My name is Natasha and I confess to being slightly obsessed with aortic stenosis.
So of course I was thrilled to be asked to review the latest BSE guideline on the 'people’s valve.'
Whilst undertaking my research degree I spent 18 months begging, borrowing and stealing any and all patients with aortic stenosis that presented in the echo lab in order to collect data for my thesis. Over time I grew to love the challenge of the discordant data patients and in fact realised there are far fewer patients with discordant measurements than I first thought. A little care and attention spent correctly collecting well aligned spectral doppler and optimizing 2D images to measure the LVOT diameter will pay dividends when it comes to reporting. No more "Well, this is in the severe range, and that’s in the moderate range, so I’ll sit on the fence and call it moderate – severe aortic stenosis." What does the clinician do with that statement?
"Trileaflet aortic valve that is thickened and calcified with reduced excursion. AV V max/Mean PG is moderately increased. AVA and DVI are severely reduced. In summary there is moderate-severe aortic stenosis."
In keeping with the theme of the most recent BSE guideline updates, the aortic stenosis guideline is joyfully prescriptive, removing some of the ambiguity of previous guides and common texts. There are step-by-step methodology and recommendations with justification for methods. There are emerging concepts such as flow rate and energy loss index that are noted but understandably not recommended in routine practice in this guideline.
Surprisingly, I have encountered countless echo reports over the years with significant aortic stenosis without a quantified or visually estimated EF. Reassuringly, this guideline has sub-headings explicitly detailing the importance of various parameters in addition to quantitative assessment of the aortic valve. One of them being systolic function by calculation or estimation of EF and encouragement of undertaking (but not mandated) GLS.
So what about Doppler – it’s just 'point and shoot' isn’t it?! I don’t remember anyone teaching me HOW to measure spectral Doppler. But over time, through echo meetings, one-to-one teaching and national conferences I came to understand there is an art to it. Not only that, it is critical in the accurate grading of aortic stenosis. And there is an excellent emphasis on how to correctly align Doppler and how to measure it! Hurrah!
Two phrases come to mind that come up every year at conference. I don’t know who originally coined them or if they’d own up to it. But they are ever resonant in this cohort:
- 'Garbage in = Garbage out'
That is to say, you can expect a tricky report with discordant measurements if you don’t take the time to do it correctly.
- 'Measure the chin, not the beard'
Now the guideline says this explicitly which is the first time I’ve read it in a guideline to my memory. However, they’ve worded it with a little more finesse in this guideline: 'Avoid measuring the transit time artefact'. Fancy!
This guideline will be useful to experienced and trainee echocardiographers alike and debunks some of the common misconceptions you hear occasionally. 'Assume the LVOT is 2cm' – absolutely not! My research was using 3D transthoracic echo assessment of LVOT dimensions and I can say with some confidence that this is the least well executed measurement in AS quantification. There has been debate over the years where the best position to take this measurement and this guideline has prescribed the insertion point of the cusps. It is the most repeatable with least intra and inter observer variability which is now well described in the literature. Maybe in the next update, I will finally be able to bring 3D LVOT dimensions to the masses… A girl can dream!!
Now if you follow me on Twitter you will know I talk about (moan occasionally) about badly quantified aortic stenosis. It has been my baby for 2 years and I’ve learnt a lot – the hard way! But this guideline is everything a diligent echocardigrapher could’ve hoped for. It is straight forward to follow and has handy guides and troubleshooting. What more could you ask for from a guideline! I hope you love it as much as I do, and go forth and enjoy far fewer problematic AS quantification!
My personal highlights:
- Check for measurement errors
- Measure accurately avoiding ‘transit time artefact’ (Measure the chin, not the beard)
- LVOT should be measured at the cusp insertion
- Use your PEDOF probe from multiple windows
- Criteria for ‘very severe’ AS specified
- Quantify EF (GLS recommended but not mandated)
- Inform referring medic – as specified in a very helpful table.
- There is a troubleshooting guide for those pesky discordant values
Thanks to Natasha for her insightful review. Check out the full guideline below:
Read the guideline