<International Circulation>:Why do we want to take central pressure? Why do we want such an accurate measurementof blood pressure? Why is waveform important?
《国际循环》：为什么我们需要测量中心血压？为什么对血压的测量要如此精确呢？为什么血压的波形如此重要？
Prof. Alvolio :The structure of the arterial system is such that when the pulse travels it changes the wave shape. By definition， the wave shape changes and the pulse pressure increases. Especially during exercise with higher heart rates， the peak pressures that one measures arterially are actually different than the peak pressures near the heart. So if one wants to assess cardiac function in terms of peak load on the heart， it becomes problematic because it is not actually the real value. The way to obtain the real value is to have the conventional cuff measurement supplemented with a wave form where that information is contained.
Alvolio教授：动脉系统的结构是这样的，当脉搏经过动脉时它会出现波形的改变。很明显，当波形改变时脉搏压力同时也增加。特别是在运动中心率增快的情况下，测量所得的动脉压力峰值实际上和接近心脏的压力峰值是不同的。所以如果我们想要通过心脏的压力负荷评估心脏功能，测量外周血压就不能准确地得出结论，因为外周血压实际上并不是心脏压力的真实值。获得心脏压力负荷真实值的方法是用一种传统的袖带测量法提供波形来反映心脏的压力负荷。
<International Circulation>:Do we have many different kinds of waveforms， competing ways of measuring central pressure or is there one accepted way?
《国际循环》：那么请问是否存在多种波形都能测量中心血压还是只有一种已经被认可的测量方法？
Prof. Alvolio :There are not competing but rather complimentary ways of measuring central pressure. Essentially， there is a technique called the general transfer function which uses the whole waveform. There is another technique that uses a feature of the wave form which is quite good in most cases that identifies the second systolic shoulder.If one calibrates that wave form， one can equate that second systolic shoulder to the peak value. In that case you do not get an ascending aortic waveform， but only the values. There are other techniques that look at applying some type of averaging where the wave form is averaged in a certain way and that average turns out to be close to the systolic pressure. Some of the devices coming out now look at central systolic pressure. Outcome studies on these devices are not yet availableto indicate whether there is use in knowing this extra number and whether it is better.We’ve seen the indicators that it seems to have additional value to the conventional measures of systolic pressure. Data are forthcoming to indicate whether treated to that value is actually better either in efficacy of treatment or avoiding treatment.
Alvolio教授：测量中心血压没有很多效果相当的方法，而是有一些互补性的方法。实际上，有一种利用全部波形的技术被称作一般传递函数。还有另外一种技术能利用波形的一些特征，在大多数情况下它的效果非常好，能识别第二个收缩性平台。如果我对波形进行测量，就会发现第二个收缩性平台等同于峰值。在这种情况下你不是得到上升的动脉波形，只能得到数值。还有其他技术旨在提供一些种类的平均值，这些均值出现于在一些特定情况下波形不变时，而且这种均值和收缩压很接近。现在新出现了一些设备主要反映中心收缩压。对这些设备的研究结果还没有显示它是否能测量其他的参数以及它是否比目前的设备更好。我们已经发现了一些指标，这些指标似乎对常规的收缩压测量有额外的价值。马上就会有资料表明治疗这些指标是否能真正能提高治疗的功效或是否能避免无意义的治疗。
<International Circulation>:You talked about intracranial pressure as well， how well are intracranial pressure and central pressure related?
《国际循环》：您同时也讲到了颅内压，请问颅内压和中心血压有什么紧密的关系吗？
Prof. Alvolio : Intracranial pressure waveform seems to be reasonably similar to the arterial pressure. It is not possible to measure pressure in the skull， so the closest one can get to this is to measure the carotid pressure which is quite close to the central aortic pressure. If one can estimate central aortic pressure， some analysis can be done on that to estimate intracranial pressure. The estimation of the wave form of intracranial pressure has some features associated with the type of tissue and fluid structure. If you have increased intracranial pressure， the brain becomes stiffer which appears to be a way that you can validate and quantify that difference.
