Good evening, everybody, and welcome to a Thursday night webinar. Usually our members webinar, but I believe we have some other non-members on, and it's a great welcome to all of you. My name is Bruce Stevenson, and I have the privilege and honour of chairing tonight's session.
I'm terribly sorry that I'm all snotty and croaky, but, the dreaded Logie has got the better of me. So, hopefully, it won't, detract. Unfortunately, I'm not your main attraction.
A little bit of housekeeping before we get going. For those of you that are new to us, if you want to ask a question, of our presenter, simply hover your mouse over your screen. A little black control bar pops up at the bottom.
There's a Q&A box. Just type your questions in there. They'll come through to me.
And Karen has very kindly agreed to answer all of those questions at the end. Something that's also very, very important with housekeeping, our sponsor tonight, Burringa Engelheim. Thank you so much guys from Boringa for, opening tonight's webinar up.
Remember that Boringa are the makers of VetMedden, a really essential product for us, as vets when we are treating heart conditions. And I'm sure Kieran will, reiterate that as we go through tonight. So thank you kindly, Boringa Engelheim.
Tonight's, you guys are in for an absolute treat. Our speaker tonight, is a clinical lead in cardiology at Langford Wits. He is a diplomat of both the American and European colleges, as well as an RCVS recognised specialist.
He has published widely, with a particular interest in feline echocardiography. Cardiac biomarkers and interventional procedures. He treats all species with heart disease and is spoken all over the world on cardiology and interventional cardiology and interventional radiology.
Kieran, welcome to the webinar vet and it's over to you. Thanks very much, Bruce. I have to say that, that I also have the lurgy.
So, great for everyone who's, who's joining us this evening. At least none of us have to talk for the next hour. So, hopefully you're all feeling better than, Bruce and I are feeling, and welcome to, our, webinar talking about heart murmurs.
When should I investigate? As Bruce said, can be sponsored by Boringer, who have had no influence whatsoever over the content of my presentation. So therefore, I don't have any conflict of interest to declare.
. This is the subtitle of the lecture. It's Help. There's a murmur.
I would like to credit my very good friend Sean with this photograph, because he allowed me to share this photograph of him. He is a vet. Any of you who know him, make sure to, let him know that you saw this.
And, just to credit him and say thanks very much for sharing, this, this wonderful photograph of you, looking stressed about a case. I think it's very stressful. To find heart murmurs, especially unexpected heart murmurs, or heart murmurs that we might think are a high importance.
So pre-anesthesia, or maybe in an animal who is systemically unwell, we all see cases, in our careers of, of endocarditis, we all see cases of the unexpected feline or or canine murmur, prior to a routine procedure. It throws a spanner in the works. It adds to the discussion with the owners that we need to think about, and it adds to our level of concern as well.
So the aims of this talk this evening, we're gonna identify the common features of a flow murmur, by which I mean an innocent murmur or a non-pathological murmur. I, I tend to use the term flow murmur, it's just easy to say, and, we're gonna compare that to a pathological murmur. So we're gonna think about us.
Auscultation and the technique of auscultation and how, a careful consideration of what we're hearing, which for me involves visualising it, because I'm quite a visual person, trying to imagine a little diagram of what we're listening to, how that might help us to identify murmurs that actually we probably don't need to worry about, compared to murmurs where we do need to worry about them. So we're gonna try and understand which heart murmurs to investigate. We're gonna think in in order about adult dogs, adult cats, so thinking more about acquired heart disease.
I'm not saying we don't see congenital heart disease in those patients. I've seen, heart failure, caused by a PDA in a 15 year old collie before. So definitely there are dogs out there who, who live into old age with congenital heart disease, and cats.
But we're gonna focus on the acquired heart diseases in those groups. Then think about congenital heart disease in dogs, particularly, and think about the murmurs in, in puppies, where investigation would be warranted. And on the way we're gonna listen to some heart murmur examples.
So if you do not have headphones close by, you might want to run and get them, because I think it's a useful thing for us to, to listen to some heart murmur examples. And these are heart murmurs that I've recorded in the clinic. So, you know, they're not perfect, but they're real cases, and, we can talk a bit about those, those, auscultation findings.
I think it's always helpful to hear examples if we can. Once upon a time, I was a proper vet in practise who used to do proper vet work. Not like the work I do now, which is very niche, very, silly stuff, cardiology work, interventional work, radiology, things like that.
When I was in practise, I was intimidated sometimes by finding heart murmurs. And I think it's very important to, try and keep your head, keep cool, and try and think about your, your physical exam findings and inform yourself as to which murmurs to, to worry about and which moves not to worry about. And don't forget, you can always get a second opinion from your colleagues.
We, teach find your students in the clinic on a daily basis, and often students are very worried about missing, a, a heart murmur or missing the significance of a heart murmur. And we always say, well, have a structured approach, think about it logically, but also ask your colleagues, you know, gain their experience and then and and use their ears as well, to try and help you make your decisions. So imagine a case, and this is, this is a, a typical case that might come in the door.
Dixie, a 1 year old female entire springer spaniel, she's presented for a spay. Now, imagine you find a grade 3 systolic heart murmur in this case. This is, this is a classic situation.
The maximum intensity to the point at which the heart murmur is loudest is the left base. So if we palpate the apical impulse on the left side and we auscultate over that apical impulse, that's roughly gonna be the left apex. A little dorsal to that is the point of maximum intensity of the left apex.
If we go a couple of rib spaces cranial, we will hear the left base where S2 is a little bit louder, a little bit more crisp. You'll hear certain murmurs at the left base and certain moves at the apex. At the apex on the left, it's more likely to be the mitral valve.
And the left base it's more likely to be aortic or pulmonic valves. And it's slightly musical sounding. So there's a little musical tone in mids Sicily with this murmur.
This dog has presented with no clinical signs whatsoever. The owner's very happy, classic springer spaniel. You let them off the lead, they're just free, they, they run, disappear into the bushes, come back covered in birds, very happy, no signs of any exercise intolerance.
The owner walks 4 miles, the dog does 16. So There was a consensus statement published a couple of years ago now, 4 years ago now, looking at the, these type of murmurs, these incidentally detected murmurs, the asymptomatic patients, no clinical signs of a problem, how to deal with these heart murmurs. And some of what I'm talking about is going to come from this consensus statement.
It's open access. So if any of you want to look this up in the Journal of Veterinary Cardiology, I think it was double published in the Journal of, the American Veterinary Medical Association as well. You can get this without being a subscriber or paying for it.
And it's a, you know, it's a fair read. These consensus statements are often quite lengthy, to reflect everyone's different viewpoints, but there are some excellent cardiologists here, who have come up with this consensus statement, and it's a very, very comprehensive document. So that's really my only reference from this talk, thinking about further reading, is how to approach these incidentally detective moms and dogs and cats, like we might find in a dog like Dixie.
So we're gonna start by talking about non-pathological murmurs. So trying to differentiate flow murmurs, innocent murmurs from murmurs we need to take more seriously. I'm not saying that you, you can tell 100% of the time, we're not perfect in assessing this, but thinking about which murmurs are likely to be non-pathological are is a very, very useful way to approach things because it means you can .
Identify patients where you don't need to worry so much about undertaking anaesthesia or undertaking whatever testing, you might want, in a, in a patient with signs of other problems that don't have signs of heart disease, or just monitoring them over and saying, oh, we'll just check it again in 6 months or 12 months at your routine health check. There are various things we need to consider. So first of all, consider the age and the breed of the patient.
