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What Does Your Aortic Stenosis Grade Mean?

Medically reviewed by Patrina Conley-Brown, D.O.
Written by Emily Wagner, M.S.
Posted on September 13, 2023

When living with a complex medical condition like aortic stenosis, you may find yourself with more questions than answers. You might be wondering, “How does my cardiologist (heart doctor) know how severe my aortic stenosis is? What does this mean for my treatment options?”

Your aortic stenosis grade refers to how severe your condition is. In this article, we’ll cover the three key features your cardiologist looks at to determine your grade and how they’re measured. We’ll also discuss what your grade means for your treatment options and outlook.

What Is Aortic Stenosis?

Your heart works hard to pump oxygen-rich blood to the rest of your body. Your left ventricle (one of the lower chambers of your heart) is responsible for pumping blood from your heart to your aorta — the largest blood vessel in your body. Your aorta carries blood out to your organs and tissues.

The aortic valve sits between the left ventricle and the aorta, opening and closing tightly to control blood flow. This valve is made of three tissue flaps (or leaflets) that stop blood from flowing back into your heart, known as aortic regurgitation.

With age, a person’s aortic valve can begin to narrow, thereby limiting the amount of blood flowing through it. This is known as aortic stenosis (or aortic valve stenosis). According to the American Heart Association, more than 12 percent of American adults over the age of 65 are living with this condition.

The aortic valve opens and closes to control blood flow. In aortic stenosis, the valve does not close properly, causing blood to flow back into the heart. (Adobe Stock)

Other causes and risk factors of aortic stenosis include:

  • Valve scarring from infection, inflammation, or disease
  • Valve calcification (calcium deposits)
  • Bicuspid aortic valve (being born with two tissue flaps instead of three)
  • Risk factors for heart disease, including hypertension (high blood pressure) and high cholesterol levels

While some people are asymptomatic and show no signs of aortic stenosis, those who are symptomatic may experience:

  • Shortness of breath
  • Syncope (fainting)
  • Angina (chest pain)
  • Dizziness
  • Heart palpitations (fast-beating or fluttering heart)

How Is Aortic Stenosis Grading Determined?

If you’re experiencing symptoms of aortic stenosis, your doctor may refer you to a cardiologist, who’ll run a series of tests to figure out what’s causing them. Once you’re diagnosed with aortic stenosis, your cardiologist will use the test results to determine the grade or severity of the condition.

There are four aortic stenosis grades:

  • Normal
  • Mild
  • Moderate
  • Severe

Your grade will affect what treatments you receive. Doctors use three different measurements to determine grading severity:

  • Mean gradient
  • Aortic jet velocity
  • Aortic valve area

The medical terms used to describe valvular heart diseases like aortic stenosis can be quite complicated. Here, we’ll break them down into simpler concepts to help you better understand your condition.

Mean Gradient

The aortic valve opens and closes to allow oxygen-rich blood from the left ventricle to flow through. When you have aortic stenosis and the valve narrows, less blood can pass through. This causes more pressure to build up between the left ventricle and the aorta.

The difference in pressure between these two areas — known as the pressure gradient — can tell your cardiologist how severe your aortic stenosis is. Aortic stenosis grading takes into account your mean transvalvular gradient (mean gradient) — that is, the average pressure across the aortic valve between the left ventricle and aorta.

Like your blood pressure, the mean gradient is measured in millimeters of mercury (mm Hg). Normally, a healthy aortic valve has minimal if any mean gradient. A high gradient is a sign of more severe aortic stenosis. Aortic stenosis is graded according to mean gradient measurements as follows:

  • Mild — Less than 25 mm Hg
  • Moderate — From 25 to 40 mm Hg
  • Severe — Greater than 40 mm Hg

Aortic Jet Velocity

Your cardiologist will also use your aortic jet velocity to determine the grade of your aortic stenosis. This is a measurement of the speed at which blood flows across the aortic valve. A healthy aortic valve has an aortic jet velocity of less than 2.5 meters per second.

When you have aortic stenosis, your aortic valve is narrowed. Your left ventricle tries to pump the same amount of blood through a smaller space in the valve, which increases the blood flow’s speed. The higher your aortic jet velocity, the more severe your aortic stenosis.

