Hello there everybody and welcome to this webinar provided by vets now for Webinar vets on a diagnosing congestive heart failure. So the idea is that this is a very brief presentation, on how to diagnose failure in both cats and dogs, very much in a, first opinion or primary care setting. It's not going to be extensive because obviously time won't allow, but it's hopefully going to give you, some of the important tools and top tips that I use to rapidly achieve a diagnosis in patients with heart failure.
And we're going to talk about patients who present really quite acutely dyspneic as a true emergency, but also, the patient that often can come in. To the clinic for a, an elective sort of an appointment that has a history, for instance, of breathing just not right. So we're going to talk about how I approach these cases and, how I work through them, particularly paying attention to what we can look out for in the history, what we can, decipher from the signalment of these patients, also the physical examination.
And then on to some of the more specific testing that we can use in clinics, so blood work, ultrasound and radiography. OK, fantastic, so. A little brief introduction, congestive heart failure is a common reason for presentation.
Certainly I used to see it a lot when I was a primary care practitioner, in the form of consultations, but also working at vets now Emergency and referral hospital. We see lots of acute and poor acute emergencies here, and certainly in cats and, probably in dogs, it is the most common cause of dyspnea. Congestive heart failure, so it should always be on our radar for those dyspneic patients.
The vast majority of patients really can be rapidly diagnosed, with a, a very strong degree of confidence in primary care practise, even with very basic equipment. That's what I'm gonna focus on, with this presentation. I'm not gonna tell you about all the fancy techniques we can use here, with very high-end equipment to make these diagnoses, but how you can make these with with your equipment, that's available in practise.
One of the important things that we're going to touch on is how we can differentiate cardiac causes of dyspnea, from respiratory causes of dyspnea. And that's often I find the most challenging thing, and I certainly see that in the referrals that we accept that that can be the most challenging thing to try and differentiate the two. Particularly in cats because we know they're not very good at outwardly showing the signs of cardiac disease, and they can be sometimes, a bit trickier to investigate, as well.
But do bear in mind that obviously, What I'm going to talk about are all general rules of thumb and the vast majority of the time they hold true, but there are always exceptions to these rules, you know, and also don't forget that some patients can present with both primary respiratory tract and, cardiac disease, and sometimes, you know, it's only one of those that's actually causing the dyspnea. So we have to keep, all our possibilities, you know, in the back of our mind when we are investigating these patients. The good news is that.
Once we've made a diagnosis of heart failure, we obviously ideally then want to go beyond that and say, well, what's this specific cardiac disease, you know, that's causing it, so is it hypertrophic obstructive cardiomyopathy in a cat? Is it, dilated idiopathic cardiomyopathy in a dog? That's great, but that's often where cardiologists come in.
And the good news is that to you know, simply make the diagnosis of congestive heart failure isn't often enough in these patients to then say, OK, well, really regardless of the cause of the underlying problem, this patient's gonna need rosemide, OK. Plus or minus other medications, but ultimately, the therapy for these patients once we've made the diagnosis of heart failure is pretty similar, so we don't have to get too worked up about the exact cause of the cardiac, disease, if that makes sense. OK.
So just a little touch on this ACVIM staging system, it's something that was first published to help us describe dogs with mitral valve disease, OK? But it has also been adopted, very recently, through the ACVIM. Which allows us to also describe the different categories of feline cardiomyopathy as well.
And it's a lovely staging system that us cardiologists use, but also we'd like, our, primary care practitioners to use as well to help us sort of accurately describe the stage of our patient's cardiac disease, OK? Now this staging system. You can access two papers that that talk about this in much more detail than I ever can, and they are through the JVIM website to the Journal of Veterinary Internal Medicine.
It's an open journal, you can go on there and have a look at their consensus statements. So they've got a fabulous consensus statement on mitral valve disease that includes this in dogs, and one on feline cardiomyopathies from very recently. And those papers are free to access online through their website.
So, we like to use this staging system because it's simply by using a letter plus a minus a number, we can quite accurately describe the stage of our patient's cardiac disease without having to use lots of long-winded, terminology. And it allows cardiologists to communicate more effectively between each other about these patients, but also cardiologists and primary care practitioners, and then primary care to other primary care practitioners. So the way that this staging system works is we go from left to right and it's forever worsening categories of disease, OK?
And. At this side of the scoring system, we have patients that are in stage A cardiac disease. So those are patients who are simply at risk of heart problems.
So they don't actually have heart disease at that point. So patients who fall into this group would be, for instance, all Maine Coons. We know that they're highly overrepresented for hypertrophic cardiomyopathy in cats.
