E:A waves

RE: E:A waves

Dave Dickson — Thu, 09 Apr 2020 11:24:03 GMT

with CW you nearly always get a higher velocity, because it samples along the whole line, so yes you probably do miss the "true" maximal velocity with PW, though in practice this doesn't matter clinically at lower velocities and at high velocities you can't measure with PW anyway so it becomes moot.

Dave

RE: E:A waves

AlanH — Tue, 07 Apr 2020 18:37:32 GMT

Thanks again! will no doubt have more queries for you very soon - got the ultrasound home to go through which no doubt will lead to queries!

For this one I think I'dve thought that I must have missed part of the flow that hit 2.5m/sec? I get the bit regarding the step up (good to know ) and that makes good sense but surely if the CW hits 2.5 then part of the flow must equate to this so id be thinking that ive missed the highest PW measurement -perhaps due to the alignment/position of my gate?

[quote userid="14690" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/28914/e-a-waves/221485"] The aortic velocity is 2.5m/s with CW, so you think it has stenosis. However, the LVOT Vmax PW is 1.8m/s and the AoVmax PW is 2.2m/s, and both PW traces are laminar. This tells you the dog probably doesn't have AS, it just has an increased LV volume causing a relative stenosis that isn't clinically important. [/quote]

Alan

RE: E:A waves

Dave Dickson — Mon, 06 Apr 2020 14:01:30 GMT

Hi Alan

Do you mean the 'leading edge to leading edge"? If so then yes, ideally. However in practice it's quite hard to tell. You are supposed to measure these at a fast sweep-speed (200mm/s) however I find that is tricky to do in practice. I look for the valve close artefact to signal aortic valve closure (red arrow) then the mitral valve opening artefact (blue arrow) and I place my measurement cursor in the middle of each valve line. See the images. Other people I know do a leading edge or a trailing edge technique. Key is to be internally consistent.

As to why you'd measure LVOT rather than just Ao - the LVOT is typically classed as the region of the LV just proximal to the Ao valve, so the region that we see SAM in cats, for example. I measure here with a PW cursor so I get the "pre-valve" velocity. Then measure in the Ao, at tips of open valve (so around the top of the sinuses of valsalva) with PW for the aortic velocity. If you get a stenotic lesion between these two PW cursor measurements, it shows as a 'step-up' in velocity. Many people quote an increase of >0.4m/s across the valve as evidence for stenosis (though I think this is far too low).

Here's an example. You have a case with a PDA and a big left heart. The aortic velocity is 2.5m/s with CW, so you think it has stenosis. However, the LVOT Vmax PW is 1.8m/s and the AoVmax PW is 2.2m/s, and both PW traces are laminar. This tells you the dog probably doesn't have AS, it just has an increased LV volume causing a relative stenosis that isn't clinically important.

Good questions!

For anyone listening in, now we all have more down time, let me know if you want to discuss any specific cardio or echo topics and I'll see if I can oblige. I might even be able to do some webinars if you can give me some specific topics.

Dave

RE: E:A waves

Roger Wilkinson — Mon, 06 Apr 2020 13:13:31 GMT

Hi Alan,

If you're using CW then you're getting a trace reflecting velocities all the way along the line of sampling -so it's certainly going to be be LVOT as a whole rather than Ao Vmax specifically.

the inner-edge or leading-edge convention really relates to measuring structures in 2D or M mode rather than time intervals. For IVRT you're just looking for the point at which LVOT systolic flow reaches zero and then point at which transmitral flow leaves baseline.

cheers

Roger

RE: E:A waves

AlanH — Mon, 06 Apr 2020 07:25:19 GMT

Looking for bit more advice please... looking back at some scans and just trying to see wether I can use E:IVRT

I used CW of the aortic flow from a sub costal view as suggested, this detects the mitral inflow and I think gives me a pretty good IVRT - I just want to check this is the sort of image you guys are using. With the measurement should I use inner edge to inner edge?

Also im trying to set up our echo machine which is lovely but I notice I can measure LVOTmax or Ao max just wondering on terminology here - ive set to Ao max - wondering why I would measure LVOT max and not Ao max...? with aortic stenosis usually subvalvular so would this be LVOT max technically if I measured where I see for example a fibrous ring then in the sub valvular location?

