Кардиомиопатии - общая характеристика

Overview of cardiomyopathies: types, characteristics, and pathophysiology explained for medical students.

Key Takeaways

Cardiomyopathies originate from intrinsic myocardial defects, not secondary conditions like hypertension or valve disease.
Dilated cardiomyopathy leads to an enlarged, weak heart with systolic dysfunction.
Hypertrophic cardiomyopathy causes asymmetric thickening of the heart muscle and dynamic obstruction.
Contractility changes differ between dilated (decreased) and hypertrophic (increased) cardiomyopathies.
Restrictive cardiomyopathy primarily causes diastolic dysfunction due to restricted ventricular filling.

What the video covers

Cardiomyopathies are myocardial dysfunctions caused by defects in the heart muscle itself, unrelated to hypertension, coronary disease, valve disease, inflammation, or congenital defects.
Three main types of cardiomyopathies are dilated (congestive), hypertrophic, and restrictive cardiomyopathy.
Dilated cardiomyopathy features dilation of ventricles, a spherical enlarged heart, and a global decrease in myocardial contractility leading to systolic dysfunction.
Hypertrophic cardiomyopathy is characterized by asymmetric hypertrophy, especially of the interventricular septum, causing dynamic obstruction of left ventricular outflow.
Hypertrophic cardiomyopathy differs from hypertrophy caused by hypertension, which is typically symmetrical.
Contractility is decreased globally in dilated cardiomyopathy but increased in hypertrophic cardiomyopathy.
Dynamic obstruction in hypertrophic cardiomyopathy worsens with increased heart activity.
Restrictive cardiomyopathy involves diastolic dysfunction due to limited ventricular cavity volume.

Chapters

What is the primary cause of cardiomyopathies?

Cardiomyopathies are caused by intrinsic defects in the heart muscle itself, not by external conditions such as hypertension, coronary artery disease, valve diseases, inflammation, or congenital defects.

How does dilated cardiomyopathy affect the heart's function?

Dilated cardiomyopathy causes dilation of the ventricles, resulting in an enlarged, spherical heart with a global decrease in myocardial contractility, leading to systolic dysfunction and reduced cardiac output.

What distinguishes hypertrophic cardiomyopathy from hypertrophy caused by hypertension?

Hypertrophic cardiomyopathy features asymmetric hypertrophy, especially of the interventricular septum causing dynamic obstruction, whereas hypertrophy from hypertension is typically symmetrical and evenly distributed across the myocardium.

Full Transcript — Download SRT & Markdown

Speaker A

Hello, friends. Medlectures is back with you. And today, in this video, we will give a brief overview of the main types of cardiomyopathy. Let’s start, of course, with the definition of what cardiomyopathy is. Cardiomyopathies are a group of myocardial dysfunctions, the

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main characteristic of which is a defect in the heart muscle itself, in the myocardium itself. What kind of defects are these, and why do they occur? We will talk about that later.

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But for now, I want you to understand the most important point: the source of the problems in cardiomyopathies is the heart muscle itself. Based on this statement that the heart muscle itself is the source, I think it is easy to

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see that myocardial dysfunction in cardiomyopathies is in no way related to the conditions I am about to list.

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Myocardial dysfunction is not related to high blood pressure, that is, arterial hypertension. It is not related to coronary insufficiency, not related to valve diseases, not related to an inflammatory process in the myocardium, and not related to congenital defects. In other words, we

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can say that to diagnose cardiomyopathy, we must first rule out these five conditions I just listed. Moving on.

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There are three main types of cardiomyopathies, and we will analyze them all one by one. The first type of cardiomyopathy is dilated or congestive cardiomyopathy. Next, there is hypertrophic cardiomyopathy. And the third type is restrictive cardiomyopathy. We will, of course,

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analyze them in order. Let’s start with the dilated one. So, dilated or congestive cardiomyopathy. Let’s start by schematically depicting what the left chambers of the heart look like in dilated cardiomyopathy. Here is our left atrium, left ventricle, and

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the aorta. If you want to remember dilated cardiomyopathy in just a couple of words, concisely and figuratively, I would suggest remembering that in dilated cardiomyopathy, the heart becomes fat and lazy. Now, let me explain this in more medical terms.

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What do I mean by the words "fat heart" and "lazy"? First, the term "fat heart."