We know that all our cabbies. Are, you know, highly overrepresented for mitral valve disease, so all of these patients, as soon as they're born, almost fall straight into this at-risk category, you know, of, of being, at an increased relative risk of developing a cardiac disease but not actually having disease at that point. We then moved to category B, and these are patients who do have cardiac disease.
So they may have a murmur, or they may have, reduced systolic function, or they may have hypertrophy of their muscle. Any change that we can see on ultrasound, on X-ray, or on auscultation, we put our patients into stage B, heart disease. We then further subdivide it into stage B1 and B2.
So B1 of those patients who have cardiac disease but it. Pre-clinical, and that's really important, sorry, to, to sort of highlight at this point. These are really pre-clinical patients, so before they started to display of these clinical signs of disease.
And B1 patients have no cardiomegaly, whereas B2 patients do have cardiomegaly. OK? So that's really important to differentiate those two, and I'm sure people will be aware of and the importance of knowing what stage B2 means for heart disease, because those are patients that often are likely to benefit from, immobendin therapy if you're a mitral valve disease dog, for instance.
So we then move on to stages C and D. So these are patients that are clinical for their heart disease and are in congestive failure. So for the talk, sorry, for the purposes of this presentation, we're really talking about these patients, we're gonna forget the A's and the Bs.
So we're looking at diagnosing patients with congestive heart failure. And patients that are stage C are the sort of, newly diagnosed. Or patients that are controlled on sort of, relatively standard doses of rosemide, whereas the patients that are stage D are those that have refractory heart failure.
So patients who are on multiple drugs, very high dosages of rosemide or have been transitioned on to other, diuretic therapy, you know, may or may not be responding successfully. OK. So these are the patients, that we're talking about.
So what that means is that to be in stages C or D, you certainly have to have enlargement, OK, so that's one of the things we're gonna look for with these patients to say, does our patient have heart disease? Well, we have to have heart enlargement to even get into categories C and D. So we're gonna look for that with our imaging.
And we're gonna look for signs of congestive failure, and we're gonna do that with our imaging, but also with our history and with our physical examination. So with heart failure, think, look for evidence of failure, look for evidence of cardiac enlargement, OK. Fabulous.
So moving on to the history and the importance of taking a good history, with cats first off, they are sneaky and they're very, very good at hiding, the signs of cardiac disease and even respiratory, distress. And as a result of that, cats really commonly present with very significant respiratory distress, when they do develop pulmonary edoema or pleural effusions because they hide the signs until much later on. And prior to going into fulminant, dyspnea, they often just display these very vague signs of lethargy and hiding, maybe hyperexia, and the client says, you know, they were just not right.
There was something that I couldn't put my finger on, . And it was progressively getting worse for a week and then the breathing difficulties started. So these cats often come in really quite dyspneic, often on a bit of a nice edge, and we'll talk about the importance then of not sort of rushing our physical exam, and, and, diagnostic testing in a few more slides.
So coughing is really not common in cats. So when I hear that one of my dyspneic patients has had a history of a chronic cough, I really start to think respiratory tract disease such as asthma or bronchitis rather than heart failure. It's really uncommon for heart failure cats to cough.
There was a recent paper, the Rapid Ca study, which looked at at a population of dyspneic cats in, in primary care practise, and that found that 20% of those cats were coughing. That's certainly nowhere near the numbers of cats that I see, that cough, but you know, there you go, it's in the evidence, it must be true. Moving on, a lot of cats that do present as well with congestive heart failure often don't have a history of cardiorespiratory disease.
So, you know, a lot of these cats that can come in in heart failure may never have had a heart murmur previously, detected. They may never have had an irregular heart rhythm or even a gallop sound, you know, and a lot of cats, their first presentation from heart disease can be formin and congestive failure. So we have to be aware of that.
With dogs, they're a bit easier to pick up signs of heart failure on their history. And that's because they generally have more progressive signs and really commonly include exercise intolerance. So that's definitely one of the main things I ask clients about.
Is your pet becoming out of breath and slowing down and struggling with the exercise they're used to. It really is a hallmark of heart failure, cos whilst that dog is sat at home in its bed, watching TV with you, they don't need a huge amount, you know. Of blood going to their muscles, to be able to do that, and their failing hearts can often keep up with demands.
Soon as they start exercising and all your skeletal muscle wants a significant increase in the blood volume going to it, your heart's job is to increase cardiac output to keep up with that. And if your heart is failing, you cannot augment that increase in cardiac output. So do look out for exercise intolerance.
