Evolving Concepts about Aortic Stenosis.
Concepts about the management of aortic stenosis have evolved over the last several years. Concerns about the safety of exercise, positive inotropic drugs, and afterload reduction have been based on the expected exponential relationship of pressure and flow predicted by the Gorlin equation. However, in most patients, even those with severe stenosis, transvalvular pressure gradient increases much less than predicted with increases in cardiac output. Furthermore, data show that exercise testing usually can be performed safely and often provides helpful information about functional status and symptoms. In addition, positive inotropes and afterload-reducing drugs, when initiated cautiously, are often beneficial for these patients. Based on newly available data, physicians are encouraged to wait until symptoms develop before replacing the aortic valve in patients with severe stenosis. Patients with severe aortic stenosis but low transvalvular gradients because of left ventricular dysfunction should have functional testing with dobutamine or nitroprusside. If an increase in flow produces only a minimal increase in transvalvular velocity or pressure gradient, the patient is less likely to benefit from surgery. Risk for noncardiac surgery may not be as high as previously reported in most patients with aortic stenosis; again, functional testing can play an important role in their clinical assessment.
Shively
BK
University of New Mexico, Albuquerque, New Mexico.