New approaches to the definition and classification of cardiomyopathies. Cardiomyopathies
Cardiomyopathy is a primary or secondary lesion of the myocardium, the causes of which are not vascular lesions, a tumor or an inflammatory process. This collective name hides a whole group of heart diseases that have both a known cause and those types of cardiomyopathy whose etiology has not been established.
When studying various types of cardiomyopathy, researchers created its classification, dividing them into primary (idiopathic) and secondary diseases.
Primary cardiomyopathy
Idiopathic include those types of myocardial lesions, the cause of which cannot be determined. The primary type of this disease includes:
Dilated cardiomyopathy
The cardiac cavities increase without thickening the walls of the ventricles. This causes systolic dysfunction, decreased cardiac output, and progression of heart failure. Sometimes ischemic cardiomyopathy, which appears in patients with coronary heart disease, is also included here.
Hypertrophic cardiomyopathy
It is expressed in thickening of the walls of one or both ventricles (over 1.5 cm). This defect can be hereditary or acquired, sometimes symmetrical, but more often asymmetrical, obstructive and non-obstructive.
Restrictive cardiomyopathy
Restrictive cardiomyopathy is rare. Its types: diffuse and obliterating. It is characterized by a decrease in myocardial contractility, which leads to a lack of blood supply to the heart chambers, which greatly increases the load on the atria.
Arrhythmogenic right ventricular dysplasia (Fontan disease)
A rare hereditary disease that represents necrosis of cardiac muscle tissue, occurring due to the abundance of fatty deposits. This variant can cause severe arrhythmias or even cardiac arrest.
Secondary cardiomyopathy
If the cause of cardiomyopathy is determined, then it is considered secondary and is more dangerous to the patient’s life than primary cardiomyopathy.
Medical statistics claim that severe secondary cardiomyopathy is much more likely to lead to death.
The classification of secondary cardiomyopathy is as follows:
Alcoholic cardiomyopathy
Alcoholic cardiomyopathy is caused by long-term alcohol abuse and leads to serious myocardial damage. More often it leads to heart failure, but sometimes to myocardial ischemia. This is the most common cause of death among all patients with cardiomyopathy.
Diabetic cardiomyopathy
It is caused by the presence of diabetes mellitus, causing biochemical changes in the myocardium and the accumulation of polysaccharides in it.
Thyrotoxic cardiomyopathy
It is a consequence of malfunctions of the endocrine system and advanced thyrotoxicosis. Its frequent manifestation is dyshormonal cardiomyopathy, which appears during hormonal therapy or during puberty.
Ischemic cardiomyopathy
The ischemic type is associated with myocardial pathology due to a number of morphofunctional diffuse disorders that occur against the background of acute or chronic myocardial ischemia. Leads to dilatation of the heart chambers and heart failure.
Metabolic cardiomyopathy
Accompanied by insufficiency of cardiac functions and myocardial dystrophy, the cause of which is certain disorders of energy-generating or metabolic processes in the myocardium.
Dysmetabolic cardiomyopathy
It ends in heart failure, which occurs due to prolonged overstrain of the heart caused by disturbances in homeostasis and the associated development of endotoxicosis. This form of the disease is most often found in young people involved in professional sports.
Toxic cardiomyopathy
Causes heart failure due to prolonged exposure to any toxins on the body.
Stress cardiomyopathy
With stress cardiomyopathy, as a result of shocks, mental and emotional influences, the myocardium weakens and its contractility decreases.
Dyshormonal cardiomyopathy
Dishormonal cardiomyopathy is a lesion of the myocardium without inflammation, caused by a lack of sex hormones due to some disturbances in the metabolic process occurring in the myocardium.
It is of non-ischemic origin. As a rule, it manifests itself as painful sensations in the chest and heart failure against the background of a sudden decrease in myocardial contractility. This form is mainly caused by emotional stress, hence its other name – “broken heart syndrome”.
In addition to the above forms of cardiomyopathies, there is another one - latent (of unclear etiology). It is characterized by some specific conditions that do not fall under any of the types listed above.
What type of cardiomyopathies have you encountered? Tell us about your illness in the comments.
Cardiomyopathies represent a large group of diseases that lead to disruption of the heart muscle. There are several typical mechanisms of myocardial damage ( actually the heart muscle), which unite these pathologies. The development of the disease occurs against the background of a variety of cardiac and extracardiac disorders, that is, cardiomyopathy can have various causes.
Initially, the group of cardiomyopathies did not include diseases hearts accompanied by lesions of the valves and coronary vessels ( own blood vessels of the heart). However, according to the recommendations of the World Health Organization ( WHO) in 1995, this term should be applied to all diseases that are accompanied by disorders of the myocardium. However, most experts do not include coronary heart disease, valve defects, chronic hypertension and some other independent pathologies. Thus, the question of which diseases are meant by the term “cardiomyopathy” currently remains open.
The prevalence of cardiomyopathy in the modern world is quite high. Even if the above pathologies are excluded from this concept, it occurs on average in 2–3 people out of a thousand. If we take into account the epidemiology of coronary heart disease and heart valve defects, the prevalence of this disease will increase several times.
Anatomy and physiology of the heart
In cardiomyopathies, the heart muscle is predominantly affected, but the consequences of this disease can affect a variety of parts of the heart. Since this organ works as a single whole, dividing it into parts can only be conditional. The appearance of certain symptoms or disturbances in work, one way or another, affects the entire heart. In this regard, to properly understand cardiomyopathy, you should familiarize yourself with the structure and functions of this organ. From an anatomical point of view, the heart has the following four sections (chambers):
- Right atrium. The right atrium is designed to collect venous blood from the systemic circulation ( all organs and tissues). Its abbreviation ( systole) distills venous blood in portions into the right ventricle.
- Right ventricle. This section is the second in volume and wall thickness ( after the left ventricle). With cardiomyopathies, it can be seriously deformed. Normally, blood enters here from the right atrium. Contraction of this chamber releases the contents into the pulmonary circulation ( pulmonary vessels), where gas exchange occurs.
- Left atrium. The left atrium, unlike the above departments, pumps arterial blood enriched with oxygen. During systole it throws it into the cavity of the left ventricle.
- Left ventricle. The left ventricle is most often affected by cardiomyopathies. The fact is that this section has the largest volume and greatest wall thickness. Its function is to supply arterial blood under high pressure to all organs and tissues through an extensive network of arteries. Left ventricular systole results in the ejection of a large volume of blood into the systemic circulation. For convenience, this volume is also called the ejection fraction or stroke volume.
In addition to the chambers of the heart, its four valves are of great importance in its work:
- tricuspid ( tricuspid) valve– between the right atrium and ventricle;
- pulmonary valve– at the exit from the right ventricle;
- mitral valve– between the left atrium and ventricle;
- aortic valve– at the border of the exit from the left ventricle and the aorta.
The most important role in the development of cardiomyopathy is played by the layers that make up the heart wall. It is the cellular and tissue composition of an organ that largely determines its damage in various pathologies.
The following layers of the heart wall are distinguished:
- endocardium;
- myocardium;
- pericardium.
Endocardium
The endocardium is a thin layer of epithelial cells that lines the inside of the heart chambers. It contains a certain amount of connective tissue fibers that participate in the formation of the valve apparatus. The main function of this layer is to ensure the so-called laminar blood flow ( no swirls) and prevention of blood clots. For a number of diseases ( e.g. Loeffler's endocarditis) compaction and thickening of the endocardium occurs, which reduces the elasticity of the heart wall as a whole.Myocardium
Actually, the term “cardiomyopathy” primarily implies damage to the myocardium. This is the middle and thickest layer of the heart wall, represented by muscle tissue. Its thickness ranges from a few millimeters in the walls of the atria to 1 - 1.2 cm in the wall of the left ventricle.The myocardium performs the following important functions:
- Automatism. Automaticity implies that myocardial cells ( cardiomyocytes) are able to contract on their own at a low frequency. This is explained by the structure of this tissue.
- Conductivity. Conductivity refers to the ability of the heart muscle to quickly transmit a bioelectric impulse from one cell to another. This is ensured through specific intercellular connections.
- Contractility. Contractility suggests that cardiomyocytes can shrink or increase in size under the influence of a bioelectrical impulse, like any muscle cells. This is explained by the presence in their structure of myofibrils - specific threads with high elasticity. To trigger the contraction mechanism, the presence of a number of microelements is necessary ( potassium, calcium, sodium, chlorine).
- Excitability. Excitability is the ability of cardiomyocytes to respond to an incoming impulse.
Pericardium
The pericardium is the outer layer of the heart wall. It is represented by a thin plate of connective tissue, which is split into two sheets. The so-called visceral layer is tightly fused with the myocardium and covers the heart itself. The outer leaf forms the cardiac sac, which ensures normal gliding of the heart during its contractions. Inflammatory diseases of the pericardium, fusion of its layers, or calcium deposits in the thickness of this layer can lead to symptoms similar to restrictive cardiomyopathy.In addition to the chambers of the heart, its walls and the valve apparatus, this organ has several more systems that regulate its functioning. First of all, it is a conducting system. It consists of nodes and fibers that have increased conductivity. Thanks to them, the cardiac impulse is generated at a normal frequency, and excitation is evenly distributed throughout the myocardium.
In addition, the coronary vessels play an important role in the functioning of the heart. These are small-diameter vessels that originate at the base of the aorta and carry arterial blood into the heart muscle itself. In some diseases, this process can be disrupted, leading to the death of cardiomyocytes.
Causes of cardiomyopathy
As noted above, according to the latest WHO recommendations, cardiomyopathies include any diseases accompanied by damage to the heart muscle. As a result, there are many reasons for the development of this pathology. If myocardial dysfunction is a consequence of other diagnosed diseases, it is customary to talk about secondary or specific cardiomyopathies. Otherwise ( and such cases are not uncommon in medical practice), the underlying cause of the disease remains unknown. Then we are talking about the primary form of pathology. The main reasons for the development of primary cardiomyopathy are:
- Genetic factors. Cardiomyopathy is often caused by various genetic disorders. The fact is that cardiomyocytes contain a large number of proteins involved in the contraction process. A congenital genetic defect of any of them can lead to disturbances in the functioning of the entire muscle. In these cases, it is not always possible to figure out what exactly caused the disease. Cardiomyopathy develops independently, without signs of any other disease. This allows us to classify it as a group of primary lesions of the heart muscle.
- Viral infection. A number of researchers believe that certain viral infections are to blame for the development of dilated cardiomyopathy. This is confirmed by the presence of appropriate antibodies in patients. At the moment, it is believed that the Coxsackie virus, hepatitis C virus, cytomegalovirus and a number of other infections are capable of influencing DNA chains in cardiomyocytes, disrupting their normal functioning. Another mechanism responsible for myocardial damage may be an autoimmune process, when antibodies produced by the body itself attack its own cells. Be that as it may, there is a connection between the above viruses and cardiomyopathies. They are classified as primary forms due to the fact that infections do not always manifest themselves with typical symptoms. Sometimes damage to the heart muscle is the only problem.
- Autoimmune disorders. The autoimmune mechanism mentioned above can be triggered not only by viruses, but also by other pathological processes. It is very difficult to stop such damage to the heart muscle. Cardiomyopathy usually progresses, and the prognosis for most patients remains poor.