Alvolio教授：颅内压波形似乎和动脉压很相似。由于不能在颅骨内测量压力，因此最接近颅内压的是测量颈动脉压力，而颈动脉压力和中心动脉压力又非常接近。如果我们能对中心动脉压进行测算，我们也能通过一些分析对颅内压进行估量。对颅内压波形的测量有一些与组织和流体构造类型相关的特征。如果颅内压增高，大脑的硬度就会增加，这样就能确定并定量化那些差异。
<International Circulation>:When you’re creating waveforms [algorithms] so that you can estimate the central pressure and the intracranial pressure， how much are you relying on standard waveforms [algorithms] or do you create waveforms[algorithms] for individuals?
《国际循环》：当您创建波形算法以估量中心血压和颅内压时，您有多大程度是依靠标准波形算法来进行的？您有没有设计出针对个体的波形算法呢？
Prof. Alvolio :Waveforms are not created and there is no normalization. These algorithms are models. The waveforms are measured. The algorithms are such that in one case with the sigma core， for example， is a constant filter for adults. Attempts have been made to individualize that filter for specific cases. If that is done， the added value is a few percent of difference which is quite interesting. Anatomically， the size of the vessels in adults， the arms， the stiffness， the thickness of those vessels， is not a factor that varies a lot. When we developed that model， we were quite surprised of the consistency of this model， especially at the low frequency end where one finds most of the power of the pulse. We thought that that should be a reasonable estimate of central pressure. In fact， the errors in that estimation are of the order or less than the error made in calling out diastolic pressure from the cuff. Usually that measurement of diastolic pressure isa matter of judgment. The operator makes a judgment when that heart sound is muffled. Automatic algorithms have the same property. So those errors are of the same order. The question is that if we can accept those sorts of measurements， we should be able to accept these other sorts of measurements that have similar errors.
Alvolio教授：波形不是被创建出的，而且并没有标准化的波形。这些算法都只是一些模型。波形是被测量出的。这些算法是这样的，比如在一种有Σ核心的情况下这些算法在在成人中是一个常数滤波器。我们已经做出努力来使这些滤波器更加个体化以适用于特殊的情况。如果能做到这些，增值将是很少百分比的差异，这是非常有趣的。在解剖学上，成人血管的大小以及这些血管的分支、僵硬度和血管壁厚度常常并不是变化很大。当我们设计出这种模型时，我们非常惊奇于这种模型的一致性，特别是在低频端发现了脉搏最有力的部分。我们认为这就是合理估测中心动脉压的方法。实际上，这种估测方法的误差和袖带测量舒张压中的误差相差无几，甚至还更小。通常对舒张压的测量是一种评价方法。操作者们根据心音的消失做出评价。自动的算法也有同样的作用。因此这些误差没有太大的差别。问题是如果我们能接受这些已经被接受的测量方法，我们就应该能接受这些误差相似的新的测量方法。
<International Circulation>:Peoples anatomy is similar enough that you end up with errors that small， but is this the anatomy of their hearts or of their vascular?
《国际循环》：人体解剖如此相似所以您能将误差降至很低，请问这种解剖学上的差异在心脏和血管上也很小吗？
Prof. Alvolio :Essentially the brachial artery system， the arteries is the one place or case where that type of model does not work. For example， if you have an obstruction of the subclavian arteries are obstructed then that doesn’t work because you are then measuring something else. Thankfully that sort obstruction doesn’t happen too often in people – people’s arms don’t fall off and so on and so forth… But it does happen， and when it does happen it can’t be used.
Alvolio教授：实际上上臂的动脉系统中的动脉血管是那种模型使用无效的地方。比如，如果你的锁骨下动脉有阻塞，这时使用那种模型就没用，因为这时测量得到的是其它的数值。庆幸的是这种阻塞并不是经常发生——人们的上臂并不是向下再向外……但是这种情况还是时有发生，并且一旦发生这种模型就不能被应用。
<International Circulation>:As an expert in vascular endothelial vascular study， how can we go about improving function?