It's much more common with heart failure in dogs than primary respiratory tract disease in dogs, it really is. Tachypnea is absolutely a hallmark of congestive heart failure. And what we sort of say, in dogs with heart failure and cardiac disease, is that if your resting respiratory rate or sleeping respiratory rate is persistently below 30 breaths per minute, it's highly unlikely you have heart failure.
If your respiratory rate is consistently above 30 breaths per minute at rest, or when asleep, you know, when you have other signs of cardiac disease such as a murmur, it's highly likely that heart failure is the cause of that dog's problems. And that's based off, a couple of really big, nice retrospective studies looking at resting respiratory rates, in dogs, with and without congestive heart failure. So then just on to coughing in dogs, you know.
I think I certainly got taught at university, you know, patients with congestive heart failure cough because of fluid in their lungs and it makes a whole heap of sense. But what we've realised again from quite a few retrospective studies is that doesn't really hold true, OK. And that a cough is much more indicative of primary respiratory tract disease as a cause of a dog's dyspnea than it is heart disease.
Yes, patients with congestive heart failure can cough, certainly when they've got lots of pulmonary edoema. And it is spilling out into their alveoli, you know, terminal, bronchioles, that will certainly stimulate coughing in some of those individuals, but it's not a reliable indicator. So, you know, I will always ask clients, is that dog coughing, but I won't use, the presence of a cough to confirm heart failure, and also I won't use the absence of a cough to rule out heart failure.
So please, please, you know, don't fall into that trap, OK? Dogs often do have, previous histories of cardiorespiratory disease. Certainly with mitral valve disease, you know, those guys have a really quite a long disease course, you know, and they often, have an incidental murmur that is detected at some point, during routine examination, and often that murmur progressively gets loud.
And that patient slowly moves from having pre-clinical heart disease to clinical congestive heart failure. So these guys are not such of a sort of surprise when they turn up at the clinic in congestive heart failure. You know, there's often a history of, of an incidental heart murmur, or they may already have been on.
Cardiac medication for an already diagnosed pre-clinical, cardiac disease, such as immobendin, used in the pre-clinical period for both DCM and mitral valve disease. So yeah, just, just be aware of those kind of things. With regards to the histories.
So now on to signalment, so, age, breed, sex, of our patients. This can help guide us as well as to, the likelihood that that, patient is presenting with congestive heart failure, . And the, the sort of the things to sort of roughly bear in mind are that with cats, males are overrepresented for cardiac disease, almost a, a ratio of 2 to 1.
So male cats are more likely, cardiac disease than females. As cats get older, the incidence of congestive heart failure does increase. But cats of any age can present with congestive heart failure, and I've certainly seen one year old cats, that present in fulminant congestive heart failure with an acquired cardiac disease and not, you know, a worsening of a congenital cardiomyopathy.
So don't let age of a cat rule out heart failure, OK? Definitely bear in mind breeds because we know that the Maine Coon, the ragdoll, Persian, British Shorthair are all breeds that are overrepresented, for hypertrophic cardiomyopathy. So do bear that in mind, you know, a dysic Maine Coon presentation to me is generally a HCM congestive heart failure cap until proven otherwise, you know, and giving that patient a dose of ruzammide before you do any further testing would be very, very reasonable.
Bear in mind some cats as well are underrepresented for cardiac disease such as Siamese. I mean, they get every other disease under the sun, but fortunately, cardiac disease is generally, not one of them. Then on to dogs, we have mitral valve disease and DCMs.
They're the two main cardiac diseases that we see in dogs. Mitral valve disease, which is, valvular degeneration leading to regurgitation through that valve and progressive volume overload. It is common in older small breeds of dogs.
So, you know, our cabbies, our Yorkies, our Daxis, those kinds of guys, OK. Now do bear in mind that obviously those breeds that I've mentioned are also the kind of breeds that quite commonly get airway disease as well. So, you know, can have, .
Tracheobronchial malaia or idiopathic chronic bronchitis. So, you know, just do bear that in mind. Whereas patients who present with dilated cardiomyopathy, which is by far the, you know, the second most common acquired cardiac disease of dogs, this tends to occur in sort of, middle-aged, large to giant breeds of dog, OK?
So again, you know, if you see a dyspneic, giant breed dog that's sort of middle aged, you've got to have cardiac, causes quite high up on your list of possibilities. And, you know, if you think it is heart failure in that type of dog, it's almost certainly going to be DTM. You know, big dogs don't really get degenerative valvular disease.
Small dogs don't really get DCM. Again, there's always, plenty of exceptions to those rules, but generally they do hold quite true. .