RE: E:A waves

AlanH — Tue, 25 Feb 2020 08:19:12 GMT

thank you both, i'll have a look at both papers mentioned- appreciate the help

RE: E:A waves

Roger Wilkinson — Mon, 24 Feb 2020 19:30:13 GMT

I adjust diuretic dose depending on appearance of lungs on ultrasound and sleeping resp rate. Lung ultrasound probably about 90% sensitive for pul oedema.

https://onlinelibrary.wiley.com/doi/full/10.1111/jvim.14692

(A lot better than radiography! In people cxr is about 40-60% sensitive)

Sleeping resp rate isn't infallible either (even if you have owners you believe are numerate and sober)

Yes, to be clear, as Dave says schober does suggest a cut off at 2.6 in E:ivrt for optimal sensitivity/specificity. In their case series there was one outlier in the non-chf group at about 3.6 and I reckon I see some in that kind of area where I believe they don't have CHF. My personal cut off at 4:1 is pitched at a level where I think if they're over that then I'm going to be pretty confident they're in failure.

It's also worth a critical look at the criteria they used to classify the dogs in that paper (it's a great paper) ...which was chest rads and clinical signs. Always going to be a bit subjective and not necessarily a clean cut off between CHF and no CHF.

To be brutally honest I find some dogs quite difficult to consistently and accurately measure ivrt. Like Dave I always take it from subcostal CW Doppler. I often measure several times before I convince myself I'm getting some consistency. Main issue is the gradual acceleration at the onset of transmitral flow in some dogs as seen from that angle (partially dependent on the angle between LVOT and long axis of ventricle in some dogs).

RE: E:A waves

Dave Dickson — Mon, 24 Feb 2020 12:08:57 GMT

Hi Alan

Like Roger, I use E:IVRT routinely and I trust it more than most other measurements, LA:Ao being my favourite.

I use a cut off of 2.5 for DMVD and 1.9 for DCM, as per Schober 2010 JVIM (Detection of Congestive Heart Failure in Dogs by Doppler Echocardiography).

However I record IVRT from a subcostal view using CW Doppler, as I can't get a reliable signal from the left apical view in dogs. I've attached an image to show you how I do it.

I don't use E waves per se to guide treatment - but they are part of the jigsaw. If I've got a dog with fairly advanced DMVD but a small E wave, I relax, as CHF is very unlikely. Equally, tall E waves in a dog with a big LA make me look harder for evidence of CHF. I don't measure the E-wave then decide to increase or decrease a diuretic dose. And I don't get dogs back in to measure the E-waves for a treatment response - I think the measurement and intrapatient variability will be too high to make this of much use.

Dave

RE: E:A waves

AlanH — Mon, 24 Feb 2020 11:52:58 GMT

Thanks roger - is E:ivrt something you would routinely measure and find useful ? And can you use E waves to guide diuretic dosage in addition to sleeping respiratory rates?

RE: E:A waves

jd2008 — Mon, 24 Feb 2020 06:16:00 GMT

My apologies - I hit the ‘react’ button in error (touch screen) and can’t seem to rescind it!

RE: E:A waves

Roger Wilkinson — Sun, 23 Feb 2020 22:38:03 GMT

Hi Alan,

Yes, generally speaking transmitral E wave velocity is a decent indicator of LA pressure in dogs.

Have to beware E/A summation which obviously leads to higher velocities.

Because restrictive LV pathophysiology is so rare in dogs the main confounding possibilities are mitral stenosis (slow deceleration slope in transmitral E wave and turbulence in colour of LV inflow) and occasional young, fit individuals with really springy ventricles who may have E waves up to 1.2m/s or so.

In schober's 2010 paper mitral E:ivrt was the best Doppler predictor of CHF. The idea being that indexing to ivrt corrects for the effect of ventricular relaxation.

E:ivrt >4 is a reliable indicator of LCHF in MVD. >2:1in primary myocardial failure ('DCM').

Best wishes

Roger