《国际循环》：您作为一位在血管内皮研究领域的专家，请问怎样才能改善内皮功能？
Prof. Alvolio : Function is improved with exercise. Exercise seems to be related to aspects of blood flow. If there is increased flow， increased shear on the endothelial cells would result in the production of certain molecules. One of which that is important is nitrous oxide， which has essentially beneficial effects in terms of dilating the vessels， improving and increasing perfusions. With increased perfusions， there is increased oxygen delivery and cells become more functional. In the larger vessels， if the nitrous oxide affects the smooth muscles， it affects the smooth muscle stiffness. That will then affect aspects of blood pressure. These are closed loop situations. Improving endothelial function is an important factor， exercise seems to do it， anti-inflammatories seem to help. There area whole cascade of processes that are currently being interrogated.
Alvolio教授：运动会改善内皮功能。运动似乎和血流相关。如果血流增肌，作用于内皮细胞的剪切力就会增加，结果会增加一些活性分子的产生。在这些活性分子中很重要的就是一氧化氮，它最基本的益处就是扩张血管，增加和改善器官的灌注。灌注增加后，氧供也会增加，细胞的功能就会得到改善。在更大的血管中，如果一氧化氮作用于平滑肌，它就会影响平滑肌的弹性。这时就会影响血压。这些是环路效应。改善内皮细胞的功能是很重要的一方面，运动似乎能做到这一点，抗炎也似乎有益处。这一领域的全部级联过程目前正在研究中。
<International Circulation>:How important is endothelial function in the whole pressure picture?
《国际循环》：请问在血压中内皮细胞的功能有多重要呢？
Prof. Alvolio : It seems to have a function in relation to the peripheral resistance. If one can modify peripheral resistance， it can therefore change the mean blood pressure. There are interesting areas that are coming out in terms of endothelial function affecting the extracellular matrix. One interesting area is changes in endothelial function， for example if there is inflammation there would be a reduction of bioavailability of nitrous oxide. When that happens， certain other processes start to take place. For example post translational modification of proteins. One area is S-nitrosylation， where we’ve been doing some work with a group at Johns Hopkins， the protein， transglutaminase2， seems to be effected by this process S-nitrosylation. When that is affected， it goes out from the cell into the extracellular matrix which causes cross linkages of collagen therefore the artery becomes stiffer. It is an interesting process of changes from the cellular function to the extracellular structural changes.
Alvolio教授：内皮细胞的功能似乎和外周阻力相关。如果我们能调节外周阻力，我们就能改变平均血压。目前出现了一个有趣的研究领域，被称为内皮细胞功能影响着细胞外基质的改变。其中一个有趣的方向是内皮细胞功能的改变，比如假设有炎症发生就会有一氧化氮生物活性的降低。当这些发生时，其他的一些反应过程就开始了。例如蛋白的翻译后修饰。其中之一就是S-亚硝基化，我们已经和霍普金斯的一个研究组合作了一些研究，结果一种蛋白，谷氨酰胺转移酶2，似乎能被这一S-亚硝基化过程所影响。当谷氨酰胺转移酶2一旦被这种作用影响，它就从细胞内进入细胞外基质，然后导致胶原的相互连接从而增加动脉的将硬度。这是一个有趣的从细胞功能到细胞外基质的改变过程。
<International Circulation>:We are seeing changes in the endothelium that end up affecting high blood pressure and the formation of collagen that are happening indirectly because the endothelium is changing and causing a cascade of effects.
《国际循环》：我们发现内皮系统的改变能影响高血压和胶原的形成，这些都是间接发生的，因为内皮系统会发生改变并导致一系列的级联反应。
Prof. Alvolio : With the advent of molecular biology， these pathways are being identified and it is quite exciting to see if in fact like the endothelial was once thought to be a lining of the blood vessel and now it is an active part of the circulatory system. Similarly with arterial stiffness， the elasticity was thought to have been mainly related to blood pressure， but can this stiffness property be modified through these cellular and molecular processes. We’ve seen the effect salt and now we’re starting to understand some these mechanisms.
Alvolio教授：随着分子生物学的进展这些通路就会被发现，而且非常令人振奋的是能看到内皮曾经被认为只是血管的内层部分，而现在发现它还是循环系统的活性部分。和动脉僵硬度相似，动脉的弹性被认为主要和血压相关，但是还不知道这种僵硬度特性能否通过这些细胞和分子的过程被调节。我们已经发现了盐的作用，现在我们已经开始探索它导致动脉发生变化的一些机制。
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