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.
Low-flow, low-gradient AS with preserved LVEF3
- 5-15% of AS cases
- More common in women and the elderly
Low-flow, low-gradient AS with reduced LVEF3
- 5-10% of severe AS cases
- More common in males with CAD
Learn more about diagnosing severe AS in LF-LG patients — because timing is everything.
PITFALLS IN ASSESSING SEVERITY
Feeding into the undertreatment of AS are common pitfalls for determining its severity.
Patients
- Body habitus and anatomy
- General status
- Postoperative, acute illness, chest disorders, COPD, etc. - Physiology: rate, rhythm
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
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
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
Analysis and interpretation
- Inter-observer error
- Intra-observer error
- Learning curve
Overcome these pitfalls
For further details on image acquisition and additional techniques on how to overcome these pitfalls, download the full LF-LG 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
Right parasternal
Apical
Supra sternal notch
Right sternal border
Right clavicular
Photography is courtesy of Piedmont Atlanta Hospital.
URGENCY IS EVERYTHING FOR DIAGNOSIS AND TREATMENT
Importance of Proper Echo Assessment - Video file
More information (see more)
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Echo techniques for LF/LG - Video file
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Download our LF-LG Echo Guide
Learn more about determining severity — because timing is everything.
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
Dahou American College of Cardiology 2015.
4
Thaden J, Nkomo V, Lee K, Oh J. Doppler imaging in aortic stenosis. J Am Soc Echocardiogr. 2015;28:780-85.
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