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So talking about heart sounds, the way I like to think about it is the heart is a drum. It's basically a drum beating away inside of the chest that actually produces sounds that reverberate within that chest cavity that we can then auscultate using the stethoscope. There are various anatomical landmarks that we can actually auscultate to listen to different parts of the heart, but it's always important to remember that the heart is a drum. So also along the same lines, talking about heart sounds, it's very, very important that you not only know the cardiac anatomy, but that you also know the way in which blood flows throughout the cardiac system. Be sure to reference our cardiac anatomy video should you be a little bit fuzzy on this topic and need some clarity. But it's super important to know this because blood is passing between these various chambers through these valves. And why is it important? It's because what we're actually auscultating in patients, whenever we're hearing lub-dub in these various anatomical regions, we're actually hearing valve closure. Make sure you go brush up on cardiac anatomy and the way the blood flows through the heart before proceeding. But let's go ahead and dive into these anatomical locations and how we're going to listen for heart sounds.
So, as far as the assessment goes in the auscultation of these various anatomical landmarks, there's a few things that it's important to keep in mind first. The first is the acronym that we actually use is ape to man, A P E T M, ape to man. It's the way in which we're going to actually remember the different valve closures that we're listening for whenever we listen. So we know that there are four valves, right: aortic, pulmonic, Erbs kind of gets thrown in there, but then we also have the tricuspid as well as the mitral. Now these are the various valves that we're actually going to be listening for whenever we're listening to cardiac sounds. And something else that's important to keep in mind, you will know if you've listened to heart sounds we hear lub-dub, right? Lub-dub is what we hear, but what does lub-dub actually reflect ? It reflects S1 and S2, which you may remember is reflective of ventricular contraction during S1 and then relaxation during S2. So, whenever you're listening and you hear lub-dub, lub-dub, lub-dub, you should be thinking S1-S2, S1-S2, or contract-relax, contract-relax.
It's important to know this because whenever we're listening for the various valvular closures, we should be hearing them during either contraction or relaxation. For instance, the aortic valve from cardiac anatomy class, the way the blood flows through the aortic valve closes during diastole, during S2, ventricular relaxation. And it opens whenever that left ventricle ejects blood out to the rest of the body. So we should hear the aortic valve, we should hear it, during S2, during diastole. That's only going to be important whenever we're actually trying to figure out murmurs, which we'll get to here momentarily.
So what are the actual anatomical locations that we're going to use to listen for these various sounds? Our aortic valve being our first one. It's going to be on our right sternal border. Remember this, here is the right side and this is the left side. So our right sternal border and our second intercostal space. Intercostal being the space in between the ribs. So, first intercostal space, second intercostal space right here on the right sternal border. That's where we're going to hear our aortic valve. So we're going to say right sternal border, second intercostal space. How about that?
Now for our pulmonic valve, we're just going to jump over the sternum. It is going to be our left sternal border on that second intercostal space. That's where we're going to hear our pulmonic valve closure. So we'll say left sternal border, second intercostal space. Now moving on to Erb's point, we'll move down just one intercostal space. So that left sternal border still, but it is now our third intercostal space. Tricuspid valve, we're going to move down further one additional intercostal space. So this is going to be auscultation on our left, sternal border and our fourth intercostal space, a left sternal border fourth intercostal space.
You might also be thinking why the heck are we listening to our aortic valve up here or our tricuspid valve down here when anatomically speaking, that's not where these valves are located? Remember, the heart is a drum and as it beats away, it reverberates, it echoes these sounds throughout that chest cavity. So where you're anatomically placing your stethoscope, doesn't always correlate anatomically with the actual location of the valve. Nonetheless, finally, the mitral valve, we're going to move to our left sternal border, sorry, not our left sternal border, but, the left midclavicular line right here. Midclavicular line going down to the fifth intercostal space. That's where we're going to actually auscultate the mitral valve. And it should also land basically right on the apex of the heart. So we're going to say, midclavicular (I can't spell I'm so sorry), midclavicular fifth intercostal space is where we're going to be able to hear the mitral valve.
