The electrocardiogram (ECG)
Although aortic stenosis does not lead to any specific findings on the ECG, it still often leads to a number of electrocardiographic abnormalities. ECG manifestations of left ventricular hypertrophy (LVH) are common in aortic stenosis and arise as a result of the stenosis having placed a chronically high pressure load on the left ventricle (with LVH being the expected response to chronic pressure loads on the left ventricle no matter how caused).
As noted below, the calcification process which occurs in aortic stenosis can progress to extend beyond the aortic valve and into the electrical conduction system of the heart. Evidence of this phenomenon may include heart block that is apparent on the ECG but otherwise undetectable.

Heart catheterization
The heart may be catheterized to directly measure the pressure on both sides of the aortic valve. The pressure gradient may be used as a decision point for treatment. Catheterization is accurate for moderate velocity stenosis, while Doppler echo is more accurate at faster velocities.

Echocardiogram
Echocardiogram (heart ultrasound) is the best non-invasive test to evaluate the aortic valve anatomy and function.
The aortic valve area can be calculated non-invasively using echocardiographic flow velocities. Using the velocity of the blood through the valve, the pressure gradient across can be calculated by the modified Bernoulli's equation:
Gradient = 4(velocity)² mmHg
A normal aortic valve has no gradient. If the mean gradient is <25>50 mm Hg the stenosis is severe; and when the gradient is greater than 70 mm Hg, the stenosis is critical. A normal aortic valve area is >2 cm2. If the valve area is between 1.3 and 2.0 cm2, the stenosis is mild; if the valve area is between 1.0 and 1.3 cm2, the stenosis is moderate; if the valve area is between 0.7 and 1.0 cm2, the stenosis is moderate-severe; areas of less than 0.7 cm2 constitute severe aortic stenosis.




Pulse Pressure
Disease of the aortic valve affects the character of the arterial pulse. Examination of the pulse in significant aortic stenosis reveals a slow rising, flat character called pulsus parvus et tardus. Blood pressure will show a narrow pulse pressure (difference between systolic and diastolic pressures). In the elderly, a rigid aorta may make this sign less obvious.