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Key Concepts

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  • Epidemiology

    • Approximately 100,000 aortic valve replacement procedures have been performed in the United States in the last 10 years. Most patients present with aortic valve pathology that requires replacement between ages 60 and 80. Replacement for aortic stenosis is performed much more commonly (85 percent) than is replacement for aortic insufficiency.

  • Pathophysiology

    • With aortic stenosis, there is a decrease in the effective valve orifice area, resulting in progressive obstruction of the left ventricle. The ventricle adapts through concentric hypertrophy, which increases diastolic stiffness and impairs the efficacy of diastolic coronary blood flow. Diastolic dysfunction precedes systolic dysfunction. With aortic insufficiency, gradual ventricular dilatation occurs, causing an increase in wall stress. This, in conjunction with the decrease in diastolic pressure, reduces diastolic coronary blood flow. With continued dilatation, fibrosis occurs, increasing ventricular stiffness and impairing diastolic relaxation. Eventually, the preload reserve of the ventricle is reached and further dilatation and fibrosis result in a decline in systolic function that may not be recoverable after aortic valve replacement.

  • Clinical features

    • Aortic stenosis patients complain of combinations of symptoms of chest pain, syncope, and congestive heart failure. The life expectancy of patients with untreated aortic stenosis who present with angina is 50 percent at 5 years, 50 percent at 3 years with syncope, and 50 percent at 2 years with congestive heart failure symptoms. A small proportion of patients with aortic stenosis present with sudden death. Aortic insufficiency has a more insidious onset and usually is characterized by the development of slow congestive heart failure and fatigue symptoms. Angina pectoris and syncope are rare in these patients. These patients may be managed on medical therapy for protracted periods with an acceptable quality of life.

  • Diagnostics

    • The work-up for candidates for aortic valve replacement includes echocardiography to estimate ventricular function and the degree of stenosis or insufficiency and cardiac catheterization to measure cardiac output, calculate aortic valve area, and image the coronary arteries for significant lesions. A careful oral examination or dental consultation is very important to prevent postoperative prosthetic valve infection.

  • Treatment

    • Aortic valve replacement options include homograft, stented and stentless xenograft tissue, and mechanical valves. The decision to use each of these is dependent on patient age and valve preference, comorbid conditions, and contraindications to the use of anticoagulants. A variety of options are available to manage potential patient–prosthesis mismatch at the time of surgery.

  • Outcomes

    • The outcomes of tissue valve replacement show 80 to 93 percent freedom from structural valve failure at 10 to 14 years. Bleeding and thromboembolic events complicate mechanical valve replacement at a rate of approximately 4 percent per patient-year. Homograft valve replacements have the highest freedom from structural valve deterioration, with rates of 81 to 93 percent at 15 years. Survival after aortic valve replacement is dependent more on patient comorbidities than on the requirement for valve replacement. Postoperative complications specific for aortic valve replacement include complete heart block (1 percent) and perivalvular leaks (1–2 percent).

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