Cardiology

Biology, Diagnosis, and Your Echocardiogram Report

At a Glance

An aortic stenosis echocardiogram grades valve narrowing by combining peak blood-flow speed, mean pressure gradient, and aortic valve area. If these values disagree, doctors use blood flow, blood pressure, heart function, symptoms, and sometimes stress echo or CT calcium scoring to clarify severity.

Understanding an echocardiogram report can feel like learning a new language. These reports use sound waves to create a map of your heart’s anatomy and measure how fast blood is moving through your valves. For aortic stenosis (AS), doctors use these measurements to determine if the disease is mild, moderate, or severe ^[1].

The Biology of a Narrowed Valve

Aortic stenosis is not simply “wear and tear.” It is an active biological process where the valve leaflets become stiff and lose their ability to open fully ^[2].

Calcific AS: This is the most common form in older adults. It begins with microscopic damage and inflammation, leading to calcium deposits that turn the once-flexible leaflets into rigid, bone-like structures ^[3]^[4].
Bicuspid Aortic Valve (BAV): About 1–2% of people are born with two valve leaflets instead of the usual three ^[5]. Because of this shape, the valve faces more mechanical stress and tends to develop calcification and narrowing much earlier in life ^[6].
Rheumatic AS: This is caused by a past bout of rheumatic fever, which triggers chronic inflammation that fuses the edges (commissures) of the valve leaflets together ^[7].

Decoding the Severity Scale

Your doctor looks at three primary numbers to grade your stenosis: Peak Velocity (Vmax), Mean Gradient, and Aortic Valve Area (AVA) ^[8]. It is crucial to remember that a single value does not diagnose your disease; your cardiologist must interpret these numbers together with your flow, blood pressure, and symptoms.

Severity	Peak Velocity (Vmax)	Mean Gradient	Valve Area (AVA)
Mild	~ 2.0 – 2.9 m/s	Less than 20 mmHg	Greater than 1.5 cm²
Moderate	3.0 – 3.9 m/s	20 – 39 mmHg	1.0 – 1.5 cm²
Severe	4.0 m/s or higher	40 mmHg or higher	1.0 cm² or smaller

^[8]^[9]^[10]

Some doctors also look for “Very Severe” AS, which is often defined as a velocity of 5.0 m/s or higher or a mean gradient of 60 mmHg or higher ^[11].

When the Numbers Don’t Agree (Low-Gradient AS)

In some patients, the echo measurements are “discordant,” meaning they don’t match. For example, your AVA might be in the severe range (below 1.0 cm²), but your Mean Gradient is low (below 40 mmHg) ^[12]. This is known as Low-Gradient Aortic Stenosis.

This happens when the heart is not pumping enough blood (low flow) to generate a high pressure across the valve ^[13]. It can be caused by a weakened heart muscle or by a very stiff, thick-walled heart that has a small “pumping chamber” ^[14]. To solve this puzzle, doctors may order additional tests, which require expert interpretation:

Dobutamine Stress Echo (DSE): You are given a medication (dobutamine) to make the heart pump harder. If the valve area stays small while the heart pumps more blood, it can help confirm the stenosis is “true-severe” ^[15].
CT Calcium Scoring: A specialized scan measures the actual amount of calcium on the valve. High scores (which vary by sex and protocol, but are usually over 2,000 for men and 1,200 for women) strongly suggest the valve is severely narrowed ^[16]^[17].

Echo Report Completeness Checklist

When you review your own report, ensure these key pieces of data are present. If they are missing, it may be worth asking your team if the test was complete ^[8]^[18]:

[ ] Aortic Jet Velocity (Vmax): The top speed of blood flow.
[ ] Mean Pressure Gradient: The average pressure difference across the valve.
[ ] Aortic Valve Area (AVA): The calculated size of the “opening.”
[ ] Left Ventricular Ejection Fraction (LVEF): A percentage showing how well your heart pumps.
[ ] Stroke Volume Index (SVi): A measurement of the volume of blood pumped per beat.
[ ] Dimensionless Index (DI): A ratio used to check the accuracy of the valve area; a value below 0.25 often supports severe stenosis.
[ ] Ascending Aorta Size: Crucial for those with bicuspid valves, as the artery can sometimes enlarge.

Common questions in this guide

How is the severity of aortic stenosis measured on an echocardiogram?