So signalment is important. Think about are there associated clinical signs or other physical examination findings which make you concerned? So do we have any abnormalities of the pulse?
Is the capillary refill time prolonged? Should we have sinus arrhythmia that's not present? So on examination.
Of a dog that's pretty relaxed in the consult room, is the heart rate 140 and metronomically regular? Because that would be inappropriate, even if there's no overt clinical signs. That suggests the animal has lost vagal tone or is under the influence of the sympathetic nervous system, which may mean we've got heart disease present.
The murmur intensity is important. Quiet murmurs are more likely to be slow murmurs, loud murmurs are more likely to be pathological. And the murmur location is also important.
So we're thinking about left side, right side, base, and apex in dogs. It's the common breed predispositions, and we're thinking about dogs initially, breed predipositions to heart disease, bulldogs, boxers, French bulldogs. We see a lot of French bulldogs with complex congenital heart disease at Langford.
And these are guys who, you know, often look fairly well. Maybe they're not exercising so great, or they're having episodes of heavy breathing, but the owners are expecting that in a patient's so brachycephalic. We see Domans obviously they have a predisposition to acquired heart disease, they get dilated cardiomopathy.
We see the small old breed dog, especially the terrier breeds, spaniel breeds, toy breeds who are affected, of course, by mitral valve disease. We see, these, these fashionable, crossbred dogs, sorry, pedigree dogs, the cockapoos, the Labradoodles, and here we have a cockapoo with my colleague Rosie Payne, and these dogs sometimes will get congenital heart diseases that we see. In a poodle or a cocker spaniel, like a PDA, or pulmonic stenosis.
So actually we see quite commonly congenital heart diseases in these patients. When I say commonly, it's a different league to the Frenchies. Frenchies are are 20 times more likely to get heart disease, as puppies than than these, these crossbred dogs.
The West Highland white terrier, we see get mitral valve disease. We also see them classically get conduction system disease, so sick sinus syndrome. They often present with episodic collapse, which is normally treated, very effectively by pacemaker implantation.
And of course, our old friend, the cavalier King Charles Spaniel, the poster child for degenerative mitral valve disease. But in puppies, we also see cavaliers get PDAs and pulmonic stenosis as well. Think about cats.
Any pedigree cat is predisposed to cardiomyopathy. That being said, we also see plenty of cardiomyopathy in domestic shorthaired cats. So I actually have given up thinking about breed predispositions in cats.
We know that every pedigree is is prone to HCM pretty much. The sphinx on the left there, the Maine Coon who's sitting in front of his own heart, who's a bit hypertrophic, the, the exotic short hairs and. The, British shorthairs, the rag dolls, and the Bengal cat on the right there is, is the only photo I've ever known of a snow leopard Bengal actually in the snow.
So these animals are all predisposed to HCM, so I've given up thinking of pre predispositions. I just think cats get heart disease. Think about patient history.
Oh, I should go back and mention, think about the the age of the patient, because obviously, acquired heart disease like DCM or mitral valve disease or HCM is more common as the patient gets older versus younger cats or dogs. However, we do see mitral valve disease sometimes in two year old cavaliers, DCM in 3-year-old Dobermans, or, or HCM in, in, in 6 month old cats sometimes. So, you know, sometimes these diseases are indiscriminate about age, but mostly they are older animals who present with.
Thinking about the patient history, let's look for warning signs. So exercise intolerance is a great warning sign of heart disease. However, we don't often see animals that actually exercise.
We often see animals who will trot around on the lead, especially these old terriers, they'll potter about, maybe sit in the owner's mobility scooter. They're not really being exercised, so it's very hard to, to test if they, are intolerant of physical activity. But if that comes up, that's an important finding.
Typnea is obviously really important, and is a cardinal sign of, increased pulmonary vascular pressures or pulmonary edoema or potentially pleural diffusion in cats. Patients who have episodic collapse or weakness definitely should be assessed by a cardiologist or at least the history reviewed, ideally a video reviewed if possible. If they've got known cardiac disease, well, of course, the heart murmur, you know, if we knew the the, the cardiac disease was there and now the heart murmur's louder or different, well, that should certainly flag us investigating the heart again.
Or if they have a pre-existing arrhythmia, that's, that's an important thing. Suddenly the arrhythmia becomes important when a murmur is heard. Family history is vastly underestimated in terms of importance, largely because as vets, we don't tend to have a great family history.
Although with some pedigree animals, maybe the owner, actually also owns a litter mate, or someone in the owner's family or or one of the neighbours owns a litter mate, they may be in contact with the. Reader to find out what's happened to the parents. And that's super important in humans, family history actually really influences how humans are screened for heart disease, even in the absence of genetic testing for a particular thing.
Family history is very important. So don't forget about that, and do think about, about following up on family history if you can. On physical examination, are the warning signs, arrhythmia, as we've said, if you've got pulse deficits, that again suggests the arrhythmia is less likely to be sinus arrhythmia and more likely to be something cardiac and and important presence of a heart murmur we know.
And loss of sinus arrhythmia, is an important thing because it suggests we've got an increase in sympathetic tone, a loss of vagal tone, and that means that we've, You know, basically got a, a patient where the, the circulatory reserve is lost, so we've got some sort of compromise to blood flow, potentially. Persistent tachycardia. So in a dog, 130 beats a minute or faster, ongoing, especially if the pulse quality is poor.
In a cat, we might say higher than that, so we might say, you know, 210 beats a minute, persistently. You know, a normal animal, when they're stressed, the heart rate will go up in the clinic, but they, it will be, it will vary, it will come down to normal, it will go up again when there's a noise or when you try to intervene. So normal animals who are stressed will have a variable heart rate.
Animals with a persistent tachycardia that's metronomically regular, that's a concern to me, it's not appropriate for the changes in synthetic and vagal tone that should be going on in a normal animal. And obviously, if we have physical evidence of congestive heart failure, so they may not report it in the history, but you might find t it near, you might have abnormal respiratory sounds and auscultation, or of course, you might have something like ascites, or dullness on thoracic percussion, and these things would suggest that congestive heart failure is, is, is present. Let's think specifically now about the auscultation.
Now what I've got here, on the right of the screen is a diagram, one of my crude, diagrams to try and show a phonocardiogram. Now, in a phonocardiogram, it's just a representation of the heart sounds recorded digitally. We can see this would be S1, so the closure of the mitral and tricuspid valves, the start of cystole.
This would be systole, tracking through, and this would be S2, so the closure of the aortic and pulmonic valves, and then we'd have diastole afterwards. So each of these little vertical sort of areas here is, is, cystole, and each one represents a heartbeat. So the characteristics of a non-pathologic murmur, the murmur should be focal.
It should not radiate widely, so you might hear it in one location in the chest, so let's say the left side, apex or base. But you can't hear it easily on the right, or if you can, it's very quiet. Maybe if you move the stethoscope dorsally or cordially or cranially to your location, you can't hear it at all.
That would suggest it's a focal murmur. So do listen around and think, can I still hear the murmur? Is it as loud in a different location?
It should be low grade. By that I mean grade 1 or 2. Some flow murmurs are grade 3.
If you have a grade 4 murmur, I would say it's almost certainly not. An innocent murmur. It almost certainly represents pathology.
Grade 3 murmurs, variable. Most grade 3 murmurs are probably pathology, but some are flow murmurs. So grade 2 and below would fit my low grade criteria.
They are systolic. You do not get diastolic flow murmurs in dogs and cats. In horses, sure.
In dogs and cats, we don't get diastolic flow murmurs. So a low murmur would have to be systolic, quiet and focal. They are short duration, by which I mean they don't tend to go all the way from S1 to S2.