- Idiopathic myocardial fibrosis. Myocardial fibrosis is the gradual replacement of muscle cells with connective tissue. This process is also called cardiosclerosis. Gradually, the heart walls lose their elasticity and ability to contract. As a result, the functioning of the organ as a whole deteriorates. Cardiosclerosis is often observed after myocardial infarction or myocarditis. However, these diseases belong to the secondary forms of this pathology. Idiopathic fibrosis is considered primary, when the cause of the formation of connective tissue in the myocardium could not be determined.
The following diseases can cause the development of secondary cardiomyopathy:
- infectious damage to the myocardium;
- cardiac ischemia;
- storage diseases;
- endocrine diseases;
- electrolyte imbalance;
- amyloidosis;
- systemic connective tissue diseases;
- neuromuscular diseases;
- poisoning;
- cardiomyopathy during pregnancy.
Myocardial infection
Infectious damage to the myocardium, as a rule, manifests itself as myocarditis ( inflammation of the heart muscle). It can be either an independent disease or a consequence of a systemic infection. Microbes entering the thickness of the myocardium cause inflammatory edema and sometimes death of cardiomyocytes. In place of dead cells, pinpoint inclusions of connective tissue are formed. This tissue cannot perform the same functions as healthy heart muscle. Because of this, cardiomyopathy develops over time ( usually dilatative, less often - restrictive).Due to lack of oxygen, gradual or rapid destruction of cardiomyocytes occurs. This process occurs most acutely during myocardial infarction, when massive necrosis occurs in a certain area of the muscle ( dying off) fabrics. Regardless of the form of IHD, replacement of normal muscle cells with connective tissue occurs. In the future, this can lead to expansion of the heart chamber and the establishment of dilated cardiomyopathy.
Many experts do not recommend including such disorders in the category of cardiomyopathies, explaining that the cause of the disease is clearly known, and myocardial damage is, in fact, just a complication. However, there are practically no differences in clinical manifestations, so it is quite appropriate to consider ischemic heart disease as one of the causes of cardiomyopathy.
The risk of developing atherosclerosis and coronary artery disease is increased by the following factors:
- elevated blood lipids ( cholesterol is more than 5 mmol/l, and low-density lipoproteins are more than 3 mmol/l);
- high blood pressure;
- obesity of varying degrees.
Hypertonic disease
Hypertension or essential hypertension can also lead to structural changes in the heart muscle. This disease can develop for various reasons, and its main manifestation is a stable increase in blood pressure to more than 140/90 mmHg.If the cause of high blood pressure is not heart pathology, but other disorders, then there is a risk of developing dilated or hypertrophic cardiomyopathy. The fact is that with increased pressure in the blood vessels, it is harder for the heart to work. Because of this, its walls may lose elasticity, being unable to transport the full volume of blood. Another option is, on the contrary, thickening of the heart muscle ( hypertrophy). Due to this, the left ventricle contracts more strongly and drives blood through the vessels even under conditions of high pressure.
Many experts do not recommend classifying damage to the heart muscle in hypertension as a cardiomyopathy. The fact is that in this case it is difficult to distinguish which of these pathologies is primary and which is secondary ( a consequence or complication of a primary disease). However, the symptoms and manifestations of the disease in this case coincide with those of cardiomyopathies of other origins.
The causes of the development of essential hypertension, leading to subsequent cardiomyopathy, may be the following factors and disorders:
- elderly age ( over 55 – 65 years old);
- smoking;
- genetic predisposition;
- some hormonal disorders.
Storage diseases
Storage diseases are specific genetic disorders that lead to metabolic disorders in the body. As a result, any metabolic products that are not excreted due to the disease begin to be deposited in organs and tissues. The greatest significance in the development of cardiomyopathy is played by pathologies in which foreign substances are deposited in the thickness of the heart muscle. Over time, this leads to serious disruption of its functioning.Diseases in which pathological deposition of any substances occurs in the thickness of the myocardium are:
- Hemochromatosis. With this disease, iron is deposited in muscle tissue, impairing muscle function.
- Glycogen storage diseases. This is the name of a group of pathologies in which too much or too little glycogen is deposited in the heart. In both cases, myocardial function can be seriously impaired.
- Refsum syndrome. This pathology is a rare genetic disease accompanied by the accumulation of phytanic acid. This disrupts the innervation of the heart.
- Fabry disease. This pathology often leads to myocardial hypertrophy.
Endocrine diseases
Cardiomyopathies can develop against the background of serious endocrine ( hormonal) disorders. Most often, there is overstimulation of the heart, an increase in blood pressure, or changes in the structure of the heart muscle. Hormones regulate the functioning of many organs and systems and, in some cases, can affect general metabolism. Thus, the mechanisms of development of cardiomyopathies in endocrine diseases can be very diverse.The main hormonal disorders that can lead to cardiomyopathy are:
- disorders of the thyroid gland ( both hyperfunction and hypofunction);
- diabetes;
- pathology of the adrenal cortex;
Electrolyte imbalance
Electrolyte imbalance refers to too low or too high levels of certain ions in the blood. These substances are necessary for normal contraction of cardiomyocytes. If their concentration is impaired, the myocardium cannot perform its functions. Prolonged diarrhea, vomiting, and some kidney diseases can lead to electrolyte imbalance. Under such conditions, the body loses a significant amount of nutrients along with water. If such disorders are not corrected in time, then after some time functional and then structural changes in the heart will follow.The following substances play the most important role in the functioning of the heart muscle:
- potassium;
- calcium;
- sodium;
- chlorine;
- magnesium;
- phosphates.
Amyloidosis
With cardiac amyloidosis, a special protein-polysaccharide complex called amyloid is deposited in the thickness of the heart muscle. This disease often develops against the background of other chronic pathologies, being their direct consequence. There are several types of amyloidosis. Heart damage occurs only in some of them.Having accumulated in the myocardium, the pathological protein interferes with the normal contraction of cardiomyocytes and impairs the functioning of the organ. Gradually, the walls of the heart lose elasticity and contractility, and cardiomyopathy develops with progressive heart failure.
Heart damage is possible with any of the following forms of amyloidosis:
- primary amyloidosis;
- secondary amyloidosis;
- family ( hereditary) amyloidosis.
Systemic connective tissue diseases
Despite the fact that the heart muscle consists mainly of cardiomyocytes, it also contains some connective tissue. Because of this, in so-called systemic connective tissue diseases, the myocardium may be affected by an inflammatory process. The extent of heart damage will depend on many factors. Intense inflammation can lead to diffuse cardiosclerosis, in which normal muscle cells are gradually replaced by connective tissue. This makes it difficult for the heart to work and leads to the development of cardiomyopathy.Heart damage can be observed with the following systemic connective tissue diseases:
- systemic scleroderma;
Neuromuscular diseases
There are a number of diseases that affect nerve fibers and interfere with the normal transmission of impulses from nerve to muscle. As a result of disruption of innervation, the activity of the heart is seriously impaired. It cannot contract regularly and with the required force, which is why it cannot cope with the incoming blood volume. As a result, dilated cardiomyopathy often develops. In severe cases, the heart walls are not even able to maintain normal muscle tone, which leads to their excessive stretching.Dilated cardiomyopathy often complicates the course of the following neuromuscular diseases:
- Duchenne muscular dystrophy;
- Becker's muscular dystrophy;
- myotonic dystrophies;
- Friedreich's ataxia.
Poisoning
There are also a number of toxins that can quickly disrupt the functioning of the heart. They mainly affect the system of its innervation or muscle cells directly. The result is usually dilated cardiomyopathy.Poisoning with the following substances can cause severe damage to the heart muscle:
- alcohol;
- heavy metals ( lead, mercury, etc.);
- some medicines ( amphetamines, cyclophosphamide, etc.);
- arsenic.
Cardiomyopathy during pregnancy
Cardiomyopathy may develop late in pregnancy ( in the third trimester) or in the first months after the birth of the child. The disease can develop through a variety of mechanisms. The fact is that pregnancy is normally accompanied by changes in hemodynamics ( increase in circulating blood volume, changes in blood pressure), hormonal changes, stressful situations. All this can affect the functioning of the heart, leading to the development of cardiomyopathy. Most often, pregnant women and young mothers experience a dilated or hypertrophic form of this disease. Given the general weakening of the body, cardiomyopathy in such cases can pose a serious threat to life.In general, secondary cardiomyopathies are often reversible. They develop against the background of other pathologies, and adequate treatment of the underlying disease can lead to complete disappearance of cardiac symptoms. This predetermines the treatment tactics for such forms of the disease.
From all of the above, we can conclude that cardiomyopathies develop against the background of a variety of pathologies according to similar mechanisms and laws. The important thing is that, regardless of the cause, many of them present with the same symptoms and require similar diagnosis and treatment.
Types of cardiomyopathy
As stated above, cardiomyopathy can have many different causes, and experts around the world are not always able to accurately determine which of them should be included in this definition and which should not. In this regard, the classification of this disease by origin ( etiological classification) is rarely used in practice. The clinical types of cardiomyopathies are much more important. The difference between them is based on the nature of structural changes in the heart muscle and the manifestations of the disease. This classification allows you to quickly make a diagnosis and begin proper treatment. This will temporarily compensate for heart failure and reduce the risk of complications.
According to the mechanism of disease development, all cardiomyopathies are divided into the following types:
- dilated cardiomyopathy;
- hypertrophic cardiomyopathy;
- restrictive cardiomyopathy;
- specific cardiomyopathies;
- unclassified cardiomyopathy.
Dilated cardiomyopathy
Dilated cardiomyopathy is the most common type of this disease. It can develop with myocardial lesions of various types and affect both the walls of the atria and the walls of the ventricles. Typically, in the early stages of the disease, only one of the chambers of the heart is affected. The most dangerous is dilated ventricular cardiomyopathy.This type of disease is an expansion of the cavity of the heart chamber. Its walls stretch abnormally, unable to contain the internal pressure that increases with blood flow. This leads to a number of adverse effects and greatly affects the functioning of the heart.
Enlargement (dilatation) of the heart chamber can occur for the following reasons:
- Reduction in the number of myofibrils. As mentioned above, myofibrils are the main contractile part of cardiomyocytes. If their number decreases, the wall of the heart loses its elasticity, and when the chamber is filled with blood, it stretches too much.
- Decrease in the number of cardiomyocytes. Typically, the amount of muscle tissue in the heart decreases with cardiosclerosis that develops against the background of inflammatory diseases or myocardial ischemia. Connective tissue has significant strength, but is not able to contract and maintain muscle tone. In the first stages, this leads to excessive stretching of the organ wall.
- Dysfunction of nervous regulation. In some neuromuscular diseases, the flow of excitation impulses stops. The heart reacts to the increase in pressure inside its chamber as blood enters and sends a signal to muscle contraction. Due to innervation disturbances, the signal does not reach, cardiomyocytes do not contract ( or they are not contracting strongly enough), which leads to dilatation of the chamber under the influence of internal pressure.
- Electrolyte imbalance. For myocardial contraction, normal levels of sodium, potassium and chloride ions in the blood and inside the muscle cells themselves are necessary. With an electrolyte imbalance, the concentration of these substances changes, and cardiomyocytes cannot contract normally. This can also cause the heart chamber to expand.
