How are you diagnosing pulmonary hypertension in GP practice?

RE: How are you diagnosing pulmonary hypertension in GP practice?

Mellora Sharman — Sun, 13 Aug 2023 19:37:20 GMT

Thanks! Very interesting.

Absolutely agree - I guess I was answering the question 'how to measure' not 'how easy is it to' evaluate for PH in a GP setting'. And without realising there was a cardiologist lingering here somewhere :-). I absolutely agree with you that evaluating the LA is a relatively easy step that most can do - even Internists.

Best Wishes!

Mellora

RE: How are you diagnosing pulmonary hypertension in GP practice?

Mark Patteson — Sun, 13 Aug 2023 18:34:29 GMT

yes you can look at the CVC. Its another little but there are increasingly more variables each time we measure another parameter that may or may not be helpful I can't say I do this as a routine (maybe i should but I woudl like to see some good data that it adds clincially relevant decision affecting info first)I am not sure I would want to rely on that to decide if there is PHT as the implications are potentially life threatening
We cant really control the respiration and get breath hold or inspiratory images as you can with human patients
most patients with PHT will haev a wider PA than usual and it shouydl be narrower at the sinus than the aortic root

agree re resp cases clearly esp brachycephaplic dogs - but I like to leave those cases to others!

we published a study recently showing that vets witha specific 4 hours training in echo can make the same decision re B1/B2 as specialists 7 times out of 8 so I encourage vets to do the simple cheaper test (ie how big is the LA ) first
echo diagnosis of PTH is much more difficult I am afraid

RE: How are you diagnosing pulmonary hypertension in GP practice?

Mellora Sharman — Sun, 13 Aug 2023 17:16:32 GMT

Hi Mark!

I recently had an echo myself and one thing they had me do to evaluate right sided pressures was the 'sniff test' - where they imaged my caudal cava through the diaphragm, then had me sniff sharply to look for caval collapse as an indicator.

I very vaguely recall a cardiologist I use to work with doing something similar with coughing - but I'm not sure if this is something anyone has evaluated as an alternative to a sniff test, which we obviously can't as easily ask our patients to do??

In terms of bronchial disease - one thing I will always consider as an underlying cause is an aerodigestive disorder - ie is there any aspect of laryngopharyngeal (can be very subtle) or more obvious reflux that might might be resulting in microaspiration, and subsequent airway inflammation. In one study of dogs a fair number of dogs presenting for coughing alone had on fluoroscopy evidence of pharyngeal or oesophaegal dysmotility resulting in micro-aspiration (https://pubmed.ncbi.nlm.nih.gov/31492390/). So I will sometimes put some of these on an omeprazole treatment trial to see if coughing improves, before I reach for steroids.

In this dog I agree I would look at the LA first, and bow to the expertise of the cardiologist around that. :-)

Best Wishes,
Mellora

RE: How are you diagnosing pulmonary hypertension in GP practice?

Sarah Keir — Sun, 13 Aug 2023 15:53:56 GMT

The latest podcast by Kieran and Jose is on Pulmonary hypertension and is excellent https://animalheartbeat.co.uk/

If you are good at echos then I highly recommend reading the ACVIM consensus guidelines on pulmonary hypertension https://onlinelibrary.wiley.com/doi/10.1111/jvim.15725

RE: How are you diagnosing pulmonary hypertension in GP practice?

Richard Carter — Sun, 13 Aug 2023 10:37:03 GMT

Thanks - we have ultrasound and I agree- it’s amazing how many’chf’ cases respond better to pred especially around harvest time

RE: How are you diagnosing pulmonary hypertension in GP practice?

Mark Patteson — Sun, 13 Aug 2023 10:24:43 GMT

WIth a caveat that I am not a respiratory specialist, and an alert that I dont like spending money that I can avoid spending even on referred cases I would say
the likely DDX is big LA due to MMVD or respiratory disease - with chronic bronchitis +/- collapsing trachea tops.
other things to catch you out would be lungworm (do snap test or treat it anyway) and a thoracic mass which is uncommon but missable (needs rads/CT but would they want a thoracotomy ?)

so for the big 2 you need to know if the LA is big so you can do chest rads and/or echo but make life simple and do the echo first You don't need to be a specialist and able to diagnose everything - so if you are happy identying LA dilation or focus some training on being able to do that you will get a good idea if that is the reason.