They tend to only be the first part of systoline. So if we now look at the homocardiogram, on the left here, we have what I would call a hollow systolic murmur, so a murmur that goes all the way from S1 to S2. This is classic for either bad stenosis of the aortic or pulmonic valve or mitral valve regurgitation or tricuspid valve regurgitation if it's on the right side, or a ventricular septal defect.
So these hollow systolic murmurs that go all the way through, systole are important because they suggest it's not a flow murmur. Flow murmurs tend to be proto-systolic. I don't tend to say that.
I tend to say early systolic because it's easier for everyone to understand. And these early systolic murmurs are easiest to hear if you ask yourself, can I hear a gap between the murmur and S2. So I don't listen for it being in the early half of Sitoly, it doesn't really work in my brain.
When I'm auscultating, I think, can I hear the gap? And if I can hear a gap. I think that's got to be a low murmur or very mild congenital heart disease.
So my level of concern is not high, if I can convincingly hear this gap. Sometimes it's hard to be sure, because the heart rate's a little high, maybe the dog's got some respiratory noises or he's panting, or he's moving, or the auscultation conditions aren't ideal. Often this might happen in the prep room or in the consult room with the owner chatting to you.
So try and control the volume if you can, just for, for a brief auscultation and ask yourself, can you hear a gap? These murmurs are found in isolation, by which I mean there's no arrhythmia, there's no gallop sound, there's no clinical signs or history of a problem. So they're found in isolation, they are truly incidental findings and isolated findings.
They can be dynamic, which means as the heart rate increases, the murmur volume or the murmur intensity increases also. So they may be very quiet or absent at low heart rates, or they may be, or or or they will increase in volume at higher heart rates. The classic situation that I think our students face when we're, we're talking about these murmurs is the student in the consult room will listen, maybe listen first.
The dog's are a little wound up. They'll hear a murmur and say, oh, I think I've got a grade 2 murmur. And then I'll come and listen and go, no, I can't hear anything, because the heart rate's come down, because the dog's been auscultated before, it's now, adapted to being on the, the concert room table maybe.
So I'm not hearing the murmur where the student heard it. It doesn't mean the student was making it up, it means that maybe we've got a dynamic flow murmur there. Let's just contrast that, the characteristics of a pathological murmur, they are medium to loud grade, grade 3 or above.
Can you get grade 2 murmurs with dilated cardiomyopathy or mitral valve disease? Yes, you can. You can get them with HCM, but if you hear a, a, a loud murmur, that suggests that you should take this further and investigate further.
It tends to radiate widely. And this is true when or more true when the murmur is louder, but if you listen to it on the left and you can hear it almost equally loud on the right, and you can hear it also at the base and the apex on the left, and you're not quite sure which one is loudest, well, that, that's a murmur that radiates widely. They can be systolic or diastolic.
Diastolic murmurs are are rare, but if you hear a diastolic murmur, it is pathological. They can be left or right sided. So with the flow murmurs, they tend to be left sided, not right sided.
Here they can be either side. And if you hear a right sided murmur, I would say it's almost certainly pathological. It goes through the whole of Sicily, so there's no gap, it's a hollow systolic murmur, goes all the way from S1 to S2.
And of course if they're associated with other abnormalities, they don't have to be, but if they are associated with other abnormalities such as a history of collapse, or a history of clinical signs of exercise intolerance, or arrhythmias, pulse deficits, pallor, slow refill time, gallop sounds, this would make me take the moment seriously irrespective of how loud it was. And these don't tend to change with heart rates, they don't diminish at low heart rates, they, they would never be absent and then present in a pathological manner, one that you need to be very worried about. So here's a real phonocardiogram rather than my sort of second class diagrams, and we can see we've got S1 is this loud heart sound here.
Then we've got an early systolic murmur. And then we've got S2. So in this phonocardiogram we can very clearly see the gap.
So listen for the gap, we can see it in this in this case. Now I think if I click here, we should be able to listen to this aortic flow murmur. And of course it's not working, so bear with me and I'll see if I can make it work.
OK, that's better. So let's listen to the moment. I think here we can hear a gap.
I'm gonna play it again because I know it's a difficult one if you're not familiar with listening to it. Look at the phonocardiogram as you're listening, and you will hear you've got an early systolic murmur, very short gap, and then S2. The other thing that we've got there is a slight musical component.
Now the electronic stethoscopes don't tend to represent musical murmurs very well, but we can just hear a little, sort of harmonic tone to that recording. So some of these early systolic flow murmurs can have a musical tone to them, that doesn't mean there's disease. Listen for the gap, that's the important thing here.
This was a a dog who was completely asymptomatic, had a normal heart rate with the sinus rhythmia, you can hear that in the recording. No other physical examination findings suggested there to be cardiac disease. And, and we could hear the gap there.
We were very, sort of open with the owners that actually we thought it was a low murmur. They were quite keen to investigate. We echoed the dog and it was completely normal.
So we were happy to say that was an aortic flow murmur. Now let's look Excuse me, let's look at a dog who has severe aortic stenosis. So first of all, just look at the, the phonocardiogram.
We can see, actually, this murmur is so loud, we can't really see S1 and S2 anymore. So S1 is somewhere hidden and S2 is somewhere hidden. This murmur is louder than the heart sounds, just looking at it visually.
So that's what we're gonna expect when we listen. And there's certainly no gap between the murmur and S2. So I can't hear the heart sounds at all.
I can just hear a murmur. And these are murmurs that actually, they're very loud, and we would call them a grade 4. If you could palpate a precordial through, you would call it a grade 5.
But 4 is louder than the heart sounds, 3 is the same volume as the heart sounds, 2 is quieter, and 1 is very quiet and focal. So this is a grade 4 murmur, at least, I can't palpate it on the screen for you, but I think it was a grade 4 murmur in real life as well. Sometimes people confuse these with the breath sounds, because you can't hear the heart sounds at all, so it's much harder to say if there's a heart murmur or not.
I'll play it one more time. And being aortic stenosis, this was a young dog, I think it was a boxer dog from memory, who are predisposed to this disease. But, importantly, this was localised into the left base.
You could hear it at the apex, you could hear it at the right, but it was loudest at the left, sort of cranial left basilar region of the auscultation. Let's think now about heart murmurs in adult dogs. So we're thinking more about acquired heart disease.
Of course we know that 75% of the heart disease that we see in dogs is mitral valve disease. We all know that's common in older, small breed dogs. We tend to say age 6 plus, can you get it younger?
Yes, but it's most common in older dogs. Can you get it in large breed dogs? Yes, but it's most common in small breed dogs.
And these murmurs can range from very quiet to very loud. Sometimes they are just very early systolic or even late systolic. I saw one this week there was a late systolic murmur in very early mitral valve disease.
But as the mitral valve disease gets worse, the murmur occupies the whole of Sicily and the murmur gets louder, and up until, Just before the dog goes into heart failure, as the disease gets worse, the murmur gets louder, which is very important when it comes to decision making, because if we find an older dog who has a grade 1 or grade 2 left apical murmur, who has no clinical signs, we don't need to worry about it then and there. Is it good to get some images of the chest? Is it good to to confirm our diagnosis with an echo?
It's it's perfectly reasonable to do that. If you've got a grade 3 murmur or grade 4 murmur or louder, this is much more likely to represent significant mitral valve disease. So we would say a grade 3 murmur in an older dog, who, which localises to the left apex, we would suggest that's, that's a good point to investigate the heart and try and stage this heart disease to see is it earlier or later stage mitral valve disease?