The expansion of the heart chamber leads to the fact that more blood begins to flow into it. Thus, more time and greater contraction force are required to contract the chamber and pump this volume. Since the wall is stretched and thinned, it is difficult for it to cope with such a load. In addition, after systole, usually not the entire volume of blood leaves the chamber. Most often, a significant part of it remains. Because of this, there appears to be a blockage of blood in the atrium or ventricle, which also worsens the pumping function of the heart. Stretching the walls of the chamber leads to expansion of the opening of the heart valves. Because of this, a gap is formed between their valves, which leads to insufficient operation of the valve. He cannot stop the flow of blood during systole and direct it in the right direction. Some of the blood will return from the ventricle to the atrium through the incompletely closed valves. It also makes the heart work harder.
To compensate for the work of the heart in dilated cardiomyopathy, the following mechanisms are activated:
- Tachycardia. Tachycardia is an increase in heart rate of more than 100 per minute. This allows you to pump even a small volume of blood faster and provide the body with oxygen for some time.
- Strengthening contractions. Increasing myocardial contraction allows a larger volume of blood to be expelled during systole ( increase in stroke volume). However, cardiomyocytes consume more oxygen.
Despite all compensatory mechanisms, heart failure progresses rapidly. It is a violation of the pumping function of the heart. It simply stops pumping the required volume of blood, which leads to stagnation. Stagnation appears in the systemic circulation, in the small circulation, and in the chambers of the organ themselves. This process is accompanied by the appearance of corresponding symptoms.
The criterion for diagnosing dilated cardiomyopathy is expansion of the cavity of the left ventricle during its relaxation ( in diastole) more than 6 cm in diameter. At the same time, a decrease in ejection fraction of more than 55% is recorded. In other words, the left ventricle pumps only 45% of the required volume, which explains oxygen starvation of tissues, the risk of complications and many manifestations of the disease.
Hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy is a condition in which the thickness of the walls of the heart chamber increases, but the volume of the chamber remains the same or decreases. Most often, the walls of the ventricles thicken ( usually left, less often right). With some hereditary disorders, thickening of the interventricular septum may also be observed ( in some cases up to 4 – 5 cm). The result is severe disruption of the heart. Hypertrophy is considered to be wall thickening up to 1.5 cm or more.Hypertrophic cardiomyopathy has two main forms - symmetrical and asymmetrical. More common is asymmetrical thickening of the walls of one of the ventricles. Symmetrical lesions of the chambers can appear in some storage diseases or hypertension, but usually this disease involves hereditary defects in muscle tissue.
The main problems with thickening of the heart walls are:
- chaotic arrangement of muscle fibers in the myocardium;
- thickening of the walls of the coronary arteries ( they contain smooth muscle cells, which also hypertrophy and narrow the lumen of the vessel);
- fibrous process in the thickness of the wall.
It is believed that myocardial hypertrophy develops faster under the following conditions:
- action of catecholamines;
- increased insulin levels;
- disorders of the thyroid gland;
- hypertonic disease;
- the nature of the mutation in genes;
- wrong lifestyle.
With hypertrophic cardiomyopathy, the following problems in the functioning of the heart are observed:
- Reduced left ventricular volume (Most often we are talking about this camera) does not allow complete blood flow from the atrium. Because of this, the pressure in the left atrium increases and it expands.
- Stagnation of blood in the pulmonary circulation. As the volume of the left ventricle decreases, blood stagnation occurs in the pulmonary circulation. This gives rise to a set of symptoms characteristic of this type of cardiomyopathy.
- Myocardial ischemia. In this case, we are talking not so much about atherosclerotic vascular damage ( although it greatly worsens the prognosis), how much about an increase in the number of cardiomyocytes. The muscle begins to consume more oxygen, and the vessels, remaining the same width, cannot provide its normal nutrition. Because of this, a lack of oxygen occurs, or, scientifically, ischemia. If at this moment the patient gives physical activity and sharply increases the muscle's need for oxygen, a heart attack may occur, although the coronary vessels, in fact, are practically unchanged.
- Risk of arrhythmia. Improperly organized muscle tissue of the left ventricle cannot normally transmit bioelectric impulses. In this regard, the chamber begins to contract unevenly, further disrupting the pumping function.
Restrictive cardiomyopathy
Restrictive ( compressive) cardiomyopathy is a variant of myocardial damage in which the elasticity of the walls of the heart is greatly reduced. Because of this, during diastole, when the muscle relaxes, the chambers cannot expand with the required amplitude and accommodate a normal volume of blood.The usual cause of restrictive cardiomyopathy is massive fibrosis of the heart muscle or its infiltration by foreign substances ( for storage diseases). The primary form of this type of disease is idiopathic myocardial fibrosis. It is often combined with an increase in the amount of connective tissue in the endocardium ( Loeffler's fibroplastic endocarditis).
With this type of disease, the following disturbances in the functioning of the heart occur:
- thickening and compaction of myocardial and/or endocardial tissue due to connective tissue fibers;
- decrease in diastolic volume of one or more ventricles;
- dilatation of the atria due to increased pressure in them ( blood is retained at this level because it does not enter the ventricles in full).
Specific cardiomyopathy
Specific cardiomyopathy usually refers to secondary myocardial lesions when the underlying cause is known. In this case, the mechanism of development of the disease may completely coincide with the three classical forms of the disease listed above. The only difference is that with specific cardiomyopathy, damage to the heart muscle is a complication, and not a primary pathology.The internal classification of specific forms corresponds to the reasons that caused it. For example, there are inflammatory, allergic, ischemic and other types ( a complete list is listed above in the “causes of cardiomyopathy” section). Cardiac symptoms and manifestations of the disease will be practically no different.
Unclassified cardiomyopathy
Unclassified cardiomyopathy is a cardiomyopathy that combines symptoms of several types of disease. For example, a variant with ventricular hypertrophy and atrial dilatation can be attributed to this form. There are many variants of symptoms and manifestations with it. In fact, they are caused by disorders that are characteristic of all three main types of cardiomyopathies.Symptoms of cardiomyopathy
Almost all symptoms observed in patients with cardiomyopathies are not specific to this group of diseases. They are caused by right- or left-sided heart failure, which also occurs in other heart pathologies. Thus, most patients experience only general manifestations of the disease, which indicate heart problems and the need to see a doctor. Typical complaints and symptoms for various types of cardiomyopathies are:
- increased heart rate;
- pale skin;
- moderate chest pain;
- enlarged liver and spleen;
- dizziness and fainting;
- increased fatigue.
Dyspnea
This symptom represents breathing problems, sometimes leading to attacks of suffocation. Attacks can appear against the background of physical activity, stress, and in the later stages of the disease without any external influences. Shortness of breath is explained by stagnation of blood in the pulmonary circulation due to left-sided heart failure. The left side of the heart does not pump the incoming volume of blood, and it accumulates in the vessels of the lungs.Cough
The mechanism of cough is the same as that of shortness of breath. It is also characteristic specifically for cardiomyopathy affecting the left side. The more the cardiac ejection fraction falls, the more frequent and severe coughing attacks become. When pulmonary edema begins, moist rales are also heard and foamy sputum appears. These symptoms indicate the accumulation of fluid directly in the cavity of the alveoli ( the smallest functional parts of the lung where gas exchange occurs).Increased heart rate
Palpitations are a common complaint in patients with hypertrophic cardiomyopathy ( less common in other types of this disease). Normally, a person at rest does not feel his heart beating. However, if it is increased or the rhythm of contractions is not stable, this may manifest itself as increased heartbeat, felt both at the level of the chest and at the level of the vessels of the neck or in the upper abdomen.Skin paleness
Pallor of the skin and lips is explained by a decrease in cardiac ejection fraction. The pumping function of the heart deteriorates and sufficient blood does not flow to the tissues. The first sign of this is pale skin. At the same time, the tips of the fingers and nose may become cold or even turn blue ( acrocyanosis).Edema
Swelling appears mainly on the legs. They are characteristic of cardiomyopathy affecting the right side of the heart. In these cases, blood is retained not in the pulmonary circulation, but in the systemic circulation. Under the influence of gravity, it descends to the lower extremities, where it partially leaves the vascular bed with the formation of edema.Moderate chest pain
Such pain appears most often with hypertrophic cardiomyopathy, when relative myocardial ischemia gradually develops. The pain itself is a consequence of oxygen starvation of the heart muscle. In the first stages of the disease, it appears after physical activity, when the myocardial need for oxygen increases.Enlarged liver and spleen
This symptom is explained by blood stasis in the systemic circulation. It is observed in right-sided heart failure. The enlargement of the liver and spleen occurs as follows. Against the background of deterioration in the functioning of the right atrium or ventricle, venous blood accumulates in the wide vena cava. Again, due to gravity, the pressure in the inferior vena cava is greater than in the superior vena cava. The increased pressure spreads to the nearest vessels that flow into this vein. It is the portal vein, which collects blood from the intestines, liver and spleen. As heart failure worsens, more and more blood accumulates in the portal vein system, which leads to organ enlargement.Dizziness and fainting
These symptoms indicate oxygen starvation of brain tissue. Dizziness can last for a long time, but fainting most often occurs unexpectedly. They are caused by a sharp drop in blood pressure if the heart suddenly stops pumping blood. This is usually not so much due to cardiomyopathy as due to its complications. Most often, fainting is accompanied by ventricular arrhythmias.Increased fatigue
This symptom is characteristic of almost all heart diseases accompanied by a decrease in cardiac output. In this case, oxygen starvation of the muscles is observed, which explains their weakness and increased fatigue.Diagnosis of cardiomyopathy
Diagnosing cardiomyopathy is a rather complex process. The fact is that the clinical picture of myocardial damage is very similar in almost all types of this disease. It can be difficult to even distinguish primary forms of the disease from secondary ones. In this regard, when making a diagnosis, the doctor is based not only on the data of a general examination of the patient, but also prescribes some specific instrumental examinations. Only by obtaining all possible information can one accurately determine the type of cardiomyopathy and prescribe the correct treatment. The following diagnostic methods are used directly to detect and classify the disease:
- physical examination;
- electrocardiography ( ECG);
- echocardiography ( EchoCG);
- radiography.
Physical examination
A physical examination is performed by a general practitioner or cardiologist to look for signs of heart damage. Despite the fact that each of the cardiomyopathies has certain signs that are characteristic of it, the data obtained during a physical examination is still not enough to make a reasoned diagnosis. This is only the first stage in the diagnosis of this pathology.Physical examination includes the following methods:
- palpation ( palpating parts of the patient's body for diagnostic purposes);
- percussion ( tapping the chest wall with a finger);
- auscultation ( listening to heart murmurs and sounds using a stethoscope);
- visual examination of the skin, chest shape, basic diagnostic procedures ( measurement of pulse, respiratory rate, blood pressure).
The following signs are characteristic of various cardiomyopathies, revealed during physical examination:
- For dilated cardiomyopathy swelling of the legs and swelling of the neck veins are characteristic. Upon palpation, you can feel a pulsation in the upper abdomen ( in the epigastrium). When auscultating the lungs, moist rales can be heard. The first heart sound at the apex of the heart will be weakened. Percussion determines the enlargement of the heart ( displacement of its boundaries). Blood pressure is often normal or low.
- Any changes during physical examination may be absent for a long time. Apex impulse ( projection of the apex of the heart onto the anterior chest wall) is often displaced and strengthened. The boundaries of the organ usually shift to the left during percussion. During auscultation, splitting of the first heart sound is noted, since contraction of the ventricles does not occur synchronously, but in two stages ( First, the non-enlarged right ventricle contracts, and then the hypertrophied left one). Blood pressure may be normal or elevated.
