Aortic stenosis echocardiography


 * Mohammed A. Sbeih, M.D. [mailto:msbeih@perfuse.org];

Overview
Echocardiography is the best non-invasive test to evaluate the aortic valve anatomy and function. Echocardiography can be used to estimate the gradient across the aortic valve using the modified Bernoulli equation (gradient = 4 X velocity2). The flow must be constant, so as the velocity increases, the valve area decreases proportionally. Echocardiography can also be used to assess the severity of left ventricular hypertrophy.

Parasternal Long Axis View
The parasternal long axis view visualizes the right and non coronary leaflets.

Parasternal Short Axis View
In the parasternal short axis view, the aortic leaflets open equally and form a circular orifice during systole. During diastole, the normal leaflets form a three pointed star with prominence at the closing point (nodules of Arentius).

Severity of Aortic Stenosis
Aortic stenosis severity can be assessed by estimating both the pressure gradient across the valve and the aortic valve area.


 * Using echocardiographic flow velocities, the aortic valve area can be calculated non-invasively to estimate the severity of aortic stenosis.


 * Using the velocity of the blood through the valve, the pressure gradient across the valve can be calculated by the equation: "Gradient = 4(velocity)² mmHg"

Normal Aortic Valve:

 * A normal aortic valve has no gradient, and
 * Aortic valve surface area is of 2.5 to 3.5 cms2.

Mild Aortic Stenosis:

 * Mean pressure gradient across the valve is less than 25 mm Hg, or
 * Valve surface area is between 1.5 and 2.5 cms2, or
 * Jet velocity less than 3.0 m per second

Moderate Aortic Stenosis:

 * Mean pressure gradient across the valve is between 25 mm Hg and 40 mm Hg, or
 * Valve surface area is between 1.0 and 1.5 cms2, or
 * Jet velocity 3.0 to 4.0 m per second

Moderate to Severe Aortic Stenosis

 * Valve surface area is between 0.7 and 1.0 cms2

Severe Aortic Stenosis:

 * Mean pressure gradient across the valve is more than 40 mm Hg, or
 * Valve surface area is less than 0.7 cm2, or
 * Jet velocity is greater than 4.0 m per second

==ACC/AHA Guidelines- Echocardiography (Imaging, Spectral, and Color Doppler) in Aortic Stenosis == {{cquote|

Class I
1. Echocardiography is recommended for the diagnosis and assessment of aortic stenosis severity. (Level of Evidence: B)

2. Echocardiography is recommended in patients with aortic stenosis for the assessment of left ventricular wall thickness, size, and function. (Level of Evidence: B)

3. Echocardiography is recommended for re-evaluation of patients with known aortic stenosis and changing symptoms or signs. (Level of Evidence: B)

4. Echocardiography is recommended for the assessment of changes in hemodynamic severity and left ventricular function in patients with known aortic stenosis during pregnancy. (Level of Evidence: B)

5. Transthoracic echocardiography is recommended for re-evaluation of asymptomatic patients: every year for severe aortic stenosis; every 1 to 2 years for moderate aortic stenosis; and every 3 to 5 years for mild aortic stenosis. (Level of Evidence: B)

Class IIa
1. Dobutamine stress echocardiography is reasonable to evaluate patients with low-flow/low-gradient aortic stenosis and left ventricular dysfunction. (Level of Evidence: B)}}