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Systolic murmurs, diastolic murmurs, and extra heart sounds - Part 1

Video transcript

- [Voiceover] Go ahead and put on your headphones for a second, because I really want you to get the full effect of these murmurs. Here you go. (thump-bump, thump-bump, thump-bump, thump-bump, thump-bump, thump-bump) (whoosh, whoosh, whoosh, whoosh, whoosh, whoosh) (whoosh-bump, whoosh-bump, whoosh-bump, whoosh-bump, whoosh-bump, whoosh-bump, whoosh-bump, whoosh-bump, whoosh-bump, whoosh-bump) (thump-thump, thump-thump, thump-thump, thump-thump, thump-thump, thump-thump, thump-thump, thump-thump) (whoosh-ba-whoosh, whoosh-ba-whoosh, whoosh-ba-whoosh, whoosh-ba-whoosh, whoosh-ba-whoosh) (bump-bump, bump-bump, bump-bump, bump-bump, bump-bump, bump-bump) (ba-da-dump, ba-da-dump, ba-da-dump, ba-da-dump, ba-da-dump) That was pretty much a whirlwind of five pretty common murmurs, and some extra heart sounds. If that really confused you, that's okay. We're going to got through all the mechanisms of these murmurs, and I'm going to have you understanding it in no time. As a quick review, we have S1 and S2. I'm going to write S1 over here again, because remember this is a cycle. In between S1 and S2 we have systole, and between S2 and S1 we have diastole. If you remember, the S1 and the S2 are actually caused by closing of the valves, for S1 specifically the closing of the mitral and the tricuspid, for S2 specifically, the closing of the aortic and pulmonic valves. These are all abbreviated here. Murmurs can occur between S1 and S2, and these would be systolic murmurs. These would be things like aortic stenosis or pulmonic stenosis, mitral regurgitation or tricuspid regurgitation. One other thing that doesn't necessarily cause a murmur, but can be accompanied by mitral regurgitation, would be something like mitral valve prolapse. The ones that we're going to talk about today are going to be the left-sided valvular conditions, so the aortic stenosis and the mitral regurgitation, as well as the mitral valve prolapse. I just realized that I made that "prolape" and so we're going to fix that. Now for diastolic murmurs meaning they occur between S2 and S1, these are going to be aortic regurgitation or pulmonic regurgitation, and mitral stenosis and tricuspid stenosis. Remember, the only way that I'm arriving at these names and when these murmurs occur is based on which valves should be open or which valves should be closed during systole and diastole. The ones that we're really going to discuss here are going to be aortic regurgitation and mitral stenosis. Again, you'll notice these are the left-sided valves. We're doing this because the left-sided valve problems are generally much more common than the right-sided valve problems. Now that we've kind of categorized these into systolic or diastolic murmurs, two questions that are going to become important are where do you hear the murmur most loudly, and what's the shape of the murmur? We're going to explain these as we go through each murmur. Since location is a pretty big concept, I want to go over the four places that we auscultate, or listen with our stethoscope. One of them is here, you'll see I'm coloring this in. This is in the second space in between ribs, also known as the second intercostal space, and this is the aortic area. This is also called the right upper sternal border. On the other side, in the same intercostal space, or space in between ribs, we have the pulmonic area. This is also called the left upper sternal border. Then, in the fourth intercostal space, we have the tricuspid area, and finally, in the fifth intercostal space, but in what's called the midclavicular line, meaning if you drew a line in the middle of the clavicle all the way down, it would intersect with this point in the fifth intercostal space. This is the mitral area. The mitral area is also called the apex. The reason why we listen in these different positions, is because we're actually listening where the blood is expected to travel as it goes through the valve in question. Let's talk about aortic stenosis. What I'm going to do is I'm going to take you through the progression of this murmur from S1 to S2 in terms of what's actually happening with the valve and with the heart muscle contracting. So, we're going to start off with S1. If you remember, S1 is the closing of this mitral valve. Let's say that this is closed. That closing is going to cause what we hear as S1. When that closes, the heart actually begins to contract, but it's contracting against a closed aortic valve. So this valve at this point is closed. That's the reason that an aortic stenosis murmur actually doesn't start with S1. There's actually a small time period, small meaning like milliseconds, in between the closing of the mitral valve and when the aortic valve actually opens, and remember, what gives us that murmur is turbulent flow through the aortic valve. When the heart starts contracting and builds up enough pressure to open up this valve, the leaflets of the valve will kind of accelerate upwards, and when they finally pop open, remember they're not opening all the way because the valve, for some reason, is stenotic, then this will first give you what's called an ejection sound, or an ejection click, and that's here, and