- Aortic stenosis (AS) in the adult population may result from calcification and degeneration of a normal valve, calcification and fibrosis of a congenitally bicuspid aortic valve, or rheumatic valvular disease.
- AS produces a pressure gradient between the left ventricle and the aorta, causing pressure overload of the left ventricle that leads to concentric hypertrophy.
- LV compliance is reduced, LVEDP rises, and myocardial oxygen demand is increased.
- Elevated LVEDP decreases the perfusion pressure across the myocardium, leading to subendocardial ischemia.
- Diagnosing significant AS may be difficult, as the condition may be asymptomatic for a number of years.
- AS should be suspected clinically with the presence of one or more of the classic symptoms in the triad of angina, syncope, and HF.
- Physical findings include a slowly rising carotid pulse that is sustained (pulsus parvus et tardus) and a mid- to late-peaking harsh systolic murmur.
- The pressure gradient across the stenotic aortic valve is directly related to the severity of obstruction and cardiac output.
- The intensity of the systolic murmur may diminish as the cardiac output decreases with increasingly severe AS. In general, murmurs of long duration that peak late in systole indicate severe AS.
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Imaging and Diagnostic Studies
- Doppler echocardiography estimates the aortic valve gradient and valve area, which correlates well with the findings at cardiac catheterization.
- TEE may be required in patients with suboptimal transthoracic echocardiograms.
- Coronary arteriography should be performed in men older than 40 years and women older than 50 years, as well as in all patients with anginal symptoms.
- Left ventriculography is indicated in patients with coexistent MR (although a high-quality transthoracic echocardiogram or a TEE may suffice).
- Most adult patients being considered for aortic valve replacement (AVR) require preoperative cardiac catheterization to determine the extent of concomitant coronary artery disease.
- Vigorous exercise and physical activity should be avoided in patients with moderate to severe AS.
- Asymptomatic patients with mild to moderate AS can be followed closely with clinical assessment and Doppler echocardiography performed at 6- to 12-month intervals.
- Infective endocarditis prophylaxis is indicated.
- Atrial (and ventricular) arrhythmias are poorly tolerated and should be treated.
- Digoxin may be useful in patients with HF in the presence of LV dilation and impaired systolic function. In severe AS caused by the fixed obstruction of LV outflow, however, inotropic therapy is of little benefit.
- Diuretics may be useful in treating congestive symptoms but must be used with extreme caution. Reduction of LV filling pressure in patients with AS may decrease cardiac output and systemic BP.
- Nitrates and other vasodilators should be used with caution in patients with severe AS, as they may result in severe hypotension and hemodynamic collapse.
- In patients with severe AS and new-onset angina, nitroglycerin should be initiated cautiously. If nitroglycerin results in hypotension that does not respond to aggressive volume expansion, parenteral inotropic agents (e.g., dobutamine) or vasopressors, or both, should be given.
- Symptomatic patients with severe AS (aortic valve area <1.0 cm2) and patients with severe AS who are undergoing cardiac or aortic surgery should undergo AVR concurrently.
- Asymptomatic patients with severe AS should be considered for AVR if LV dilation or decreased systolic function is present or if they have a hypotensive response to exercise.
- Intra-aortic balloon counterpulsation may stabilize patients with critical AS and hemodynamic decompensation until AVR can be accomplished. An IABP should not be used when significant aortic insufficiency (AI) coexists.
- Percutaneous balloon aortic valvuloplasty can reduce the aortic valve gradient and improve symptoms and LV function with relatively low morbidity and mortality in selected patients.
- Restenosis occurs in approximately 50% of patients within 6 months.
- At present, this therapeutic modality is used primarily in patients who require noncardiac surgery before definitive AVR.