Cath Lab Digest - March 2008 - (Page 46)

46 CLINICAL UPDATE MARCH 2008 Is it possible to do this with angiography in most cases? Most physicians want to try to extend their stents to normal-to-normal tissue if possible, particularly with DES. With bare-metal stents, we paid a big price — the longer the stent we used, the higher the rate of restenosis. Unlike bare-metal stents, DES do not have the big change in restenosis rates according to stent length, but we do have the issue of geographical miss with DES. If you stent a fairly short segment of vessel and are leaving the ends of the stent in diseased segments, there most likely will be a price to pay with edge restenosis. My own approach with DES has been to stent from normal-to-normal tissue when possible. Most interventionalists try to do just that, but if they are using angiography to determine the normal tissue, we know that angiography is not very sensitive for detection of mild-to-moderate disease. IVUS is much better, so if you are using angiography to determine where your normal reference vessel is, in many instances, you are simply mistaken. The reason why angiography is so insensitive is that as plaque deposits in the vessels, the vessel remodels or expands to accommodate that plaque. Remodeling is a well-observed phenomenon that we have known about for over 50 years, and we can see it with IVUS. If I am using IVUS to determine normal tissue, the determination will be accurate. As a result, the rate of stent edge restenosis and also in-segment restenosis, defined as within 5 mm of the stent, will be reduced. Again, however, that’s observational data from my own experience. Hopefully we will have stent registries that start looking at some of these issues in the future. What are the limitations of IVUS? The main limitation is that IVUS is a catheter and there are certain vessels the catheter can’t go down: tortuous vessels and highly angulated take-offs of circumflex vessels are often difficult to ultrasound, for example. The IVUS catheter often will not pass through highly calcified vessels. So there are technical limitations on vessels you can IVUS. Of course, it is an invasive procedure with the attendant risks. People who are not interventionalists, i.e., non-interventional physicians, should not be using IVUS because there are rare vessel dissections that can occur with IVUS. Although, interestingly, I don’t think I’ve ever seen a severe vessel dissection from IVUS use in the 14 years that I have been using this technology. The main morbidity is intracoronary spasm, which is easily preventable with ample intracoronary nitroglycerin. So the two main limitations are vessel anatomy — some anatomy is not suitable for IVUS — and that it is an invasive procedure, which limits the application of its use to some extent. An additional limitation is that many interventionalists are not trained in intracoronary ultrasound. They simply do not have a good understanding of how to interpret the images, how to measure properly, how to interpret the measurements properly and so forth. I have now been giving training courses for several years to interventionalists not using a lot of IVUS. The last thing most experienced interventionalists want to admit to anyone is that they don’t really know how to use IVUS correctly. But I find when I get people into my courses, by the questions they ask, by their own admission or by just asking questions to them myself, that many, many interventionalists don’t clearly understand how to interpret and use IVUS. Fortunately, it is obviously a very correctable limitation. One of my concerns is that many academic training centers actually have relatively low IVUS usages. It is not everywhere, but I do know of training programs where the use of IVUS is very low. How can you train fellows to be expert in IVUS if you’re not using it in the first place? Do you find that experienced staff are helpful in IVUS use? We do have some staff who are experienced and who have been to IVUS courses. Some of our staff are extremely good at both the mechanics (the “buttonology”), and measuring and interpreting IVUS images. If an interventionalist who is not a frequent IVUS user is working with a staff member who is very comfortable using IVUS, we sometimes see that the physician is more likely to IVUS. Sometimes a technologist will suggest to the physician, “Why don’t you IVUS that?” But obviously if that tech is very uncomfortable with IVUS, they will not make that recommendation. Labs with IVUS should definitely make an attempt to train as many people as they can to be adept at both doing IVUS and understanding the image they see. ■ Dr. Michael Foster MFoster@scheart.com can be contacted at

Table of Contents Feed for the Digital Edition of Cath Lab Digest - March 2008

Cath Lab Digest - March 2008 Are You Being Paid Fair Market Value in 2008? A Cardiac Cath Lab Professionals Survey by Cath Lab Digest and the Society of Invasive Cardiovascular Professionals Saint Joseph’s Hospital Invasive Imaging Tools for Optimizing Coronary Stent Deployment Contents Clinical Editor’s Corner A Workflow Revolution in Cath Lab Reporting Advantages of a New Digital Lab at Baystate Medical Center Cardiac Computed Tomography: What Does it Mean for the Cath Lab? The Latest in Cardiac Magnetic Resonance Imaging (MRI) Cellular Cardiomyoplasty and Cardiac Regeneration Intravascular Ultrasound in the Cath Lab: A Powerful — and Underutilized — Tool to Improve Patient Outcomes The Stentplus™ Patient Success Program Cardiac Cath Lab Clutter — or, Spring into Action! Groin Bleeds and Other Hemorrhagic Complications of Cardiac Catheterization: A List of Relevant Issues Ask the Clinical Instructor: A Q&A Column for Those New to the Cath Lab What Do You Think? Experience with a New Guidewire: The Terumo Runthrough NS The Ostial Pro™ Stent Positioning System: Perfecting Aorto-Ostial Stent Placement Precious Minutes The Ten-Minute Interview with…Mark Bowles, BSN, CCRN Vascular Care in the Cath Lab: Planning a Smooth Transition Cath Laughs CMS 2008 OPPS Final Rule Review An Extensive Set of Review Courses for the CCI Basic Science, Non-Invasive Echocardiography and Vascular, and ARDMS Ultrasound Exams Meetings Calendar CEU Education Center Clinical & Industry News STEMI Interventions Classifieds Advertisers Index

Cath Lab Digest - March 2008

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