Hypertrophic Cardiomyopathy (HCM) Explained Clearly – Exam Practice Question

Hypertrophic Cardiomyopathy (HCM) Explained Clearly – Exam Practice Question

August 18, 2019 14 By Bertrand Dibbert


Wow well welcome to another MedCram
comm board vitals question this question comes from the cardiology and family
medicine question banks forty year old male presents to your medical clinic to
establish care he has no known prior medical history and does not take any
medications he complains of occasional shortness of breath on walking more than
two blocks he has never had any chest pain
he has never smoked and denies any alcohol or drug abuse history he was
adopted and does not know anything about his parents or siblings
he takes occasional multivitamins his vitals in your office our blood pressure
110 over 80 heart rate 90 and he’s in no acute distress on physical examination
he has a normal jvd clear lungs and a harsh crescendo decrescendo systolic
murmur that begins slightly after s1 and is heard best at the apex and lower left
sternal border ECG is shown below which of the following is the best statement
to describe further clinical management a no further workup is indicated B
echocardiogram is indicated which is the correct choice C start furiosa might for
diuresis or D start aspirin and plavix now let’s take a look at that ECG so
what’s the best answer well the first thing we need to do is kind of go over
the question stem and figure out what’s going on since we’re on the ECG let’s
talk about that one first so this is a 12-lead ECG and i think the biggest
thing that you’ll notice without going through rate rhythm and axis is these
very large s waves in v1 and these very large are waves specifically in v5 so if
you actually look at these and count them up you’ll notice that the S wave
and lead 1 v1 actually is let’s see how long it is that’s about five millimeters
10 millimeters 15 20 25 almost 30 millimeters s wave and v1 and the R wave
in lead v5 is let’s count it 5 10 15 20 25 30 so the criteria
area four left ventricular hypertrophy is the S wave in lead v1 plus the R wave
in lead v5 is greater together than 35 millimeters well we see it’s about 30 in
both so we’re about 60 millimeters which is well past the cutoff of the criteria
for left ventricular hypertrophy so I think that’s what we’re dealing with
here so let’s go back to the question stem and see what else we can pick up we
hear this harsh crescendo decrescendo systolic murmur that begins slightly
after s1 and is heard best at the apex and lower left sternal border now this
is kind of a classic type of murmur that you would see with something called
hypertrophic obstructive cardiomyopathy where you have a sub a or text enosis
that is actually very dangerous because these people if they’re ventricular size
gets small enough and the subaortic stenosis becomes great enough their
cardiac output will fall drastically so let’s talk a little bit more about
hypertrophic obstructive cardiomyopathy the other name for this also that you
may see is I H s s which is idiopathic hypertrophic subaortic stenosis so this
is the area that we’re talking about here here’s the right atrium right
ventricle left atrium left ventricle and you can see here that the septum I’m
drawing this kind of schematically here is so hypertrophy that it’s actually
blocking the outflow tract that’s going to the aorta so normally what happens is
is that the sound of a murmur or the amplitude of the murmur is dependent on
the amount of blood that’s passing through the valve and so therefore if
the chamber that’s upstream from the valve that’s
creating the murmur is larger you’re going to get a larger sounding murmur so
normally speaking if you’re looking at just regular a or t’k stenosis what will
make a or text enosis go up in amplitude will be anything that makes the
ventricle larger that would be squatting l
the legs or a handgrip squatting because when you squat more blood gets back to
the heart because of the pressure and therefore the left ventricle increases
in size which causes the murmur of aortic stenosis to increase elevating
the legs causes more blood to come back to the heart that’s going to increase
the size of the left ventricle and it’s going to do the same for now the way of
thinking of this is that what we’re actually looking at is we’re looking at
sub a or text enosis not a or text enosis and so in sub a or text enosis
we’re actually looking at the distance right here if this distance gets smaller
the stenosis is going to get worse and therefore the sound or the amplitude of
the sub a or text enosis is going to get worse well that happens when the
ventricle becomes smaller and so the opposite maneuvers are going to make the
murmur of subaortic stenosis get larger and so as a result of that we see the
arrows going in the opposite direction okay so standing is going to make the
heart smaller therefore these two are going to come together more therefore
the subaortic stenosis is going to become worse a valsalva maneuver where
you bear down causes less venous return and that causes the left ventricle to
get smaller and therefore sub a or texture notices to get louder and then
finally nitroglycerin it’s going to cause vasodilation that’s going to cause
the left ventricle to get smaller and of course diuresis with lasix or furosemide
is going to go ahead and do that and all of these things that make the ventricle
smaller are all things that could make sudden cardiac death so these patients
who have hypertrophy which is what we saw on the EKG and I’ve never had any
other kind of intervention they need to have echocardiography to see whether or
not the subaortic stenosis exists because these are people that you don’t
want doing strenuous exercise because of sudden cardiac death so again looking at
this EKG we can clearly see here is a very large s wave and here is a very
large R wave and that’s the key to left ventricular hypertrophy and if we scroll
on up and take a look at the actual question we’ll
see in the question that echocardiography is indicated and is the
correct answer why is no further workup indicated
because if this person goes on to do exercise he could die from sudden
cardiac death if you’re OSA might of course as we talked about is not a good
idea because it’s going to make the ventricles smaller and therefore more
dangerous and starting aspirin and plavix isn’t going to have any effects
on this portion of the heart it’s just going to prevent thrombosis in the
coronary arteries so clearly the best answer here is echocardiography which is
indicated because this patients at risk for having Holcomb thank you very much
for joining us