Cath Lab Digest - October 2007 - (Page 8)

8 CLINICAL UPDATE OCTOBER 2007 continued from page 1 Fibromuscular Dysplasia Furthermore, some may present with stroke, cardiac failure or other manifestations of end organ damage or ischemia. Typical clinical manifestations are renovascular hypertension, stroke, subarachnoid hemorrhage, abdominal angina or claudication of the legs or arms. In patients with symptoms, percutaneous transluminal angioplasty has emerged as the treatment of choice in most involved vascular beds.2 absence of a bruit does not rule out significant vascular disease. Classifications of FMD FMD lesions are classified according to the arterial layer they affect: intima, media or adventitia. As stated previously, the most common form of FMD in children is intimal fibroplasia, which can occur in any arterial bed. Intimal fibroplasia may present as either a focal bandlike narrowing, or a long, tubular narrowing, which is often mistaken for various vascular diseases, such as Takayasu arteritis.1 The affected intima segment exhibits circumferential or eccentric collagen deposition that often projects into the lumen, and internal elastic lamina may be duplicated or disrupted but can be identified.1 Medial hyperplasia is a rare form of FMD which presents as a concentric focal band of narrowing and may be a variant of intimal fibroplasia. Medial fibroplasia most commonly affects women between the ages of 25–50 and accounts for approximately 75% to 80% of all FMD cases.9 Upon angiographic observation, the appearance of the affected artery resembles a “string of beads.” Thickened segments of the media, alternating with thinned segments of the media, produce an aneurysmal dilatation. Thickened media is replaced by collagen and the internal elastic lamina may be thinned or fragmented. When FMD affects the renal arteries, the aneurysms normally occur in the middle and distal portions of the vessels and tend to affect both arteries (35%). Perimedial fibroplasia accounts for fewer than 10% of FMD cases and tends to occur in females between 15–30 years of age. This subtype preferentially affects the mid-portion of the renal arteries and is similar in appearance to medial fibroplasias, as it forms the same “bead-like” pattern. However, there are fewer beads with diameters smaller than the normal artery size.1 Collagen deposition often occurs in the outer half of the media, replacing the external elastic lamina. The adventitial connective tissue, however, is intact. Failure to treat bilateral renovascular perimedial fibroplasia may result in renal failure. Adventitial fibroplasia, also known as periarterial fibroplasia, is very rare and accounts for less than 1% of FMD cases. Collagen replaces the fibrous adventitia and may extend beyond artery into surrounding tissues. Figure 1. Conventional angiography. Panel A: Tight narrowing with a small aneurysm of 2 mm at the trifurcation of the left renal artery. Post balloon dilatation dimensions are shown in Panel B. Etiology The etiology of FMD is currently unknown, although genetic, hormonal, and mechanical factors have been suggested.3 FMD is probably not a single disease entity. Most likely it has multiple etiologies with similar phenotypic expression and in some instances, may be an autosomal dominant disease with variable penetrance.4 The absence of large FMD-affected pedigrees, however, precludes confirmation of this proposal. A majority of female FMD patients suggests a connection between exposure to endogenous or exogenous estrogens and the disease. This suggestion has not been proven. In addition, the risk of FMD may be elevated with smoking, a family history of hypertension, and disorders of the vasa vasorum.5,6 Recent work from the National Institutes of Health suggests that there is a previously unrecognized variant of Ehlers-Danlos syndrome (EDS), distinct from the vascular form of EDS (mutations in COL3A1) and from the LoeysDietz syndrome (mutations in TGFBR1 or TGFBR2), with FMD as a major clinical feature in addition to the skin and joint abnormalities.7 Figure 2. Conventional angiography. Panel A. In children, bilateral renal artery FMD is as common as unilateral FMD. Panel B. FMD rarely affects the carotid vessels in children, but these should be screened by CTA/MRA or at the time of conventional angiography. Diagnosis of FMD FMD can be diagnosed by invasive and non-invasive means. Non-invasive testing includes captopril renal scintigraphy, duplex ultrasonography, magnetic resonance angiography, gadoliniumenhanced magnetic resonance angiography, and computed tomographic angiography (CTA).10 Access to higher quality non-invasive diagnostic techniques has decreased the utilization of captopril renography in primary renal-artery stenosis screening.9 Duplex ultrasonography can determine blood flow and pressure waveforms, but exhibits a 10–20% failure rate attributed to the presence of obesity, bowel gas or operator inexperience.5 Despite being non-nephrotoxic, magnetic resonance angiography (MRA) does present with shortcomings, including image resolution that is not yet adequate to detect FMD lesions in small branch vessels.9 The accepted gold standard has been conventional angiography (CA) (Figures 1 and 2). However, by virtue of its invasive nature and concern about contrast-related nephrotoxicity, it may not be an optimum first-line diagnostic tool. Of note, CTA and MRA are incrementally replacing CA. In a recent study that compared the utilization of CA with CTA in the diagnosis of FMD, CTA proved to be a non-invasive, costeffective, accessible, quick method for evaluation, and had 100% diagnostic accuracy of FMD lesions in the main and accessory renal arteries11 (Figure 3). In children where the 3rd and 4th order renal vessels are frequently involved, CTA’s diagnostic accuracy is unproven. Treatment of FMD in Children and Adolescents Various options for treatment of FMD exist, including both medical and surgical interventions. The principals of treatment involve controlling high blood pressure, re-establishing vascular flow, preventing clotting of the affected vessel(s), and eliminating factors that contribute to further vessel damage (e.g., smoking in teenagers). Medical therapy for hypertension in children follows the guidelines from the Fourth Task Force Report.12 When the renal disease is unilateral, it is safe to use angiotensin-converting enzyme inhibitor (ACE inhibitors) and/or angiotensin II receptor blockers. Bilateral renovascular disease is more problematic and typically requires multiple anti-hypertensive medications, including a diuretic, calcium channel blocker, and beta-blocker to control the hypertension. Aspirin may also be administered in children with FMD as anti-platelet therapy to prevent thrombosis in affected vessels. Percutaneous transluminal renal angioplasty (PTRA) remains the treatment of choice for renal-artery FMD.2 Indications for this intervention include recent or rapid onset of hypertension, Clinical Presentations In children, renovascular disease accounts for approximately 10% of all causes of secondary hypertension. The presence of hypertension is often determined during routine physical examination. Prior to the diagnosis of hypertension, children often report various non-specific symptoms including headache (42%), insomnia (27%), fatigue (26%) and chest or abdominal pain, which may be indicative of hypertension.8 A minority of children with hypertension present with neurological symptoms including seizures, transient ischemic attacks, cerebral infarctions, subarachnoid hemorrhages, and cranial nerve palsies. A bruit may be present over the affected vascular bed, although

