Aortic Stenosis (cont.)
Daniel Lee Kulick, MD, FACC, FSCAI
Daniel Lee Kulick, MD, FACC, FSCAI
Dr. Kulick received his undergraduate and medical degrees from the University of Southern California, School of Medicine. He performed his residency in internal medicine at the Harbor-University of California Los Angeles Medical Center and a fellowship in the section of cardiology at the Los Angeles County-University of Southern California Medical Center. He is board certified in Internal Medicine and Cardiology.
William C. Shiel Jr., MD, FACP, FACR
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
How is aortic stenosis treated?
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Patients without symptoms can be observed until symptoms develop. Patients with mild aortic stenosis do not require treatment or restriction of activity. Patients with moderate aortic stenosis (valve area 1.5 to 1.0 square centimeters) are advised to avoid strenuous activities such as weight lifting or sprinting. Aortic stenosis can progress over a few years. Therefore, patients are usually examined annually and evaluated by echocardiography periodically to monitor disease progression. Since valve infection (endocarditis) is a serious complication of aortic stenosis, these patients are usually given antibiotics prior to any procedure in which bacteria may be introduced into the bloodstream. This includes routine dental work, minor surgery, and procedures that may traumatize body tissues such as colonoscopy and gynecologic or urologic examinations. Examples of antibiotics used include oral amoxicillin (Amoxil) and erythromycin (E-Mycin, Eryc, PCE), as well as intramuscular or intravenous ampicillin (Unasyn), gentamicin (Garamycin), and vancomycin (Lyphocin, Vancocin).
When symptoms of chest pain, syncope, or shortness of breath appear, the prognosis for patients with aortic stenosis without valve replacement surgery is poor. Medical therapy, such as the use of diuretics to reduce high lung pressures and remove lung fluid can provide only temporary relief of symptoms. Patients with symptoms usually undergo cardiac catheterization. If severe aortic stenosis is confirmed, aortic valve replacement is usually recommended. The overall mortality risk for aortic valve replacement surgery is about 5%. Advanced age should not be a reason for not recommending aortic valve replacement for aortic stenosis. Otherwise healthy patients in their 80s with strong heart muscles often benefit dramatically from aortic valve replacement for critical aortic stenosis.
Replacement aortic valves processed from pigs (porcine) or cows (bovine) are called bioprostheses. Bioprostheses are less durable than mechanical prostheses (discussed below) but have the advantage of not needing life-long blood thinning (anticoagulation) medication to prevent blood clots from forming on the valve surfaces. The average life expectancy of an aortic valve bioprostheses is 10 to 15 years. Bioprostheses rapidly calcify, degenerate and narrow in young patients. Therefore, bioprostheses are primarily used on older patients or in patients who cannot take blood thinners. Recently, aortic valves from human cadavers have been used in younger patients to avoid the need for anticoagulation medication. However, the availability of human aortic grafts is limited; though probably better than the other bioprostheses, its long term durability is unknown. The new "Ross Procedure" consists of moving the pulmonic valve to the aortic position and replacing the pulmonic valve with a valve from a human donor. This procedure has not been performed long enough to evaluate the long-term performance of the pulmonic valve when moved to the aortic position.
Mechanical prostheses have proven to be extremely durable and can be expected to last from 20 to 40 years. However, mechanical prosthetic valves all require life-long anticoagulation with blood thinners such as warfarin (Coumadin) to prevent clot formation on the valve surfaces. Otherwise, blood clots dislodged from these valves can travel to the brain and cause embolic stroke or embolic problems in other parts of the body. The original caged-ball Starr-Edwards prosthesis of the 1960s was replaced by the tilting disc Bjork-Shiley of the 1970s and early 1980s. Although the Bjork-Shiley valve provided a larger opening for blood flow, a second generation model of the valve posed the risk of potential breakage resulting in death, and is no longer available in the United States. The tilting pivoting disc Hall-Medtronic valve and the two leaflet (bileaflet) carbon St. Jude valve are commonly used mechanical prostheses today. These valves provide excellent flow characteristics but require life-long anticoagulation with blood thinners such as warfarin (Coumadin), to prevent embolic complications.
The aortic valve area can be opened or enlarged with a balloon catheter (balloon valvuloplasty) which is introduced in much the same way as in cardiac catheterization. With balloon valvuloplasty, the aortic valve area typically increases slightly. Patients with critical aortic stenosis can therefore experience temporary improvement with this procedure. Unfortunately, most of these valves narrow over a 6 to 18 month period. Therefore, balloon valvuloplasty is useful as a short-term measure to temporarily relieve symptoms in patients who are not candidates for aortic valve replacement. Patients who require urgent noncardiac surgery, such as a hip replacement, may benefit from aortic valvuloplasty prior to surgery. Valvuloplasty improves heart function and the chances of surviving non-cardiac surgery. Aortic valvuloplasty can also be useful as a bridge to aortic valve replacement in the elderly patient with poorly functioning ventricular muscle. Balloon valvuloplasty may temporarily improve ventricular muscle function, and thus improve surgical survival. Those who respond to valvuloplasty with improvement in ventricular function can be expected to benefit even more from aortic valve replacement. Aortic valvuloplasty in these high risk elderly patients has a similar mortality (5%) and serious complication rate (5%) as aortic valve replacement in surgical candidates.
There is a new alternative available to high risk surgical patients, referred to as transcutaneous aortic valve insertion (TAVI). In this procedure, a prosthetic aortic valve is inserted through the artery in the groin or via direct insertion into the heart, but without the need for open heart surgery. While the preliminary data is encouraging, it has only recently been released from investigational status, and its ultimate role in management is still being evaluated.
Reviewed by William C. Shiel Jr., MD, FACP, FACR on 8/27/2012
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