访谈撷要

肾动脉狭窄与高血压

　　肾动脉狭窄诊断方法
　　在谈到肾动脉狭窄诊断方法时，de Leeuw教授认为最重要的是选择最合适技术，可选择CT血管造影（CTA）或数字减影血管造影（DSA）。肾动脉狭窄可由动脉粥样硬化或纤维肌肉发育不良引起，磁共振血管成像（MRA）在诊断纤维肌肉发育不良时并不十分敏感，因此，尽管MRA是非常好的技术，但它可能漏掉很多狭窄病变。与MRA相比，CTA或常规血管造影发现纤维肌肉发育不良的几率明显增加。并且，在一些病例中MRA可能高估病变情况。CTA比MRA更可靠。现在很多人愿意选择CTA或MRA等微创检查，但临床上依然更多选择常规造影检查。
　　肾动脉狭窄应早期干预治疗
　　对于肾动脉狭窄病变干预治疗时机，de Leeuw教授强调早期干预治疗的重要性。近年来大量研究均显示，即使肾动脉动脉狭窄程度很轻，也可能出现肾脏功能异常。如果动脉狭窄达到70% ~80%时再进行干预，肾脏已经存在很多不可逆损伤。应在早期进行血管成形术或支架置入治疗。目前de Leeuw教授正准备进行一项临床试验以证实该结论的可靠性。

　　International Circulation: There are a lot of different ways to go about diagnosing renal artery stenosis such as magnetic resonance angiography (MRA) and digital subtraction angiography (DSA). How do we choose which technique to use?
　　Dr de Leeuw: The point is if you look at the techniques that are most suitable， you have either computed tomography angiography (CTA) (rather than MRA) or digital subtraction angiography. So far we find that MRA is a good technique but misses a number of stenoses. We have atherosclerotic stenoses but there is also fibromuscular dysplasia and MRA in particular is not very sensitive in picking up fibromuscular dysplasia. If you go to the CTA or the conventional angiography you have a far greater chance of picking up those abnormalities. On the other hand， we have experiences where MRA over-estimates abnormalities in some cases. For instance， you find a stenosis on MRA and you do a DSA and nothing pops up. All together， in our experience， the CTA is more reliable than the MRA although they have the disadvantage of course that you have to use contrast material. Many people prefer the CTA or MRA because it is less invasive， but in our clinic we still do a lot of conventional angiograms.
　　《国际循环》：现在有很多诊断肾动脉狭窄的检查方法，包括磁共振血管造影术（MRA）和数字剪影血管造影（DSA）。在诊断肾动脉狭窄时我们如何选择检查方法呢？
　　Dr de Leeuw：选择检查方法的重点在于你选择的是否是最合适的技术，可以选择的有CT血管造影CTA（而不是MRA）或数字剪影血管造影。到目前为止我们发现MRA是非常好的技术但是这种检查方法会漏掉很多狭窄病变。肾动脉狭窄有些是动脉粥样硬化引起的狭窄，但是也有纤维肌肉发育不良引起的狭窄，而MRA在诊断纤维肌肉发育不良时并不十分敏感。如果选择CTA或常规血管造影发现纤维肌肉发育不良的几率就会明显增加。另一方面，经验告诉我们MRA在一些病例下会对高估病变情况。比如，MRA检查发现了狭窄，但是再做DSA就没有狭窄了。总的来说，根据我们的经验，尽管CTA有缺点比如需要使用对比剂，但是它比MRA更可靠。很多人愿意选择CTA或MRA是因为这些是微创检查，但是在我们医院我们依然更多选择进行常规造影。
　　International Circulation: Generally the indications for treatment are the degree of narrowing of the vessels and depending on whether the stenosis affects just one or both kidneys. Can you outline the indications for treatment and when treatment should occur? And when do you think stenoses start having an effect on the kidney?
　　Dr de Leeuw: It is a difficult issue. The consensus is that a stenosis becomes significant when you have more than 70-80% luminal narrowing. In fact， if you look at the data upon which this is based， it is all in animal experiments where you create a stenosis acutely but in the human situation， stenosis develops over many years and it is quite a different phenomenon. In our minds， but I admit we are a bit like apostles trying to convince the world， we think you should intervene at an earlier stage because if you intervene only when the stenosis is 70% or 80% then there is already a lot of damage in the kidney. We have done a number of studies over the years where we see that also with low-grade stenosis there are demonstratable abnormalities in the kidney. There is now emerging experimental data showing also that with low-grade stenosis you may find some intrarenal abnormalities. If you make a comparison， for instance， with your heart， if you have 80-90% stenosis you are not going to salvage the myocardium. You are going to intervene at an earlier stage when the patient has a complaint. If the patient experiences angina at 50% stenosis then you would perform an intervention on the heart. I think the same line of reasoning should apply to the kidney. Why should you wait until the kidney has reached a phase of renal impairment because you know you will not be able to salvage the tissue? What is lost is lost; it will not regenerate. I think we should intervene at an earlier stage. There is no clinical data to support that though， so I am trying to get enough evidence so as to be able to convince people to do a trial in low-grade stenosis.
　　《国际循环》：一般来说是否需要治疗取决于血管狭窄的程度以及狭窄影响的是一个还是两个肾脏。您能概括一下治疗适应证以及什么时候需要开始治疗吗？您认为什么时候狭窄会影响肾功能？
　　Dr de Leeuw：这是个比较难的问题。共识是当管腔狭窄大于70%～80%时称为显著狭窄。实际上如果你想查阅这一标准的依据，就发现这都来源于建立急性狭窄模型的动物实验，但是在人体中狭窄病变是经过很多年的进展逐渐形成的，这是和动物模型完全不同的情况。在我们的观念里，在这里我承认我们有一点像试图说服世界的传道者，我们认为应该在早期进行干预治疗因为如果当狭窄达到70% 或 80%再处理时肾脏就已经存在很多损害了。在过去的几年里我们做了很多研究，发现即使狭窄程度很轻肾脏功能异常也可能出现。现在已经有很多实验数据显示狭窄程度轻时也会发现一些肾脏内的异常。假如做个对比，例如在心脏中，如果动脉狭窄达到80%～90%是否需要挽救心肌。当患者有症状时就会在早期进行干预治疗。如果患者的冠脉狭窄程度仅为50%但是患者发生了心绞痛，这时医生就会对心脏进行干预治疗。我认为同样的道理适用于肾动脉狭窄。既然你知道已经损坏的组织无法挽救为何还要等到肾功能出现明显障碍的时候再行动呢？失去的已经无可挽回，不能再生。我认为应该对狭窄病变进行早期干预治疗。尽管还没有临床资料支持这种观点，但是我正试图找到足够的证据来说服人们对轻度肾动脉狭窄程进行试验。