A terrier with a cough post rest and no exercise intolerance makes me think respiratory diease - but of course it can have both MMVD with a big LA and chronic bronchitis

re the pulmonary hypertension (PHT) measuring tricuapid regurg (TR) and sometimes also pulmonary regurg (PR ) velocity to estimate PA pressure (systolic and diastolic respectively) is routine stuff for cardiologists and with a good deal of training and the right kit this isn't too bad (its not 100% reliable for anyone especially if there is a tachycardia or arrhythmia).
Not all dogs have TR and a low frequency probe will help to measure this You need to be very careful to line up with the TR jet or you will understimate the pressure
some dogs with PHT have a new right sided heart murmur (due to high pressure TR) and some have a split S2 heart sound (sounds a bit like a gallop sound and may be very subtle)
The most common cause of PHT is MMVD usually stage C ie they have CHF too, but not always This case doesn't sound like it has congestive heart failure but a sleeping resp rate is a key measurement in these cases. Really important to train teh owner to do this - lots of help online
Other causes would be lung worm, dirofilaria, clots causing an embolus (much more common than you might think and often due to other bad disease eg neoplasia, Cushings, immune mediated stuff) and chronic pulmonary disease (a few other rare ones, no high altitude in the UK)!
Cath pressure measurement is usually reserved for dogs having an intervention.
CT is the best way to assess lungs and vessels in these cases - sorry I wish I could say that plain rads were anywhere near as useful
so sadly PHT cases often don't come cheap if they need a slightly complex echo and CT and adding bronchoscopy add even more

so to summarise:
start by checking the LA (and LVDDN) on echo, (you might want to do rads too) If it has a big LA treat it
but I always tell owners of dogs with MMVD that we are preventing clincial signs such as breathlessness and that the cough isnt going to go away compeletely and so that isn't the objective

dont worry too much about PHT in this case yet They are usually ex intolerant and breathless and sometimes are ascitic

Your question is likely is this dog B1/B2 or C MMVD and so what do you use (B1 nothing, B2 Pimo, C pimobendan plus frusemide +/- benazepril and spironolactone)
you might want to do endoscopy and BAL but if it isn't a big LA the chances are the dog has chronic bronchitis
most of my elderly patients with bronchitis get inhaled steroids

sorry - a bit of a ramble but it's a Sunday so my brain hasn't reached working levels yet

Mark

RE: How are you diagnosing pulmonary hypertension in GP practice?

Richard Carter — Sun, 13 Aug 2023 09:05:02 GMT

Excellent- thank you

RE: How are you diagnosing pulmonary hypertension in GP practice?

Mellora Sharman — Sun, 13 Aug 2023 08:22:23 GMT

Hi Richard,

With the caveat that I am not a cardiologist, and am an Internal Medicine Specialist. Diagnosing pulmonary hypertension either requires direct cardiac catheterization, which is not often performed in veterinary medicine in either referral or primary care. Or requires indirect methods would involve echocardiography and measurement of either tricuspid regurgitation velocity, and/or the velocity of any pulmonary insufficiency present. A diagnosis of hypertension can then be made by calculating the pressure gradient across the valve using the Bernoulli equation, and classifying if any PH present is mild, moderate or severe. Pulmonary artery flow profiles can also be helpful.

Of course the presence of concurrent myxomatous tricuspid valve disease might complicate things as some regurgitation may be present with this as well and slightly alter pressure, but velocity should still be useful overall.

Other considerations might be evaluation of thoracic radiography to look for right sided cardiomegaly, and I always try and check out the width of the intra-thoracic portion of the caudal vena cava as well. These things can be tricky to interpret depending upon the conformation of the dog - so our more barrel shaped dogs and terriers can have a subtle appearance of right sided cardiomegaly, but actually be ok.

In this dog coughing could be due to MMVD and cardiomegaly resulting in pressure on the airways, assuming that no CHF is present. But might also be due to primary pulmonary / bronchial disease. We could see pulmonary hypertension in conjunction with left sided cardiac disease due to increased pulmonary pressures secondarily, but it's also possible that any pulmonary hypertension identified could be due to primary pulmonary disease if present.

A combination of thoracic radiography, and echocardiography including evaluation for right sided cardiomegaly, and regurgitation velocities as suggested above, is most likely to be helpful to determine this as a first line of diagnostics (if pulmonary disease is documented, other diagnostics might be indicated). You could certainly manage this dog for MMVD in the first instance according to the ACVIM Guidelines and based upon the stage of disease you've identified and come back to further evaluation depending upon the response seen as you have no exercise intolerance, or syncope at the current time point.

The most recent guidelines for managing MMVD are here --> https://onlinelibrary.wiley.com/doi/10.1111/jvim.15488

I hope this helps!

Best Wishes,
Mellora