alzheimer’s disease ; Perfusion imaging
• 刊名：Current Neurology and Neuroscience Reports
• 出版年：2015
• 出版时间：June 2015
• 年：2015
• 卷：15
• 期：6
• 全文大小：3,422 KB
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  17.-/div>Rasmussen PM, Jespersen SN, ?stergaard L. The effects of transit time heterogeneity on brain oxygenation during rest and functional activation. J Cereb Blood Flow Metab. 2015;35:432-2. The authors show that incorporation of capillary transit time heterogeneity into descriptions of the relation between CBF and brain oxygenation provide superior fits to experimental data, and that CTH and MTT tends to change in parallel in vascular networks, maintaining constant CoV. View Article PubMed
  18.-/div>Angleys H, ?stergaard L, Jespersen SN. The effects of capillary transit time heterogeneity (CTH) on brain oxygenation. J Cereb Blood Flow Metab. 2015. doi:10.-038/?jcbfm.-014.-54 . The authors extend the original flow-oxygenation model by Jespersen and ?stergaard to take the ongoing oxygen utilization in tissue into account and find that the paradox ‘malignant CTH-phenomenon is a general feature of realistic capillary flow distributions. They discover a dissociation between tissue oxygenation and oxygen tension that may have implication for the interpretat
• 作者单位：Leif ?stergaard (1) (2)
  Sune N?rh?j Jespersen (1) (3)
  Thorbj?rn Engedahl (1) (2)
  Eugenio Gutiérrez Jiménez (1)
  Mahmoud Ashkanian (1)
  Mikkel Bo Hansen (1)
  Simon Eskildsen (1)
  Kim Mouridsen (1)
  
  1. Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark
  2. Department of Neuroradiology, Aarhus University Hospital, Building 10G, 5th Floor, N?rrebrogade 44, 8000, Aarhus, Denmark
  3. Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
  
• 刊物主题：Neurology; Neurosciences;
• 出版者：Springer US
• ISSN：1534-6293

文摘

In acute ischemic stroke, critical hypoperfusion is a frequent cause of hypoxic tissue injury: As cerebral blood flow (CBF) falls below the ischemic threshold of 20?mL/100?mL/min, neurological symptoms develop and hypoxic tissue injury evolves within minutes or hours unless the oxygen supply is restored. But is ischemia the only hemodynamic source of hypoxic tissue injury? Reanalyses of the equations we traditionally use to describe the relation between CBF and tissue oxygenation suggest that capillary flow patterns are crucial for the efficient extraction of oxygen: without close capillary flow control, “functional shunts-tend to form and some of the blood’s oxygen content in effect becomes inaccessible to tissue. This phenomenon raises several questions: Are there in fact two hemodynamic causes of tissue hypoxia: Limited blood supply (ischemia) and limited oxygen extraction due to capillary dysfunction? If so, how do we distinguish the two, experimentally and in patients? Do flow-metabolism coupling mechanisms adjust CBF to optimize tissue oxygenation when capillary dysfunction impairs oxygen extraction downstream? Cardiovascular risk factors such as age, hypertension, diabetes, hypercholesterolemia, and smoking increase the risk of both stroke and dementia. The capillary dysfunction phenomenon therefore forces us to consider whether changes in capillary morphology or blood rheology may play a role in the etiology of some stroke subtypes and in Alzheimer’s disease. Here, we discuss whether certain disease characteristics suggest capillary dysfunction rather than primary flow-limiting vascular pathology and how capillary dysfunction may be imaged and managed.