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Course: NCLEX-RN > Unit 3
Lesson 9: Cardiomyopathy- What is cardiomyopathy?
- Cardiomyopathy signs and symptoms
- Dilated cardiomyopathy: Pathophysiology and diagnosis
- Hypertrophic cardiomyopathy: Pathophysiology and diagnosis
- Restrictive cardiomyopathy: Pathophysiology and diagnosis
- Cardiomyopathy treatment
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Restrictive cardiomyopathy: Pathophysiology and diagnosis
Created by Matthew McPheeters.
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- What would happen if you have a higher ejection fraction than 75%? Wouldn't you be even healthier because your organs including your heart are getting more oxygen? This would allow for what would otherwise be bradycardia to be normal heart rate.
But how does more cardiac muscle raise the ejection fraction and thus the stroke volume and not just keep the stroke volume and ejection fraction the same and raise BP?(6 votes)- The circulation is a closed system. Oversimplified, increasing ejection fraction to up to 100%, and keeping all other things equal, would only force more fluid forwards through this closed loop, pushing the same amount of blood ahead of it back into the heart chambers. The tissues of the body wouldn't be "healthier". More is not better. The tissues would simply 'ignore' this excess blood because they don't need it. Using autoregulation they only allow themselves the amount of blood perfusion needed, and shunt the excess, untouched, back into the veins. So nothing is gained by increasing ejection fraction, stroke volume, CO, or any other blood variable to an amount above what whatever the tissues of the body need. More, wont bring health. It would just waste energy, and submit the structures of the body to harmful forces or environments for no good reason. The 'best' amount of ejection fraction, is whatever is able to perfuse the body as much as is needed to give tissues what they want with enough left over to bring used blood back to the heart and lungs to rinse and repeat.(4 votes)
- At8:20, why is the ejection fraction in restrictive cardiomyopathy normal if there is a problem with filling the heart?(4 votes)
- both sides of the fraction are reduced, meaning it is the same. for example if you had the fraction 2/4 it would be the same as 1/2 because 2/4 simplifies to 1/2(3 votes)
- at4:20you talk about granulomas, what are granulomas?(2 votes)
- Granuloma is an inflammation found in many diseases. It is a collection of immune cells known as histiocytes. Granulomas form when the immune system attempts to wall off substances it perceives as foreign but is unable to eliminate. Such substances include infectious organisms including bacteria and fungi, as well as other materials such as keratin and suture fragments. -Wikipedia(2 votes)
Video transcript
- [Voiceover] Let's talk
about the pathogenesis, and diagnosis of
restrictive cardiomyopathy. But before I get too far into this, I want to just briefly review some normal cardiac or heart physiology. So I'm going to just draw in here, a simplified diagram of the heart. Now the heart can kind of
be thought of as a series of two pumps that are separated
by the lungs in the body. And when you're looking at this heart, I want you to think of
it as if you're looking at it inside of someone
else who you're facing. And so, the sides are
going to be a little bit mirror imaged as if you're facing someone, so over here on the
left side of the image, is what is called the right heart. And the right heart takes blood from the body, and it enters
this right atrium here. And then it sends blood through the right ventricle to the lungs. And over here would be
the left side of the body. Blood comes in from the
lungs after it's oxygenated, so I'll draw it in as red blood, into the left atrium
here, and then it's taken into the left atrium and
sent out to the body, and then that blood is used by the body, and then eventually returns
back to this right atrium. All right now, so as we're going
through this cardiac cycle, I want to emphasize what's
going on in the ventricles, and by the ventricles
I mean these chambers down here at the bottom of the heart. And there's two major phases, and these phases are known
as diastole and systole. During these two phases,
we'll emphasize what's happening in the muscles of the ventricle, and what's happening with
the blood in the ventricles. And, during diastole, the
muscle is dilating, or relaxing so write that in here, and you
can remember D for diastole. And during this time blood
is filling the ventricles. And during systole, the
muscles are contracting. And this causes blood to
eject from the ventricles. And during diastole, these
muscles lining the ventricle, the muscles of the heart, they relax, and this causes the ventricles to dialate, so let's see that happen,
and you can see that as that muscle dilates, it
draws blood in from the atria, and then now we'll move
to the second phase of the cardiac cycle, which is systole, where the muscles of the
ventricle begin to contract, and on the right heart, this
blood is going to the lung, and from the left heart,
this blood is going out of the aorta, back to the body, and then after systole, you
go right back to diastole, where the muscles relax,
and notice here that when the muscles relax before blood enters the ventricles from the atria, not all of the blood was
ejected from the ventricles. Only about 3/4s or so
was, and the proportion of blood that was ejected
versus the amount that's remaining in the ventricle is known as the ejection fraction, and
the normal ejection fraction is between about 50 and 75 percent. All right, so now let's
talk about the pathogenesis of restrictive cardiomyopathy. And remember that if you break
down the word cardiomyopathy into cardio, myo, and
pathy, you can remember that it is a disease, a pathy,