Doctors interpret three main measurements together: peak velocity, mean pressure gradient, and aortic valve area. Severe-range values include a peak velocity of at least 4.0 m/s, a mean gradient of at least 40 mmHg, or a valve area of 1.0 cm² or less, but a single number does not determine severity by itself.

What does low-gradient aortic stenosis mean?

It means the calculated valve opening is in the severe range, but the pressure difference across the valve is below 40 mmHg. This can happen when the heart pumps too little blood, so a dobutamine stress echocardiogram or CT calcium score may help determine whether the narrowing is truly severe.

What is a bicuspid aortic valve, and why does it matter?

A bicuspid aortic valve has two leaflets instead of the usual three. Its shape can place extra stress on the valve, leading to earlier narrowing and calcium buildup, and the ascending aorta may need monitoring for enlargement.

Which measurements should be included in an aortic stenosis echo report?

A complete report commonly includes peak velocity, mean pressure gradient, aortic valve area, left ventricular ejection fraction, stroke volume index, and dimensionless index. It should also report the ascending aorta size, especially when a bicuspid valve is present.

Why might my aortic stenosis echo numbers not match?

The measurements can disagree when the valve area suggests severe narrowing but the pressure gradient is low. Low blood flow, a weakened heart muscle, a stiff thick-walled heart, or high blood pressure during the test can affect interpretation, so a cardiologist considers all measurements together.

What tests can clarify whether aortic stenosis is truly severe?

A dobutamine stress echocardiogram uses medicine to make the heart pump harder and checks whether the valve area remains small as blood flow increases. A CT calcium score estimates how much calcium is on the valve; high scores can support severe narrowing, with thresholds varying by sex and scan protocol.

Answer a question to get research tailored to you. Your answers are private.

Get notified when new evidence is published on aortic valve stenosis.

We monitor PubMed for new peer-reviewed studies on this topic and email a short summary when something meaningful changes.

Curated prompts to bring to your next appointment.

1.Does my report show 'concordant' numbers, or do the valve area and the pressure gradient disagree?
2.What was my 'stroke volume index' during the test, and did I have high blood pressure that day that might have affected the readings?
3.Is my valve considered 'bicuspid,' and if so, how does that change the way we monitor my aorta?
4.If I have 'low-flow' stenosis, would a dobutamine stress echo or a CT calcium score help clarify if my valve is truly severe?
5.What was my 'dimensionless index,' and how does that number help you confirm the severity of my narrowing?

Key takeaways

Aortic stenosis severity is assessed by combining peak velocity, mean pressure gradient, and aortic valve area rather than relying on one number.
The severe range is generally defined by a peak velocity of 4.0 m/s or higher, a mean gradient of 40 mmHg or higher, or an aortic valve area of 1.0 cm² or smaller, with discordant results requiring further interpretation.
Low-flow, low-gradient results can occur when the heart pumps too little blood or has a stiff, thick wall, so additional testing may be needed.
A complete report should include left ventricular ejection fraction, stroke volume index, dimensionless index, and ascending aorta size in addition to the main valve measurements.
A bicuspid valve has two leaflets and can lead to earlier narrowing and calcium buildup, while also prompting monitoring of the ascending aorta.

References (18)

