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The Value of IVUS Technology

By Kenneth Kollmeyer, M.D., President and founding partner of DFW Vascular Group, Dallas-Fort Worth, Texas
By Kenneth Kollmeyer, M.D., President and founding partner of DFW Vascular Group, Dallas-Fort Worth, Texas
This monthly column in Cath Lab Digest reviews important points of distinction in vascular imaging, from characteristics to techniques, to provide valuable and relevant information about this technology. Dr. Kollmeyer is President and founding partner of DFW Vascular Group, a leading vascular surgery practice in North Texas. He has practiced at Methodist Dallas Medical Center for over 25 years, as well as serving patients at the Baylor Heart Hospital in Plano, Texas. Board-certified in both vascular surgery and general surgery, Dr. Kollmeyer is a Fellow of the American College of Surgeons. He has been named each year in D Magazine’s “Best Doctors in Dallas” for the past five years, recognizing him as one of the best vascular surgeons in Dallas. Dr. Kollmeyer received his medical degree from the University of Colorado School of Medicine in Denver and a PhD in physiology from the University of Cincinnati. How does intravascular ultrasound (IVUS) complement other imaging modalities? The primary benefit of IVUS is that it offers a 360-degree view of the vessel wall from the inside, allowing a more complete and accurate assessment of a vessel than possible with angiography alone. IVUS has better resolution than angiography, and can potentially provide specific information about the significance of calcifications and thrombi. Additionally, IVUS has the power to differentiate the true luminal characteristics and size of a vessel from plaque. How has IVUS impacted your clinical practice? IVUS has made our interventions more accurate. For example, angioplasty of the external iliac artery, which can be fraught with hazards, may be done more precisely with IVUS. Using IVUS, we are able to determine the outside dimensions of the vessel and therefore select the appropriate stent size, thus potentially avoiding rupture or dissection of the artery. In which cases do you most commonly use IVUS? The majority of the interventions in which I use IVUS are in the aorta and lower extremities, most commonly in the iliac, femoral and popliteal arteries. I most commonly use IVUS to facilitate sizing of grafts in the repair of aneurysms. I recently presented a series of 150 aneurysms I have followed for eight years with no migration or leaks, and one of the biggest points of discussion was my 100-percent utilization of IVUS to appropriately size these grafts. Why is IVUS useful for graft sizing in the treatment of aneurysms? Computed tomography (CT) scans and x-rays can potentially oversize aneurysms due to parabolic artifacts. In fact, in almost every case, our CT scan measurements are larger than those obtained with IVUS. Graft selection with IVUS is easy and quick. Using a standard ultrasound probe and the sheath already present for repairing the aneurysm, we can readily assess the aorta and common and external iliac arteries to select a graft. I recently treated a patient with bilateral iliac artery aneurysms. Because of his young age, we wanted to preserve the flow in his internal iliac artery, and we used IVUS to size a graft that sealed perfectly. This would not have been possible without IVUS. What are the advantages of using IVUS, in conjunction with angiography, for treating lower extremity occlusive disease? IVUS is a very important tool for safely, accurately and thoroughly treating tibial disease. IVUS assists us in accurately sizing the smaller tibial vessel, which is very delicate and can be very diseased, with varying amounts of calcium. An oversized balloon or device increases the risk of vessel rupture, thrombosis, or other problems that may require surgical intervention. How does understanding plaque morphology through the use of IVUS impact your treatment strategy? Characterization of plaque morphology through IVUS can influence device selection. For example, if plaque in the superficial femoral artery is homogeneously well-organized and calcified, I might choose a particular atherectomy device for debulking or treatment, whereas if only a thrombus is present and the vessel seems less diseased, I might initially treat it more aggressively with thrombolytics, rather than with a mechanical atherectomy device. Are you using IVUS to aid in contrast reduction? IVUS can reduce the amount of contrast required during a procedure, in that the patient’s vessel can be mapped with IVUS instead of an angiogram. I have done a number of cases with IVUS only and no contrast, with excellent results and no compromise to the patient’s renal system. Are you using IVUS for venous work? We have many people present to our practice with leg pain and swelling who are miserable and undiagnosed. IVUS is a very useful tool to aid us when diagnosing May -Thurner’s syndrome and deep vein thrombosis. We also use IVUS when treating patients with an iliac stent or the placement of vena cava filters. Where do you see a potential for expanded use of IVUS amongst your colleagues nationally? It is surprising how rarely IVUS appears to be used. At a recent meeting, only a small number of the surgeons — who had collectively repaired hundreds of aneurysms endovascularly — had used IVUS as an adjunct. I think surgeons do see its utility and are ready to accept the technology. Even though cardiologists seem to have been using IVUS in the coronary field, its use in peripheral interventions is much less, so this is a potential area for huge growth over the next five years. Sponsored and prepared by Boston Scientific Corporation.