Last Updated on September 9, 2026 by Don Gerig, RDCS
The right parasternal window in aortic stenosis can record a higher transvalvular velocity than the traditional apical window. This is particularly important in older patients, where changes in aortic geometry may alter the direction of the stenotic jet and make right parasternal continuous-wave (CW) Doppler better aligned with blood flow.
Why does this matter?
Because failure to interrogate the aortic valve from multiple Doppler windows can underestimate peak aortic velocity (Vmax), calculated pressure gradients, and ultimately the severity of aortic stenosis.
Published studies have demonstrated that the right parasternal window is not simply an optional additional view. In some patients, it provides the highest and most accurate Doppler velocity obtained during the examination.
Why Is Aortic Stenosis Velocity Higher From the Right Parasternal Window?
The answer is primarily Doppler alignment.
Continuous-wave Doppler measures velocity most accurately when the ultrasound beam is parallel to the direction of blood flow. As the angle between the Doppler beam and the stenotic jet increases, the measured velocity decreases.
Aortic stenosis jets are three-dimensional and are not necessarily directed toward the cardiac apex.
For some patients, the apical window provides excellent alignment. For others, the stenotic jet is directed in a way that makes the right parasternal window more parallel to flow.
When that happens:
Apical CW Doppler → greater angle to the jet → lower measured Vmax
Right parasternal CW Doppler → better alignment with the jet → higher measured Vmax
The higher right parasternal velocity is not necessarily an overestimate.
The lower apical velocity may be an underestimate caused by Doppler misalignment.
Why Does This Matter So Much for Aortic Stenosis Gradients?
Aortic stenosis pressure gradients are calculated from velocity using the simplified Bernoulli equation:
ΔP = 4V²
Because velocity is squared, an error in measured velocity has an amplified effect on the calculated pressure gradient.
For example, if poor Doppler alignment causes the peak velocity to be underestimated, the resulting peak and mean gradients may also be substantially underestimated.
This can influence whether a patient is classified as having moderate, severe, low-gradient, or very severe aortic stenosis.
Why Is the Right Parasternal Window Particularly Important in Older Patients?
Aortic stenosis predominantly affects older adults, and aging can also change the geometry of the aortic root and ascending aorta.
The relationship between the left ventricular outflow tract, aortic valve, and ascending aorta may become more angulated. This changes the spatial direction of the stenotic jet.
In some patients, the resulting jet is less favorably aligned with an apical Doppler beam and more closely aligned with a beam directed from the right parasternal position.
This provides an anatomic explanation for something experienced sonographers frequently encounter:
A technically good apical CW Doppler tracing may still produce a lower velocity than the right parasternal Pedoff tracing.
What Does the Research Show?
Right Parasternal Doppler Produced the Highest Vmax in 50% of Patients
Thaden and colleagues evaluated 100 consecutive patients with severe aortic stenosis using multiple Doppler windows.
The highest Vmax was obtained from the:
- Right parasternal window in 50% of patients
- Apical window in 39%
- Other nonapical windows in the remaining patients
Overall, 61% of patients had their highest velocity recorded somewhere other than the apical window.
More importantly, if nonapical windows had not been evaluated, 23% of patients would have been misclassified with respect to aortic stenosis severity.
The investigators also found that patients with more acute LV–aortic root angulation were more likely to have their highest velocity recorded from the right parasternal window.
Aortic Geometry Predicts When the Right Parasternal Window Matters
Cho and colleagues subsequently evaluated 263 patients with greater than moderate aortic stenosis.
They found that aortic root geometry, specifically the aortoseptal angle, independently predicted whether the highest Vmax would be obtained from the right parasternal window.
The right parasternal approach was particularly important in patients with a more acute aortoseptal angle.
These findings provide a physiologic explanation for why the optimal Doppler window varies between patients.
More Recent Evidence Confirms the Clinical Impact
A 2022 study evaluated 276 patients with severe aortic stenosis with a mean age of approximately 79 years.
Adding right parasternal Doppler increased measured peak velocity and mean pressure gradient and changed clinically relevant classifications of aortic stenosis severity.
The proportion of patients meeting the Vmax criterion for very severe aortic stenosis increased when right parasternal measurements were incorporated.
The investigators concluded that reliance on the apical approach alone may underestimate aortic stenosis severity.
Why Use a Pedoff Probe?
A nonimaging continuous-wave Doppler transducer, commonly called a Pedoff probe, is particularly useful for aortic stenosis because of its small footprint and flexibility.
Unlike a standard imaging transducer, the Pedoff probe allows the sonographer to search for the acoustic position that provides the strongest alignment with the stenotic jet without being constrained by obtaining a conventional 2D image.
Potential CW Doppler windows include:
- Apical
- Right parasternal
- Suprasternal
- High right parasternal
- Modified apical or other patient-specific positions
The objective is straightforward:
Find the window with the beam most parallel to the stenotic jet that produces the highest reproducible velocity with a complete, well-defined spectral envelope.
How to Obtain the Right Parasternal Pedoff Signal
- Position the patient in the right lateral decubitus position with the right arm raised (rolled alltthe way on their right side).
