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Video transcript

- [Voiceover] So the last systolic murmur or sound that I want to talk to you about is mitral valve prolapse. And this is pretty much exactly what it sounds like. The valve actually prolapses or billows into the left atrium, and so this causes a click. And so this is a click that's kinda similar to the one that we talked about in aortic stenosis, which was an ejection click, but this is a click that's not associated with ejection of blood through a valve. And so this is really a non-ejection click, and it's also not right at the beginning of systole. It's actually a mid- or mid-to-late systolic click. And so you'll see I've labeled that for you there. And what causes that is as the left ventricle begins to contract-- Remember this would make the mitral valve close to cause S1, so the valve closes normally, not like what's shown in this picture, closes and causes your S1. And then as the pressure builds, this valve will actually accelerate into the left atrium, and when it stops abruptly because it's held by, or should be held by, these corday tendonay here, then there's this rapid tensing of either the corday or that leaflet and that causes this little click. Now this condition is also associated with mitral regurgitation, and so you can imagine if this valve kind of billows up here, there's probably some problems closing, and maybe it doesn't close completely correctly, and so you can get blood flow in here. And if that's the case, then after the click, you're gonna have the murmur of mitral regurgitation. And so you'll get this. And so I want to make a point here. I've seen some textbooks that show that this is a flat murmur, and others that say that it's a crescendo murmur. For our purposes here, we're not going to dwell too much on the shape of the murmur following the click, but what's important is the click itself because the click, a mid-systolic click, is virtually diagnostic for mitral valve prolapse. So overall this is described as a mid-systolic click with a late-systolic murmur. And this, like mitral regurgitation, is heard best at the apex or the mitral area. So now that we're done with systolic murmurs, let's move on to the diastolic murmurs. So now that we're going to talk about diastolic murmurs, I'm gonna switch my pen color here to green, and we're gonna move on to the first diastolic murmur, and that's gonna be aortic regurgitation. And so we know that this means that blood is going to be coming back through the aortic valve when it's supposed to be closed. And so for aortic regurgitation, this is a little counterintuitive because you would think maybe that aortic would go to the aortic area, but because this blood is coming back this way, we're actually going to listen for this kind of in this area. And so this wasn't really one of our defined areas but we're basically going to say along the left sternal border, meaning on the left side of the sternum. And the reason is because the blood's flowing the other way so why would you listen in the normal aortic area when the blood's gonna be traveling the other direction? And so this time because we're talking about diastolic murmurs, these murmurs are actually gonna occur between S2 and S1. And so let's talk about about S2 for a second. S2 is actually gonna be caused by the closing of the aortic valve, and then soon after that, the mitral valve will actually be open. And then the heart's in diastole, meaning it's filling with blood. But because this is aortic regurgitation, that means there's a closing problem with this aortic valve. And so blood, right when this tries to close because the pressure will actually be greater here than here. Right at S2 blood is going to be coming through here. But blood is also filling the ventricle from the atrium, and so the pressure, this little p, is actually gonna start to get a little bit bigger. And so at the beginning when the pressure is still little a bunch of this blood is gonna come back through the aorta. And so you get this very intense part of the murmur that I've drawn. And as that pressure gets a little bit bigger in the ventricle, then this is gonna kinda diminish. And so this is the shape that you actually get with aortic regurgitation. And this is called an early diastolic murmur. It's happening in the beginning of diastole. And its shape is decrescendo. And just to mention the right-sided condition, a pulmonic regurgitation, would be the same type of murmur, an early diastolic decrescendo murmur, but this time it would actually be heard along the upper left side of the sternum, whereas this one was kind of generally just along the left side of the sternum. So the last murmur that I want to talk to you about is mitral stenosis. So now that mitral valve is having trouble opening, and because the mitral valve is open during diastole, this is also a diastolic murmur. So if we start at S2 again. Remember that's the closing of the aortic valve. And that would be here. What happens just milliseconds after that is that the mitral valve should open, and it does this to fill up the ventricle in diastole. And so instead of a nice, big opening, we kinda get this tiny, little opening that we're gonna show like this. And so in the beginning of diastole, you actually have the most blood coming from the left atrium through to the left ventricle. And this is known as rapid filling. So the ventricle actually fills up with more blood in the beginning of diastole than it does at the end. And that's due to a pressure difference, meaning throughout diastole the beginning of it is where that pressure difference between the atrium up here and the venticle down here, it's when that pressure difference is actually the highest, at the beginning portion of diastole. And so at the beginning portion, you're gonna have the most intense part of that murmur. But before that happens we have to talk about this extra sound that we may hear. And so right after the aortic valve closes, the mitral valve is gonna open, but because this valve is stenotic, when it's about to open the leaflets can only just open a little bit and they kind of snap open. And so this is an opening snap. And this kinda similar to an ejection click in the systolic murmurs. But in diastole this is called an opening snap. And it's from these stenotic valve leaflets shooting open during the rapid