The single most useful test is Doppler echocardiography, which allows measurement of the velocity of blood flow through the stenotic valve: the more severe the stenosis, the higher the velocity. A simple formula relates the velocity to the estimated pressure gradient across the valve: where AP is the pressure gradient (in mmHg), and V is the maximum outflow tract velocity (in m/s). When ventricular function is normal, a pressure gradient of 50-60 mmHg is likely to be associated with hemodynamically significant stenosis. The remainder of the echocardiogram should demonstrate a calcified, poorly mobile aortic valve and left ventricular hypertrophy.
An electrocardiogram should be examined. The presence of left ventricular hypertrophy and left atrial enlargement suggest significant stenosis. The chest radiograph may show evidence of a calcified aortic valve, cardiomegaly, and congestive heart failure.
What are the causes of aortic stenosis?
In patients over age 70 years, the most common cause is senile calcific degeneration. In younger patients, the most common cause is calcific degeneration of a congenitally bicuspid valve. Rheumatic heart disease is diminishing in importance as a cause for aortic stenosis. In children and young adults, congenital stenosis is most common. Methysergide, a vasodilator medication used for migraines, is a rare cause of aortic stenosis.
Of what value is cardiac catheterization?
The main value of catheterization is to define the degree of stenosis accurately. This is done by estimating the valve orifice area through use of an equation relating area to cardiac output, pressure gradient across the valve, and duration of systole, all of which are measured during catheterization. The procedure is also useful for defining left ventricular function and for assessing coronary artery disease in patients over age 40. Significant coronary stenoses should be bypassed at the time of valve replacement.
Describe the natural history of aortic stenosis.
In patients with mild to moderate stenosis (valve area 1.0 cm2), the prognosis is excellent. The mean time between diagnosis and surgery is well over a decade. In patients with severe stenosis, the outlook is not as good. In one study of patients who refused surgery, survival rates depended on symptoms. Mean survival was 45 months for those with angina, 27 months for those with syncope, and only 11 months for those after the onset of left-heart failure. Patients with severe stenosis seldom die suddenly prior to the onset of symptoms.
When should aortic valve surgery be considered?
Most agree that aortic valve replacement should be performed only when stenosis causes symptoms. Some believe that valve replacement should be performed in asymptomatic patients when the valve reaches a critical degree of narrowing, usually defined as a valve area 0.8 cm2 as determined at catheterization. Firm evidence that this latter approach improves outcome is lacking, however.
When is balloon valvuloplasty a useful procedure?
This procedure has not replaced surgical valve replacement because of high rates of restenosis and complications. It may be useful in patients with severe symptoms whose lifespans are limited by other diseases such as malignancy. It may also buy time in patients with severe heart failure or intercurrent illness, such as pneumonia, in order to improve surgical risk. The procedure may be more useful in children or young adults with congenital stenosis.
Can chronic aortic regurgitation cause heart failure?
Yes. Although aortic regurgitation is generally better tolerated than stenosis, it may lead to irreversible left ventricular dysfunction. This may occur prior to the development of symptoms. Thus, patients with severe aortic insufficiency must be followed carefully.
What symptom is found with aortic regurgitation?