And bear in mind as well your general breed association, so yeah, I don't have to really remind people that mitral valve disease affects cavaliers and DCM affects Dobermans, for instance, but, OK, so now we move on to physical examination, and really the physical examination is so useful in diagnosing congestive heart failure or increasing your suspicion. You know, cardio respiratory disease, well, sorry, cardiovascular disease itself is one of the, the best sort of, it's, it's where the physical examination really comes into its own, more so than than diseases of many other organ systems. So really be thorough with your physical exam in these patients, you know, and try not to overlook anything.
And the first thing that I always say, particularly in cats, is simply observe. Before you even put your hands on that patient, just observe it and, watch its breathing pattern. Listen to its breathing sounds, before you put the stethoscope on that chest, cos that can be really telling.
For instance, if you see a paradoxical breathing pattern where the chest wall moves out as the abdominal wall moves in, that is highly suggestive of respiratory fatigue and it's really commonly seen in cats with a pleural effusion. If you see a cat, that presents with open mouth breathing. We know again that that is really worrying and that that patient is going to be in severe respiratory distress.
And before we even put the stethoscope on that patient's chest, we actually might be better popping them on oxygen and giving them a little bit of sedation, OK, before we even examine them, because in some of these fractious dyspneic cats, the examination itself can push them into an episode of cardiorespiratory arrest. So we've got to be very, very careful. If we're gonna give some sedation to facilitate examination, we want to use drugs that do not depress the cardiovascular system, and an excellent choice would be bornol at 0.2 to 0.3, nigs per kg, IV or IM in these individuals.
Stick them on oxygen, just monitor their respiratory rate and their respiratory pattern. And when they look like they're a bit calmer, then we can examine them. So with regards to the actual parameters of the physical exam, .
The best things to look for, to give us an indicator that cats in heart failure are a low rectal temperature below 37.5, the presence of a heart murmur, an irregular heart rhythm or arrhythmia, and a gallop sound. So the gallop sound is that third heart sound that makes the the cat's heart rhythm sound like a galloping, hooves of horses.
So these are all good indicators that that dysneic patient has heart failure. Other things as well that have been highlighted, in various studies include increased heart rate, but it's gonna be really quite increased, so above 220 beats per minute and markedly increased respiratory rates above 80 breaths per minute are more consistent with congestive heart failure as a cause of dyspneia than respiratory tract disease. But do bear in mind as well that cats are weird little creatures, and they do have this, phenomenon where they can also actually present with quite profound bradycardia, and congestive heart failure.
So that's really unusual because normally your heart is failing, and your stroke volume is dropping, your heart rate goes up in response to the sympathetic tone to help augment your cardiac output. But some cats present with bradycardia, so heart rates, you know, in the order of 140. 160 beats per minute.
So yeah, if you see a dysneate cat with a marked bradycardia, that might ring alarm bells for congestive heart failure as well. We can auscultate the lungs and try and hear pulmonary crackles, but they're not always appreciated even in cases with quite moderate pulmonary edoema. So if I hear crackles, you know, and I think that sounds like a wet lung, great, it probably is heart failure.
If I don't hear them, I certainly won't exclude heart failure. Listen out for muffled heart and lung sounds as well, because they are obviously indicative of a pleural effusion. So a lot of that information that I've just mentioned on the physical exam kind of came out of this rapid CAT study, which is, a study that I think was published through the JSAP, and, it basically within that study had this lovely flow diagram, that if you want to get hold of that paper if you're a member of the BSAVA, there's this flow diagram that you can use, with that acutely dyspneic cat to kind of work through whether it sounds more like a heart problem or a lung problem.
OK. So I recommend you you look that up. If you remember.
Now on to dogs, again, observe the breathing pattern and sounds, you know, as per, the cats. And then we're gonna get our hands on and start doing some auscultating. Pulmonary crackles again, you may hear them in patients with really quite severe pulmon edoema, but the absence of crackles definitely does not exclude congestive heart failure.
Looking at respiratory rates as well are very important because they're generally elevated, with congestive heart failure. And certainly more elevated than you would generally expected primary, respiratory tract disease. And heart rates, really important, dogs with congestive heart failure really tend to have a normal, a high normal even, or an elevated heart rate, OK, compared to a patient that's got respiratory tract disease.
So do look out for those. A, a, a good little top tip as well is that, dogs often, in the examination room, you know, when they're healthy, happy individuals will have a sinus arrhythmia. Where the respiratory rate, obviously correlates with increases and decreases, in their, heart rates.