DCM is much less common. Is it out there? Yes.
Is it underdiagnosed? You betcha. But we would say from published studies that 10% of dogs with heart disease have dilated cardiomyopathy.
These tend to be middle aged or older large breed dogs. The 2 year old Doman, the 3-year-old Doberman, yeah, we do see it, but it's the middle aged to older dogs. Over half of them do not have a heart murmur, and this poses a particular challenge because all dogs with clinically significant mitral bowel disease will have a murmur.
That is easier to deal with because there's a flag there for you on physical exam to say, hang on a minute, this dog's got a heart disease we might need to know about. With DCM it's not true. They hide their heart disease, probably less than half, have a heart murmur, in early disease.
So mitral valve disease, just thinking about pathophysiology, I've got a couple of diagrams here, and, the top right diagram there is is a normal schematic, and you can see in the centre we've got a dog with degenerative valve disease, and we can see that on the, mitral valve there, we've got a thickened mitral valve, which is causing regurgitation. So here we've got an echocardiogram from a dog with bad mitral valve disease. We can see we've got the left atrium here, mitral valve.
And the left ventricle. And the right side of the heart is over here, there's a little movement from the tricuspid valve we can see, atrium and ventricle either side. So if you look at the mitral valve here, we can see the mitral valve in in dogs should close at about this angle where my laser pointer is.
So it shouldn't really cross the horizontal as it's doing, and you see how it looks thick and sort of gnarled and bends back into the atrium insistsly. If you look at the normal schematic in the top right here, you can see the normal position of closure of the mitral valve, makes the left atrium look a bit like a hexagon, OK? Whereas here, the left atrium is.
Sort of rounded, structure, and this mitral valve doesn't close in an angular way. It flattens and it bends back towards the atrium. We call that mitral valve prolapse, and that's, the typical finding along with thickening and distortion of the valve leaflets that we see on an echo to say, the dog has mitral valve disease.
If we place the colour flow mapping or colour Doppler on the echo, over the mitral valve, we can see this aliasing, this green mosaic. This is turbulent fast blood flow caused by regurgitation of blood through the mitral valve. That's the source of your murmuring mitral valves, is it?
This is a view looking at atrial size. So here, we've got the aortic valve in the middle. Some people say it looks like a Mercedes-Benz sign with three cusps to it.
So this is the aortic valve opening and closing. The right side of the heart is over here, we can ignore that for the purposes of this view. And this is the left atrium.
So the left atrium should be about 1.5 times this aortic valve diameter. We can see in the the still image up here of a normal dog, this is the sort of size we'd expect the atrium does this.
And the aorta is a fairly similar size. The atrium is not more than 1.5 times.
When it's more than 1.6 times, that suggests it's significant atrial dilation. There's some debate on the cut-off limits, you know, between cardiologists, but we use, a ratio of 1.6, which is based on a consensus statement, published this year looking at mitral valve disease last year, sorry, I'm still not quite in 2020 yet.
So we can see the left atrium here is just eyeballing it, huge compared to the aorta. It's definitely more than 1.6 times.
It's definitely more than twice the diamond of the aorta, and it sort of looks like a, a large cartoon drawing of a whale or a jab of the hut or something. So it's definitely not a normal atrial size. This is the consensus statement, thinking about how to approach dogs with mitral valve disease.
It's a very nice statement, it's very, written in a very, very straightforward way, and again it's open access, so you can get that without paying for it, and take a look at what the recommendations are for different stages of mitral valve disease. But very briefly. We think about mitral bowel disease as having 4 stages, which are A, B, C, and D.
D is the very bad refractory treatment close to death. They are not responding to our routine doses of frozamide and, despite being on, on normal therapy, alongside that. Working backwards stage C is clinical signs of congestive heart failures, these dogs have had pulmonary edoema.
Stage B is the most interesting group, and the group that I think we need to, direct a lot of effort trying to detect. These are the dogs who have mitral valve disease. In other words, they have a murmur detected, they're, they're flagging themselves to you.
But, they do not have clinical signs of heart disease yet. Stage A is a bit of an a sort of academic group, really, they're the at-risk group. In humans, we define that risk from family history, genetic testing, looking at a lifestyle, for heart disease.
But in dogs, we largely base it on breed. So we would say that a cavalier puppy in utero is stage A, and as the cavalier gets older, they become sort of stage A plus, because the disease is more like come with old age. So stage A is very difficult to define in dogs unless you do have a very clear family history.
Stage B is the one to, to focus on briefly, because in stage B, we have a low risk and a high risk group. So stage B1 is the mitral valve disease dogs with no cardiomegaly. And stage B2 is the mitral mitral valve disease dogs with cardiomegaly.
So based on the, the recent consensus statement, the left atrial size is 1.6 times the diameter of the aorta. And if you're doing a little bit more involved echocardiography, then the left ventricular internal diameter, normalised for body weight should be, greater than 1.7 to call them stage B2.
So we look at both those measurements in our clinic to say whether a dog has got significant cardiomegaly or not. Now, the important thing about this is that we know we can help dogs in stage B2 mitral valve disease by prolonging their life, improving their quality of life on treatment with Pimabendam. We don't know if that's true for stage B1.
It probably isn't for most of B1. So we would target the dogs for stage B2 because we have got good data, published from the EPIC trial, showing us that these dogs will benefit from pending treatment. And actually it prolonged the asymptomatic phase of heart disease by about 15 months for the average dog.
So when do we investigate a murmur in an older small breed dog? Well, if they have clinical signs, it's a no brainer. We've got a heart murmur, we've got respiratory signs, we think about looking for heart disease.
Think about sinus arrhythmia again and heart rate. If they're tachycardic, if they've lost their sinus arrhythmia, dogs should have sinus arrhythmia. So the absence of sinus arrhythmia with a loud heart murmur suggests you should investigate the murmur as a priority.
If you've got an audible irregularity that's not just a sinus arrhythmia, if it sounds like an irregular arrhythmia, rather than a a a a regularly irregular arrhythmia like sinus arrhythmia, then that could be problematic. Again, family history, think about asking. Grade 3 murmurs are the most important.
So grade 1, grade 2 in a 10 year old cavalier, you know what, I'm gonna go out on a limb and say they've probably got mitral valve disease, but grade 3 is where I'm gonna say, really, we should take this more seriously and investigate either by taking some thoracic radiographs or by performing an echo. This is the EPIC study, and again, open access, something you can, you can review. You know, it kind of feels like a long time ago now, it's, it's, almost 4 years since it was published, but it's a very, very important study which does show, a pre-clinical benefit of a drug, and it's the first trial to actually show pre-clinical benefit of a drug ever, .
And this was the survival curve, which shows the, the, the time to reaching the endpoint of either dying from heart disease or developing heart failure. So we can see, we've got two groups of dogs here, we've got a group of dogs on Pumaendin. They were in that group randomly, and, no one knew they were on Puma Bendin.
They, they had a very good placebo, which looked identical. And they were also randomised to placebo. So you can see how the group in the, sorry, the dogs in the Pendon group lived on average 15 months longer before developing signs of heart failure than dogs in the placebo group.
So super important trial and definitely something that we use to guide our, our decision making in investigating these murmurs. Moving on to think about, second most common heart disease in dogs, dilated cardiomyopathy. So here we don't have a primary valve problem, so the mitral valve is represented here as being thin and normal, but we do have a dilated left ventricle which has relatively thin walls compared to the chamber size, but the whole thing is grossly enlarged.