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

Saints Medical Center Fibromuscular Dysplasia in Children and Adolescents Cerebral Vascular Accident Following a Pulmonary Embolism: Search for the Hidden Patent Foramen Ovale Contents Clinical Editor’s Corner Meetings Calendar CEU Education Center Radiation Tracking in the Cardiac Catheterization Lab Letter to the Editor Carotid Stenting: An update Release from Stent-jail: Beneficial Snow-Plowing? Patient Management Guidelines Searching for a Cardiovascular Position? Tips for Creating a ‘Stand-Out’ Resume Long-Term Implications of Short-Term Closure Decisions – The Evolution to Vascular Access Management and the Boomerang Catalyst System The Ten-Minute Interview with… Angie Bowles, RN, CCRN CMS Issues Final FY 2008 IPPS Rule ACVP• Membership Page Experience with a New Workhorse Guidewire Ask the Clinical Instructor: Q&A for Those New to Cath Lab A Glimpse of the Future of Clinical Education: Boston Scientific’s SimSuite Bus Visits Carnegie Institute 2007 Educational Fair Held at the Washington Hospital Center Research Update: Original Contribution Abstracts from The Journal of Invasive Cardiology What Do You Think? A Virtual Cath Lab Viewer (VCL): The Development of an Online 3D C-arm Simulator and Coronary Anatomy Viewer Clinical & Industry News Cost-Effectiveness of the Radial versus Femoral Artery Approach to Diagnostic Cardiac Catheterization

Cath Lab Digest - October 2007

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