But patients who have congestive heart failure, they have an increase in their sympathetic tone, and one of the first things that happens is you lose your sinus arrhythmia. So if you have a dyspneic dog, and it has a sinus arrhythmia, it's highly unlikely that patient has heart failure and much more likely it's primary respiratory tract disease, OK? And conversely, you know, vice versa, basically, but yes, so listen out for, for, for that, and if you hear any dysrhythmias, in a dysmic patient, so other than a sinus arrhythmia but a genuine dysrhythmia, that would be much more consistent with the diagnosis of congestive heart failure than respiratory tract disease.
Mitral valve disease patients, these guys have a big telltale sign that they're, possibly dysneic because of primary cardiac disease, and that's often because of a loud, left apical, systolic heart murmur, often with quite wide radiation. So if you've got a dyspneic small breed dog, and it does not have a, a old small breed dog. And it does not have a heart murmur, it's highly unlikely that patient has heart failure because it's highly unlikely it's got mitral valve disease, because it doesn't have a loud apical systolic heart murmur.
You generally have to have a grade, really 344 or above heart murmur to be in heart failure with mitral valve disease. So really listen out for heart murmurs in older. You know, tereotypes, and really concentrate on grading that murmur, you know, that patient's really dyspneic and they've only got a grade one systolic heart murmur.
It's really, really, really, really unlikely that their mitral valve disease is severe enough to, to cause them to be in failure. They really have to be grade 4 or above. Bear in mind as well that mitral valve disease patients commonly present with congestive heart failure, so pulmonary edoema, but they very rarely, present with signs of low output or for forward failure.
So those are the signs of pale mucous membranes, prolonged capillary refill times, . Reduced peripheral pulse quality, certainly they can have those to some degree, but you know that's nowhere near as common as in dogs with DCM where that really is one of the hallmarks of those patients, so, do bear that in mind. Also look for signs of right-sided congestive heart failure, as well in dogs, with suspected mitral valve disease, because, 30% of mitral valve disease dogs also have concurrent tricuspid valve disease, or it might be patient with mitral valve disease that has developed pulmonary hypertension and then started to develop right-sided heart failure as well as left-sided.
So do look out for those signs, and those signs are generally quite easy to spot. They are pleural effusion, ascites. Jugular distension and jugular pulsation, OK.
Moving on to DCM dogs, these guys do not always have a heart murmur. So when I've got a dyspinic dog, I'm really, really, really particular about listening to their heart, to be sure whether they've got a murmur or not, because if a large breed dog, With dyspnea has a murmur, even if it is really, really low grade, that is very significant because DCM patients, it's, you know, they don't have loud heart murmurs, they don't have primary valvular disease. They are primary myocardial diseases, so even a very, very low grade heart murmur in a large breed dog is, you know, consistent with heart failure, which is different from very small breeds of dog.
And as I say, the absence of a heart murmur absolutely does not rule out DCM in a dog, OK? These guys do often have signs of low output forward failure, so mention that in the last slide. So obviously we're gonna look for those in our large breed, dogs as well.
And they can have right-sided congestive heart failure at presentation. And that's simply because most DCM dogs, start with, systolic dysfunction, failure of the left side of the heart, but it can quite rapidly, start to affect the right side as well. Fabulous.
So we've done our history taking, we've, done our physical examination, we're starting to think about whether or not this patient's got cardiac disease or respiratory tract disease. How do we investigate further? Well, I think.
Absolutely, the most useful thing that you can do is put an ultrasound probe on that patient's chest, and that is something that we are trying to do, that's now emergencies routinely in all of our, cardio respiratory emergencies. So our primary, you know, out of hours practitioners, you know, not referral clinicians, everybody, is used to doing this, and this is. A very easy technique to perform with very, very basic equipment.
Now I'm not going to go into much detail at all because it's far beyond the scope of this short presentation. There are lots of good resources out there, but what I would say is that really start to think about ultrasound superseding X-rays in a lot of the investigation of dyspneic patients. So what we will do in every patient who presents to us dyspneic.
Is we'll pop them on a table for examination once we've examined them, as this patient here on the right shows, we'll just have them, with a little simple bit of manual restraint, no sedation needed, internal, so they're in a nice position to be able to, to breathe effectively, plus or minus oxygen supplementation, and we'll just spray some spirit onto the side of the chest wall. We don't even need to clip. In most patients, and they'll put an ultrasound probe against their chest wall, and this can really, rapidly allow us to diagnose a pleural effusion, to a rapidly diagnose pulmonary edoema and to screen for cardiomegaly, because if we on this point of care ultrasound see evidence of pulmonary edoema, evidence of cardiogaly, it's almost certain that the patient's got congestive heart failure as their cause of dyspnea, OK, and they need ruzamide.