- Place the Pedoff along the right sternal border and systematically sweep between intercostal spaces, using the audio signal and spectral display to search for the best alignment. (Some say closing your eyes and listening helps!!)
- Fine-tune the angle until you obtain the highest reproducible velocity with a dense, well-defined envelope
- The goal is not a predetermined probe position, but the most parallel alignment with the stenotic jet.
A Beautiful Doppler Envelope Doesn’t Guarantee Optimal Alignment
A dense, well-defined CW Doppler envelope may look technically excellent but it does not prove that the Doppler beam is optimally aligned with the stenotic jet.
Don’t stop at the best-looking waveform. Search for the best angle.
The goal of multiple-window interrogation is to find the beam most parallel to the stenotic jet. Better alignment is what leads us to the highest reproducible velocity.
What Should Echo Labs Take Away From This?
A comprehensive aortic stenosis examination should include interrogation from multiple CW Doppler windows when technically feasible.
The right parasternal window with a Pedoff probe deserves particular attention in older patients and whenever Doppler measurements appear discordant with valve morphology, symptoms, or other indicators of AS severity.
Published evidence demonstrates that nonapical Doppler interrogation can:
- Identify higher and potentially more accurate Vmax measurements
- Reduce Doppler alignment error
- Increase calculated transvalvular gradients when apical measurements underestimate velocity
- Change the classification of aortic stenosis severity
- Help resolve otherwise discordant AS findings
The right parasternal window therefore should not be viewed simply as an optional additional measurement.
In some patients, it may provide the most accurate assessment of the stenotic jet obtained during the entire examination.
Beyond the Highest Velocity: Diagnostic Cohesiveness
Accurate aortic stenosis assessment requires more than obtaining individual measurements—it requires evaluating whether the findings make sense together. Valve morphology, Vmax, mean gradient, calculated valve area, dimensionless index, flow state, and the overall clinical picture should tell a physiologically consistent story.
When one measurement does not fit, the first question should not be which value to disregard, but why the findings are discordant. In aortic stenosis, failure to obtain the highest velocity because of suboptimal Doppler alignment is one potentially correctable source of that discordance.
This is the broader principle of diagnostic cohesiveness: using the relationships among findings to recognize when a study may be incomplete, technically limited, or physiologically inconsistent. The right parasternal Pedoff window is a practical example of how better acquisition can improve not just a single measurement, but the confidence and coherence of the final interpretation.
Frequently Asked Questions
Yes. Aortic stenosis severity should be assessed using the highest reproducible transvalvular velocity obtained from proper CW Doppler interrogation. The goal is to align the Doppler beam as parallel as possible to the stenotic jet, which is why multiple acoustic windows should be evaluated rather than relying on the apical window alone.
Because the right parasternal Doppler beam is better aligned with the stenotic jet. Aortic stenosis jets do not always travel directly toward the apex. When the apical beam intersects the jet at an angle, it underestimates velocity. A right parasternal Pedoff beam may be more parallel to the jet and therefore record a higher—and more accurate—Vmax.
Yes. A nonimaging CW Doppler transducer, commonly called a Pedoff probe, should be used to interrogate the aortic stenosis jet from multiple acoustic windows when available. Its small footprint makes it particularly useful for right parasternal, suprasternal, and modified positions that may provide better alignment than a standard imaging transducer.
Yes. Age-related changes can increase angulation between the left ventricle, aortic root, and ascending aorta, changing the direction of the stenotic jet. In these patients, the right parasternal window may provide better Doppler alignment than the apical window and a more accurate measurement of the true transvalvular velocity.
Judith Buckland, MBA, RDCS, FASE
Learn how CardioServ helps cardiovascular imaging programs identify diagnostic variability, strengthen clinical quality, and build more consistent, evidence-based imaging practices. Contact Us
References
- Thaden JJ, Nkomo VT, Lee KJ, Oh JK. Doppler imaging in aortic stenosis: the importance of the nonapical imaging windows to determine severity in a contemporary cohort. Journal of the American Society of Echocardiography. 2015;28(7):780-785. doi:10.1016/j.echo.2015.02.016.
- Cho EJ, Kim SM, Park SJ, et al. Identification of factors that predict whether the right parasternal view is required for accurate evaluation of aortic stenosis severity. Echocardiography. 2016;33(6):830-837. doi:10.1111/echo.13181.
- Benfari G, Gori AM, Rossi A, et al. Feasibility and relevance of right parasternal view for assessing severity and rate of progression of aortic valve stenosis in primary care. International Journal of Cardiology. 2017;240:446-451.
- Shimamura T, Izumo M, Sato Y, et al. Additive value of the right parasternal view for the assessment of aortic stenosis. Echocardiography. 2022;39(10):1338-1343. doi:10.1111/echo.15464.
- Poniros A, Nevin K, Tang GHL, Safi LM. How to Scan Patients With Severe Aortic Stenosis. JACC: Case Reports. 2025;30(21):104415. doi:10.1016/j.jaccas.2025.104415.
- Springhetti P, Benfari G, Nistri S, et al. Diagnostic Contexts of Echocardiographic Nonapical Window. JACC: Case Reports. 2024;29(9):102287. doi:10.1016/j.jaccas.2024.102287.
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