- During the examination, swelling of the legs and swelling of the neck veins are often noted. In the later stages of the disease, enlargement of the liver and spleen may be observed due to stagnation of blood in the systemic circle. Percussion reveals a moderate enlargement of the heart on both the right and left sides. During auscultation, a weakening of the I and II heart sounds is noted ( depending on which ventricle is affected).
Electrocardiography
Electrocardiography is a study of the electrical activity of the heart. This diagnostic method is very easy to implement, does not take much time and gives fairly accurate results. Unfortunately, for cardiomyopathies, the information that can be obtained with its help is limited.A standard ECG is taken by installing special electrodes on the patient’s limbs and chest. They record the passage of an electrical impulse and display it in the form of a graph. By deciphering this graph, you can get an idea of the structural and functional changes in the heart.
The electrocardiogram is taken along 12 main axes ( leads). Three of them are called standard, three are reinforced and six are chest. Only a scrupulous analysis of data from all leads can help in making an accurate diagnosis.
Signs on the ECG characteristic of each type of cardiomyopathy are:
- For dilated cardiomyopathy signs of left ventricular hypertrophy can be detected ( less often - left atrium or right ventricle). The RS-T section in leads V5, V6, I and aVL often shifts below the isoline. Rhythm disturbances may also occur.
- For hypertrophic cardiomyopathy Characteristic signs of thickening of the wall of the left ventricle and deviation of the electrical axis of the heart to the left. Deformations of the QRS complex, reflecting excitation of the ventricular myocardium, may be observed. With relative ischemia, a decrease in the RS-T segment below the isoline may be observed.
- For restrictive cardiomyopathy ECG changes can be varied. A decrease in the voltage of the QRS complex and changes in the T wave are characteristic. Specific signs of overload of the atria with blood are also noted ( according to the shape of the P wave).
Echocardiography
Echocardiography is also called ultrasound of the heart because it uses ultrasound waves to obtain images. This examination method is the most informative for cardiomyopathies, as it helps to see the chambers of the heart and its walls with your own eyes. An echocardiography device can measure wall thickness, cavity diameter, and in Doppler mode ( dopplerography) – and blood flow speed. It is on the basis of this study that the final diagnosis is usually made.In case of cardiomyopathies, echocardiography can reveal the following characteristic abnormalities:
- With dilated form the heart cavity expands without significant thickening of the walls. At the same time, other chambers of the heart may be slightly enlarged. The valves may still work normally. The ejection fraction of blood decreases by at least 30–35%. Blood clots may appear in the enlarged cavity.
- In hypertrophic form thickening of the wall and limitation of its mobility are revealed. In this case, the chamber cavity is often reduced. Many patients are found to have problems with their valves. When the left ventricle contracts, blood is partially thrown back into the atrium. Turbulence in the bloodstream leads to the formation of blood clots.
- With a restrictive form Thickening of the endocardium is detected ( to a lesser extent – myocardium) and a decrease in left ventricular volume. There is a violation of filling the cavity with blood in diastole. The disease is often accompanied by insufficiency of the mitral and tricuspid valves.
- For specific forms it is possible to detect a focus of fibrosis, valve disorder, fibrous pericarditis or other diseases that led to the development of cardiomyopathy.
Radiography
A chest x-ray is a diagnostic procedure in which a beam of x-rays is passed through the patient's body. It gives an idea of the tissue density, shape and size of the organs of the chest cavity. This study involves dosed ionizing radiation, so it is not recommended to conduct it more often than once every six months. In addition, there is a category of patients for whom this diagnostic method is contraindicated ( for example, pregnant women). However, in some cases an exception can be made and radiography is carried out taking all precautions. This is typically done to quickly and inexpensively evaluate structural changes in the heart and lungs.X-rays in most cases indicate an increase in the contours of the heart, its shape ( takes the shape of a ball) and displacement of the organ in the chest. Sometimes it is possible to see a more accentuated pattern of the lungs. It appears due to dilation of the veins when there is stagnation in the pulmonary circulation. It is almost impossible to recognize the type of cardiomyopathy based on X-ray results.
In addition to the above basic methods, the patient may be prescribed a number of different diagnostic procedures. They are necessary to detect concomitant diseases, which is especially important if secondary cardiomyopathy is suspected. Then it is necessary to detect and diagnose the primary pathology to begin effective treatment.
The following diagnostic procedures may be prescribed for patients with cardiomyopathies:
- ECG with stress ( bicycle ergometry). This method allows us to identify how the work of the heart and basic physiological indicators change during physical activity. Sometimes this helps to give the patient the right recommendations for the future and assess the risk of complications.
- General and biochemical blood test. Many storage diseases can alter the peripheral blood pattern and the concentrations of many chemicals. Exactly Blood test for hormones. This study allows us to identify endocrine diseases that could cause cardiomyopathy.
- Coronary angiography and ventriculography. These procedures are invasive methods in which a special contrast agent is injected into the cavity of the heart or into the lumen of the coronary vessels. It allows you to better see the contours of the organ and blood vessels on an x-ray. Typically, these studies are prescribed only to some patients when deciding on surgical treatment. The reason is the difficulty of performing these diagnostic procedures and their high cost.
- Biopsy of the endocardium and myocardium. This procedure involves taking a tissue sample directly from the heart wall. To do this, a special catheter is inserted into the organ cavity through a large vessel. This method is used extremely rarely due to the high risk of complications and complexity of implementation. But the obtained material often allows us to identify the cause of fibrosis, the presence of congenital abnormalities of muscle tissue or the nature of the inflammatory process.
- Genetic research. Genetic studies are prescribed for those patients who have already had cases of heart pathology in their family ( not necessarily cardiomyopathy). They suspect hereditary causes of the disease and conduct DNA testing. When defects in certain genes are detected, a correct diagnosis can be made.
Treatment of cardiomyopathy
Treatment tactics for cardiomyopathy depend entirely on whether the pathology is primary or secondary, as well as on the mechanisms that led to heart failure. For secondary cardiomyopathies, treatment is aimed at eliminating the primary disease ( for example, taking anti-inflammatory drugs and antibiotics for myocardial infections). In primary forms, attention is paid to compensation of heart failure and restoration of heart function. Thus, an accurate diagnosis is necessary to begin treatment. Patients with suspected cardiomyopathy are recommended to be hospitalized until its final formulation. However, in the absence of severe symptoms, diagnosis and treatment on an outpatient basis is allowed ( with periodic visits to a cardiologist or therapist).
Cardiomyopathy can be treated in the following ways:
- drug treatment;
- surgery;
- prevention of complications.
Drug treatment
Drug or conservative treatment plays the most important role in the treatment of cardiomyopathy. With the help of various pharmaceutical drugs, doctors try to restore normal heart function, and, above all, compensate for heart failure. At the same time, the so-called “unloading of the heart” is carried out. The fact is that even pumping the usual volume of blood can be a problem for a diseased heart. A variety of groups of drugs can be used for these purposes.Drugs used in the treatment of various types of cardiomyopathies
| Group of drugs | Mechanism of action | Name of the drug | Recommended dosage |
| Angiotensin-converting enzyme inhibitors | Drugs in this group reduce blood pressure and stress on the heart. This slows the progression of heart failure. | Enalapril | From 2.5 mg 2 times a day. |
| Ramipril | From 1.25 mg 1 time per day. | ||
| Perindopril | From 2 mg 1 time per day. | ||
| Beta blockers | This group of drugs fights well against arrhythmias and tachycardia, which are observed in most patients with cardiomyopathies. | Metoprolol | 50 – 100 mg 2 times a day. |
| Propranolol | 40 – 160 mg 2 – 3 times a day. | ||
| Calcium channel blockers | They also fight arrhythmia and stabilize the functioning of the heart muscle. | Verapamil | 40 – 160 mg 3 times a day. |
| Diltiazem | 90 mg 3 – 4 times per day. |
If necessary, the doctor can greatly change the doses of the above drugs and add drugs from other pharmaceutical groups. For example, diuretics ( diuretics) reduce swelling in congestive heart failure and relieve the first signs of pulmonary edema. Antiplatelet drugs fight the formation of blood clots and reduce the likelihood of thromboembolism. Cardiac glycosides increase heart contractions, which compensates for disturbances in dilated cardiomyopathy. The only rule for their use is mandatory consultation with a specialist. Without it, the risk of severe complications and even death of the patient is high.
Surgery
Surgical treatment for cardiomyopathies is rarely used. It is usually necessary in secondary forms of this disease to eliminate the cause that caused the problem. For example, cardiomyopathies associated with congenital heart defects often require surgery to replace heart valves. The advisability of surgical treatment in each specific case should be discussed with the attending physician.Prevention of complications
Such situations often arise ( especially in primary cardiomyopathies), when there is no complete treatment for the pathology. Then the patient has to learn to live with his illness. First of all, this involves changing your lifestyle and eliminating factors that can cause complications.Prevention of complications of cardiomyopathy involves compliance with the following rules:
Quitting sports entirely is not the best option, as movement promotes blood circulation and eases the work of the heart. However, heavy physical activity sharply increases the myocardial oxygen demand and increases the risk of ischemia.Complications of cardiomyopathy
The development of cardiomyopathy is associated with the risk of many different complications that can threaten the patient's life. Preventive measures and therapeutic measures are aimed at preventing these complications. The most dangerous complications of cardiomyopathy are:
- heart failure;
- myocardial infarction;
- thromboembolism;
- arrhythmias;
- pulmonary edema.
Heart failure
As mentioned above, with different types of cardiomyopathy, a variety of types of heart failure can occur. The most common is chronic deficiency. It manifests itself as a gradual decrease in cardiac output and oxygen starvation of tissues.Acute heart failure develops suddenly and can take the form of cardiogenic shock. Without urgent resuscitation measures, it quickly leads to the death of the patient, since the lack of oxygen is fatal to brain cells.
From the point of view of the development of heart failure, a distinction is made between systolic and diastolic forms. Systolic is a weakening of heart contraction and a decrease in ejection fraction. It usually occurs with dilated cardiomyopathy. The development of diastolic heart failure is based on insufficient filling of the ventricle with blood during its relaxation. This mechanism is more typical for restrictive cardiomyopathy.
Myocardial infarction
A heart attack is an acute necrosis of an area of the heart muscle due to lack of oxygen. It is the most serious form of manifestation of ischemic heart disease. Most often, a heart attack occurs in patients with hypertrophic cardiomyopathy, since their myocardium needs more oxygen and nutrients. Congenital anomalies of the structure of the coronary arteries, atherosclerosis and hypertension greatly increase the risk of this complication.A heart attack is manifested by sharp pain behind the sternum, which can radiate to the left shoulder. The patient quickly turns pale, cold sweat and shortness of breath appear. The pulse may be very weak and irregular. With timely intervention, myocardial necrosis can be stopped. If the patient survives, a patch of connective tissue forms at the site of death of healthy cells ( post-infarction focal cardiosclerosis). This, in turn, will worsen heart failure in the future.
Thromboembolism
As noted above, any form of cardiomyopathy carries a risk of blood clots. This is due to a disruption in the normal flow of blood from one chamber of the organ to another. Various turbulences and stagnation of fluid in the heart lead to activation of the so-called coagulation system. Thanks to it, platelets and other blood cells stick together to form a blood clot.Thromboembolism is the release of a formed blood clot from the heart cavity and its fixation in one of the peripheral vessels. This causes an abrupt cessation of blood supply to an organ or anatomical area. Because of this, tissue begins to die.