The function of the left ventricle is reduced. This is a dog with dilated cardiomyopathy in the moving image. The still image here again just shows that normal looking left ventricle.
You can see the nice geometry of a bullet shaped left ventricle here. And in the moving image, this was from a boxer dog, we can see a very dilated hypofunctional left ventricle. And the atrium is so large that it leaves the screen.
It's not a nice small hexagonal looking atrium. It's, it's a very large atrium indeed. So we don't need to measure this to say it's got dilated cardiomy.
I think everyone who knows this is the heart will look at it and say the function looks poor. This is a, a dog, I think this is a Doberman now, who does have the related cardiomyopathy, but it's a bit more subtle, isn't it, than the previous one. It looks like it is still moving, but it's not moving enough if we measure it, the function is reduced, and also if we measure it, the chamber size is increased as well.
So when do we investigate a murmur in a large breed dog? Well, my answer would be, if it's a new murmur, always investigate it. I don't really care how loud it is cos most DCM is not associated with a murmur, but always investigate it unless it's a flow murmur in a boxer dog.
Very hard to define, but boxer dogs seem to have a relatively high incidence of flow murmurs within the breed. And of course, boxer dogs are very excited. They have a very high outflow from the left ventricle when they're being auscultated.
So again, go back to your, your findings of auscultation to think, is that a flow murmur or not? So why bother trying to find these diseases as early as possible? Why not just wait till the onset of clinical signs?
You probably will all know this, but in dilated cardiomyopathy, we know that we can prolong the pre-clinical phase before we get signs of congestive heart failure by giving pumabendin. That was evidenced by the Prote trial. It was in Dobermans, but we believe it's true mechanically in, in all the breeds of dogs, so we, we don't just apply it for Dobermans, we apply it for everything.
And also in stage B2 mitral valve disease, as evidenced by the APIC trial. These are very tight studies, they're very nice, and, and they are used to, to guide our decision making very strongly. Best thing about cats, I talked about evidence-based medicine in dogs.
In cats, I can't give you much evidence, I'm afraid. Cats are are more challenging. So we have some complications of auscultating cats.
These 3 photographs are to scale. At best, with a stethoscope, we can auscultate a cat's heart, we can't auscultate base or apex. So I've given up trying to describe things as basilla or apical in cats.
I just say left sided or right sided murmurs, OK. When you're listening to cats, try and listen underneath the cat's chest. Listen as close to the sternum as you can, just where the rib and the sternum join.
That's where the murmurs are gonna be loudest because that's where the outflow tracks of a cat is. Most murmurs are outflow murmurs in cats. So if you can see the photograph of me auscultating this cat here, you see I'm almost lifting the cat up, and I'm putting the stethoscope underneath by the sternum.
So I would say left sternum or right sternum. I wouldn't talk about left base or left apex, or right base right apex in cats. Another complications, cats make noise, cats purr commonly, or they tell you off like this cat's doing here.
And we can see that actually auscultating these patients, when they're being very vocal or purring, can really hamper your, your, sensitivity of detecting problems. The only evidence base I'm gonna talk about really for cat murmurs is actually a study performed by my colleague, er, Rosie Payne, which was called a CAT scan study, which was looking at the prevalence of heart disease in apparently healthy cats in rehoming centres. So these were cats that presented to the .
Had to see, cats and dogs home, the, obviously the cats bit, and also the Cats Protection League in London. So these were not cats being referred, these were not cats who were sick, going to the vets. They were just a background population of cats that people thought were healthy enough to go to rehoming centres and be rehomed.
Rosie Osk will take them on 3 occasions over the day, and if you look at the bar chart here on the left, you can see that if you listen to a cat more times during the day, you will detect a greater frequency of murmurs than you would do, in, if you listen to them less. Now it sounds a little obvious, but actually what that means is cat murmurs come and go, and that's very common that cats have these dynamic murmurs even with pathology. So that doesn't necessarily mean they're a flow murmur in cats.
Look at the statistics from this, 41% of all cats had murmurs. That was greater in older cats. 91% varied in intensity, which means the vast majority of them were dynamic murmurs.
So they may come and go. You may listen to them and think, oh, it's got quieter or it's gone away. I must have been making it up.
No, it probably was there. And over half of them were grade 2, so that means that barely the majority, but just the majority of these cats had a low grade murmur, whether or not they had heart disease. So cat murmurs are not that useful compared to dog murmurs, say.
So here's the sort of heart disease cats get, they get hypertrophic cardiomyopathy. This is the left atrium here. The left ventricle.
The mitral valve in the 2. And we can see the aortic outflow here and the aortic valve. If they want to go thrashing in the background, don't worry, I'm OK.
It's just that my wife dropping her laptop. Sorry about that. So we can see the aortic valve ending and closing here.
This is the outflow track from the left ventricle from the left ventricle coming up to the subaortic region, and we can see the, mitral valve opening and closing. The mitral valve with a keen eyed amongst you is doing a little kink, a little bend in cytoly which looks like it's high fiving the interventricular septum here. If you look in this region, I'll move the pointer out of the way.
That's called systolic anterior motion of the mitral valve, and that can obstruct outflow through the aorta in cats, which can, of course, generate murmurs much like a sub aortic stenosis in dogs. This is dynamic, so it gets worse with greater catechoamines, higher heart rates, and this is why we see so, so many dynamic heart murmurs in cats. We Don't know if this is a a a bad prognostic indicator or a good prognostic indicator in cats to have this, and what we do know is it's associated with hypertrophic cardiomyopathy.
And we can see in this patient, we've got thickening of the left ventricular free wall. I'd probably have to measure it, but I think it's 7 millimetres or so, just eyeballing it. And the left atrium looks a little bit large in this view.
So going back to Rosie's data, overall, 15% of cats, that's 1 in 7 cats, had HCM. And actually, this population was biassed towards young and middle aged cats. There weren't so many older cats, and we know that older cats are more likely to get it.
So in an older population of cats, this is a much greater proportion who are affected by HCM. You can see a tiny sliver of this pie chart here, a very frugal portion of pi was allocated to other heart diseases. It's probably less than 1% from memory.
So we don't really worry about other heart diseases in cats when we're thinking about murmurs. Do they get them? Yes, they do get other heart diseases, but primarily, let's think about HCM.
So think about a population of young cats based on Rosie's data. Here we can see the white cats are cats who don't have a heart murmur. The cats in pink or red do have a heart murmur, and specifically the cats in red have HCM on an echo, or have an abnormality on echo.
So what's important here is approximately 5 times the number of cats have heart murmurs that have heart disease. So if you have a young cat, less than 3, and you find a heart murmur, 4 out of 5 times, that cat will have a normal heart on echo. This is what I mean by cats being challenging and cats posing some difficulties.
In older cats, this is cats over 9. And the white cats don't have a murmur. See, the majority of cats have a murmur in cats over 9, based on Rosie's unbiased, non-selected data.
We can see the proportion of red cats here is greater, so roughly 50% of cats. With a murmur in the population of older animals will have heart disease. That's important.
So if you have a young cat and you hear a murmur, chances are, cat's fine. If you have an old cat and you hear a murmur, you just can't say. You might as well toss a coin to say whether or not this cat has heart disease based on auscultation.
Thinking just about cats with murmurs in some detail, the younger cats, the juvenile cats up to 12 months of age, in cats with murmurs, 1 in 5, approximately, maybe 1 in 6 had heart disease. Cats 1 to 3 years old, about a quarter of them had heart disease if they had a murmur. 3 to 9, around about a third, greater than 9, about 42%.