Aortic stenosis is graded according to aortic jet velocity as follows:

  • Mild — 2.5 to 2.9 meters per second
  • Moderate — 3 to 4 meters per second
  • Severe — More than 4 meters per second

Aortic Valve Area

The aortic valve area refers to the size of your aortic valve when it’s open. A healthy aortic valve area is between 3 and 4 square centimeters. As your aortic stenosis progresses, the valve begins to narrow, and the area becomes smaller. The smaller your aortic valve area, the more severe your aortic stenosis.

Aortic stenosis is graded according to aortic valve area as follows:

  • Mild — 1.5 to 2 square centimeters
  • Moderate — 1 to 1.5 square centimeters
  • Severe — Less than 1 square centimeter

Echocardiography Is Used To Diagnose Aortic Stenosis

We know that cardiologists grade aortic stenosis using three key measurements, but what tests do they use to get these numbers?

Echocardiography is a gold standard for diagnosing aortic stenosis. Also known as a cardiac ultrasound, echocardiography uses sound waves that bounce off your heart to create pictures of how your heart works in real time. Doppler echocardiogram is a specific feature used to measure the speed and direction of blood through your heart and across the valves.

An echocardiogram produces valuable information regarding heart and valve function. It can actually measure each of the components needed to evaluate aortic stenosis, including mean gradient, aortic valve area, and aortic jet velocity.

A transthoracic echocardiogram is the primary noninvasive test — meaning it doesn’t pierce your skin — for evaluating aortic valve stenosis. However, a doctor may use a more invasive type, called transesophageal echocardiogram, to gather additional information — especially in planning aortic valve surgery.

Checking Your Left Ventricle Health

Your cardiologist may also take a look at other parts of your heart to check its overall health. People with aortic stenosis often have left ventricular hypertrophy (an enlarged left ventricle). When the heart chamber has to work extra hard to pump blood through the narrowed aortic valve, it can become larger over time. This is similar to how your biceps become larger after lifting more weights.

Your cardiologist may also check your left ventricular ejection fraction (LVEF), which reflects how much blood your left ventricle pumps out to your body with each heartbeat. According to the Cleveland Clinic, a healthy LVEF is between 50 percent and 70 percent. People with aortic stenosis may or may not have a lower-than-normal LVEF — meaning your heart may pump less blood than normal. LVEF can also be measured from an echocardiogram.

Other heart studies useful in evaluating heart function and aortic stenosis include stress testing, cardiac catheterization, and cardiac CT or MRI.

By learning more about your heart’s health, your cardiologist can determine when you might need additional treatment or surgery.

What Your Aortic Stenosis Grade Means

Your cardiologist will use your aortic stenosis severity or grade to create your treatment plan. Below is a table highlighting the three factors used to diagnose and grade aortic stenosis.

Aortic Stenosis Grade Mean Gradient (Millimeters of Mercury, or
mm HG)
Aortic Jet Velocity (Meters per Second)Aortic Valve Area (Square Centimeters)
NormalLess than 5Less than or equal to 23 to 4
MildLess than 25Less than 3Greater than 1.5
Moderate25 to 403 to 41 to 1.5
SevereGreater than 40Greater than 4Less than 1

For mild aortic stenosis, your cardiologist may recommend making lifestyle changes, like eating a heart-healthy diet and exercising more.

If you’re diagnosed with moderate aortic stenosis, it’s important that you take steps to prevent it from progressing to heart failure. Your cardiology provider may prescribe you medications to take better care of your cardiovascular health. These can include cholesterol and blood pressure medications or ones to help regulate your heart rhythm.

Severe aortic stenosis can be life-threatening and requires surgery to replace the damaged heart valve. You may have a transcatheter aortic valve replacement or a surgical aortic valve replacement. Replacing the valve can treat your symptoms and help prevent heart failure. Your doctor can further discuss these options with you and help determine which may be the most appropriate.

Talk With Others Who Understand

On MyHeartDiseaseTeam — the social network for people with heart disease and their loved ones — more than 57,000 members come together to ask questions, give advice, and share their stories with others who understand life with heart disease.

What questions do you have about aortic stenosis and grading? Share your experience in the comments below, or start a conversation by posting on your Activities page.

    Posted on September 13, 2023
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    Patrina Conley-Brown, D.O. holds a Bachelor of Science from Vanderbilt University, a Master of Science from the University of South Florida, and a Doctor of Osteopathic Medicine from Nova Southeastern University. Learn more about her here.
    Emily Wagner, M.S. holds a Master of Science in biomedical sciences with a focus in pharmacology. She is passionate about immunology, cancer biology, and molecular biology. Learn more about her here.

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