The most dangerous types of thromboembolism are:
- pulmonary embolism ( when a blood clot has formed in the right side of the heart);
- ischemic stroke ( if a blood clot gets to the brain);
- intestinal necrosis ( with blockage of the mesenteric arteries supplying the intestines);
- thrombosis of the vessels of the extremities, which leads to tissue death and gangrene.
Arrhythmias
As noted above, arrhythmias occur in almost 90% of patients with cardiomyopathies. They are caused by structural changes in tissues, due to which the bioelectric impulse cannot propagate normally throughout the myocardium. Depending on the location of the arrhythmia, supraventricular ( atrial) and ventricular forms. Ventricular arrhythmia is considered the most dangerous, since with it there is practically no pumping of blood through the systemic circulation.Pulmonary edema
Pulmonary edema develops due to severe stagnation of blood in the vessels of the pulmonary circulation. This complication is observed with congestive cardiomyopathies in the left side of the heart. If the atrium or ventricle stops pumping a normal volume of blood, excess blood accumulates in the vessels of the lungs. Gradually they expand and the liquid part of the blood ( plasma) begins to leak through the walls of the alveoli.The accumulation of fluid in the alveoli is accompanied by severe respiratory distress, moist rales, and the release of feathery pink sputum. There is practically no exchange of gases between arterial air and blood. Without urgent medical attention, pulmonary edema leads to the death of the patient from respiratory and circulatory arrest.
Myocardial dystrophy during menopause.
Myocardial dystrophy in thyrotoxicosis.
Alcoholic myocardial dystrophy.
ICD 10
G62.1 Alcoholic myocardial dystrophy.
Causes of myocardial dystrophy.
The causes are diseases and conditions leading to depletion, mutation and decreased performance of heart muscle cells.
Hypovitaminosis and avitaminosis (insufficient intake or absence of vitamins in the body).
Fasting (improper therapeutic fasting, diets).
General dystrophy, cachexia (in severe, long-term debilitating diseases).
Myasthenia gravis, myopathy (neuromuscular disorders).
Toxic poisoning (carbon monoxide, barbiturates, alcoholism, drug addiction).
Thyrotoxicosis (thyroid disease).
Anemia (anemia).
Endocrine disorders (disorders of protein, fat and carbohydrate metabolism).
Water-electrolyte imbalance (dehydration).
Hormonal imbalance (menopause).
Pathogenesis and pathological anatomy.
- Violation of central regulation leads to increased myocardial oxygen demand.
- ATP production and oxygen use are reduced.
- Activation of peroxidation and accumulation of free radicals leads to further damage to the myocardium.
Clinical manifestations
Unpleasant sensations and discomfort in the heart area.
Stitching, aching and pressing pain in the heart.
Shortness of breath on exertion.
General weakness.
Decreased performance and exercise tolerance.
Heart rhythm disturbances (arrhythmias).
Swelling may appear in the legs.
Expanding the boundaries of the heart.
Heart sounds are muffled, systolic murmur is at 1 point.
The most common variants of myocardial dystrophy.
Long-term alcohol consumption (chronic alcoholism) leads to disruption of cellular structures and metabolic processes in the myocardium.
Develops in women after 45–50 years (during menopause or after it).
Diagnosis of myocardial dystrophy.
There is no specific diagnosis of myocardial dystrophy.
The diagnosis is made based on:
clinical symptoms;
ECG signs are an increase in heart rate (tachycardia), arrhythmia and smoothness of the T wave;
X-ray of the heart: increase in size;
Myocardial biopsy.
Cardiomyopathies (CM)- disease of the myocardium, accompanied by its dysfunction.
In 2006, the American Heart Association (American Heart Association) proposed a new definition of CMP.
Definition of cardiomyopathy
Cardiomyopathy- a heterogeneous group of diseases of various etiologies (often genetically determined), accompanied by mechanical and/or electrical dysfunction of the myocardium and disproportionate hypertrophy or dilatation.
Classification of ILC.
Types of cardiomyopathies (WHO, 1995):
Hypertrophic;
Dilation;
Restrictive;
Arrhythmogenic dysplasia of the right ventricle;
Unclassifiable.
The AHA also proposed a new classification of ILC:
Primary cardiomyopathy is a disease in which isolated myocardial damage occurs.
Secondary cardiomyopathy is myocardial damage that develops as a result of a systemic (multiple organ) disease.
HYPERTROPHIC CARDIOMYOPATHY
DEFINITION
HCM is a hereditary disease characterized by asymmetric hypertrophy of the left ventricular myocardium.
I 42.1. Obstructive hypertrophic cardiomyopathy.
I 42.2. Other hypertrophic cardiomyopathy.
EPIDEMIOLOGY
The incidence of this pathology varies in different populations (for example, in Greece the prevalence of HCM is 1.5–2 times higher than in the USA).
This disease occurs 2 times more often in men than in women.
CLASSIFICATION
Currently, the hemodynamic classification of HCM is accepted.
● Obstructive
● Latent
● Non-obstructive.
ETIOLOGY
HCM is a hereditary disease that is transmitted as an autosomal dominant trait. Currently, about 200 mutations responsible for the development of the disease have been identified.
PATHOGENESIS
● Hypertrophy of the interventricular septum.
● Left ventricular outflow tract obstruction.
● Impaired relaxation of the left ventricular myocardium.
● Myocardial ischemia.
CLINICAL PICTURE
HCM can manifest at any age.
Patients with HCM experience the following most characteristic symptoms:
shortness of breath (14–60%);
chest pain (36–40%);
dizziness, which was regarded as presyncope (14–29%);
syncope (36–64%);
weakness (0.4–24%).
PHYSICAL INVESTIGATION
Inspection. Upon examination, there are no characteristic clinical signs.
Palpation. A high, diffuse apical beat is detected, which is often shifted to the left.
The pulse is accelerated.
Auscultation: systolic murmur, which is detected at the apex and in the fourth intercostal space to the left of the sternum.
LABORATORY TESTS no changes.
DNA analysis of mutant genes is the most accurate method for verifying the diagnosis of HCM.
INSTRUMENTAL RESEARCH
Instrumental studies include:
Electrocardiography (overload and/or hypertrophy of the LV myocardium, rhythm and conduction disturbances),
X-ray examination of the chest: signs of enlargement of the LV and left atrium,
Holter monitoring ECG,
EchoCG is the “gold” standard in the diagnosis of HCM;
Magnetic resonance imaging is indicated for all patients before surgery.
Coronary angiography. It is performed for HCM and constant chest pain (frequent attacks of angina).
INDICATIONS FOR CONSULTATION WITH OTHER SPECIALISTS
To exclude genetic diseases and syndromes, patients should be referred to a genetic counseling specialist.
Consultation with a cardiac surgeon.
DIFFERENTIAL DIAGNOSTICS
HCM must be differentiated from diseases accompanied by LV myocardial hypertrophy.
DILATED CARDIOMYOPATHY
DEFINITION
Dilated cardiomyopathy (DCM) is a primary myocardial lesion that develops as a result of the influence of various factors (genetic predisposition, chronic viral myocarditis, immune system disorders) and is characterized by a pronounced dilation of the chambers of the heart.
I 42.0. Dilated cardiomyopathy.
EPIDEMIOLOGY
The incidence of DCM is 5–7.5 cases per 100,000 population per year. In men, the disease occurs 2–3 times more often, especially at the age of 30–50 years.
Among all types of cardiomyopathies, DCM accounts for 60%.
CLASSIFICATION AND ETIOLOGY
Depending on the etiological factor, DCM is classified into primary (idiopathic, familial, associated with genetic factors) and secondary.
Types of secondary dilated cardiomyopathy:
inflammatory (9%);
ischemic (8%);
cardiomyopathy of pregnant and postpartum women (4.5%);
hypertensive (4%);
with amyloidosis (3%);
with HIV infection (3%);
with chronic alcoholism (3%).
PATHOGENESIS
As a result of the influence of etiological factors on the heart, damage to cardiomyocytes occurs with a decrease in the number of functioning myofibrils.
This leads to the progression of heart failure, expressed in a significant decrease in myocardial contractility with the rapid development of dilatation of the heart cavities.
CLINICAL PICTURE
The disease most often occurs in young and middle-aged people.
In the early stages of the disease, only isolated symptoms of heart failure are detected.
As left ventricular failure progresses, shortness of breath and attacks of suffocation occur, and rapid fatigue and muscle weakness are characteristic.
On palpation, there is a wide apical impulse and a cardiac impulse appears.
On percussion there is cardiomegaly, all boundaries of the heart are expanded.
Auscultation of the heart reveals tachycardia, weakened heart sounds, auscultation of the third and often fourth heart sound, and systolic murmur.
In 40–50% of cases, the course of DCM is complicated by the occurrence of ventricular arrhythmias, which is accompanied by syncope.
Signs of right ventricular failure (swelling in the legs, heaviness in the right hypochondrium, enlargement of the liver and abdomen with the development of ascites) appear later.
DIFFERENTIAL DIAGNOSTICS
Differential diagnosis is carried out with other forms of CMP, and it is also necessary to exclude the presence of a left ventricular aneurysm, aortic stenosis, chronic pulmonary heart disease, etc.
LABORATORY RESEARCH
In primary DCM it is normal, in secondary DCM there is an increase in CPK, LDH, and ASAT in the LBC.
INSTRUMENTAL RESEARCH
X-ray of the chest organs. Expansion of the heart.
ECG at rest: changes in the ST segment and T wave, decreased wave voltage, deformation of the QRS complex, often sinus tachycardia, various rhythm and conduction disturbances
Holter monitoring ECG.
Echocardiography.
Cardiac catheterization and angiography
Endomyocardial biopsy.
RESTRICTION CARDIOMYOPATHY
DEFINITION
Restrictive cardiomyopathy (RCMP) is a rare form of CMP characterized by impaired diastolic filling of the ventricles due to their rigidity.
I 42.3. Endomyocardial (eosinophilic) disease.
I 42.4. Endomyocardial fibroelastosis.
I 42.5. Other restrictive cardiomyopathy.
EPIDEMIOLOGY
RCM is a rare disease. There are no data on its prevalence. The disease is reported sporadically throughout the world.
CLASSIFICATION
It is customary to distinguish primary (idiopathic) and secondary forms of RCM.
ETIOLOGY, PATHOGENESIS
RCM is classified as a group of mixed origin CCM, since they have features of both hereditary and acquired diseases.
Drug-induced restrictive cardiomyopathy can develop during treatment with anticancer drugs.
Radiation restrictive cardiomyopathy. Heart damage from radiation exposure can also lead to RCM. Most of these cases arise as complications of local radiotherapy.
CLINICAL PICTURE
The early stages of restrictive heart disease are characterized by the appearance of weakness, fatigue, and paroxysmal shortness of breath at night.
At later stages, signs of congestive heart failure appear with the development of hepatomegaly, ascites, and swelling of the neck veins.
DIFFERENTIAL DIAGNOSTICS
RCM must be differentiated, first of all, from constrictive pericarditis.
LABORATORY RESEARCH
To diagnose RCM, laboratory tests have no diagnostic value.
