IC: Have you had to use this flexibility a lot?
　　Dr. Applegate: Yes. One of the things learned by the CoreValve experience in the United States was that we were mandated to use CT scanning to define the anatomy of the aortic valve. While we did not realize this before， today it is the bench mark metric for determining the severity of the aortic stenosis， but in terms of the peculiar anatomy of the annulus of the coronaries sinuses， we realize the CT scan is now also the gold standard. Even though SAPIENs and CoreValves are being placed in Europe， I think the proctors began to recognize the value of the CT scan for looking at the anatomy. We do a lot of preplanning; we look repeatedly at these CT scans. It needs to be understood that， despite original claims， one can replace a valve without removing the patient’s. In fact， it is the anatomy itself that allows placement of a stent valve and it is the constituent elements of the valve that keep it in place. Some degree of calcification is good， if a valve has no calcification， one would have to question whether or not senile calific aortic stenosis had even occurred.
　　The second thing is the importance of the relationship between the stent valve and the coronary ostium. The SAPIEN valve can be placed because of its low profile: the top of the stent valve is actually below the coronary ostium， which is generally in the upper portion of the sinuses of Valsava. However， there will be cases when this is risky. During the positioning of the SAPIEN valve， the patient’s own valve may be pinned up against the walls of the sinuses， and if the sinuses are not very tall， they may close off the coronary arteries. Good planning and an understanding of that relationship will make this a rare occurrence.
　　With the CoreValve， this is addressed by having an hour class appearance：larger just below the annulus in the LV outflow tract， narrower around the coronary sinuses， and larger again to accommodate the ascending aorta. The struts and the interstices of the stent valve are large enough that flow to the coronary arteries is unimpaired. Those are the two major differences at the sight of the aortic valve.
　　In terms of their effectiveness， both are associated with a low gradient post-procedure. With SAPIEN， we have long term data that indicate a sustained relief of the obstruction and no return of the gradient. I think we will see the same with the CoreValve. One small nuance is the issue of aortic regurgitation in the CoreValve， though the amount immediately after the procedure almost always diminishes as the nitinol cage expands and settles into the valve. These are both hemodynamically effective valves.
　　《国际循环》：你是否经常会利用此种灵活性？
　　Applegate教授：是的，我从在美国应用CoreValve的经验中学到的一件事情是我们被要求应用CT扫描来明确主动脉瓣的解剖情况。之前我们并没有意识到这一点，现在CT扫描已经成为评估主动脉瓣狭窄程度的基本检查，但是就冠状动脉窦瓣环的特定解剖学情况来说，我们认识到CT扫描是当前的金标准。尽管欧洲也植入了一些SAPIEN和CoreValve瓣膜，我想监管机构也开始认识到CT扫描对观察主动脉瓣解剖情况的价值。我们预先做了很多工作，我们反复地看CT扫描。需要了解的是，尽管之前有人声称不用移除患者自身瓣膜而植入瓣膜。但事实上，是解剖情况本身允许瓣膜被植入，而瓣膜的成分则使瓣膜能够保持原位。瓣膜有一定程度的钙化是好的，如果瓣膜没有钙化，大家可能会质疑是否为老年性钙化性主动脉瓣狭窄。
　　其次，重要的是支架瓣膜和冠脉动脉口之间的关系。由于位置较低，可放置SAPIEN瓣膜：支架瓣膜的顶端实际上位于冠状动脉口之下，后者通常位于Valsava窦的上部分。但是，某些情况下此种做法还是有风险的。在放置SAPIEN瓣膜的过程中，患者自身的瓣膜可能被挤到动脉窦的壁上，如果动脉窦不是很高，可能会关闭主动脉。良好的设计和理解支架瓣膜与冠状动脉口之间的关系将有助于减少上述问题。
　　对于CoreValve，通过采三叶式外观而解决了这一问题：左室流出道的瓣环之下体积较大，冠状动脉窦周围体积较小，容纳升主动脉的部分体积较大。支撑杆和支架瓣膜间隙较大，不会影响到主动脉的血流。这是两个瓣膜系统在主动脉瓣膜上的两大区别。
　　就疗效来讲，两个瓣膜系统植入后都会使跨瓣压差减小。SAPIEN瓣膜系统有长期随访的数据，提示其能够持续改善梗阻，跨瓣梯度不会再次增加。我认为，CoreValve瓣膜系统也会有类似作用。一个小的问题是CoreValve的主动脉瓣反流问题，尽管植入后随着镍钛合金的膨胀和放置于瓣膜内反流立即减少。SAPIEN和CoreValve瓣膜系统都是能够改善血液动力学的瓣膜系统。