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
Statistic showing aortic stenosis cases and how many match the definition

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

 

 

A blue circle with the word diastole in the middle
A blue circle with the word systole in the middle

Normal LVEF
Normal-flow
High-gradient

A diagram that shows how blood pumps through a heart in diastole with high-gradient and normal flow
Illustration of a heart with high-gradient and normal flow in a systole cardiac cycle

Normal LVEF "Paradoxical"
Low-flow
Low-gradient

A diagram that shows how blood pumps through a heart in diastole with low-gradient and low flow
Illustration of a heart with low-gradient and low flow in a systole cardiac cycle

Low LVEF “Classical”
Low-flow
Low-gradient

A diagram that shows how blood pumps through a heart with low LVEF, low-gradient, and low flow
Illustration of a heart with low LVED, low-gradient, and low flow in a systole cardiac cycle

PITFALLS IN ASSESSING SEVERITY

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

Decorative element
Patients
  • Body habitus and anatomy
  • General status
    - Postoperative, acute illness, chest disorders, COPD, etc.
  • Physiology: rate, rhythm
Decorative element
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
Decorative element
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
Decorative element
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
Decorative element
Analysis and interpretation
  • Inter-observer error
  • Intra-observer error
  • Learning curve
Decorative element
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
Apical echo sheet showing data related to heart function
Right parasternal
Right parasternal echo sheet showing a graph of heart function data
Apical
Healthcare professional performing an apical assessment on a patient
Supra sternal notch
Healthcare professional conducting a supra sternal notch assessment on a patient
Right sternal border
Healthcare professional performing a right sternal border assessment
Right clavicular
Healthcare professional performing a right clavicular assessment

Photography is courtesy of Piedmont Atlanta Hospital.

URGENCY IS EVERYTHING FOR DIAGNOSIS AND TREATMENT

View this video to learn more about the importance of performing a proper echo assessment on a patient.
More information (see more) Less information (see less)

Watch this video to learn more about echo techniques for low-flow and low-gradient patients.
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Go to Structural Heart
TAVR education and resources

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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.

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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.