OK, 43%. So it's still not even as good as tossing a coin. This is very important because it's quite common for people to hear a heart murmur and say, oh we shouldn't anaesthetize this cat, because it's probably got heart disease.
At no stage in life is that true, based on just the presence or absence of a murmur. So we need more to help us determine is this murmur important or not. So we should echo every character with a murmur, right?
Probably not. It's not very practical. The RSPCA last year estimated there were 7.4 million cats in the UK.
If 40% have heart murmurs, that's 2.44 million cats who need an echo at any one time. I like cats, but I don't think I can fit 2.44 million in in the next few months.
In fact, it's very impractical. If we imagine, and it is imaginary, it's not real, if we imagine that echoes are only done by cardiology specialists or advanced practitioners. That's 38,000 cats each.
My fastest catecho would give me about 25 cats a day. So if everyone was doing that, it'd take 5 years with no days off and no breaks, just for cats that have murmurs today. So you see how we can't echo all these cats.
So which heart murmurs are important? Well, again, like dogs, clinical signs of respiratory history, syncope, unexplained weakness, or even vacant episodes, they're important to think about. Physical exam findings, if we have a gallop sound, an arrhythmia, abnormalities of the apical impulse.
This is is something I mean where if we palpate the, the thorax on either side and the right side of the chest, the apical impulse feels stronger than on the left side of the chest, then actually that means there's cardiac remodelling in most cases. If there's jugular pulsation, it suggests right sided heart disease. If the murmur's very loud, right sided or even diastolic, then that would suggest significant heart disease.
Gallop sounds are 3 sounds, which obviously is not what horses do when they gallop, they have 4 beats when they gallop, so it's more a counter sound, but we're stuck with the terminology I'm afraid, the way it is. Gallop sounds are a third heart sound, an abnormal heart sound. So we can see the phonocardiogram here, we can see an S1, S2, and S3 in this case.
Listen to the gallop sound. So, this gallop sound, you can just hear that third heart sound, and sometimes they will come and go, but this gallop sound suggests that there is very high pressure in the heart. Because of high pressure in the atrium, you get a very rapid filling of the left ventricle when the mitral valve snaps open, fills the left ventricle and causes reverberation of the heart.
And that's an audible third heart sound in animals as small as cats or dogs. In a horse, that's a normal thing because the hearts are so big. So the context of a heart murmur is very important in cats.
We've talked about age, we've talked about how heart disease is common in older patients, or more common in older patients. Data from Rosie's CAT scan study allows us to, to look at these cats and try and estimate the risk of HCM being present. And working on that data, she's come up with an algorithm where there are 4 very important factors.
The first is the murmur grade, the murmur intensity. Grade 3+ was much more likely to be associated with heart disease and grade 1 or 2. The Age was important causes heart disease is more common in older age.
The sex was important. Boys get more heart disease, in, in, cats than than the girls do, or they certainly get it younger. And also, body condition score was important.
That's interesting. In humans, they get a thicker left ventricle if they're overweight. Now the body condition score cut off here was greater than 6 or greater than or equal to body condition score 6, which is not morbidly obese.
I mean, I, I'm a 6, but I think the the important thing here is that there was an influence of it, not the weight. So we should think about the body condition in addition to the weight when we're recording these factors in our consult room. So my recommendation would be to investigate a murmur in a cat, if it's grade 3 or louder, it's right sided, if it's accompanied by a gallop sound or an arrhythmia, if there's a history of clinical signs, if it's a breeding animal, or if there's a family history, and of course, if they're male, if they're overweight, or if they're older, again that adds weight to your, your recommendation for an echo.
Let's just listen to a couple of cat murmurs. Very different to hospital taking jobs. Got a quiet murmur here.
I would grade is maybe a 2. But the heart rate poses some challenges for us. But listen to the next one.
Very similar, but we can hear a gallop sound as well. The second murmur, very similar to the 1st, has a gallop. And that gallop suggests we should investigate.
In cats, especially, don't forget anaemia. When you have anaemia, there's reduced viscosity of the blood, that increases the tendency for turbulence to occur, and turbulence causes murmurs. So if you have an animal who who you think is tachycardic, pale, and there may be a reason for anaemia, for example, chronic kidney disease, then, you know, this is something that's quite important.
Anaemia itself can cause the heart to enlarge. So don't get confused if you've got an anaemic patient and the heart looks dilated and enlarged with a big left atrium, then actually that could be the anaemia doing it. So always echo them once you've resolved the anaemia and treated it, because hopefully they'll have a degree of reverse remodelling and the heart may not be as bad as you think it is when they're anaemic.
We're gonna very quickly cover murmurs in young dogs. So, congenital heart disease is relatively common in my clinic, very common in my clinic. In yours it's probably not that common.
What we know from a a large study in Europe is the most common heart diseases we see in dogs are pulmonic stenosis, subaortic stenosis, PDA VSDs and other, other things that are much less common. So let's go back to Dixie, we'll listen to her murmur. That's a very quiet murmur.
Early systolic, not musical, not radiating widely, that's very different to if you hear something like this. This is an example of a continuous heart murmur, so it's cystole diastole all the way through the whole cardiac cycle, it sounds like wind blowing through a tunnel or something like that. And this is is classic for a a patent ducts arteriosis.
What about if we hear this on the right side? Murmurs on the right side in dogs tend to either mean tricuspid regurgitation or a ventricular septal defect. This in a young dog would suggest to me that we might have a ventricular septal defect.
It's very loud. Tricuspid regurgitation doesn't tend to be so loud, although it can be. So I would say it's a grade 4 systolic murmur on the right side.
What about if you hear this at the left base? So we've got a murmur that's quite coarse sounding at the left base there, it's as loud, if not slightly louder than the heart sounds. So I'd be thinking about aortic stenosis or pulmonic stenosis.
It's only systolic, there's no diastolic component, so it can't be a PDA. So here's an angiogram just to outline the anatomy of pulmonic stenosis. So we can see we've got a catheter coming, I'll use my laser pointer again, I'm sorry.
A catheter coming down here through the cranial vena cava. And it ends in a little bubble there, it's a balloon on the tip of the catheter. We're injecting contrast.
We're injecting dye, so we highlight it on the, the X-ray technology of the fluoroscope. We can see the right ventricle here, a pacify. And then it comes up to this valguar region.
You can see how the, the valve leaflets don't open all the way. They open like a wind sock, and that's because these valve leaflets are fused. Then beyond that, we have a big dilation of the pulmonary artery, it should really run like this up to its bifurcation.
You see a very large post-dinotation, this sort of hat, the baseball cap sitting on top of the pulmonary artery. So this suggests we've got very severe pulmonic stenosis. We know this from an echo, but I quite like showing geographic images because it shows you, the anatomy, you get much, a sort of larger field of view, if you like.
This is a dog with aortic stenosis. I will make it play. On echo.
So here we've got the left ventricle, got the aorta. The aortic valve, and you can see how in the subaortic region here, there's this white ridge of fibrous tissue in this region below the valve, which is causing a tunnel of stenosis. This region here should be as wide as the aorta above it.
So that's a classic position for a sub aortic stenosis. This is an image of a patent duct's arteriosis. The anatomy here is difficult to identify.
We have the pulmonary artery here. We've got the PDA coming down into it from the aortas. The aorta is looping over the top of the image here, we can't really see it.
We've got the patent ducts arteriosis coming down here and you can see the green spray of blood continuously through cytoly and diastole into the pulmonary artery. So that's classic for a PDA and that's why they get a continuous murmur. So when do we investigate heart murmurs in young dogs?