So just to show you a couple of images. This is a point of care thoracic ultrasound on a dog, and we have a large volume of anechoic fluid here around the lungs. This patient has a pleural effusion.
OK, great, we know it needs draining. This is a patient, where we put the probe against the chest wall and we see bee lines. So these are these are white rockets that we see vertically here, interspersed between these black lines of more, sort of normal, well.
They're they're actually the normal tissue lung tissue, but basically this pattern of white and black lines is indicative of fluid within the lungs, OK? And, we can easily, you know, spot these lines with a little bit of practise with this technique between two ribs at one of the intercostal rib spaces. And then we can also look for cardiogaly, and the view that we all talk about in, cats and dogs is this view, which is, it's a right parasternal short axis view, which is at the level of the base of the aorta.
So this is the aorta coming out to us, as a tubular structure and here are the three, semi-lunar valves. This is the left atrium here and this is the left aricular appendage. If you're doing this technique already.
If you're not, I highly recommend you read up about it and possibly go on, on, on a course. And basically, we can measure the diameter of the aorta, the diameter of the left atrium, and do this little ratio of the two. And what we know is that if that ratio is above 1.5 in cats and 1.6 in dogs, that is consistent with cardiomegaly.
And therefore, a diagnosis of congestive heart failure. So this is a normal cat with a normal size left atrium, OK, with a ratio below 1.5, just to show you what an abnormal one looks like, is this patient.
So you can clearly see just from looking at this left atrium, how much bigger that is, subjectively than this normal cat. So even if you don't manage to take any measurements, you can get used to putting ultrasound probes on cat and dog hearts and saying wow, they look pretty big, those left atriums, compared to those aortas. But as you do the measurement in this patient, 2.45 is the ratio, it shouldn't say centimetres there, my apologies, it is a ratio.
So that's very high, you know, above 1.5. So this is a cap with quite marked cardiomegaly and congestive heart failure.
This is another view as well that I particularly like to use in CATs for point of care thoracic ultrasound, and it's called the right parasternal long axis 4 chamber view. It's quite a mouthful, but it is dead easy to acquire. And we teach this to all of our interns here, as one of their sort of day one skills, and you could do this to look at the four chambers of the heart, left atrium, left ventricle, right ventricle, right atrium, and take a simple, measurement of the diameter of the left atrium, OK?
So from the inter atrial septum to this free wall of the atrium, in this cat that measures 2.1 centimetres and anything above 1.6 centimetres from this view.
Is consistent with cardiogaly in a cat. So I don't use this view for measuring the left atrium of dogs in an emergency. I use this view, OK, the short axis view, but in cats I actually much prefer using this view than the short axis one.
I just find it much easier to acquire a nice image on this view than I do on this one. OK, brilliant. So, hopefully, that's convinced some of you about the utility of point of care ultrasound.
For those of you who have, not got ultrasound available at your clinics, then radiography is gonna be, your go to technique to diagnose heart failure. And that's because congestive heart failure really is, what we call a radiographic diagnosis. We're looking for evidence of pulmonary edemia and, cardiomegaly.
So ideally we want to get orthogonal views, so a DV and a right lateral. But if you can only obtain one view, the best one certainly is the right lateral in dogs in particular for diagnosing congestive heart failure. One thing to point out is that we have to avoid general anaesthesia in these patients.
They are dyspneic or if we're suspecting they've got advanced cardiac disease, we do not want to anaesthetize them and . You know, affect, their, cardiovascular system with our drugs because we could, make things a lot, lot worse. So instead, if we are going to take radiographs, we want to do it in a very controlled fashion, in a very stress-free environment with oxygen supplementation.
And we want little or no chemical or physical restraint. So what I tend to do is often just simple, very minimal physical restraint with sandbags on the limbs if they will tolerate that. And if they won't, a little bit of butterphenol, as previously mentioned, can be useful in dogs or cats.
0.2 to 0.3 migs per gig IV or IM.
And if that's not quite enough, it's often very safe to top them up with some midazolam at 0.2 migs per gig, IV or IM cos both of those drugs really don't suppress your cardiovascular function, OK? So pulmonary edoema is spotted on radiographs because of the presence of alveolar interstitial or alveolar interstitial patterns.
And sometimes we can get a bit of an idea about whether it is cardiogenic pulmonary edoema based on its distribution. So in dogs we typically see that pulmonary edoema is perihya. So it's basically kind of above the heart, a point at that area, on the next film.
