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 It has been known for a long time that very often peculiar changes are observed in the arteries of elderly people: the walls of the arteries are compacted, thickened, in some places flat nodes are visible on them - yellowish or white plaques.
These changes are probably as old as modern mankind: they were even found in Egyptian mummies.
The disease, which is expressed by the compaction and thickening of the walls of the arteries with the formation of numerous flat nodes, or plaques, eventually received the name arteriosclerosis, which translated from Greek means hardening (stiffness) of the arteries. The name of arteriosclerosis is still in use to this day, but about 60 years ago it was proposed to replace it with another term - arterial atherosclerosis. This Greek word also denotes the hardening of the walls of the arteries (sclerosis), but at the same time emphasizes the presence in their walls of areas of shapeless mushy masses (from the Greek word "athere" - gruel). The new name - atherosclerosis - became widespread and almost supplanted the old term - arteriosclerosis. The term atherosclerosis is more accurate, because it includes an indication of both main properties of painfully altered arteries - their hardening and the accumulation of mushy foreign masses in their wall.
Further research showed that these masses are a mixture of various fatty substances, among which there is always a large amount of complex animal fat, which has long been called cholesterol. Naturally, this complex fatty substance has attracted a lot of attention from scientists. It turned out that cholesterol is extremely common in humans and animals. It is included in a small amount in each cell; especially important is its role as a substance that limits the permeability of cell membranes and membranes.
Further, it turned out that cholesterol constantly enters our body from the outside in the composition of many food substances of animal origin. It is especially abundant in the yolks of chicken eggs, animal fat, butter, cream, and brains. In addition, the body has the ability to produce (synthesize) cholesterol itself in the course of metabolic processes. The main organ that synthesizes cholesterol is the liver, but small amounts of this substance are formed in other organs and tissues. At the same time, significant amounts of cholesterol are constantly excreted from the body - mainly with bile.
Thus, the body has a constant exchange of cholesterol: its intake from the outside with food, synthesis in tissues and excretion. In this complex process, many aspects of it have not yet been fully clarified. It is characteristic that cholesterol, like other fatty substances, easily forms complex compounds in the body, especially with proteins. So, in the blood, cholesterol is mainly in combination with some proteins of the blood plasma and in this form constantly circulates in the circulatory system.
The combination of cholesterol with blood proteins determines its solubility in the blood, since free cholesterol in the blood and, in general, is insoluble in aqueous fluids. Being poorly soluble in blood and body juices, cholesterol is relatively easily deposited in them and accumulates in tissues.Such accumulations of cholesterol, along with other fats, as well as protein substances, and make up the bulk of those mushy (atheromatous) deposits in the arteries, which have already been mentioned ...
 The above brief information on the properties and metabolism of cholesterol is generally sufficient to form a general idea of the role of this substance in the development of arterial atherosclerosis.
At the beginning of this century, some French doctors suggested a connection between the development of atherosclerosis of the arteries with the accumulation of cholesterol in their walls. However, these were more talented guesses than theoretical propositions, well substantiated by factual material.
Many representatives of medical science have expressed a wide variety of views on the development of arterial atherosclerosis. For a long time, the opinion was held that it was simply a manifestation of the aging of the organism, the result of "wear of the arteries." Due to the constant tension of the walls of the arteries, seals consisting of fibers appear in them - plaques, which then undergo degeneration, decay, and the products of such decay are the fatty substances so often found in the walls of the arteries in atherosclerosis.
Other researchers have viewed atherosclerosis as a result of inflammation of the arteries, based on the fact that the development of dense fibrous (scar) tissue is highly characteristic of the later stages of inflammation.
Finally, still others believed that the plaque-like thickening of the arteries, characteristic of atherosclerosis, is formed as a result of the release of protein substances from the blood, convolutions; the latter are deposited on the wall of the arteries, and then grow in fibrous tissue.
We will not cite here all the many conflicting opinions on the nature and origin of atherosclerosis contained in the medical literature. We emphasize only one significant circumstance: in all opinions, the dominant idea was that the main initial process in atherosclerosis (arteriosclerosis) is the proliferation of dense fibrous (connective) tissue in the inner lining of the arteries. This, in turn, leads to the formation of plaques (thickenings on the walls of the arteries), characteristic of this disease.
Since the thickening of the inner shell, due to the development of fibers and cells in it, is also observed with age, it would seem natural to identify both processes - age-related thickening of the arteries and atherosclerotic changes. However, a later, more thorough study of the age-related changes constantly observed in the walls of the arteries, and atherosclerotic changes showed a very significant difference between the two. The main difference between them, in addition to a number of structural features, is the absence of fatty accumulations in the thickened inner lining of the arteries with age-related changes and the presence of such accumulations in atherosclerosis.