1
Recommendations on the Echocardiographic Assessment of Aortic Valve Stenosis: A Focused Update from the European Association of Cardiovascular Imaging and the American Society of Echocardiography.
Baumgartner H, Hung J, Bermejo J, et al.
Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 2017; (30(4)):372-392 doi:10.1016/j.echo.2017.02.009.
PMID: 28385280
2
The Role of Endoplasmic Reticulum Stress in Calcific Aortic Valve Disease.
Liu X, Li T, Sun J, Wang Z
The Canadian journal of cardiology 2023; (39(11)):1571-1580 doi:10.1016/j.cjca.2023.07.025.
PMID: 37516250
3
Development of calcific aortic valve disease: Do we know enough for new clinical trials?
Kostyunin AE, Yuzhalin AE, Ovcharenko EA, Kutikhin AG
Journal of molecular and cellular cardiology 2019; (132()):189-209 doi:10.1016/j.yjmcc.2019.05.016.
PMID: 31136747
4
NFκB (Nuclear Factor κ-Light-Chain Enhancer of Activated B Cells) Activity Regulates Cell-Type-Specific and Context-Specific Susceptibility to Calcification in the Aortic Valve.
Gee T, Farrar E, Wang Y, et al.
Arteriosclerosis, thrombosis, and vascular biology 2020; (40(3)):638-655 doi:10.1161/ATVBAHA.119.313248.
PMID: 31893948
5
The American Association for Thoracic Surgery consensus guidelines on bicuspid aortic valve-related aortopathy: Executive summary.
Borger MA, Fedak PWM, Stephens EH, et al.
The Journal of thoracic and cardiovascular surgery 2018; (156(2)):473-480 doi:10.1016/j.jtcvs.2017.10.161.
PMID: 30011756
6
Molecular and Mechanical Mechanisms of Calcification Pathology Induced by Bicuspid Aortic Valve Abnormalities.
Kazik HB, Kandail HS, LaDisa JF, Lincoln J
Frontiers in cardiovascular medicine 2021; (8()):677977 doi:10.3389/fcvm.2021.677977.
PMID: 34124206
7
Immune Mechanisms of Heart Valve Development, Homeostasis, and Disease.
Gonzalez BA, Yutzey KE
Arteriosclerosis, thrombosis, and vascular biology 2026; (46(7)):e323160 doi:10.1161/ATVBAHA.125.323160.
PMID: 42165146
8
Impact of Stress Echocardiography on Aortic Valve Stenosis Management.
Synetos A, Vlasopoulou K, Drakopoulou M, et al.
Journal of clinical medicine 2024; (13(12)) doi:10.3390/jcm13123495.
PMID: 38930024
9
Grading of Aortic Valve Calcification Severity and Risk Stratification in Aortic Stenosis.
Tastet L, Ali M, Pibarot P, et al.
Journal of the American Heart Association 2024; (13(15)):e035605 doi:10.1161/JAHA.123.035605.
PMID: 39023065
10
The current diagnosis and treatment of patients with aortic valve stenosis.
Henning RJ
Future cardiology 2021; (17(6)):1143-1160 doi:10.2217/fca-2020-0140.
PMID: 33728942
11
Early Surgery or Conservative Care for Asymptomatic Aortic Stenosis.
Kang DH, Park SJ, Lee SA, et al.
The New England journal of medicine 2020; (382(2)):111-119 doi:10.1056/NEJMoa1912846.
PMID: 31733181
12
How Do We Reconcile Echocardiography, Computed Tomography, and Hybrid Imaging in Assessing Discordant Grading of Aortic Stenosis Severity?
Delgado V, Clavel MA, Hahn RT, et al.
JACC. Cardiovascular imaging 2019; (12(2)):267-282 doi:10.1016/j.jcmg.2018.11.027.
PMID: 30732722
13
Low-flow/low-gradient aortic stenosis-Still a diagnostic and therapeutic challenge.
Vogelgesang A, Hasenfuss G, Jacobshagen C
Clinical cardiology 2017; (40(9)):654-659 doi:10.1002/clc.22728.
PMID: 28543102
14
Factors Associated with Low Flow in Aortic Valve Stenosis.
Leong DP, Pizzale S, Haroun MJ, et al.
Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 2016; (29(2)):158-65.
PMID: 26615522
15
Dobutamine Stress Echocardiography for Management of Low-Flow, Low-Gradient Aortic Stenosis.
Annabi MS, Touboul E, Dahou A, et al.
Journal of the American College of Cardiology 2018; (71(5)):475-485 doi:10.1016/j.jacc.2017.11.052.
PMID: 29406851
16
Computed Tomography Aortic Valve Calcium Scoring in Patients With Aortic Stenosis.
Pawade T, Clavel MA, Tribouilloy C, et al.
Circulation. Cardiovascular imaging 2018; (11(3)):e007146 doi:10.1161/CIRCIMAGING.117.007146.
PMID: 29555836
17
Workup and Management of Patients With Paradoxical Low-Flow, Low-Gradient Aortic Stenosis.
Annabi MS, Clisson M, Clavel MA, Pibarot P
Current treatment options in cardiovascular medicine 2018; (20(6)):49 doi:10.1007/s11936-018-0642-y.
PMID: 29721704
18
Dimensionless Index in Patients With Low-Gradient Severe Aortic Stenosis and Preserved Ejection Fraction.
Altes A, Thellier N, Rusinaru D, et al.
Circulation. Cardiovascular imaging 2020; (13(10)):e010925 doi:10.1161/CIRCIMAGING.120.010925.
PMID: 33076698

This page is for informational purposes only and does not constitute medical advice. Your cardiologist should interpret your echocardiogram in the context of your symptoms, blood pressure, and other findings.

Guide Contents