But in cats it's very, very varied, so we don't typically see perihylar pulmonary edoema in cats. It could just be pulmonary edoema that that's anywhere. Do bear in mind as well, when we're looking for cardiogaly, I've mentioned how useful cardiac ultrasound is, in both cats and dogs for, screening for cardiogaly.
With X-rays, it is really, really good in dogs, but not good in cats. And that's because dogs who have cardiomegaly tend to have eccentric carddiomegaly where their hearts get bigger and their cardiac silhouette increases in size, whereas a lot of cats, particularly those with hypertrophic cardiomyopathy, they have concentric. Hypertrophy, meaning the heart thickens, but it thickens inwards rather than outwards.
The actual silhouette of the cat's heart often doesn't increase much in size, even with advanced, heart disease. I highly, highly recommend when you're taking your X-rays and looking for evidence of cardiogaly that you perform the vertebral heart score, particularly in dogs, it is so robust and well, studied that you should definitely be doing it. I'll show you how I do that in the next slide.
And what I tend to use for reference ranges are below 9.7 plus minus 0.5 is normal for a dog, or, more simply, below 10.5.
And with cats, 7.5 plus minus 0.3.
Now do bear in mind that those are very sort of rough guidelines is what we class as a normal vertebral heart score. And depending on particularly the breed of the dog, you can get quite a variance in what is a normal vertebral heart score. So what I would say is, if at all possible, do a quick Google search and see if you can find a breed specific reference range for vertebral heart score to use.
You know, with your measurement, because certainly, cavaliers, for instance, even normal cavaliers without advanced, you know, cardiac disease, often have much larger hearts than you would expect, you know, and you can have cabbies that certainly have hearts, the normal hearts that are above, a vertebral heart score of 10.5. So here's a right lateral radiograph of the patients and we can actually see this sort of diffuse interstitial patterning, alveolar interstitial patterning through this lung field here consistent with pulmon edoema.
This is the perihila region round here where you most commonly see pulmonedema in dogs. There's not a huge amount in in this one in that area. But when we're talking about cardiogaly.
The two things that we're going to do is the vertebral heart score which I'll show you in a second, but also look at the position of the trachea. So the trachea itself should run and be divergent from these vertebral bodies. So, at about a 5 to 10 degree angle, the trachea sort of here should start to point downwards and be divergent from the spine, whereas here you can see it continues really running parallel with the spine.
So that's what we call tracheal elevation, and that would be consistent with cardiogaly. So for a vertebral heart score, we're gonna put one line from the Carina, which is this little black circle here, at the base of the heart, down to the apex, and then we're gonna bisect that at a 90 degree angle, from the front of the heart to the back of the heart at the level here where the caudal vena cava enters the heart, which is this structure here. We're gonna take those two lines and then we're gonna stick them up here next to the vertebral bodies, and we're gonna put them in line with T4, so the 4th thoracic vertebra, which is this one here, and we're then gonna count our number of vertebral spaces and for that first line, which is this one here, we've got 6.4.
We then take this line and put it here. And we count the number of vertebral bodies and we get 5.8.
So we add those together, and there's our vertebral heart score of 12.2. So that is significantly over what we would class as normal, being 10.5.
So that's highly consistent with cardiogaly, great. We pretty much have a diagnosis. Now in this patient, it's a patient with advanced mitral valve disease, and we know that those guys often get really quite significant enlargement of their left atrium.
We also see the same in DCM Dobermans as well, well, any DCM dog might I say. So we can actually look for the left atrium on this radiograph and here it is. So this is the left atrium, this large, bulge of soft tissue opacity here at the top and the back of the heart on the lateral view.
So that's a really big left atrium. What the left atrium should actually look like in a normal dog would be more like this line. So you almost.
With the back of the heart to have a nice gradual forward slope to the back of the heart. Whereas in this patient, they've got a very vertical and straight caudal border to their heart because of this really enlarged left atrium. So if you can spot that as well on your radiographs, that could be very useful for evidence of cartiogaly.
On the DV view, I think the best way really to look for cardiogaly is just to say, is the heart wider than 2/3 of the width of the chest cavity. So in this dog, we measure the width of the heart as the red line, the width of the thoracic cavity is the yellow line, and that red line is way over 2/3 the length of the yellow line. So again, highly consistent with cardiomegaly.
Brilliant, last couple of slides now, just on ECGs my sort of top tip would be, if you've got an ECG don't be afraid to use it. If you're happy to interpret them yourself, that's fantastic. If you're not, take recordings, send them to a cardiologist who can look at them for you.
