Welcome to Dr. Warrick's podcast channel. Warrick is a practicing cardiologist and author with a passion for improving care by helping patients understand their heart health through education. Warrick believes educated patients get the best health care. Discover and understand the latest approaches and technology in heart care and how this might apply to you or someone you love. Hi, my name's Dr Warrick Bishop and welcome to my videocast and podcast channel and of course welcome to the Healthy Heart Network. Today I'd like to talk a little bit about the specific tests that we tend to use when we try to evaluate cardiac failure. In a previous session I will have talked about history and examination and some of the basic tests. But let's drill down in a little bit more detail on some of the more specific tests that we would be looking to use to try and evaluate exactly what's going on with someone's heart if we really believe that cardiac failure is a problem. Well, probably the single most important go-to test is an ultrasound of the heart. Ultrasound of the heart is a test that we also call echocardiography. Echo pertaining to sound, cardio pertaining to heart,ography pertaining to picture. So we reach for an echocardiogram as soon as we can. An echocardiogram is a fantastic... real-time dynamic study that literally looks at how the heart beats with each beat. It gives us an opportunity to look at how the muscle is contracting. It looks at the right side, left side, the atria and the ventricles. We can evaluate each of these chambers. As they work together, we can measure them independently. We can compare sizes. we can assess their function, we can measure how much the left ventricle, the main pumping channel of the heart, is expelling with each beat. The amount of blood as a percentage of the total volume of the left ventricle expelled is the ejection fraction. And that number is a very important figure for us to start to get a handle on what's going on within that individual. Our echocardiogram also gives us an idea as to how well the heart is relaxing. So if the heart function in contraction looks normal, we can also ascertain if there are problems with the heart functioning relaxation. So the echocardiogram starts to help us understand not only the contraction of the heart and whether there's problems, but also the relaxation of the heart. If there are problems with contraction of the heart, then the echocardiogram can tell us, is that globally, i.e. is all the heart affected equally? Or are we dealing with a process where one area of the heart is not working properly compared to other areas? We would call that a regional abnormality. This information becomes really important as commonly a regional abnormality may be associated... with a blocked blood vessel which has given rise to a myocardial infarction or if you like a heart attack which is a colloquial term in that area. Mainly meaning that there's an area of scar tissue because that bit of muscle basically was starved of blood and died. Our echocardiogram is also really valuable for looking at the valves and it can do an assessment of each of the valves and we can physically look at them and see how they're working. We can use flow over the valves and ascertain pressures within the heart and pressures over the valves as well. There are equations that relate velocity to pressure and by using velocity assessment We can then start to calculate pressures within the heart and this information becomes vital in trying to understand exactly what's going on. The echocardiogram is an invaluable tool that has completely revolutionized the way we're able to deal with cardiac failure and guide therapy. Once we have that information, if we do know that the patient is in cardiac failure, then we can start to make plans. There are other tests, of course, that are available, and one of them, which is an interesting test, which allows us some certainty in situations where we think that the heart may be the problem, but we're not exactly sure, is a test called brain natriuretic peptide, also known as B-type natriuretic. Now, whether it's called brain natriuretic peptide or B-type natriuretic peptide, the abbreviation is the same, BNP. So we can write BNP on our pathology forms and know that we'll get this result back. Now, a BNP, or a brain natriuretic peptide, is a substance released by the heart cells when they are under strain. So if the heart is working well and a patient is short of breath, then a brain natriotic peptide level will be normal. If the patient presents short of breath, we think the echo shows that there may be a problem with the heart, but we're not 100% sure at this stage, and we check the brain natriotic level and it's through the roof, then this patient has some sort of strain going on within their heart. and it's our job to find out more and understand more about exactly what's going on. The brain natriuretic peptide can be a really useful discriminator to help us clarify, is there clearly problems with the heart here, or may this shortness of breath or these symptoms be related to something other than the heart? It's a valuable test in that regard. It can also be a really valuable test. In the longer term, when we're following patients who have a valve abnormality, particularly if that valve abnormality over time may lead to more and more strain on the heart, there is the opportunity to check the brain natretic