Aortic stenosis (AS) is one of the most common valvular diseases you’ll encounter in echocardiography, and accurately grading its severity is important for clinical decision-making. While AS can seem complex at first, it becomes much easier to grasp once you understand the key parameters.

What is Aortic Stenosis?

Aortic stenosis is a progressive narrowing of the aortic valve, increasing resistance to left ventricular outflow. Over time, this leads to pressure overload, LV hypertrophy, and eventually, heart failure. The tighter the valve, the harder the heart has to work to push blood through it—much like trying to force water through a kinked garden hose. The most common causes of AS include age-related degenerative calcification, congenital bicuspid aortic valve, and rheumatic heart disease.

Aortic Sclerosis vs. Aortic Stenosis

Aortic sclerosis is an early-stage degenerative process characterized by aortic leaflet thickening and calcification without significant obstruction to blood flow. Aortic sclerosis does not cause a significant pressure gradient across the valve (Vmax < 2.5 m/s). While it is often asymptomatic, it is not entirely benign—patients with aortic sclerosis have an increased risk of progression to aortic stenosis. Routine follow-up and risk factor management (e.g., hypertension, hyperlipidemia) are key in these patients.

5 Key Parameters to Grade AS

Echocardiography uses a combination of the following parameters to accurately diagnose and monitor the severity of AS.

• Peak Aortic Velocity (Vmax)

• Mean Pressure Gradient (Mean PG)

• Aortic Valve Area (AVA)

• Indexed Aortic Valve Area (AVAi)

• Velocity Ratio (Dimensionless Index)

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