INSTRUMENTAL RESEARCH
Electrocardiography. The ECG reveals nonspecific changes in the ST segment and T wave.
Echocardiography.
Cardiac catheterization.
Endomyocardial biopsy.
Cardiomyopathy is a disease in which the heart muscle weakens, stretches, or has other structural abnormalities. This often occurs when the heart cannot function well. Most people with cardiomyopathy have heart failure.
Cardiomyopathy (CM) is a group of diseases that are associated with similar mechanisms of action on the heart muscle. At first, several symptoms may appear or there may be no clinical symptoms at all. Some patients complain of shortness of breath, feeling tired, or swollen legs due to heart failure. Irregular heart rhythm, as well as pre-fainting and fainting conditions may be a concern. Victims have an increased risk of sudden cardiac death.
In 2015, 2.5 million people were diagnosed with cardiomyopathy and myocarditis. Hypertrophic cardiomyopathy affects approximately 1 in 500 people, and dilated cardiomyopathy affects 1 in 2500. Since 1990, ILC has caused 354,000 deaths. Arrhythmogenic right ventricular dysplasia is more common in young people.
Some people with cardiomyopathy have no signs or symptoms and do not need treatment. In other patients, the disease develops quickly, the clinical picture is severe, and serious complications arise in the future. In such cases, treatment is required, which includes lifestyle changes and medications. Surgery may be involved, and a device may be implanted to correct arrhythmias. If necessary, non-surgical procedures are prescribed.
Video Cardiomyopathies - general characteristics
Description
In cardiomyopathy, the heart muscle changes. It may enlarge, thicken, or become stiffer and unable to contract. In rare cases, the muscle tissue in the heart is replaced by scar tissue.
In the International Classification of Diseases, Tenth Revision (ICD-10), the group of cardiomyopathies is coded I42.
As cardiomyopathy progresses, the heart becomes weaker. It pumps blood less intensively throughout the body and is not able to maintain a normal heart rhythm.
In severe cases, CMP leads to heart failure or irregular heartbeats called arrhythmias. In turn, heart failure can cause blood to pool in the lungs, legs, or abdomen. A weakened heart can also cause other complications, such as problems with the heart valves.
Depending on changes in the myocardium, cardiomyopathy is classified into the following types:
- Hypertrophic cardiomyopathy (including asymmetric obstructive hypertrophy with muscular subaortic stenosis)
- Dilated cardiomyopathy (congestive, congestive)
- Obstructive cardiomyopathy (constrictive, restrictive)
Depending on the cause of development, cardiomyopathies are divided into the following forms:
- Alcoholic cardiomyopathy
- Pericardial cardiomyopathy
- Cocaine cardiomyopathy
- Drug-induced cardiomyopathy
- Arrhythmogenic right ventricular dysplasia
- Takotsubo cardiomyopathy
Unskilled cardiomyopathy is considered separately. Cardiomyopathy in children is of great importance, since in such cases there are certain features of the course of the disease, its diagnosis and treatment.
Causes
There are acquired and hereditary cardiomyopathy. “Acquired” means that a person is not born with this disease, but it develops during life against the background of another disease, condition or factor.
“Hereditary” means that parents passed on to their child the gene responsible for the development of cardiomyopathy. Researchers continue to look for genetic links to cardiomyopathy and are also studying how these links cause or contribute to different types of the disease.
In many cases, the cause of cardiomyopathy is unknown. This often occurs when the disease develops in children.
Reasons for the development of certain forms of cardiomyopathy:
- Hypertrophic cardiomyopathy is most often inherited. It is caused by a mutation or change in certain genes in the heart muscle proteins. It can also develop over time due to high blood pressure, aging, or other diseases such as diabetes or thyroid disease. Sometimes the cause of the disease is unknown.
- Dilated cardiomyopathy. The cause of extended CMP is often unknown. About a third of people who have this disease inherit it from their parents.
- Obstructive cardiomyopathy. The most common causes of this form of CMP are amyloidosis (a disease in which abnormal proteins accumulate in organs, including the heart), connective tissue overgrowth, hemochromatosis (a disease in which too much iron accumulates in the body), sarcoidosis (a disease that causes inflammation and may affect various organs), some cancer treatments such as radiation and chemotherapy.
Certain diseases, circumstances and substances can also contribute to the occurrence of cardiomyopathy:
- Alcohol, especially in combination with poor diet
- Some toxins such as poisons and heavy metal salts
- Complications during the last months of pregnancy
- A number of diseases: coronary heart disease, myocardial infarction, high blood pressure, diabetes, thyroid disease, viral hepatitis and HIV
- Use of drugs such as cocaine and amphetamine, and some drugs used to treat cancer
- Infections, especially viral ones, which have a tropism for the heart muscle.
Risk factors
People of all ages and races can develop cardiomyopathy. However, certain types of disease are more common in certain groups.
Dilated cardiomyopathy is more common in African Americans than in whites. This type of disease is also more common among men than women.
Adolescents and young adults are more likely than older adults to develop arrhythmogenic right ventricular dysplasia, although this form of cardiomyopathy is rare in both age groups.
Main risk factors
- Family history of cardiomyopathy, heart failure, or sudden cardiac arrest
- Having a medical condition that may be complicated by cardiomyopathy (coronary heart disease, heart attack, or a viral infection that affects the heart muscle)
- Diabetes or other metabolic diseases, including severe obesity
- Diseases that can damage the heart, such as hemochromatosis, sarcoidosis, or amyloidosis
- Frequent increases in blood pressure
- Asymptomatic cardiomyopathy
- Chronic alcoholism.
Identifying people who may be at high risk of disease is very important. This may help prevent serious problems in the future, which could include severe arrhythmia (irregular heartbeats) or sudden cardiac arrest.
Video Cardiomyopathy - symptoms, causes and risk groups
Kinds
The main types of cardiomyopathy such as hypertrophic, dilated, obstructive, unskilled, as well as arrhythmogenic dysplasia of the right ventricle will be considered.
Hypertrophic cardiomyopathy
It is very common and can develop in people of any age. The disease is equally common in both men and women. It occurs in approximately 1 in every 500 people.
Hypertrophic cardiomyopathy occurs when the heart muscle becomes enlarged and thickened for no apparent reason. Typically, the ventricles (the lower chambers of the heart) and the septum (the wall that separates the left and right sides of the heart) thicken. The affected areas cause narrowing and blockage of the ventricles, which makes it even more difficult for the heart to pump blood. Hypertrophic cardiomyopathy can also increase the stiffness of the ventricular myocardium, change the structure of the mitral valve, and provoke cellular abnormalities in the heart tissue.
Dilated cardiomyopathy
This form of cardiomyopathy is characterized by dilatation and weakening of the ventricles. Most often, the left ventricle is affected first; over time, the pathological process can spread to the right ventricle. Weakened heart chambers do not work as efficiently to ensure normal blood circulation throughout the body. As a result, over time the heart loses its ability to pump blood effectively. Dilated cardiomyopathy can be complicated by heart failure, heart valve disease, irregular heart rhythm, and blood clots in the chambers of the heart.
Obstructive cardiomyopathy
The disease develops in cases where the stiffness of the ventricular myocardium increases, although the walls of the heart do not thicken. As a result, the ventricles do not fully relax, which means they are not filled with a normal volume of blood. As the disease progresses, cardiac output falls and the heart muscle weakens. Over time, restrictive cardiomyopathy can lead to heart failure and problems with the heart valves.
Arrhythmogenic right ventricular dysplasia
The pathology is a rare type of cardiomyopathy that most often occurs when the myocardium of the right ventricle is replaced by fatty or connective tissue. This often leads to disturbances in the heart's electrical signals, leading to arrhythmias. Arrhythmogenic right ventricular dysplasia is usually diagnosed in adolescents or young adults. In severe cases, it can cause sudden cardiac arrest in young athletes.
Unclassified cardiomyopathy
- Hypertrabelarity of the left ventricle (is a congenital cardiomyopathy in which a normal and second “spongy” layer of myocardium is found inside the left ventricle).
- Takotsubo cardiomyopathy, or broken heart syndrome, develops due to extreme stress, which leads to heart failure. Although this phenomenon is rare, this disease is more often diagnosed in postmenopausal women.
Clinic
Some people who have cardiomyopathy have no signs or symptoms. In others, the clinical picture in the early stages of the disease is mild.
As cardiomyopathy progresses, the patient's general condition worsens and heart function weakens. This usually results in signs and symptoms of heart failure, which include:
- Shortness of breath or difficulty breathing, especially with exercise
- Fatigue or severe weakness
- Swelling in the ankles, legs, abdomen and veins in the neck
Other symptoms of cardiomyopathy may include dizziness; delusional; fainting during physical activity; arrhythmia (irregular heartbeats); chest pain, especially after exercise or heavy meals. Heart murmurs are also often detected - these are additional or unusual sounds that are heard during the heartbeat.
Diagnostics
The diagnosis of cardiomyopathy is made based on the patient's medical and family history, as well as physical examination and results of laboratory tests/instrumental procedures.
Consultation with specialists
Cardiomyopathy is primarily dealt with by a cardiologist or pediatric cardiologist who evaluates and treats the patient. A cardiologist specializes in the diagnosis and treatment of cardiovascular diseases. A pediatric cardiologist is a doctor who treats children.
Medical and family history
A survey of the patient is conducted, during which the complaints and symptoms presented by the patient are determined. It also finds out how long the symptoms of the disease bother the patient.
The doctor may ask if anyone in the patient's family has cardiomyopathy, heart failure, or sudden cardiac arrest.
Physical examination
During the physical examination, the doctor will use a stethoscope to listen to the heart and lungs, which can be used to detect sounds that often indicate cardiomyopathy. Such auscultatory signs may even allow us to make a presumptive conclusion regarding the type of disease.
For example, with obstructive and hypertrophic cardiomyopathy, loud heart murmurs are detected. It is also common to hear a “crunching” sound in the lungs, which can also be a sign of heart failure, which most often develops in the later stages of cardiomyopathy.
Additionally, there may be swelling in the ankles, feet, abdomen, or veins in the neck, which indicates fluid accumulation (a sign of heart failure).
Diagnostic tests
- Blood analysis. During the test, a small amount of blood is taken. Most often, they take it from a vein in the arm using a special needle. The procedure is usually quick and easy, although some short-term discomfort is common. A blood test helps determine the general condition of the patient.
- Chest X-ray records on film an image of the organs and structures located in the chest (heart, lungs and blood vessels). This test can show if the heart is enlarged or if there is fluid in the lungs.
- ECG is a simple diagnostic method that records the electrical activity of the heart. Shows how fast the heart beats and what its rhythm is (normal or irregular). An ECG also records the strength and timing of electrical signals as they pass through each chamber of the heart.
- Holter monitoring. The patient is asked to wear a small, portable device for 24 or 48 hours that records the electrical activity of the heart while the person goes about their daily activities.
- Echocardiography (echoCG) is a test that uses sound waves to create a moving image of the heart. The monitor shows the work of the organ, its size and shape. There are several types of echocardiography, including stress testing. This study is conducted similar to a stress test. A stress echo may show decreased blood flow to the heart as well as signs of coronary artery disease. Another type of echocardiography is a transesophageal study, which gives an idea of deep-seated lesions in the heart.
- Stress test. Some heart problems are easier to diagnose when the organ is under strain. During stress testing, the patient exercises or takes medication to increase their heart rate. This type of testing may be combined with cardiac scanning, echocardiography and cardiac positron emission tomography.