peptide on a regular basis as we check the heart with an ultrasound to assess the function of a failing or problem valve. echocardiogram shows the valve is getting worse and the brain natriuretic peptide increases then everything is in synergy and we can be pretty sure that things are worsening for that individual. If the echocardiogram looks unchanged but the brain natriuretic peptide leaps up then that's quite possible that the heart is under more strain than represented by the echocardiogram alone and we may look more closely at that patient to try and understand. if there really has been a deterioration that our echocardiogram has just not picked up. Conversely, the echocardiogram may show or suggest changes where the valve that we're tracking is suggested to be worsening, but if the brain matriotic peptide has not changed at all, that may just invite us to look a bit more closely and check again our echocardiogram and make sure everything is matching up. So that's brain or B-type natriuretic peptide. There are, of course, other tests that can come into play for cardiac failure. There are tests related to evaluation of blood flow to the heart. We certainly, if we see someone whose heart function is diminished... want to know what the artery status is like so we will investigate for coronary artery disease or ischemia which means lack of blood flow or infarction which means damage death to the tissue through lack of blood evaluation for ischemia might include things like treadmill testing depending on how fit the patient is or able is it may include ct imaging of the heart to evaluate the arteries in a non-invasive way or it may include invasive coronary angiography where a catheter is passed literally into the heart arteries to obtain a picture. Whatever we do, we do need to be clear if coronary artery disease is contributory to an individual's cardiac function because in many situations we are able to do something about that. One of the other tests which we are using more and more is magnetic resonance imaging or MRI imaging. When we consider the heart, we call this cardiac magnetic resonance or CMR. This is an exquisite test which gives us beautiful images. It's incredibly valuable for showing us scar within the heart. and inflammation within the heart so if we're dealing with someone whose left ventricle their main pumping chamber is not working properly and we want to know what is going on within the muscles and within the connective tissue a cardiac MRI scan can be incredibly valuable it can show us inflammation it can show us integrity of the cells It can show us scar tissue. Scar and inflammation become very important in trying to understand our future management for individuals with cardiac failure, as you might imagine. Very occasionally there may be situations where we think that there is something going on within the muscle and within the connective tissue. holding the muscle cells together. There might be an infiltration of a particular protein, which we think could be detrimental to how the heart may be able to relax. So occasionally, if we haven't got all the answers or all the information we need from the tests I've already talked about, we go to biopsying the heart. This is pretty significant. It's not done everywhere. Certainly not a routine test. but occasionally we just need to get a little bit of muscle tissue and put it under a microscope so we can see exactly what's going on at a cellular level. I'm going to wrap that up there. I've talked about some of the most cardiac-specific tests. I've talked about echocardiography, which is really our go-to test when we suspect cardiac failure. I've talked about the brain metritic peptide, which is a great discriminator, telling us if the heart is under strain or not. I've talked about trying to investigate for ischemia or lack of blood flow to the heart, looking for coronary artery disease. I've covered that in other presentations, of course, but it is important to be aware that we could use functional testing, like a stress test. We could use CT imaging of the heart which is a really nice non-invasive way to see if the arteries are okay and sometimes it'll be indicated for us to use an invasive coronary angiogram where we literally squirt to die down the arteries. I've also talked about cardiac magnetic resonance imaging or MRI or cardiac MR. This is a great test for showing the scar and inflammation. It also shows us function superbly well and it also shows us valve function very, very well. It gives us beautiful information on regurgitation or leaking of valves and narrowing of valves. Last day I spoke about biopsy. Well, if after all those things we don't know what's going on, then we're in a bit of a corner. So hopefully I've covered everything that's important about the cardiac-specific investigations we would be thinking about in someone who appears to have a problem with their heart and appears to have cardiac failure. I hope I've explained some bits and pieces that make some sense to you. If you have any queries or questions, as always, please let us know. If you have any ideas for our future podcasts, please also let us know. As always, I'd like to wish you the very best. Take care and bye for now. You have been listening to another podcast from Dr. Warrick. Visit his website at drWarrickbishop.com for the latest news on heart disease. If you love this podcast, feel free to leave us a review.