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Naturally, this is not about fat accumulating somewhere in the heart. It is about the fact that one of the global problems in dilated cardiomyopathy is the dilation of the left and right ventricles. And because the ventricles stretch, firstly, the

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volume of their cavities increases, and secondly, the heart acquires a spherical shape. It becomes large. And on my diagram, you can see that I drew the left ventricle, at least I tried to depict it, in a spherical shape. Moving

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on. The second word. I said that the heart becomes lazy, and that gives us the opportunity to move on to the second global problem observed in dilated cardiomyopathy. This problem is that this disease causes a decrease in myocardial contractility. Just in case,

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I remind you here that contractility includes two concepts. It includes both the speed and the strength of myocardial contraction. Well, in dilated cardiomyopathy, there is a decrease in both the strength and speed of myocardial contraction. Accordingly, that is why we say that there is a

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decrease in contractility. And it is very important to understand here that this is not just a decrease in contractility, but a so-called total or global decrease in contractility. This means that myocardial contractility is not reduced in just one area, not

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locally, but rather there is a decrease in the contractility of the entire myocardium. Its contractility is reduced in all areas. I would like to provide an example here. If the decrease in contractility were local, if we observed a decrease in

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contractility in just one area of the myocardium, for example, in this part, it would be immediately clear that this problem has nothing to do with dilated cardiomyopathy. This local decrease in myocardial contractility is most likely related to other causes, such as

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coronary artery disease. But let's return to our total or global decrease in myocardial contractility. By the way, a decrease in contractility is also called hypokinesia. And so we can say that in dilated cardiomyopathy, there is total or global myocardial

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hypokinesia. And this global myocardial hypokinesia leads to the development of —what do you think—systolic or diastolic dysfunction? I hear that most of you are telling me in response that, of course, this leads to the development of systolic dysfunction,

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because during diastole, naturally, these stretched ventricles can fill with blood quite calmly and normally.

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But during systole, the insufficient speed and strength of the myocardial contraction prevent the heart from providing an adequate cardiac output, which is the manifestation of systolic dysfunction. Well then, let's move on.

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And now let's talk about hypertrophic cardiomyopathy. First, let's draw a diagram again. First, we draw the normal, healthy left side of the heart: the left atrium, left ventricle, aorta, and aortic valve. Now, I think that based on the name "hypertrophic

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cardiomyopathy," you can guess that there must be hypertrophy somewhere here. And yes, indeed, that is the case. In hypertrophic cardiomyopathy, there is myocardial hypertrophy, which we will mark on our diagram like this.

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Just in case, I remind you here—and I hope you remember this from pathological anatomy and pathophysiology—that hypertrophy is an increase in cell size, in this case, an increase in the size of cardiomyocytes. And the most important, key point here is what I am going to

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draw now. This is the fact that in hypertrophic cardiomyopathy, this very hypertrophy is most pronounced in one area of the myocardium, namely in this area, that is, in the region of the interventricular septum. And you can see that here, due to the hypertrophy,

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this section of the interventricular septum seems to bulge into the cavity of the left ventricle. And that would be fine, but look at what happens during ventricular contraction. The thing is that this section of the interventricular septum naturally also

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contracts during systole. And during contraction, it sort of flattens, yes, squeezes, and bulges even further into the ventricular cavity, creating an obstruction to the blood flow from the left ventricle into the aorta. And to be more precise, this is a so-called

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dynamic obstruction. Why is it dynamic? Because the more actively the heart works, the more dynamic it is, the more pronounced this obstruction unfortunately becomes in this situation. Now, friends, I want to draw your attention to one important point. The

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fact is that the hypertrophy in this disease, hypertrophic cardiomyopathy, is in a sense unusual. I will now explain what I mean. To do this, we will depict the hypertrophy, say, in arterial hypertension, here on the left in a small diagram. And this

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hypertrophy will look something like this. And what do we see here? We see that in arterial hypertension, the myocardium is hypertrophied evenly in all areas, or almost evenly. And therefore, such hypertrophy is called symmetrical hypertrophy. And now, if we

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look back at our diagram of hypertrophic cardiomyopathy, how the left parts of the heart look, we remember that in this disease, the hypertrophy is most pronounced in one of the areas. It is more pronounced than in the other areas of the

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myocardium. And therefore, hypertrophic cardiomyopathy has another name. It is also called asymmetrical hypertrophic cardiomyopathy. Now, because the area where the hypertrophy is most pronounced, as you remember, creates a dynamic obstruction, hypertrophic cardiomyopathy also has a third name.

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It is called obstructive hypertrophic cardiomyopathy. I think that all three names should now be absolutely clear to you. And now let us make a small comparison between dilated and hypertrophic cardiomyopathy. So, we remember about dilated cardiomyopathy that it involves a total or global

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decrease in myocardial contractility. Note that, in contrast, in hypertrophic cardiomyopathy, the force and speed of myocardial contraction are, conversely, increased.

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take a patient with dilated cardiomyopathy and perform an ultrasound examination of the heart, i.e., an echocardiogram, we will be able to see a characteristic feature of this disease on the echo. This is that the ventricular cavities will have a

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characteristic spherical shape. In contrast, a characteristic echocardiographic finding in hypertrophic cardiomyopathy is that the left ventricular cavity takes on a specific, so-called banana-like shape.

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And what I’m drawing now may not look much like a banana, but let's use our imagination and picture this as our banana-shaped left ventricular cavity.