Diagnostic procedures
Confirming the diagnosis may require one or more medical procedures to confirm the diagnosis or prepare the patient for surgery. These studies may include cardiac catheterization, coronary angiography, or myocardial biopsy.
- Cardiac catheterization. This procedure determines blood pressure and blood flow in the chambers of the heart. It also makes it possible to collect blood samples and evaluate the condition of the arteries of the heart using X-rays. During cardiac catheterization, a long, thin, flexible tube called a catheter is placed in a blood vessel in the arm or in the groin (upper thigh) or neck and guided into the heart.
- Ischemic angiography. This procedure is often combined with cardiac catheterization. During the study, a dye that can be seen on an x-ray is injected into the coronary arteries, thereby examining the hemodynamics of the heart and blood vessels. Dye can also be injected directly into the chambers of the heart. This allows the doctor to study cardiac output function.
- Myocardial biopsy. During this procedure, the doctor removes a small part of the heart muscle. For this purpose, cardiac catheterization is performed. Subsequently, the taken biopsy of the heart muscle is studied under a microscope, as a result of which changes in the cells are visible. Myocardial biopsy is used to diagnose some types of cardiomyopathy.
- Genetic testing. Certain types of cardiomyopathy run in families. Genetic testing is used to look for the disease in a patient's parents, siblings, or other family members. If the test shows that a person is likely to get the disease, the doctor can begin treatment early in the disease's development, when medications work best.
Treatment
If you have cardiomyopathy without signs or symptoms, treatment is often not prescribed. Sometimes, extensive cardiomyopathy that develops suddenly may go away on its own. In other cases, cardiomyopathy requires treatment, which depends on the type of disease, severity of symptoms, associated complications, and the age and general health of the patient.
Treatment for cardiomyopathy may include:
- Lifestyle change
- Use of medications
- Undergoing non-surgical procedures
- Surgical exposure
- Device implantation
- Heart transplant
The main goals of treatment for cardiomyopathy include:
- Monitoring clinical manifestations so that the patient has a normal quality of life
- Management of predisposing factors that cause or contribute to disease
- Preventing complications and the risk of sudden cardiac arrest
Lifestyle change
To improve the general condition of the patient, it is useful to adhere to the following recommendations:
- Practice healthy eating
- Keep body weight within acceptable limits
- Avoid stressful situations
- To live an active lifestyle
- Stop smoking
Use of medications
Various medications are used to treat cardiomyopathy. In particular, drugs are prescribed for:
- Restoring electrolyte balance in the body. Electrolytes are necessary to maintain fluid levels and acid-base balance within acceptable limits. They are also involved in the functioning of muscles and nerve fibers. Poor electrolyte concentrations can be a sign of dehydration (lack of fluid in the body), as well as heart failure, high blood pressure, or other diseases. Aldosterone blockers are often used to regulate electrolyte balance.
- Normalization of heart rate. Antiarrhythmic drugs help prevent the development of arrhythmia because they adjust the heart to a normal rhythm.
- Reduced blood pressure. ACE inhibitors, angiotensin II receptor blockers, beta blockers, and calcium channel blockers are used to effectively lower blood pressure.
- Preventing the formation of blood clots. Anticoagulants are most often prescribed for this purpose. Such drugs are especially indicated in the presence of dilated cardiomyopathy.
- Reducing the inflammatory process. A similar goal is achieved with the help of drugs from the group of corticosteroids.
- Eliminate excess sodium. Diuretics and cardiac glycosides are mainly used, which remove sodium from the body and reduce the amount of fluid in the blood.
- Slow heart rate. Beta blockers, calcium channel blockers and digoxin are used. These groups of drugs are also used to lower blood pressure.
Medicines prescribed by your doctor should be taken regularly. You should not change the dosage of the drug or skip a dose unless your doctor tells you to do so.
Video Dilated cardiomyopathy. Symptoms, Signs and Treatments
Surgical exposure
Doctors use several types of surgery to treat cardiomyopathy. Depending on the indications, septal myectomy, device implantation, or heart transplantation are performed.
- Septal myectomy
The operation we present is performed on an open heart. Used to treat people with hypertrophic cardiomyopathy to relieve severe symptoms. It is prescribed to young patients in case of lack of effect from the medications they are taking, as well as to those patients for whom medications do not help well.
During the operation, the surgeon removes part of the thickened septum that protrudes into the left ventricle. This improves the hemodynamics of the heart and the overall blood supply system. After removal, the myocardium does not grow. If necessary, the surgeon can also repair or replace the mitral valve at the same time. Septal myectomy is often successful and allows you to return to normal life without symptoms.
- Device implantation
Surgeons may place several types of devices in the heart to improve function and relieve symptoms, including:
- Device for cardiac resynchronization therapy. With its help, contractions of the left and right ventricles of the heart are coordinated.
- Cardioverter-defibrillator. Helps control life-threatening arrhythmias that can lead to sudden cardiac arrest. This small device is implanted in the chest or abdomen and connected to the heart through special wiring. If a dangerous change in heart rhythm occurs, then an electrical signal is sent to the myocardium to help restore normal heartbeat.
- Left Ventricular Assist Device. Helps the heart pump blood throughout the body. Can be used for long-term therapy or short-term treatment of people awaiting a heart transplant.
- Pacemaker. This small device is placed under the skin of the chest or abdomen to monitor various forms of arrhythmia. The device works by generating electrical impulses, which causes the heart to beat at a normal speed.
Heart transplant
For this operation, the surgeon replaces a person's diseased heart with a healthy one taken from a deceased donor. Heart transplantation is the latest treatment option for people with heart failure, which is often a complication of cardiomyopathy. In such cases, the patient's condition is so serious that all types of treatment, except heart transplantation, cannot be successful.
Non-surgical procedures
Doctors may use non-surgical methods such as ablation to treat alcohol-related cardiomyopathy. During this procedure, the doctor injects an ethanol solution through a tube into a small artery that supplies blood to a thickened area of the heart muscle. The alcohol kills the cells, causing the thickened myocardium to shrink to a more normal size. After this procedure, blood flows more freely through the ventricle, which improves the clinical picture.
Forecast
The prognosis for cardiomyopathy depends on many different components, including:
- Cause and type of cardiomyopathy
- How well does the body respond to treatment?
- Severity and severity of the clinical picture
The occurrence of heart failure during CMP most often indicates a long-term (chronic) course of the disease. Over time, the condition may worsen. Some people develop severe heart failure that requires surgery. In extreme cases, medications, surgeries, and other treatments may no longer help.
Prevention
It is almost impossible to prevent the development of hereditary types of cardiomyopathy. However, you can take steps to reduce the risk of diseases or conditions that can lead to or complicate cardiomyopathy. In particular, prevention of coronary heart disease, high blood pressure and myocardial infarction should be carried out.
If necessary, the doctor may advise you to make changes to your usual lifestyle. Most often recommended:
- Avoid alcohol and drugs
- Getting enough sleep and rest
- Eat a heart-healthy diet
- Get enough physical activity
- Don't give in to stress
- Quit smoking
Cardiomyopathy can be caused by an underlying disease or condition. If it is treated at an early stage of development, then complications of CMP can be prevented. For example, it is important to promptly control high blood pressure, high blood cholesterol and diabetes:
Video About the most important thing: Cardiomyopathy
“... any classification is incomplete and acts as a bridge between complete ignorance and absolute understanding...” (Goodwin J.F. The frontiers of cardiomyopathy // Brit. Heart. J. - 1982. - Vol. 48. - P.1-18.)
"Cardiomyopathy" (CM) translated from Greek (kardia - heart; mys, myos - muscle; pathos - suffering, disease) means "disease of the heart muscle." This term was first proposed by W. Bridgen in 1957 and was used to refer to myocardial diseases of unknown etiology, characterized by the appearance of cardiomegaly, ECG changes and a progressive course with the development of circulatory failure and an unfavorable prognosis for life. The same interpretation of the ILC was adhered to by J.F. Goodwin, which in the period 1961–1982. conducted a number of fundamental studies on this problem. In 1973, he proposed the following definition of CMP: “acute, subacute or chronic damage to the cardiac muscle of unknown or unclear etiology, often involving the endocardium or pericardium, and not due to structural deformation of the heart, hypertension (systemic or pulmonary) or coronary atheromatosis.” It was J.F. Goodwin first identified three groups of CMP: congestive (dilated - DCM), hypertrophic (HCM) and restrictive (RCMP).
The next step was a meeting of a special group of experts of the WHO, the International Society and the Federation of Cardiology (WHO/IFC) in 1980. In its report, the WHO/IFC defined CMP as “a disease of the heart muscle of unknown etiology.” At the same time, three groups of myocardial diseases were identified: unknown etiology (KMP), specific (of known etiology or associated with lesions of other organs and systems) and unspecified (cannot be attributed to any of the above groups). According to the 1980 WHO/IFC report, the term “cardiomyopathy” should have been used only in relation to myocardial diseases of unknown etiology and not used in relation to diseases of known etiology. This classification reflected the actual state of knowledge at that time: the etiology of the vast majority of CMPs was unknown and, therefore, they were considered idiopathic.
In 1995, a WHO/IFC expert working group revised the nomenclature and classification issues and proposed calling CMP “myocardial diseases that are associated with cardiac dysfunction.” At the same time, it was recommended to use the term “specific cardiomyopathy” to refer to myocardial lesions of known etiology or that are a manifestation of systemic diseases. This was a serious step forward. First, the term “cardiomyopathy” itself was clarified. Secondly, a number of new nosological units were introduced into the classification. For the first time, arrhythmogenic right ventricular cardiomyopathy was identified. The subsection of “unclassified” CMP was significantly expanded, which included fibroelastosis, noncompacted myocardium, systolic dysfunction with minimal dilatation, and mitochondrial involvement. The group of “specific” CMP was clarified and expanded, which included ischemic, valvular, hypertensive, peripartum CMP, etc. The change in terminology and clarification of the classification became possible thanks to scientific advances in the field of studying the etiology and pathogenesis of CMP. In particular, the role of viral infection in the origin of not only myocarditis, but also idiopathic dilated cardiomyopathy has been more clearly defined. Much data has emerged on the pathogenetic role of genetic factors in the development of CMP. As a result, the lines between idiopathic and specific CMPs began to blur.
Over the past 20 years, tremendous advances have been made in understanding the mechanisms of myocardial dysfunction and damage. A large number of clinical and population studies have been conducted, invasive and non-invasive research methods have been introduced and improved (echocardiography, Doppler echocardiography, magnetic resonance and computed tomography, endomyocardial biopsy, radioisotope research methods, etc.), and new histological data have been obtained. The use of molecular biology and genetics methods played an important role in clarifying the pathogenesis of CMP. These methods have contributed to a deeper understanding of the molecular basis of pathological processes in the myocardium. With the in-depth study of CMP, not only new diseases were identified, but also a number of difficulties appeared in determining their “class”. Increasingly, early and atypical manifestations of the disease, the development of a pathological process with minimal classical manifestations, and unusual forms that do not belong to any of the generally accepted categories of diseases have begun to be identified. As genetic research has advanced, medical science has faced a number of challenges. Firstly, the existence of a whole group of ILCs that are inherited was finally proven. Secondly, the question arose about the lack of a clear division between the concepts of “norm” and “not normal” in people with genetic disorders. Third, as a wide range of mutations leading to the development of CMP have been identified, a serious problem with the “overlap” of phenotypes has arisen. At the beginning, it was generally accepted that mutations in one gene lead to the development of one disease. Today the genetic formula has expanded significantly. It is already known that mutations of one gene can cause the development of many diseases with different phenotypic manifestations. Moreover, it has been proven that the development of one disease can be caused by mutations in several genes. Fourthly, many questions have arisen due to the lack of correlation between macro- and microscopic features in a number of diseases. An example is one of the familial forms of HCM with a morphological picture characteristic of this disease and the absence of significant hypertrophy of the walls.