I should add about this photograph, we just love Frenchies. I know that they're wrong and afflicted, but they're very sweet individuals. Maybe they can't breathe well enough to not be sweet.
I don't know. But if we have a grade 3 or louder murmur, you see a theme emerging in the recommendations here. If we have a diastolic component, whether it's a continuous murmur or a to and fro murmur, which is basically two murmurs of vowel stenosis and a vow of insufficiency, sounds a little bit like this.
Like someone sawing wood. If they're on the right side, they're not low murmurs. Or if it's associated with poor growth, you know, ill thrift, the dogs can be small in stature with congenital heart disease.
Episodes of breathlessness, either persistent or intermittent, this is why the brachycephalic dogs pose as a challenge. Or again, family history of heart disease. If they're a breeding animal, any murmur should be taken seriously.
So this is how we try and resolve the common congenital heart diseases, if we can, or at least help. On the left here we can see what we do for a balloon valvularplasty, which is where we, dilate the stenotic pulmonic valve. You can see here we've got a wire coming through the heart and out of the pulmonary artery, and then we're inflating a balloon and watch as the balloon goes, pop.
There was a waste there, a stenosis, which opens up when the valve opens. And on the right here we can see a dog with a gross cardiogaly from a PDA and actually probably heart failure from the PDA as well. The reason I can tell it's got a PDA is because we've put a plug in the end of it to close that PDA, interventionally.
So this is a transarterial route, this is a trans venous route, and these are things we can do to help these animals, to, to minimise the impact of congenital heart disease. Sometimes we have very complex congenital heart disease. This is a patient who closed an atrial septal defect with a, a, a specific device, and we also stented a very abnormal synoptic pulmonic artery.
So sometimes we have these very, complex diseases which can help, but the most common ones are the ones that have the very loud murmurs are the ones that might benefit from referral. So to summarise, investigating a heart murmur in any animal depends on the context of the murmur. Always investigate if it's associated with the history of clinical signs, a family history maybe littermates, arrhythmias or gallop sounds article protection.
In dogs, if it's grade 3 or louder, diastolic or right sided, these are must investigate murmurs. In cats, who knows? Cats are crazy, but our general recommendation is grade 3 murmurs or louder, especially in the boys and especially in the older boys.
OK, it doesn't mean that young female cats can't get HCM, but it's more common in the older male cats. So definitely take those cases seriously. So instead of help, there's a murmur.
Let's aim for, there's a murmur. Let's have a think about this. Can I hear a gap?
Where does it localise? Can I hear it elsewhere in the chest? Are there any other abnormalities?
Let's turn the panic into logic and try and approach these cases more carefully. That'll take a lot more stress out of your job and it'll help you get a better result for your patients. So thank you very much everyone for listening and attending, whether you're live or whether you're watching after the event.
I'm happy to take any questions. Kieran, that was absolutely fascinating and as always, you guys that are so good at what you do, you make it sound so simple until we get back in the consult room. But that was fabulous.
Thank you so much. Thanks very much. Thank you, Bruce.
Right, we do have quite a few questions coming through. So, let's see if I can find some of the beginnings here. Greg wants to know how risky is it to echo an old cat with a grade 4 or 5 pansystolic murmur, which was asymptomatic with no signs of arrhythmias or congestive heart failure.
How risky is the echo, and I guess it depends on, on whether you sedate or not and what sedative combination you use. Obviously, uncontrolled stress can also pose a risk to a, to a patient with heart disease. And so if you have got a patient who's very stressed, then probably it's less risky for them.
If you, if you give them a little bit of sedation. My sedative of choice will usually be something like buorphenol, 0.2 to 0.4 milligrammes per kilo intramuscular injection.
I often add what I would call, hopefully not offending any homoeopaths. I would call it a a a homoeopathic dose of ACP which to me is just a, like a needle hub full, a very tiny amount, of ACP added to that dose of buorphenol, which can help just to break the anxiety a bit. That works very well for cats who are a little anxious, who you might just want to calm down a bit, facilitate holding.
If you've got a cat who you can't really touch, other than to auscultate it, then, you probably should do something a little more heavy, like, a combination of butorphenol, midazolam, alfaxolone, which can be given intramuscularly and, is often very, very effective. About 20 minutes or so. If you're going to take longer than 20 minutes, I'd say once they're sedated with that combination, 0.2 milligrammes per kilo buorphenol, 0.2 milligrammes per kilo midazolam, and a dose of alfaxolone that is the same as the induction dose that I can never remember, and I have to look up on the leaflet every time, but it's the same as the induction dose.
Give that intramuscularity. And and then place an IV catheter and just top up the sedation when you need to with a little bit more of alfaxolone. We tend to give 0.1 mLs an assessed response and give another 0.1 mL and you know, to, to effect.
And that works very nicely and you can sedate them for a little while. Excellent. Laura wants to know about HCM in cats.
She said that she has read an article from King EL that shows that ACE inhibitors do not prolong their lives. I would agree with, with your assessment of that article. It's recent study, well, recent article, the study was more than a decade ago, but the data in there is not perfect.
There are some weaknesses with the study, which. Might mean that a subpopulation of cats benefit from ACE inhibitors. However, I do not routinely use ACE inhibitors in cats, with heart failure or prior to the onset of heart failure.
My routine treatment would be furozamide to control signs of congestive failure, and also clopidogrel, the antiplatelet drug, to reduce the risk of arterial thromboembolism. I don't use ACE inhibitors routinely in cats. OK.
Richard asks, how accurate is pro BMP blood testing to differentiate significant murmurs, especially in cats? That's a whole other lecture. Maybe, maybe.
What, what I'm gonna do is, oversimplify it and say that, pro BMP, whether you're using the, the quantitative test from IDEX, which has a cut-off of upper end of normal of about 100. Or the snap test, the point of care test, which is in the ISA, which tells you normal or abnormal, with abnormal being over about 120 to 150 depending on the batch you get. .
Whichever one you use, it probably has a very strong negative predictive value, by which I mean, if you measure pro BMP less than 100 quantitative or it looks normal on the snap test, point of care at ISA, then probably that cat does not have clinically significant heart disease. So it's a very useful tool, I think, in those cats where an incidental murmurs detected, it's a grade 2 murmur, you know, maybe grade 3, no clinical signs, and you just want to screen them prior to, anaesthesia, say, then what I would do is, is run the pro BMP and if it's normal or or or or or negative. On those tests, I would say probably the cat is fine, let's repeat it next year and see if anything's changed.
If it's high, it does not mean the cat has heart disease. So although it's a good rule out, it's not a good rule in. So my recommendation would be, if you have a positive, you should do an echo or a radiograph or something, ideally an ultrasound to, to look at the size of the heart and the function of things.
If you have a negative, you you would probably be fine to put that imaging on hold. OK, you answered two questions in one cause Alan was asking that exact question. You know, what is the, the benefits of using the pro pro BNP before you do your scan.
So you've covered that beautifully. Thank you. There's a couple of questions.
I'm not gonna read through the one that's quite long, but basically the, the person is asking, if you're just a mediocre person with a normal scan. I doubt that. I doubt that.
I have an expensive scanner and a lot of experience, but it doesn't mean that people in practise can't do it. Well, this was the question. The question was if you are of mediocre good with a scan, what books would you recommend to learn from, and websites, and, and how would you start doing scans to learn about cardiac scans?
I learned a number of years ago, in first opinion practise, on a very old scanner, using a textbook, which was by June Boone. Now, June Boone is a vet tech in the US, so she's a vet nurse who's qualified in cardiology, and she does a lot of echo. She's a fantastic, echocardiographer and fantastic speaker.