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Of course, besides this, on an echo for hypertrophic cardiomyopathy, we see, first, that there is hypertrophy, and second—which is more important—this hypertrophy is asymmetric. I hope this brief comparative summary of dilated and hypertrophic cardiomyopathy helps you better remember the facts I’ve

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tried to convey. Now I want to mention two more important facts about hypertrophic cardiomyopathy. First, in almost 100%of cases, hypertrophic cardiomyopathy is caused by a genetic defect. Of that 100%, half of the cases are hereditary or familial, and the

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other half, the remaining 50%, are so-called sporadic cases. And now I will explain what I mean. Look, if we have 100 patients with hypertrophic cardiomyopathy, all of them have a genetic defect, or a mutation, that leads to this disease. At the same time

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, for half of these patients, for fifty of them, this mutation was passed down from a relative, meaning they have a complicated family history. In contrast , for the fifty remaining patients, the other half, their family history regarding this disease is clear. No one

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suffered or suffers from hypertrophic cardiomyopathy. Meaning that for these fifty patients, this genetic defect, this mutation, arose for the first time . And that is why such cases are called sporadic. The last and very interesting fact for today about hypertrophic

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cardiomyopathy is that you have surely heard of cases where young athletes, for example, soccer players, collapsed and died right on the field during a match. And later we heard or read on the internet that a certain soccer player fell and died of cardiac arrest

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right during a match. Well, in fact, hypertrophic cardiomyopathy is the most frequent and common cause of sudden cardiac death in young athletes. And now, knowing what kind of problem exists with hypertrophic cardiomyopathy , we can imagine what happens when this

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young, say, soccer player, a guy around 25-26, goes out onto the field, starts playing, and is, of course, under intense physical exertion. And as you know, during physical activity, the heart works harder. We remember that in hypertrophic cardiomyopathy, there is

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dynamic obstruction. And naturally, during this intense physical exercise, that obstruction is aggravated. Accordingly, it turns out that the aorta doesn't receive enough blood.

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Moreover, during intense physical exertion, peripheral arterioles dilate, and blood rushes primarily into them. And here, please remind me, which vessels branch off from the aorta first ? These are, of course, the coronary vessels. And on my diagram, I will

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depict only one coronary vessel, but we remember that two coronary arteries branch off from the aorta, the left and the right. And it turns out that since blood is essentially flushed primarily into the dilated peripheral arterioles, the coronary vessels simply do not

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receive enough blood and enough oxygen. As a result, the myocardium undergoes quite severe ischemia, and ischemia is one of the main factors triggering conduction disturbances. And this conduction disturbance leads to ventricular fibrillation, that is, to a deadly arrhythmia, during which a

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life-incompatible drop in cardiac output occurs. And, in fact, this is exactly what these young athletes die from. Well, on that sad note, let's move on to the last type of cardiomyopathy. This is restrictive cardiomyopathy. To start, as always,

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let's draw schematically what the left chambers of the heart look like in restrictive cardiomyopathy: the left atrium, the left ventricular cavity, the aorta, and the myocardium itself. I will say right away that the main problem with restrictive cardiomyopathy

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is that the myocardium in this disease becomes stiff, rigid, and unable to relax normally during diastole. This, in turn, leads to a restriction of the ventricular volume during diastole, and they cannot fill with blood normally during the diastolic phase. In other

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words, in restrictive cardiomyopathy, we observe diastolic dysfunction. And, by the way, if you pay attention to the name of the disease, restrictive cardiomyopathy, the word "restrict" translates as limitation. And, clearly, it refers to the limitation of the volume of the ventricular cavities. The

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stiff, rigid state of the myocardium I described in restrictive cardiomyopathy is often associated with so-called pathological infiltration of the myocardium. We will depict this pathological infiltration on our diagram in approximately this way, and infiltrating the myocardium......can be , for example, amyloid in a disease

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like amyloidosis. It can be hemosiderin in a condition, or rather a state, known as hemochromatosis; in one of the previous lectures, I told you that hemochromatosis is a condition where the body is overloaded with iron. And also, the myocardium can be infiltrated

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by so-called non-caseating granulomas in a rare disease like sarcoidosis. But note here that this state of the myocardium in restrictive cardiomyopathy is not always necessarily linked to pathological infiltration. It can also be a consequence of, for example, a disease

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like diabetes mellitus, it can be hereditary, and it can also be idiopathic, meaning it has an unknown cause. Well then, friends, that was a brief overview of the main types of cardiomyopathy. If you enjoyed this video, or if you found it useful,

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please let me know. And if you would like me to make a detailed video on each type of cardiomyopathy, let me know about that too. Thank you for your attention. M.

Topics:cardiomyopathydilated cardiomyopathyhypertrophic cardiomyopathyrestrictive cardiomyopathymyocardial dysfunctionheart musclesystolic dysfunctiondiastolic dysfunctioncardiac contractilitydynamic obstruction

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