filling phase of diastole. And so what you get is just milliseconds after S2, you get an opening snap OS, and then like I said, because the pressure difference is greatest during this rapid filling time, you actually have the highest intensity of the murmur here. And then it starts to slow down as the pressures become a little more equal. And then finally what happens at the end of diastole is that the atrium actually gives a little contraction to push any leftover blood into the left ventricle. And so we're gonna show that like this. And it's gonna push any leftover blood into the ventricle. And that's going to give you this little up slope, like this little extra kick at the end. And so this is called pre-systolic, right before systole, accentuation, which is really just a fancy word for getting bigger. Pre-systolic accentuation. And so this murmur is heard in the mitral area or again, like some people like to call it, the apex or apical area. And so the way people describe this murmur is actually an opening snap followed by a mid-diastolic rumble. And people say this sounds like a rumbling sound, and it's also kinda because that murmur is a weird shape. You see how it kinda goes down and then comes back up. And so they say an opening snap followed by a mid-diastolic rumble. And just to mention the right-sided valve condition, tricuspid stenosis, this would produce the same murmur, an opening snap followed by a mid-diastolic rumble, but instead you would hear this in the tricuspid area. And so the last thing that I want to talk about are extra heart sounds. And so whether you've realized it or not, we've actually covered two types of extra heart sounds already. One of them being the click. And remember this can be an ejection click or a non-ejection click. The ejection one being associated with aortic stenosis, and the non-ejection one being a little bit later in systole and being associated with mitral valve prolapse. The other extra heart sound that we've covered is the opening snap. And remember that's associated with mitral stenosis. The other two really important extra heart sounds that we're going to talk about are what are called S3 and S4. And so you'll realize that we have S1 here, S2 here, so these are the next two heart sounds. But generally when these are present, it's not a good thing. So S3 and S4 are really not murmurs. They're just another sound. It almost sounds like another S1 but just in a different location. Or another S2 and in a different location. And so these are actually heard best in the mitral or apex position here, but specifically if you have the patient lie in what's called the left lateral. We're going to abbreviate that lat. decubitus position. Decubitus. And all that really means is that the patient rolls over to their left side, and the physician or the nurse, or whoever's taking care of you, will listen with their stethoscope in the mitral position. And the reason for this is just that it brings the heart closer in position to where the actual stethoscope is gonna be. When you roll over, your heart will shift a little bit, and actually come closer to the rib cage. So what causes this S3 and S4? Well, S3 is classically a volume overload condition. And so you hear this in early diastole, so around here. And this occurs during the rapid filling phase during diastole that we talked about before. And so in this rapid phase, if you have too much blood, too much volume, this ventricle's gonna fill up really quickly. And what happens is you get a tensing of these strings, or these corday tendonay here. And that tensing actually causes the S3 sound. So quickly again, it happens in the rapid filling phase of diastole due to the tensing of the corday tendonay when all that volume fills up the left ventricle. And so in kids or adolescents, and we'll kinda just write young here, an S3 can actually be present. But that's usually normal. And this kinda just means that the heart is capable of taking extra volume and expanding. And you'll still hear that sound, but it's a normal condition. But in a middle-aged or old person, or that's not very nice, an elderly person, this is usually a bad thing. And it's usually due to heart disease, something like congestive heart failure, where they have too much volume coming into that ventricle and you get an S3. And there are many other conditions that can cause an S3, but for our purposes let's just know that it's related to volume overload. So S4 is a pressure overload problem. And what happens is when the heart has to contract against increased pressure, so let's kinda just say that maybe there's increased pressure here, greater than the normal amount. So let's say maybe in a case of high blood pressure. The heart is contracting against this increased pressure, and over time the heart is going to actually hypertrophy or increase in size. But this is actually called concentric hypertrophy, meaning the muscle increases in size, but inward. And so it actually makes this ventricle really stiff. And so the S4 sound is what you hear when the atrium, remember that the atrium at the end of diastole contracts to get that last little bit of blood out. And so the S4 is what you hear when the atrium contracts into a very stiff ventricle. And so this sound occurs at the end of diastole just before the next cycle of systole is gonna take place. And I'm not sure if we mentioned this, but S4 is also heard in the mitral area, and best heard in the left lateral decubitus postion. And so if you'll notice both of these sounds are in diastole, just different parts of diastole. And so other common names that I should probably tell you so that when you hear them you're not confused are that people call S3 a ventricular gallop. Remember this is a large volume of blood coming in and tensing those corday in the ventricles. And people call S4 an atrial gallop. And that's because this sound is really caused by this atrium contracting into the stiff ventricle. And so the S4 is always pathological, meaning it's always bad news. And so I'm gonna run you through that original montage of heart sounds and murmurs, and let's see if you can figure it out. I'm gonna put up a label of which murmur it actually is towards the end of each individual murmur. (pulsing heartbeat) (pulsing heartbeat) (pulsing heartbeat) (pulsing heartbeat) (pulsing heartbeat) (pulsing heartbeat) (pulsing heartbeat)