we're going to label that EC for ejection click. That's caused by these valve leaflets moving up really quick, and then stopping really quick and shooting open. So when the valve first opens, you're going to get a little bit of blood flow through this valve. As the heart continues to contract more and more, as shown by these arrows, squeezing out more and more and more forcefully, you get more and more flow. Then eventually, as the heart starts to relax a little bit, and we're going to now get rid of these arrows, you're going to get less and less flow. So the way that this murmur actually looks, the shape of the murmur, is that, like we said, as it contracts more forcefully, you get more and more flow, and the murmur becomes more and more intense, and then as the ventricle starts relaxing, it becomes less and less intense. So we call this a crescendo-decrescendo murmur, and you'll also hear people call this or refer to this as a diamond-shaped murmur. You can kind of see that around here if you were to outline this. Aortic stenosis is called a systolic ejection murmur. That makes sense because you're ejecting blood out of the aorta, and it can often have an ejection click, and it's usually heard most loudly at the aortic area. The last thing I want to tell you about this is that commonly this murmur can actually radiate to the neck or the carotids. The reason for that is that this murmur is occurring in the aorta. If you remember, some of the first branches off of the aorta are actually the carotid arteries, and so you can hear the murmurs resonating up through the carotid arteries in the neck. A quick note, and you'll notice this for all the other murmurs that we go through, pulmonic stenosis, which is really just the same thing as aortic stenosis but on the other side of the heart, the right side, is virtually the same murmur. It's a systolic ejection murmur, crescendo-decrescendo, and you can have an ejection click, but this one's not going to radiate to the neck or the carotids. Instead of being heard in the aortic area, it's normally heard in the pulmonic area. The next murmur that I want to talk about is mitral regurgitation. Remember, we're still on systolic murmurs. Mitral regurgitation is going to be best heard in the mitral area, or apex. This murmur is actually what we call a holosystolic or a pansystolic murmur. All that means is that it lasts throughout the entirety of systole. Let's start at S1. In a normal heart, S1 is caused by the closing of the mitral valve. That closing occurs because the pressure in the ventricle, this P here, is greater than the pressure in the atrium, this small p here. Normally, this valve would close and that would give you your S1. In addition, you have your closed aortic valve here. But instead of closing, remember we're talking about mitral regurgitation, so this is a closing problem. As the pressure starts to build in this left ventricle, but still with the aortic valve closed, blood is actually getting through this valve, so that's going to cause a murmur right when S1 occurs, so right as that valve tries to close it doesn't close fully, and because the pressure's higher in the left ventricle than the left atrium, you actually start that murmur right at S1. As soon as the heart begins to eject blood, this aortic valve opens right up, and blood comes out this way. Because the pressure remains higher in this ventricle than the atrium the whole time, you actually get flow through this regurgitant valve throughout the entire cycle. You would think naturally that as the heart contracts harder that maybe this pressure would become bigger, and the truth is that the pressure actually does become bigger, but in chronic mitral regurgitation, which is what we're talking about, the atrium actually gets bigger, or dilates. By doing this, it becomes more compliant. What that means is that it can accept the blood that's coming back into it at a lower pressure, so it can accept more volume at a lower pressure. As a result, that pressure in the atrium does not go up so much. But because the pressure difference between the left ventricle, which is really high ... remember, that's the workforce of the body ... and the left atrium, which is pretty low, because it's just receiving blood from the lungs, which is a low-pressure system, the jets of blood that actually come through here make a sound that, to our ears, doesn't change in intensity, and it occurs all the way until the second heart sound, when this aortic valve closes. At that point in time, a millisecond or so later, the mitral valve will open again and start a new diastolic cycle. So as I've written here, we actually call this a holo- or pansystolic murmur. In addition, it's also referred to as a flat murmur, because the intensity does not change. This murmur will actually radiate to the axilla. If you picture this valve, kind of sitting in this general area somewhere, when blood flow goes back the other way, it's going to kind of be forced in the direction of this guy's armpit over here. Again, just to mention the right-sided valve problem, tricuspid regurgitation, you have the same murmur, a holosystolic, flat murmur, but in that case, you would hear it in the tricuspid area. That murmur wouldn't radiate to the axilla because the valve is in a different position.