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Detecting low-flow, low-gradient
aortic stenosis

Identify low-flow, low-gradient
(LF-LG) aortic stenosis criteria
found in ACC/AHA Guidelines.

AORTIC STENOSIS VARIATIONS AND INCIDENCE

Low-flow, low-gradient Aortic Stenosis (AS) is defined by AVA ≤ 1.0 cm2 but with gradients in non-severe range (<40mmHg)1.

Paradoxical LF-LG normal EF3

  • 5-15% of AS cases
  • More common in women and the elderly

Classical LF-LG low EF3

  • 5-10% of severe AS cases
  • More common in males with CAD
An image of a stat showing AS cases and how many match the definiton.

Learn more about diagnosing severe AS in LF-LG patients — because AS can’t wait.

Download LF-FG echo guide

SEVERE AS VARIATIONS

THE FOLLOWING ILLUSTRATIONS REFER TO EXAMPLES OF SEVERE AS WITH THE AVA ≤ 1.0 CM2

 

 

An image of a blue circle with the word diastole in the middle.
An image of a blue circle with the word systole in the middle.

Normal LVEF
Normal-flow
High-gradient

An image of a diagram of a heart that shows how blood pumps through it.
An image of an illustration of a hearts systole cardiac cycle.

Normal LVEF "Paradoxical"
Low-flow
Low-gradient

An image of a second diagram of a heart that shows how blood pumps through it.
An image of an illustration of a hearts systole cardiac cycle.

Low LVEF “Classical”
Low-flow
Low-gradient

An image of a third diagram of a heart that shows how blood pumps through it.
An image of an illustration of a hearts systole cardiac cycle.

PITFALLS IN ASSESSING SEVERITY

Feeding into the undertreatment of AS are common pitfalls for determining its severity.

Icon of a patient reinforces the importance of the need to personalize patient care.
Patients
  • Body habitus and anatomy
  • General status
    - Postoperative, acute illness, chest disorders, COPD, etc.
  • Physiology: rate, rhythm
A heart icon represents the importance of lowering blood pressure to help those at high-risk stay healthy.
Image acquisition:
Max velocity & mean gradient
  • Highest velocity missed due to lack of using all windows
    - Non-parallel intercept angle
  • Over- or underestimation if spectral Doppler not traced appropriately
A heart icon represents the importance of lowering blood pressure to help those at high-risk stay healthy.
Image acquisition: AVA by continuity equation
  • Underestimation of AVA if highest VTI or velocity not recorded
  • Difficulty measuring LVOT diameter
  • Inaccurate PW sampling
  • Subaortic obstruction leading to difficulty measuring LVOT or VTI
Icon of tools represents the importance of having the right tools to care for patients.
Method of assessment
  • Most parameters are flow dependent
  • DVI is least flow-dependent measure of AS severity
  • Low-dose dobutamine challenge may be needed to assess contractile reserve
Icon of a magnifying glass represents the importance of focusing on hypertension.
Analysis and interpretation
  • Inter-observer error
  • Intra-observer error
  • Learning curve
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Overcome these pitfalls
For further details on image acquisition and additional techniques on how to overcome these pitfalls, download the full LF-LG echocardiography guide.
Download LF-FG echo guide

ASSESSMENT OF MAX VELOCITY AND MEAN GRADIENT

Use multiple windows to avoid misevaluating the severity of AS.

  • Required to avoid underestimation of max velocity due to nonparallel intercept angle between ultrasound beam and aortic jet.4
  • Non-imaging probe is useful in obtaining optimal alignment.4
  • Vmax is located outside the apical imaging window in 61% of patients.4
  • Neglecting the non-apical windows has resulted in the misclassification of AS severity in 23% of patients.4
Apical
An image of an apical echo information sheet used to make relevant medical decisions.
Right parasternal
An image of a right parasternal echo information sheet used to make relevant medical decisions.
Apical
An image of an apical assessment on a patient done by a doctor.
Supra sternal notch
An image of a doctor performing a supra sternal notch assessment on a patient.
Right sternal border
An image of a right sternal border assessment performed by a doctor.
Right clavicular
An image of a right clavicular assessment performed by a doctor.

Photography is courtesy of Piedmont Atlanta Hospital.

URGENCY IS EVERYTHING FOR DIAGNOSIS AND TREATMENT

See why a proper echo is vital to diagnosing symptomatic severe aortic stenosis.
More information (see more) Less information (see less)

Experts share why it’s important to go beyond gradients when detecting the severity of aortic stenosis.
More information (see more) Less information (see less)

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Go to Structural Heart
TAVR education and resources

View more clinical data
and access procedural resources.

Medtronic Academy
Download our LF-LG Echo Guide

Learn more about determining severity — because AS can’t wait.

Download the guide
Visit our AS video library

Check out expert conversations on the ACC/AHA guidelines.

Visit the Library
1

Otto C, Nishimura R, et al. 2020 ACC/AHA guideline for the management of patients with valvular heart disease. Circulation. 2021;143:e1-e156.

2

Awtry E, Davidoff, R. Low-flow/Low-gradient aortic stenosis. Circulation. 2011;124:e739-e741.

3

Clavel M, Burwash I, Pibarot P. Cardiac imaging for assessing low-gradient severe aortic stenosis. J Am Coll Cardiol. 2017;10:185-202.

4

Thaden J, Nkomo V, Lee K, Oh J. Doppler imaging in aortic stenosis. J Am Soc Echocardiogr. 2015;28:780-85.