So without further ado, let's dive in a bit to the murmurs and then wrap this up. So also I'd like to touch on murmurs briefly. First thing that we need to know is what is a murmur? A murmur is basically an adventitious heart sound, instead of hearing the nice lub-dub that we would hear during S1 and S2. Instead, we're going to hear a whooshing sound either during S1 or during S2. But what is a murmur reflective of? A murmur is reflective of either a stiff and stenotic heart valve that's making it difficult for blood to be pumped through that narrow stiff valve, or it's reflective of a regurgitant and leaky valve. Instead of blood being pumped forward. like it's supposed to, you have a leaky regurgitant valve, which allows blood to be leaking backwards into the chamber from which the blood came. We differentiate these into S1 and S2 murmurs. So instead of lub-dub, lub-dub for an S1 murmur, we would hear whoosh-dub or for an S2 murmur, we would hear lub-whoosh. Again, whether it's the stenotic or regurgitant, we're going to be hearing a whooshing sound. And so then it begs the question - how do we determine if what we're hearing is due to a stenotic valve or due to a regurgitant valve? Well, let's use the aortic valve as an example, right? We know that the aortic valve is located here on the right sternal border, second intercostal space. So let's say we're listening for our aortic valve over the proper anatomical location. This is why it's important to know the cardiac anatomy and the blood flow. What is the aortic valve supposed to be doing? Right? When does it close? We're listening for valvular closure. So when is the valve supposed to be closing?
As we previously mentioned, the aortic valve closes during diastole, whenever the heart is at rest and filling with blood. So we should hear lub-dub, lub-dub. No problem. We know that the aortic valve is closing during diastole. So during diastole is when we're supposed to be able to hear this aortic valve. So what if, for instance, instead of lub-dub, we heard lub-whoosh. Well, we know that that would be an S2 murmur cause we're hearing woosh during the S2 spot. And we know that the valve, the aortic valve, is supposed to be closing during S2. So if instead, we're actually hearing lub-whoosh, well, when that valve is supposed to be closing, it's actually not, it's still loose. It's leaky. It's regurgitant. So instead of lub-dub the closing of that valve, we're hearing lub-woosh, and that is a leaky valve.
On the other hand, if we heard, instead of lub-dub, we heard woosh-dub over top of the aortic valve. Well, we know that during systole that aortic valve is opening to allow blood to be ejected from that left ventricle up into the aorta. If, instead of lub-dub, we're hearing woosh-dub, or the reason why we're hearing that whoosh we're hearing that S1 murmur is because that valve is supposed to be open, but it's more stiff. It’s more narrow. And as blood gets ejected out of that left ventricle during S1, instead of lub, we're hearing that whooshing sound and that's due to a stenotic valve.
And so to summarize our heart sounds video here, let's remember that the heart is a drum. It's beating within that chest, reverberating sound within that chest that can then be auscultated using a stethoscope. Remember S1-S2, lub-dub, contract-relax, systole-diastole. All of these are interchangeable, but what we're hearing whenever we auscultate dub we're hearing and listening for the closure of these valves. Also understanding the anatomical landmarks that we went over using the acronym, A P E T M also known as ape to man: aortic, pulmonic, Erbs, tricuspid, and mitral. Also being able to identify some of the murmur types, knowing that murmurs are caused by either stenotic or regurgitant valves and the way in which we're able to classify them between S1 and S2 murmurs. We have to know what the valve is supposed to be doing. When is that valve supposed to be closing? And if we know that and we're able to identify whether we're dealing with a stenotic or a regurgitant valve.
Guys, I know that was a lot of information. I really hope that that helped bring some clarity to your assessment skills and whenever you're listening and auscultating for heart sounds. I hope that you guys have a great day. Be sure to check out some of the other references and resources that we have down below. Go out there and be your best selves guys. And as always, happy nursing.
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