Managed Care - January 2008 - (Page 55) TOMORROW’S MEDICINE sue bioacceptable by destroying antigenicity, and stabilizes the collagen crosslinks for durability. Bioprosthetic valves are typically stented, meaning the animal tissue is supported by a polyester-covered plastic frame. A sewing cuff is attached to the valve and enables the surgeon to sew the valve in place. But the patented new technology, termed Linx technology, that is applied is the key breakthrough. After the animal bioprosthetic valve has been fixed with glutaraldehyde, an ethanol treatment is applied. This reduces a number of risks. It reduces glutaraldehyde toxicity, a known calcification risk. Ethanol also removes 99 percent of cholesterol and 94 percent of the phospholipids that are potential binding sites for tissue calcification. It also results in a more stable collagen helix. In sheep models, the use of the Linx technology demonstrated excellent resistance to leaflet calcification compared to glutaraldehyde controls. The Linx technology competes with a technology named ThermaFix, which is used by a major competitor of SJM, Edwards Lifesciences. ThermaFix is a proprietary thermal technology that also aims to reduce calcification through a two-step process to reduce glutaraldehyde and phospholipids. There is no head-to-head study to compare the two processes available at this time. The Epic valve will be sold in the United States this year. Complete data for more comprehensive evaluation are unavailable at this time, but given the FDA’s recent reluctance to approve advances in technology without compelling evidence, it is likely that this new approval has acceptable clinical support. The author is a director in the value-based health department at Genentech Inc. During the last three years, before taking the Genentech position, he received honoraria or other financial benefits from: Amgen, Amylin Pharmaceuticals, AstraZeneca, Biogen Idec, Centocor, Galderma, GlaxoSmithKline, Johnson & Johnson, Merck, Novartis, Novo Nordisk, Pfizer, Procter & Gamble, Q-Med, Sanofi-Aventis, Teva Pharmaceuticals Industries, UCB, and Wyeth. The views expressed in Tomorrow’s Medicine are the author’s alone. Forces and flows ach time the heart beats, blood moves forward through valves that prevent backward movement during the resting phase. The heart contains four valves, two between the left and right atria and ventricles (tricuspid and mitral valves) and two at the output side of the ventricles and the large blood vessels (pulmonary and aortic valves). Valves make the typical “lub-dub” sound you can hear by placing an ear on the chest of a willing participant. This “lub-dub” noise changes considerably in the presence of valvular disease, and each valve makes a particular noise when compromised. These noises are called heart murmurs. In many cases, a heart murmur is benign and requires no therapy. A variety of tests can be done to determine the exact defect and to determine the appropriate therapy. These tests include echocardiography, cardiac catheterization, electrocardiogram, chest X-rays, and exercise testing, to name a few. E Causes There are many causes of valve disease. The most common cause of aortic stenosis is calcification of the valve. This is an active disease process with many similarities to atherosclerosis. It is characterized by lipid accumulation, inflammation, and calcification. Rheumatic fever is a less common cause of aortic stenosis. Rheumatic aortic stenosis is invariably accompanied by mitral valve disease. In fact, rheumatic fever is the most common cause of mitral stenosis. Another common valvular disorder is mitral valve prolapse. MPV can be either familial or nonfamilial. Another cause of heart valve disease, one that created quite a stir in the media a few years ago, is the diet regime Fen-Phen. This reached national attention and led to huge legal settlements for those affected. Obviously, as with most implants, managed care organizations seldom become involved with reviewing the actual type of implant. For this reason, this valve is unlikely to be evaluated by most plans. But the SJM Epic valve demonstrates the march of medical technology and the remarkable amount of competition in medical science. It also ensures that each of us will benefit from Tomorrow’s Medicine. MC JANUARY 2008 / MANAGED CARE 55
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