In recent years, publications have increasingly begun to appear in which not only the need to revise the existing classification is discussed, but also new variants are proposed. In particular, in 2004, work was published by a group of Italian researchers, which expressed the opinion that the term “cardiac dysfunction” should imply not only decreased contractility and impaired diastolic function, but also rhythm disturbances, conduction system, and a state of increased arrhythmogenicity (enhanced arrhythmogenicity). In particular, this work raised the question of whether CMP should be considered myocardial dysfunction without visible structural changes, leading to the development of life-threatening cardiac arrhythmias and a high risk of sudden cardiac death? The authors discussed the inclusion of a number of pathologies in the classification of CMP in which genetic defects lead to disruption of ion channels and the risk of developing “electrical paralysis” of the heart. The same work presents a genomic or “molecular” classification of hereditary CMPs. Three groups of diseases have been proposed:
- cytoskeletal CMP (or “cytoskeletopathies”): DCM, arrhythmogenic right ventricular dysplasia (ARVD) and CMP with skin manifestations (Cardiocutaneous syndromes) (E. Norgett et al., 2000);
- sarcomeric CMP (or “sarcomeropathies”): HCM, RCM;
- Ion channel CMP (or “channelopathies”): long and short QT interval syndromes, Brugada syndrome, catecholaminergic polymorphic VT.
In 2006, a new American Heart Association (AHA) classification of CMP was published. It proposed a new definition of CMP as "a heterogeneous group of myocardial diseases associated with mechanical and/or electrical dysfunction, which usually (but not without exception) manifest as inappropriate hypertrophy or dilatation and arise from a variety of causes, often genetic . CMP is limited to the heart or is part of generalized systemic disorders, always leading to cardiovascular death or progression of heart failure...” This classification highlighted:
- Primary cardiomyopathy: isolated (or prevalent) myocardial damage.
- Secondary cardiomyopathy: myocardial damage is part of generalized systemic (multiorgan) diseases.
Among the primary CMPs the following are identified:
- Genetic:
- HCM;
- ARVD;
- non-compact myocardium of the left ventricle;
- disorders of glycogen storage;
- PRKAG2 (protein kinase, AMP-activated, gamma 2 non-catalytic subunit);
- Danon disease;
- conduction defects;
- mitochondrial myopathies;
- ion channel disorders (long QT syndrome (LQTS); Brugada syndrome; short QT syndrome (SQTS); Lenegre syndrome; catecholaminergic polymorphic ventricular tachycardia (CPVT); unexplained sudden nocturnal death syndrome (Asian SUNDS)).
- Mixed:
- DCM and RCM.
- Purchased:
- inflammatory (myocarditis);
- stress-induced (takōtsubo);
- peripartum;
- tachycardia-induced;
- in children born to mothers with insulin-dependent diabetes mellitus.
At first glance, the classification may seem complex and confusing. However, a more detailed examination shows that it is based on two simple principles. Firstly, as in the previous classification, the division according to the “cause-and-effect” principle is preserved: primary and secondary ILCs are distinguished. Secondly, the principle of division is used depending on the possibility of inheritance. Primary CMPs are divided into three groups: hereditary (familial/genetic), non-hereditary (acquired) and mixed CMPs. “Mixed CMP” refers to a group of diseases that can be caused by both genetic defects and develop as a result of the influence of various factors.
What's new in this classification? Its main fundamental differences from previous classifications are:
- new definition of ILC;
- lack of a principle of primary grouping depending on anatomical features;
- for the first time in the official classification, the principle of dividing the IMC depending on the possibility of inheritance was applied;
- new types of ILC have been identified.
Let's look at these differences in more detail.
First, the current classification of the American Heart Association (AHA) recognizes that CMP is a “heterogeneous group” of diseases. In addition, the definition for the first time stated that CMP may be based not only on “mechanical” but also on “electrical” dysfunction. In this regard, “ion channel disorders” or “channelopathies” have been introduced into the group of genetic CMPs. It is assumed that since mutations in ion channel genes are responsible for disruption of the biophysical properties and structure of proteins, i.e. for changes in the structure of surfaces and the architecture of ion channels, then, therefore, we can say that “channelopathies” are a pathology of cardiomyocytes, that is, a disease of the myocardium, and they can be considered CMP.
Secondly, there is no “general” identification of forms of CMP depending on the phenotype, or in other words, on anatomical features. In the new AAS classification, DCM, HCM, RCM and ARVC are actually the third subclass of “primary” CMP. The new classification also does not include “idiopathic,” “specific,” or “unclassified” CMPs. Some of the CMPs that were previously classified in these categories ("non-compact myocardium", mitochondrial CMP, inflammatory CMP, peripartum CMP) are included in the main groups of the modern classification of CMP. Others - fibroelastosis, ischemic, valvular, hypertensive CMP - are not classified as CMP at all.
Thirdly (and this is very important), in the new classification of AAS, in contrast to previous official classifications, for the first time the principle of dividing IMC depending on the possibility of inheritance is used. What does this mean? For the first time, the presence of certain types of ILC, which can be inherited, has been officially recognized. It would seem, what's new in this? The works of J. Towbin et al. are well known. (1994, 2000), P.J. Keeling et al. (1995), K. Bowles et al. (1996), L. Mestroni (1997, 1999). The scientific literature has been discussing the “family” ILC for several years. However, this is the first time such a division has been used in the official classification of the Society of Cardiologists.
Fourthly, the group of acquired ILCs was clarified. For the first time, such forms as tachycardia-induced, stress-induced (takоtsubo) and CMP in children whose mothers suffer from insulin-dependent diabetes mellitus have been identified.
In 2008, a new classification of the European Society of Cardiology (ESC) was published. This classification, as its authors indicate, was created not only to clarify the concept and update the division of CMP into groups, but also for widespread use in everyday clinical practice. Currently, in most clinics in the world, it is not possible to conduct extensive research to identify genetic mutations before the onset of clinical symptoms or before the incidental detection of myocardial pathology. Moreover, the presence of an established genetic defect in a family is not always accompanied by clinical and/or morphological manifestations. In addition, treatment of such patients is extremely rarely started before the diagnosis of CMP is established. Therefore, the EOC classification is more clinically oriented and is based on the division of CMP depending on the morphological and functional changes in the myocardium of the ventricles of the heart.
The EOC defines the concept of ILC somewhat differently than the AAS. According to the ESC, CMP is “a pathology of the myocardium in which its structural or functional disorders occur that are not caused by coronary heart disease, hypertension, valvular defects and congenital heart diseases...” CMP are grouped depending on the morphological or functional phenotype:
- HCM.
- DCM.
- APZhD.
- RCMP.
Unclassified: non-compact myocardium, Takotsubo cardiomyopathy.
All ILC phenotypes, in turn, are divided into:
- Family/family (genetic):
- unidentified gene defect;
- subtype of the disease.
- Non-familial/non-family (non-genetic):
- idiopathic;
- subtype of the disease.
The division of CMP into familial and non-familial is intended to increase physicians' awareness of the genetic determinants of CMP and direct them to conduct specific diagnostic tests, including the search for specific mutations in appropriate cases.
The diagnosis of DCM should be made in cases of dilatation and impaired systolic function of the left ventricle in the absence of causes (coronary heart disease, valvular pathology, hypertension) leading to their development. The DCM phenotype can develop due to mutations in various genes encoding cytoskeletal proteins, sarcomeric proteins, Z-disks, nuclear membranes, defects in the X chromosome, etc. Manifestations of DCM may be present in mitochondrial cytopathies, metabolic disorders (hemochromatosis), deficiency conditions, endocrine diseases, when using cardiotoxic medications, in the late stages of inflammatory processes in the myocardium. A separate form of DCM with moderate ventricular dilatation has been identified: mildly dilated congestive cardiomyopathy. This form is diagnosed in patients with heart failure with severe systolic dysfunction in the absence of significant dilatation (an increase of only 10-15% compared with normal) or restrictive hemodynamics. DCM also includes peripartum cardiomyopathy, which develops in the last month of pregnancy or within 5 months after birth.
Previously, HCM was defined as the development of myocardial hypertrophy not associated with hemodynamic stress and systemic diseases such as amyloidosis or glycogen storage disorders. It was believed that it was necessary to differentiate true hypertrophy of cardiomyocytes from that caused by interstitial infiltration or intracellular accumulation of metabolic substrates. The modern EOC classification proposes a more simplified definition of HCM: “the presence of a thickened wall or an increase in myocardial mass in the absence of factors contributing to their development (hypertension, valvular defects).” This allows us to interpret the term “HCM” somewhat more broadly and not be limited only to a certain phenotype with a single etiology (for example, pathology of sarcomeric proteins).
In the new classification, RCM is defined as a physiological state of the myocardium with normal or reduced volumes (diastolic and systolic) of the cavity of the heart ventricle (one or two) and normal thickness of its (their) walls. It is necessary to distinguish primary RCMP, or idiopathic, from secondary - developed as a result of systemic diseases such as amyloidosis, sarcoidosis, carcinoid disease, scleroderma, anthracycline CM, fibroelastosis, hypereosinophilia syndrome, endomyocardial fibrosis.
The EOC classification is indeed more simplified and closer to clinical practice than the one proposed by the AAS. It provides a greater degree of freedom for making a clinical diagnosis of CMP. However, there is a certain disadvantage to this. For example, the possibility of a broader interpretation of the diagnosis of HCM or a subtype of DCM. In the latter case, the ESC classification suggests considering DCM as sporadic (non-familial, non-genetic) in the absence of the disease in other family members. It is proposed to divide sporadic DCM into “idiopathic” and “acquired”. At the same time, it is indicated that acquired cardiomyopathy are those in which ventricular dysfunction “...is more likely a complication of the disease than its direct manifestation.” However, they miss the fact that, for example, with mutations in mitochondrial RNA, the development of a CMP phenotype is possible, which should be considered both “acquired” and “genetic”. However, these mutations are not necessarily transmitted to subsequent generations.
In conclusion, I would like to note that the emergence of new classifications of AAS and EOC indicates the accumulation of a large amount of new information about the etiology of CMP and a deeper understanding of the pathogenetic mechanisms of this group of diseases. At the same time, these classifications should be regarded only as the next stage, which brings us closer to a complete understanding of the pathological process. The revision of definitions and classification by international societies makes it necessary to make changes to the domestic ILC classification. In this regard, below are drafts of new classifications of cardiomyopathy and myocarditis, which are proposed for use in Ukraine. The projects take into account the changes proposed by the EOC and the AAS.
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V.N. Kovalenko, D.V. Ryabenko
National Scientific Center "Institute of Cardiology named after Academician N.D. Strazhesko" of the Academy of Medical Sciences of Ukraine, Kiev
Ukrainian Journal of Cardiology
