hi let's talk about cardiac auscultation in this video we'll discuss the various heart sounds
what they are and what creates them as well as discussing where one can specifically auscultate
or listen for the functioning of the different valves so heart sounds are audible occurrences
that result from cardiogenic events and it's usually the sound of blood doing something
so there are two large categories here there are primary heart sounds and secondary heart
sounds primary heart sounds are the classic lub dub where the the love is what we would call s1
sound one the dub s2 sounds - now I really like this particular illustration that relates heart
sounds - what is happening with the heart so in green we have what's occurring with ventricular
pressure in yellow atrial pressure and then in red aortic pressure so let's take a look here
so just after T zero we see an elevation first in atrial pressure and then in ventricular pressure
that is commensurate with that atrial pressure increase so what's going on here is atrial systole
so the atria are contracting and as they contract that gets to the end of ventricular
filling so that they're ejecting approximately about a quarter of the total volume of blood
that the ventricles are going to receive in a cardiac cycle so following that we're going
into a period of ventricular systole and as ventricular pressure rapidly rises one
of the first events is the closure of those atrioventricular valves blood pushes against
the valve cusps they're held very tightly by the chordae tendineae and the the papillary muscles
that are also contracting to tug on those chordae tendineae and as a result the valve
cusps are brought into close approximation for closure as the valves close ventricular
pressure rises quickly so that pushes blood out through the semilunar valve so a or tick
and pulmonic into the aorta and the pulmonary trunk as pressure increases increases increases
and then as pressure reaches a maximum and starts to decrease again the blood that's
in the pulmonary trunk and a Horta can begin to move backwards towards the heart now when that
happens the blood is caught by the cusps of the semilunar valves causing those semilunar valve
cusps to close or to come into approximation and there's there's turbulence there then
ventricular pressure declines to clients declines declines and we enter into a period of diastole
that's when both the atria and the ventricles are relaxed in those AV valves open wide again
and blood rushes through into the the ventricles and then diastole is followed again by atrial
systole it's an ongoing process with a lot of luck and so what is heard as s1 and s2
or the lub dub is blood turbulence as valves are closing s one relates to the closure of
the atrioventricular valves s2 relates to the closure of the semilunar valves
now the secondary heart sounds aren't always heard and when they're heard
they're not always bad sometimes they can be benign especially in children
as is largely the the rule for heart murmurs so for secondary sounds we have
s 3 and s 4 sounds so there's s 3 and I've added s 4 there so let's remember what's
going on during these times so s 3 is during diastole whereas s 4 is during atrial systole
so with s 3 the AV valves are wide open the atria and the ventricles are relaxing and
blood is rushing in through the atria through the AV valves and into the ventricles and what
is heard in s 3 is that turbulence of blood as it's filling the ventricles this is a very common
sound hurt in children and is generally quite benign now this order s1 s2 s3 has a cadence to
it it's called a gallop oftentimes people refer to it as a kentucky gallop because the cadence
of Kentucky explains the cadence of those sounds so Kentucky is how the S3 sound blends in with s1
and s2 now S4 if it's present it's a very rare sound to hear occurs during atrial systole so
the atria are contracting and blood is being forced into the ventricles and so ventricular
pressure increases a little but s 4 is generally heard when the walls of the ventricle aren't
compliant they're not stretching to accommodate that blood it might be because you know there's
a hypertrophy of the wall right there might be cardiomegaly for some pathological reason now
s4 proceeds s1 and s2 so when hurt its s4 s1 s2 or that the cadence would be tennessee tennessee
like that now a murmur can be anything else that that isn't typical so a clicking sound
a gurgling sound of whooshing or a rushing sound generally not always but generally murmurs tend
to be quite benign in children and if caught in adults can can be indicative of valvular
disorders but so they could be benign or not but it's it's important that that a murmur is
is fully evaluated to make that determination by the physician so the heart can be oscillated
from a number of different positions but the valves have very particular places on the on
the thorax to best listen to them or auscultate them so it's it's probably best to understand
that wherever a heart valve projects to the the sternum or the ribs isn't where you listen to it
so for instance you know this is approximately the location of the aortic valve mm-hm yet you
would not place the bell of a stethoscope there to auscultate the aortic valve rather you would
place the bell of a stethoscope in a in the path of blood in an area that is unencumbered
by bone so if this is the valve you take you know a right angle here you go perpendicular to follow
the path of blood out and once you're clear of the sternum is where you would auscultate in
the case of the aortic valve it's the right second intercostal space right at the sternal border for
the pulmonary valve it would be the left second intercostal space at the sternal border but also
you can try the third intercostal space notice these intercostal spaces are named for the ribs
above them so the second intercostal space is between second and third the third intercostal
space between third and fourth in the cases of the atrioventricular valves the blood is moving
inferiorly and laterally to the left and so for the tricuspid valve one would listen first or
first attempt auscultation in the left fifth intercostal space just off the sternal border
if unsuccessful you can also try the fourth intercostal space or the sternal angle there
so this is quite a variable range of locations to auscultate the tricuspid valve in the case
of the bicuspid valve the auscultation point is pretty close to the sterno costal projection for
the apex of the heart you want to take about the midclavicular line and go in the fifth intercostal
space along that midclavicular line for the bicuspid or the mitral valve on on the left
side so the mnemonic here is apartment B so a or dhic pulmonary tricuspid and then bicuspid
or mitral so you can do apartment m as well and that leads us to our assessment question
for the video and that is when auscultate in the aortic valve the bell of the stethoscope
should be placed where so if we think about the aortic valve the aortic valve is projecting blood
upwards and to the right and so it's sitting generally about in the third intercostal space
so one would look in the second intercostal space on the right hand side just at the sternal border
so a would be the correct answer be the second to third intercostal space just right of the sternum
that sounds more like the pulmonary valve see the fourth or fifth intercostal space just left
of the sternum that's the tricuspid valve in D the fifth intercostal space along the left
midclavicular line that would be the bicuspid or mitral valve thank you very much for you time