- [voiceover] go aheadand 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 gotthrough all the mechanisms of these murmurs, andi'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 byclosing of the valves, for s1 specifically theclosing of the mitral and the tricuspid, for s2 specifically, theclosing 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 ortricuspid 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'regoing to talk about today are going to be the left-sidedvalvular conditions, so the aortic stenosis andthe 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 stenosisand tricuspid stenosis. remember, the only way that i'm arriving at these names and whenthese 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 reallygoing to discuss here
are going to be aortic regurgitation and mitral stenosis. again, you'll notice theseare the left-sided valves. we're doing this because the left-sided valve problems aregenerally 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 goingto become important are
where do you hear the murmur most loudly, and what's the shape of the murmur? we're going to explain theseas we go through each murmur. since location is a pretty big concept, i want to go over the four places that we auscultate, orlisten with our stethoscope. one of them is here, you'll see i'm coloring this in. this is in the secondspace in between ribs,
also known as the secondintercostal space, and this is the aortic area. this is also called theright upper sternal border. on the other side, in thesame intercostal space, or space in between ribs,we have the pulmonic area. this is also called theleft upper sternal border. then, in the fourth intercostal space, we have the tricuspid area, and finally, in thefifth intercostal space,
but in what's calledthe 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 inthese 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 isi'm going to take you through the progression of this murmur from s1 to s2 in terms ofwhat's actually happening with the valve and with theheart muscle contracting. so, we're going to start off with s1. if you remember, s1 is theclosing of this mitral valve.
let's say that this is closed. that closing is going tocause 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 thatan 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 flowthrough the aortic valve. when the heart starts contracting and builds up enough pressureto open up this valve, the leaflets of the valvewill kind of accelerate upwards, and when they finally pop open,
remember they're not opening all the way because the valve, forsome 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'regoing to label that ec for ejection click. that's caused by these valve leaflets moving up really quick, andthen stopping really quick
and shooting open. so when the valve first opens, you're going to get alittle bit of blood flow through this valve. as the heart continues tocontract more and more, as shown by these arrows, squeezing out more andmore and more forcefully, you get more and more flow. then eventually, as the heartstarts to relax a little bit,
and we're going to nowget rid of these arrows, you're going to get less and less flow. so the way that thismurmur 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 becomesmore 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 alsohear people call this or refer to this as adiamond-shaped murmur. you can kind of see that around here if you were to outline this. aortic stenosis is calleda systolic ejection murmur. that makes sense becauseyou'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 wantto 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, someof the first branches off of the aorta are actuallythe carotid arteries, and so you can hear the murmurs resonating
up through the carotidarteries in the neck. a quick note, and you'll notice this for all the other murmursthat we go through, pulmonic stenosis, which is really just the same thing as aortic stenosis but on the other side ofthe 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 theneck 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 isgoing 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, s1is caused by the closing of the mitral valve. that closing occurs because the pressure in the ventricle, thisp here, is greater than
the pressure in theatrium, this small p here. normally, this valve would close and that would give you your s1. in addition, you have yourclosed aortic valve here. but instead of closing, remember we're talkingabout mitral regurgitation, so this is a closing problem. as the pressure starts tobuild in this left ventricle, but still with the aortic valve closed,
blood is actually gettingthrough this valve, so that's going to causea murmur right when s1 occurs, so right asthat valve tries to close it doesn't close fully, and because the pressure's higher in the left ventriclethan the left atrium, you actually start thatmurmur right at s1. as soon as the heartbegins to eject blood, this aortic valve opens right up,
and blood comes out this way. because the pressure remains higher in this ventricle thanthe atrium the whole time, you actually get flow throughthis regurgitant valve throughout the entire cycle. you would think naturallythat 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 actuallygets 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 theworkforce of the body ... and the left atrium, which is pretty low, because it's just receivingblood from the lungs, which is a low-pressure system,
the jets of blood thatactually come through here make a sound that, to our ears, doesn't change in intensity, and it occurs all the wayuntil the second heart sound, when this aortic valve closes. at that point in time, amillisecond 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 aholo- or pansystolic murmur. in addition, it's alsoreferred 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 thisgeneral area somewhere, when blood flow goes back the other way, it's going to kind of beforced in the direction
of this guy's armpit over here. again, just to mention theright-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 ina different position.