Aortic stenosis is an important health issue because it is the most common cardiac valve problem, yet there is no effective medical therapy. Because of the increasing age of the U.S. population, this is a condition that family physicians will have to deal with more frequently in the future. Carabello reviews the management of aortic stenosis using the case history of a 60-year-old man with a loud systolic murmur noted on examination.
The author mentions other physical examination features that may be noted while aortic stenosis is progressing to at least moderate severity. These features include later peaking of the murmur in systole, palpable delay of the carotid upstroke, and a softening of the second heart sound as the aortic component is lost.
Hemodynamic disturbance ensues as the aortic valve area drops from the normal 3 to 4 cm2 to 1.5 to 2.0 cm2. The mean pressure gradient across the valve rises rapidly as the stenosis progresses to less than 1.0 cm2. The author's cutoff for severe aortic stenosis is a mean aortic-valve gradient above 50 mm Hg, although he notes that there is no universally accepted definition relying on valve area or gradient.
The review emphasizes that clinical symptoms of decompensated left heart function (angina, syncope, or congestive heart failure symptoms) are much more crucial than the echocardiographic measures of gradient and valve area in determining whether to proceed with valve replacement. Asymptomatic patients are generally best served by observation; fewer than one third of patients with symptomatic severe stenosis are alive in two years without surgical intervention. Clearly, symptomatic patients and patients with suggestive symptoms and gradients greater than 50 mm Hg or valve areas less than 1.0 cm2 should proceed to valve replacement, according to the author. Exercise testing may reveal occult ventricular dysfunction in seemingly asymptomatic patients with severe stenosis by echocardiography.
Aortic stenosis that progressed to ventricular dysfunction with a low ejection fraction has traditionally been cited as a contraindication to valve surgery. The author recommends that patients with low ejection fractions who still have an elevated valve gradient (greater than 40 mm Hg) should be considered for surgery because it appears to improve their survival. A low ejection fraction with a low gradient is usually an ominous sign of highly decompensated left heart function that does not improve with valve surgery.