Aortic Stenosis (cont.)
What might the doctor find in patients
with aortic stenosis?
The carotid arteries carry blood from
the aorta to the brain and are the closest arteries to the aortic
valve that can be felt by the doctor examining the neck. Patients
with significant aortic stenosis have a delayed upstroke and lower
intensity of the carotid pulse which correlates with the severity
of narrowing. Aortic valve stenosis causes significant turbulence
to blood flowing during contraction of the left ventricle resulting
in a loud murmur. The loudness of the murmur does not, however,
correlate with the severity of stenosis. Patients with mild stenosis
can have loud murmurs, while patients with severe stenosis and
heart failure may not pump enough blood to cause much of a murmur.
How is aortic stenosis diagnosed?
Electrocardiogram (EKG):
An EKG is a recording
of the heart's electrical activity. Abnormal patterns on the EKG
can reflect a thickened heart muscle and suggest the diagnosis
of aortic stenosis. In rare instances, electrical conduction
abnormality can also been seen.
Chest x-ray: A
chest x-ray usually shows a normal heart shadow. The aorta above
the aortic valve is often enlarged (dilated). If heart failure
is present, fluid in the lung tissue and larger blood vessels
in the upper lung regions are often seen. A careful inspection
of the chest x-ray sometimes reveals calcification of the aortic
valve.
Echocardiography: Echocardiography uses ultrasound waves to obtain images of the
heart chambers, valves, and surrounding structures. It is a useful non-invasive tool, which helps doctors diagnose aortic valve disease. An
echocardiogram can show a thickened, calcified aortic valve
which opens poorly. It can also show the size and functioning
of the heart chambers. A technique called
Doppler can be used
to determine the pressure difference on either side of the aortic
valve and to estimate the aortic valve area.
Cardiac catheterization:
Cardiac catheterization is the gold standard in evaluating aortic
stenosis. Small hollow plastic tubes (catheters) are advanced
under x-ray guidance to the aortic valve and into the left ventricle.
Simultaneous pressures are measured on both sides of the aortic
valve. The rate of blood flow across the aortic valve can also
be measured using a special catheter. Using these data, the aortic
valve area can be calculated. A normal aortic valve area is 3
square centimeters. Symptoms usually occur when the aortic valve
area narrows to less than 1 square centimeter. Critical aortic
stenosis is present when the valve area is less than 0.7 square
centimeters. In patients over 40 years of age, x-ray contrast agents
can be injected into the coronary arteries (coronary angiography)
during cardiac catheterization to evaluate the status of coronary
arteries. If significant narrowing of the coronary arteries is
found, coronary artery bypass graft surgery (CABG) can be performed
during aortic valve replacement surgery.
Next: How is aortic stenosis treated? »
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