Cath Lab Digest - September 2007 - (Page 14)

14 CLINICAL REVIEW SEPTEMBER 2007 Percutaneous Treatment of Peripheral Arterial Chronic Total Occlusions: Device Options and Clinical Outcomes Jinnette Abbott, MD and David Williams, MD ABSTRACT Endovascular specialists are increasingly facing the challenges of treating peripheral arterial chronic total occlusions (CTOs). The two primary issues concerning these lesions are the ability to safely achieve initial angiographic success and the long-term durability of therapy. The advent of new techniques and devices, including reentry catheters, has increased the crossing success rates for even the most difficult CTOs. Although more effective ways of maintaining vessel patency are needed, nitinol stents have improved immediate outcomes and become the mainstay of therapy. This article will review the percutaneous treatment of peripheral CTOs. Reprinted with permission from Vascular Disease Management 2007;4(4):133-140. attempt percutaneous revascularization of CTOs depends on many factors, such as severity of symptoms, and lesion characteristics, including location, calcification and length, and operator experience and institutional availability of the specialized devices discussed. Diagnostic Considerations Prior to Intervention The treatment of CTOs involves a fundamental understanding of the management of PAD in general. The level of occlusive disease can often be determined based on history and physical examination, including an ankle brachial index. Segmental limb pressures and duplex ultrasound are also routinely used as initial diagnostic modalities to determine the level and extent of PAD. Imaging studies, either CT or MR angiography, should be considered in patients that are candidates for revascularization. Although angiography remains the gold standard for diagnosis and allows for both anatomic and hemodynamic assessment of PAD, noninvasive imaging prior to angiography is useful in many respects. For patients with renal insufficiency, the risks of noninvasive imaging must be weighed against the potential information gained. Contrast nephropathy from CT angiography, similar to invasive angiography, can be minimized with appropriate prophylactic measures, such as intravenous hydration, sodium bicarbonate infusion, and N-acetylcycteine. Magnetic resonance angiography (MRA) using gadolinium is much less likely to cause nephrotoxicity, but its use in patients with advanced renal disease has recently been associated with nephrogenic systemic fibrosis.9 This acquired condition, which has no clear treatment, causes fibrosis of the skin and other organs and results in significant morbidity and mortality. Therefore, gadolinium studies should be avoided in patients with acute renal failure or chronic kidney disease, with a glomerular filtration rate (GFR) < 30 ml/min or on dialysis. When total Introduction The number of percutaneous revascularization procedures performed for symptomatic peripheral arterial disease (PAD) has significantly increased over the past several years.1 Traditionally, the use of percutaneous techniques were limited to certain anatomic subsets, such as stenosis or focal occlusions, with surgical treatment preferred for more extensive disease.2 More recently, endovascular specialists are facing the challenges of treating commonlyencountered peripheral chronic total occlusions (CTOs). Furthermore, unlike the coronary circulation, these occlusions are often long and associated with other features of complexity. The two primary issues concerning these lesions are the ability to safely achieve initial angiographic success and the long-term durability of therapy. This article will focus on the current status of treating lower extremity peripheral CTOs and expected clinical outcomes. Distribution of Occlusive Disease The distribution of PAD, including CTOs, varies with multiple factors, such as age and the presence of cardiovascular risk factors. Aortoiliac disease is associated with young age, females, and current smokers.3,4 Femoropopliteal involvement in occlusive PAD is extremely common and, in one series, was present in 80% of symptomatic patients undergoing angiography.3 The predilection of disease in this segment may be due to its conduit-like nature, with no or few major branches, and torsion or stretching resulting from limb movement. These characteristics may cause relatively more damage of the vaso vasorum and endothelium than other limb segments, leading to accelerated atherosclerosis.5 Additionally, the flow characteristics following the development of a stenosis may promote long occlusions. Infrapopliteal disease is associated with diabetes mellitus, and diffuse and occlusive disease is common. Despite the complex nature of infrapopliteal disease, endovascular techniques have acceptable limb salvage rates.6–8 This approach, therefore, may be increasingly used for CTOs in patients with limited surgical options, due to comorbidities or lack of bypass conduits or target vessels. Overall, CTOs are more the norm than the exception in PAD. The decision to occlusions are identified, the length of the occlusion and often collateral supply can be identified. When CT angiography is used, the degree of calcification can also be gauged. These noninvasive techniques may provide incremental information about the true length of a CTO segment compared to angiography, as the retrograde filling of the distal segment is often more complete (Figure 1). Involvement of arterial segments that are more difficult to treat percutaneously, such as the common femoral artery and the popliteal artery, can be identified and, in some cases, surgical revascularization may be preferred to the percutaneous approach. In addition to identifying the extent of disease, preintervention imaging can be used to plan the access site(s) and determine if an antegrade or retrograde approach is more favorable. Furthermore, at the time of the intervention, a complete diagnostic angiogram may not need to be performed, shortening procedure time and decreasing contrast use. In terms of the morphologic characteristics of obstructive lesions, the TransAtlantic inter-Society Consensus (TASC) classification is commonly used to describe disease extent.2 In brief, lesions are divided into four types, A through D, with increasing complexity, and defined for each arterial segment: aortoiliac, femoropopliteal, and infrapopliteal. For femoropopliteal disease, a focal stenosis or occlusion 5 cm or multiple lesions are type C and longer complete occlusions are type D. The recent guidelines of the management of From Rhode Island Hospital, Brown Medical School, Providence, Rhode Island. Manuscript submitted March 21, 2007, provisional acceptance given May 14, 2007, accepted May 21, 2007. Correspondence Address: Jinnette Abbott, MD, Rhode Island Hospital, Brown Medical School, Division of Cardiology, 814 APC, 593 Eddy St., Providence, RI 02903. E-mail: jabbott@lifespan.org. Disclosure: The authors report no financial relationships or conflicts of interest regarding the content herein. Figure 1. Comparison of angiography (a) and CT angiography (b) for determining the true length of a total occlusion of the superficial femoral artery. Late filling of the vessel distal to the occlusion via collateral arteries shows a short segment occlusion.

Table of Contents Feed for the Digital Edition of Cath Lab Digest - September 2007

St. Dominic Hospital The Genous Bio-engineered R Stent Percutaneous Treatment of Peripheral Arterial Chronic Total Occlusions: Device Options and Clinical Outcomes Contents Clinical Editor’s Corner Percutaneous Revascularization of Peripheral Chronic Total Occlusion — Which Patients, Why, and How? Myocardial Infarction and Syncope: A Manifestation of the “Raynaud-Prinzmetal Syndrome”? Essential Technical Components of the Transradial Approach If You Build It, Will They Come? Evidence-Based Medicine with Drug-Eluting Stents Back to School: The Value of Education in Cardiovascular Services The ACVP Standards and Competencies: Are You Using Them Effectively? What Do You Think? My Experience with Fibromuscular Dysplasia and Stroke A Brief Review of Fibromuscular Dysplasia Letter to the Editor A Look at On-the-Job Training: Perceptions, Reality and Our Profession Doing the Wave: Inventory Management with RFID The Ten-Minute Interview with… Paul Pinsker, RCIS CLD’s Annual Salary Survey Harrisburg Area Community College Volunteer Survey CEU Education Center SICP* Section Ask the Clinical Instructor: A Q&A Column for Those New to the Cath Lab Clinical & Industry News

Cath Lab Digest - September 2007

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