I tend to recommend running ECGs in any patient that has got an abnormally high or an abnormally low heart rate, OK, because it increases the, the likelihood that they've got, an abnormal heart rhythm, OK. I would also recommend an ECG in any patient who's got an abnormal heart rhythm on auscultation, OK? And if you are performing ECGs in dysneic patients and you're seeing lots of abnormalities on those ECGs, again, that is going to reinforce your diagnosis of heart failure.
Even if you're not totally sure what those abnormalities are, you've then got time to treat the heart failure, pop that ECG over to a cardiologist for their opinion, you know, and the patient should, should do well. I tend to recommend just, performing a lead to ECG, a rhythm strip simply 30 seconds is, is more than enough, either on a paper printout or a continuous, monitoring readout on a multi-parameter, monitor. And, the most common cardiac, sort of rhythm changes that we see on our ECGs are sinus tachycardia, and ventricular ectopy such as VPCs, vent.
Premature complexes, accelerated, accelerated idioventricular rhythms or ventricular tachycardia, and we also quite frequently see, supraventricular ectopy as well. So supraventricular premature complexes, supraventricular tachycardia and atrial fibrillation. Fab.
So I think this is my last slide, and this is just on clinical pathology. So what kind of blood tests are we gonna do in these congestive heart failure patients? I think it's really useful at baseline, once these patients aren't, you know, overtly dyspneic, just get a PCV and total solids so that we can monitor their hydration.
Cause we're gonna hammer these guys with diuretics, and it's a good way to get a baseline on these patients and then be able to monitor their hydration status as well as, you know, physical examinations. Check their electrolytes. They may have already been on, a loop diuretic, or if they're not, you're definitely gonna put them on one, and that's gonna cause quite profound hypokalemia.
As well as hyponatremia and hypochloremia. So again, get your electrolytes at baseline, monitor them every 12 hours or so whilst that patient's in hospital, and, 7 days post discharge, and renal values as well, for a variety of reasons, you know, it allows us to also assess hydration status, we know, so should say renal values, not renal valves, hydration status. It can help us check for evidence of cardiorenal syndrome, so as the heart is failing, it can often affect, kidney function.
So I tend to monitor the renal values every 12 to 24 hours in hospital and again 7 days, post discharge to check for aotemia. So Ntiro BMP snaps, I'm sure a lot of people out there are using them or thinking about using them, so what's their sort of utility in these cases? Well, they're available for an IDEX, as a, an in-house test in cats, and NTro BMP is increased in patients with Cardiomegaly because of stretch of the heart.
So with this test, what it does is it looks for cardiomegaly. It doesn't test for cardiac disease, it doesn't test for congestive heart failure. It tests for cardiomegaly.
And when you test positive on an antiro BMP snap test, it means you're likely as a cat to have at least moderate if not marked cardiomegaly. OK? So if you've got a disknee cap.
Who's got a heart murmur or an irregular heart rhythm or a gallop sound, say it's got a low rectal temperature, everything's looking like heart failure, you might want to do an NT Pro BMP snap if you don't have point of care, thoracic ultrasound, and if that test is abnormal. In a dysneate cap with referable signs of cardiac disease, that is pretty robust diagnosis of congestive heart failure. The test is not 100% sensitive or specific, so you can get false positives and false negatives, but it is a very useful test for differentiating heart from respiratory causes of dyspnea in cats, .
I briefly put in here quantitative anti-Pro BMPs of debatable use, simply because, you know, you have to send it out. It takes a while for it to come back and there is no cutoff that says this patient is in heart failure or this patient is not. It gives you an idea about cardiogaly.
It gives you an Idea about the likelihood, perhaps of, of congestive failure being present, but it doesn't give you a diagnosis. And I think often by the time you've got the results of this, antipro BMP back, you've already taken X-rays, done a cardiac ultrasound, and you're well on the way to treating the heart failure, so it's of much less use. And finally, troponin, I generally don't recommend you guys use it that often in primary care practise, cause, it, it can't be used to make a diagnosis of congestive heart failure or to screen for cardiac disease, but we do use it, as cardiologists to, to, to screen for certain, diseases such as myocarditis in dogs, and we can use it to help prognosticate the outcome, in our cats with heart failure.
Fab. So I hope people have found that informative and you have a few useful hints and tips that you can take with you into primary care practise, to hopefully allow you to make a rapid and reliable diagnosis of congestive heart failure in your cats and dogs. Thank you very much for listening and all the very best.
