Common mistakes - Aortic Stenosis
As Albert Einstein put it:
Success comes from curiosity, concentration, perseverance and self criticism.
So lets jump right into some of the things that I learned by making mistakes. This time we will deal with the topic of aortic stenosis here are the top five:
1) You are focusing too little on the 2D imageJust because you record a high velocity does not mean the patient has aortic stenosis. There are several pitfalls: the high velocity is related to an LVOT obstruction (as in HCMP or subvalvular AS), you are seeing pressure recovery or you are actually measuring an MR signal. The degree of LVH is also importantit is not only associated with the severity of aortic stenosis (and the presence of hypertension).
My tip: Look at the morphology of the valve, the shape of the signal, use color Doppler as a guidance and know exactly where your sample volume is placed
2) You are not using multiple views to measure the maximal velocityDid you know that most patients with AS and bicuspid valves have eccentric jets? The classic 5-chamber view is often not the view where you would always get the highest velocity. Use different variations and also try from a right parasternal approach A slightly different orientation of the 5-chamber view when using CD-Doppler gives you a significantly different maximal velocity
My tip: Take your time when you look for the maximal gradients and try different transducer positions even within one view
3) You are extrapolating the measurements of maximal velocitiesSure, we want to get the highest possible velocity, but this is not a competiton. So do not over measure. Not only will you impact on the management on the patient but it is also frustrating at follow up to match the previous measurements The maximal velocity was measured at 5.1m/s. However, the true peak of the curve is lower (more towards 4 meters).
My tip: Try to increase the quality of the spectrum so that you can really see the contours. Stick to the main (brightest) contour
4) You rely too much on the continuity equationDo you love numbers and cut off values? They can certainly help, but be critical of these numbers. The aortic valve area often does not match the gradients when you are quantifying aortic stenosis. There are many reasons: wrong measurement of the LVOT, shape of the LVOT, fluctuations of velocities, some even suggest that there is a systematic error.
My tip: “Over measure” the LVOT to account for its oval shape, this way the AVA will better match the gradients you measured.
5) You are not interpreting the gradients in the context of other findingsGradients can change very quickly (even in the same patient). Anything that affects stroke volume can play a role: Anxiety, medications (catecholamies, euphylin), heart rate, or a drop in ejection fraction. To better interpret the gradients look at these cofactors. This is where conditions such a low flow low gradient AS comes into play
My tip: Look at the size and function of the left ventricle – but even more so focus on the LVOT velocity, it is an easy surrogate of stroke volume and tells you if the gradients are under- or overestimating the true severity of AS
I hope you enjoyed this part of our teaching series, leave a message, share your views and stay tuned for the next part this series.