Lim C S, Gohel M S, Shepherd A C, Paleolog E, Davies A H
Imperial Vascular Unit, Department of Surgery and Cancer, Faculty of Medicine, Charing Cross Hospital, Imperial College London, London, UK.
J Vasc Res. 2011;48(3):185-94. doi: 10.1159/000320624. Epub 2010 Nov 23.
Venous hypoxia has long been postulated as a potential cause of varicosity formation. This article aimed to review the development of this hypothesis, including evidence supporting and controversies surrounding it. Vein wall oxygenation is achieved by oxygen diffusing from luminal blood and vasa vasorum. The whole media of varicosities is oxygenated by vasa vasorum as compared to only the outer two-thirds of media of normal veins. There was no evidence that differences exist between oxygen content of blood from varicose and non-varicose veins, although the former demonstrated larger fluctuations with postural changes. Studies using cell culture and ex vivo explants demonstrated that hypoxia activated leucocytes and endothelium which released mediators regulating vein wall remodelling similar to those observed in varicosities. Venoactive drugs may improve venous oxygenation, and inhibit hypoxia activation of leucocytes and endothelium. The evidence for hypoxia as a causative factor in varicosities remains inconclusive, mainly due to heterogeneity and poor design of published in vivostudies. However, molecular studies have shown that hypoxia was able to cause inflammatory changes and vein wall remodelling similar to those observed in varicosities. Further studies are needed to improve our understanding of the role of hypoxia and help identify potential therapeutic targets.
长期以来，静脉缺氧一直被认为是静脉曲张形成的一个潜在原因。本文旨在综述这一假说的发展情况，包括支持该假说的证据以及围绕它的争议。静脉壁的氧合作用是通过氧气从管腔内血液和血管滋养管扩散实现的。与正常静脉仅外三分之二的中膜被氧合相比，静脉曲张的整个中膜都由血管滋养管进行氧合。没有证据表明曲张静脉和非曲张静脉血液中的氧含量存在差异，尽管前者在体位改变时显示出更大的波动。使用细胞培养和离体组织块进行的研究表明，缺氧会激活白细胞和内皮细胞，这些细胞会释放调节静脉壁重塑的介质，类似于在静脉曲张中观察到的情况。血管活性药物可能会改善静脉氧合，并抑制白细胞和内皮细胞的缺氧激活。缺氧作为静脉曲张致病因素的证据仍然不确凿，主要是由于已发表的体内研究存在异质性且设计不佳。然而，分子研究表明，缺氧能够引起类似于在静脉曲张中观察到的炎症变化和静脉壁重塑。需要进一步的研究来增进我们对缺氧作用的理解，并帮助确定潜在的治疗靶点。
