International Circulation: At what grade of stenosis do we start seeing effects on the kidney? How early should one start treatment or open the artery?
《国际循环》：狭窄何种程度时我们开始看到其对肾脏的影响？如何早期开始治疗或打开动脉？
Dr. Textor: That is a very valid question. Let me just expand a thought. The size of the kidney and the blood flow are quite plastic. The kidney gets a lot of extra blood flow， though it does not need it for its own metabolic requires as it is a filtering organ. You will hear the term “hemodynamically significant lesions.” It is true that if you do studies find out at what point in the occlusion do you start to see a drop in flow or pressure， you find that it has to be 70% or more occlusion before you can even measure a drop. Once you get to that point， you can start to see a drop in blood flow， function， and size of the kidney. To our surprise， the kidney is able to adapt to that well. It can preserve oxygen levels in the cortex and medulla， it can compensate for the drop in blood flow， and biopsy data would show that they are not terribly damaged. This is part of the reason by people have been able to manage this medical therapy without tremendous hazard to the kidney， and in some case for a long time. There is a limit to that， the kidney can only adapt so much until it gets hypoxic. We are just now beginning to have the tools to look at hypoxia and injuries to happen to the kidney. These tools will help us to indentify when stenting in necessary or when drug treatment will suffice. To answer your question directly， we do not have good tools， and that is the quandary here. Also， this is an older group of people， they have a lot of other diseases， and they are going to run into other things before their kidneys catch up. That has been the unspoken element. Some have argued that you cannot perform an effective trial because you cannot get a population that can be generalized.
Dr. Textor：这是一个非常有效的问题。请让我展开思想。肾脏和血流的大小非常具有可塑性。肾脏得到了很多额外的血流，虽然其自身代谢需求并不需要，因为它是一个过滤器官。你将会听到这个术语“血流动力学显著的病变。”事实是如果你开展研究去寻找闭塞至哪种程度你会开始看到流量或压力的降低，你会发现在你甚至可以衡量到降低之前，闭塞必须为70％或以上。一旦达到那种程度，你就可以开始看到甚至血流、功能和尺寸的降低。出乎我们的意料，肾脏能够适应良好。它可以维持皮质和髓质中的氧含量，它可以弥补血流量的降低，活检资料显示没有严重受损。这是人们能够用药物治疗管理这种病变而没有对肾脏造成巨大危害的部分原因，在某些情况下，是很长一段时间，这有一定限度，肾脏只能适应这么多直至其缺氧。我们刚开始有工具来观察肾脏发生的缺氧和损伤，这些工具将帮助我们确定何时有必要进行支架置入术或者何时药物治疗就足够了。直接回答你的问题，我们还没有很好的工具，这就是现在的窘境。另外，这是一组年龄较大的人，他们有很多其他疾病，在涉及肾脏之前，他们会遇到其他事情。这一直是不言而喻的要素。有些人认为，你不能进行有效的试验，因为你得不到一个可以推广的人群。

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