She's written a very large tome of a textbook, which I would not recommend unless you're sitting your, your cardiology diploma when you sort of have to read it, really. It, it's a great reference text for me and, and for my residents now. It's not an easy one to pick up and learn.
However, Someone has published a very distilled version of her book, which is maybe 50 pages long, and if you go on Amazon or other websites or prefer preferably an independent bookstore, who might be able to order it for you. If you look for this, it's, I think it's called, . A cardiography of small animals, and it's by June Boone, and it, it's maybe 30 pounds or 40 pounds, the full textbook is like 100 pounds, so you'll you'll be able to tell the difference.
And that little distilled textbook was what got me through my 1st 100 echoes or so, and we still have a copy in, in our consult room, . For our students to look at, I, I think it's an excellent book, a very good go to. If you want a really nice, thorough coverage of every single echo view possible and beautiful pictures of how to achieve them, what the angles look like and everything, and also some other great.
Stuff in there. The BSAVA manual of thoracic imaging is a fabulous book, probably better for the echo chapter in the Thoracic radiograph chapter than the Cardiology manual. So for the imaging, go to the Thoracic Imaging manual by BSAVA.
It's super good, a little bit more expensive than the June Boone book, but it does cover more stuff. But, but the June Boone one is, is sort of uniquely gifted because it's written by someone who's just so good at echo and so experienced. Wonderful.
Charlotte has asked, do most innocent murmurs go in young puppies by 16 weeks old? Many innocent murmurs will go, yes. Not all of them, and 16 weeks is a little bit early, to sort of draw your cut off.
I, I would say most flow murmurs in, in puppies are gone by 6 months. Some will have flow murmurs for a long time, and we do see flow murmurs in adult dogs, especially, you know, a bull terrier or a boxer dog or something. But, you know, those are also breeds that are predisposed.
To diseases like aortic stenosis. So that's where your murmur volume, and a good quality auscultation comes in, because these dogs may have a flow murmur into adulthood, but if you have a grade 3 or grade 4 murmur, you don't want to call it a flow murmur until they've had a full echo. OK.
Question from Anna. I'm going to read it to you. Have you had many cases of transient hypertrophic cardiomyopathy in young cats?
And how long would you advise treatment for if the signs of congestive heart failure are present? That's one of my favourite topics, because I was at the Royal Vet College, doing my residency when we first identified some of these. And I remember my cats that I saw with this very well.
They're all in the case series that was written up in, Jan by Jose Mattos, who. Has, worked and done a PhD at the Roy Royal Vett College recently. And these cats were all young cats who, just for, for everyone else who maybe hasn't heard of this before, they were all cats who developed, an echocardiographic appearance at a, a physical exam, .
Picture that really looked like HCM with very bad heart failure. Many of them were in cardiogenic shock, many of them were hypotensive, they have very large atria and pleural effusion, pulmonary edoema, on the echo, high troponin. Very high, sort of too high for HCM and, and we believe these guys have got some sort of myocardial inflammation potentially associated with a stressful event, potentially associated with something else that we don't fully understand.
And these cats, if you can get them through the 1st 24 or 48 hours, if they survive, they seem to resolve and normalise. And they're fabulous because of that. But at the time, when you first see them, you can't know that they are a transient myocardial thickening, we call them TMT, transient myocardial thickening, and, it's a retrospective diagnosis.
So this is something that's very difficult because I think many vets in practise would see a young cat with very severe heart failure, hypotension, and they would say to an owner, I'm really sorry, this prognosis is grave. And maybe the cat gets euthanized, but actually a number of those cats will survive and normalise with time. So just live a normal life afterwards.
They're challenging because of this situation. Have I seen many? Yes, I can't tell you the number.
Maybe 50% of the cases in that RBC case series are ones that I was involved with at the Royal Vet College. A couple of the cases that I've seen since, I, I've seen two in the last year, or rather we in our clinic have seen two in the last year. And they don't get any easier.
And sometimes you, you see them thinking they've got HCM for a routine follow-up at 3 months, and you echo them, and they look normal, and you think, well, that's great news. But I was wrong in my diagnosis. It just shows the challenges that that cats can pose.
So my advice would be to, if you think the cat might be a transient myocardial thickening, is run troponin. Troponin is, is a nice stable molecule so you can stick it in the post over a weekend and you'll get an accurate result the next week, so you don't have to worry about fancy handling or anything if you see the amount of hours. And if the troponin is high, by which I mean, you know, normally it's up to 0.1 or 0.07, actually with the IDEX, I say, and I'm thinking two.
Some cats were over 50, you know, off the scale high, you know, so varying degrees of, of elevation. But if the troponin is high, that suggests that maybe you've got this inflammatory process, especially if they're very high, you know, 50 or more. .
And I would follow them up. I would, I would repeat the echo a month. I'd treat them for heart failure as normal, get them out of the hospital on there, frozenide clopidogrel, make sure they're eating and comfortable at home and the compliance of medication is good.
I'd re-evaluate them at 1 month, and if it looks like their, their dimensions on the echo, the wall thickness is reducing, the left atrial size is reducing, I'd probably follow them up at 3 months as well, and I, I may start to wean medication at 1 month, or I may leave that if I'm uncertain and may start to wean it at 3 months. . That's a long answer to say, I don't know how best to manage these cases, but that's how I do it.
Fabulous. Kieran Gal wants to know what is your safest protocol for sedation of dogs, especially stressy dogs. Safes protocol, you know, my anaesthetist would say, well, there's no such thing as safe sedation, there's only a safe anaesthetist.
But I, I think, we, I, I really like using brophenol alone, in dogs, maybe again with that microdose of ACP, so 0.2 to 0.4 migs of, migs per kg of borphenol, plus that kind of.
Full of ACP, which probably equates to about 2 mics per kilo or something. Given IM or IV, and, and that generally is enough to take the anxiety out in dogs. Again, if it's not, you, you should be able to get IV access at that point, and you can use something like, midazolam alfaxolone to top that up, and, and, and give you a little bit more sedation.
OK, great. Question from you, Ruth, it's a, it's about her own cat actually. 7 years old, domestic short hair with a grade 3 murmur, exercise intolerance, weakness in the hind limbs, and the potassium is, sort of borderline low.
Would this be something you would be concerned that is connected to the heart murmur in, in cats or, or unrelated? The, the potassium specifically, and I wouldn't expect a cat with, you know, routine cats with HCM or or or whatever heart disease to have hypokalemia, unless they're on diuretics, in which case, of course, the frozamide can cause hypokalemia. It's certainly something I would investigate though, Ruth.
I think I, I would, I would get an echo in that case and just make sure there's nothing cardiac, triggering things there. Excellent. We've got loads and loads of comments coming through.
Kiren, commenting about how fabulous your presentation was and how wonderful and insightful, this, webinar has been and I can only echo that sound. Thank you so much for your time and making it sound all so easy and so simple for us. Thank you very much.
And thanks everyone for tuning in. Really appreciate your time. Folks, that's it for tonight.
We've run out of time, I'm afraid. I'm sure like me, you could sit and listen to Kieran for hours. But we'll have to get him back again and get him doing some more of these cardiology talks for us and, maybe a couple of others as well.
Kieran, once again, thank you very much to our sponsors, Bringa Engelheim, Makers of Wet Medden. Thank you so much for your sponsorship. Remember folks, we need to support those who are supporting us.
So let's show Bohringer our appreciation for their support tonight and and their sponsorship by supporting their products. And from myself to all of you for attending, thank you very much and good night.