of the heart, cardio, muscle, myo, so cardiomyopathy is a disease of the heart muscle. So the first step in the pathogenesis of restrictive cardiomyopathy is a problem with the heart muscle, and in
restrictive cardiomyopathy, there's kind of two processes
that could be going on. The first one is that you could
have fibrosis, or scarring of this heart muscle, so let's draw that in here so we can... And this fibrosis can be
caused by things like radiation from cancer treatment,
or it can be idiopathic, meaning that we don't really
know exactly what causes this. And the other form of
problem with the heart muscle in restrictive cardiomyopathy is something known as infiltration,
and with infiltration, there's different particles
that actually get deposited into the heart muscle,
and this can be caused by things like amyloidosis,
in which proteins are deposited in the heart muscle, or sarcoidosis, in which
there are granulomas in the heart muscle, this can be caused by inborn areas of metabolism,
which I'm just going to just abbreviate IEM, and this is a set of genetic diseases in
which certain metabolites are deposited here in the heart muscle. And then the last one I want to mention is something called hemochromatosis, which is also a genetic
disease in which iron is deposited in the muscle fibers. And whether it's fibrosis or infiltration, the physiology is very similar. This heart muscle isn't able to relax, so remember before, we had
this relaxation of the heart? Well, in restrictive cardiomyopathy, that isn't able to happen,
the muscle just stays the same size, and so the heart isn't able to fill properly, because
it's that relaxation of the heart during diastole, that dilation that causes filling. So let's just write that in here. And when the heart isn't
able to fill properly, even if it contracts, and has
a normal ejection fraction, you're still going to
have a decreased volume of blood exiting the heart,
and since this problem is during the filling stage
or the diastolic phase of the cardiac cycle, this is known as a diastolic heart failure. So this decreased filling
prevents a normal amount of blood from being
ejected out of the heart, and so you get a decreased outflow, resulting in the signs and
symptoms of heart failure. So now we're talking about the signs and symptoms of heart failure, of restrictive cardiomyopathy. How is it diagnosed? Well, the first step is to consider the history and physical exam, which I'm going to just
abbreviate H and P. And this is going to be
consistent with heart failure. Things like shortness of breath, they may have weakness and fatigue, and then since the heart is
not able to pump blood forward, the blood gets backed up into the body, and you get swelling of
the legs or the abdomen known as edema or
ascites, and the next step is to do some routine tests. And normally in routine
tests, we think about labs, but there aren't any
labs that are specific to restrictive cardiomyopathy,
so although a provider may perform labs in the
workup of cardiomyopathy, there's none that are really
specific to this disease. The next one is a chest x-ray. And a chest x-ray is going
to show pulmonary congestion, which is a sign that fluid is getting backed up into the lungs, but it's going to show a normal heart size. And the reason this is
important is because pulmonary congestion is common in other types of heart failure
like ischemic heart failure, or dilated cardiomyopathy,
but in those conditions, the heart is going to be enlarged. So it is important that
you're going to have a normal heart size in
restrictive cardiomyopathy. And then, a provider may also get an electrocardiogram, or an
ECG, and this is going to show low voltage QRS complexes. And now, after some of these
routine tests have been done, we'll go on to some more special tests. And the most important of
these is the echocardiogram. Which is an ultrasound of the heart. And in an echocardiogram,
what you're going to see is increased ventricular thickness, which you can kind of appreciate here in this diagram of
restrictive cardiomyopathy. And then you might also
see, although not always, is bi-atrial enlargement,
and I didn't draw this in in this diagram, but what this means is as the heart chambers are not able to dilate and expand, and fill with blood, the atrium here and here,
blood gets backed up in them, and they start to expand to accommodate that backup of blood so sometimes, these atria will be
enlarged and so you can see that on an echocardiogram. But another important
finding that is consistent with restrictive cardiomyopathy
versus other causes of heart failure, on the echocardiogram, you'll see a normal ejection fraction. Now, at this point, all
of these findings here on these tests can look
similar to other conditions like pericarditis,
which is an inflammation of the heart muscle, so
there's a couple of other tests that can be
performed, to confirm that someone has restrictive cardiomyopathy. And these are things like an angiogram, or a cardiac MRI, and these
can rule out pericarditis. Or, a cardiac biopsy can be performed. And a biopsy doesn't need to be performed to diagnose restrictive cardiomyopathy, but sometimes they're performed, and they can give specific evidence to the actual cause of the
restrictive cardiomyopathy whether it's amyloidosis,
sarcoidosis, or radiation and so this biopsy will vary
by the different causes, underlying causes of the
restrictive cardiomyopathy. So, to briefly recap this,
remember cardiomyopathy is a disease of the heart muscle, and in restrictive cardiomyopathy, this problem with the
heart muscle has to do with fibrosis or infiltration
that causes the muscle to be unable to dilate,
and therefore fill properly with blood, so this causes
a diastolic heart failure, and to diagnose it, the main test is going to be an echocardiogram, which will show increased ventricular thickness, with a normal ejection fraction, and sometimes a cardiac
MRI or angiogram needs to be performed to rule out pericarditis.