It is remarkable that in all the above-mentioned views on the origin of arterial lesions in atherosclerosis, very little attention was paid to the role of fatty substances and, in particular, cholesterol, which often accumulate in the walls of the arteries in this disease in very large quantities. Fatty substances, including cholesterol, were most often considered as secondary, insignificant products of decomposition of the fibrous tissue of atherosclerotic plaques.
However, over time, these "decay products", studied in detail both for their chemical nature and for their properties to cause changes in tissues, turned out to be more characteristic and essential components in the altered walls of arteries in atherosclerosis.
The underestimation of the importance of fatty substances, and in particular cholesterol, in the development of atherosclerosis is explained mainly by the fact that the amount of these substances in the arteries during the disease is very different. Often there are a lot of them, they accumulate in the form of large masses, and often even their breakthrough into the lumen of the arteries is observed and the formation of ulcers on the inner membrane and plaques with the deposition of blood clots (thrombi) on them.
In other cases, on the contrary, there are much less fat masses, sometimes they are even almost absent, and the changes in the arteries under consideration at the time of the study consist only of a large accumulation of fibrous tissue that forms thickenings (plaques) of the inner membrane.
Thus, the question of the nature and origin of atherosclerosis, as well as the changes characteristic of it in the arteries, remained completely unclear for a very long time. Numerous attempts to solve the problem of atherosclerosis of the arteries through clinical, anatomical and experimental research have remained unsuccessful; the opinions of scientists were extremely contradictory. Meanwhile, the need to clarify this tangled issue became more and more obvious. Not only treatment, but also the prevention of the disease depended on the correct understanding of the essence and development of atherosclerosis.
This was all the more necessary since medical statistics confirmed the extreme frequency of the spread of arterial atherosclerosis in humans. It has now been proven that among the population of European countries and the United States in old age, arterial lesion by atherosclerosis is almost always present, although it is expressed in very different degrees.
Quite often, arterial disease with atherosclerosis leads to serious consequences. Due to the narrowing of the lumen of the arteries caused by atherosclerotic plaques, as well as the formation of blood clots (thrombi) on their walls and in the lumen, blood flow is disturbed or even stopped. In this regard, there is a weakening, and sometimes cessation of the function of the organs supplied with blood through this artery, including some vital organs, for example, the heart, brain. In the vast majority of cases, atherosclerotic lesions of the arteries underlie many diseases of organs and parts of the body (heart attack, stroke - cerebral stroke, gangrene - death of toes and feet in the elderly). And these lesions represent a major cause of disability and death in older people.
 The study of atherosclerosis is carried out on patients in the clinic by studying disorders of the vital functions of organs and tissues. The intravital study of the disease is clarified and verified by postmortem examination of the affected parts with a simple eye and under a microscope.
There is also a third, very promising way of studying human diseases, namely through reproducing them in experiments on animals. It is not surprising that with regard to arterial atherosclerosis, attempts have been made for a long time to understand the essence and development of it by means of reproducing similar changes in blood vessels in various animals. experiments on animals.
It was only at the beginning of this century that a reliable method was finally found that would make it possible to permanently obtain arterial damage in animals, very similar to that observed in humans with atherosclerosis. This method consists in the fact that cholesterol is mixed with ordinary animal food, that is, a substance that is almost constantly found in the walls of arteries during atherosclerosis, and sometimes in large quantities.
Experimentally induced atherosclerotic lesions of the arteries arise as a result of two closely interrelated processes: the deposition of fatty substances with a large admixture of cholesterol and the development of fibers with the formation of thickenings (plaques). In the coronary arteries of the heart, plaques were so large that they almost blocked the lumens of the vessels. As a result, as in humans, degenerative changes and areas of necrosis in the heart muscle occurred. Thus, a picture was noted that was fundamentally identical with that characteristic of myocardial infarction and cardiosclerosis - the development of dense fibrous tissue by the intermuscular fibers of the heart.
At first it was believed that experimental atherosclerosis in animals, very similar to human, can be caused only in rabbits and pigs, that is, in animals that are far from humans in terms of their organization and type of nutrition. However, the subsequent years of lesions of the arteries, very similar to the observed lesions in humans, were reproduced experimentally, by feeding with cholesterol, and in many other species of animals: rats, dogs, chickens, pigeons. Finally, quite recently successful results were obtained in experiments on monkeys.
In all these studies, carried out in very large numbers over the last half-century, there was one common characteristic point - an increase in the food of animals of cholesterol, sometimes pure, sometimes mixed with other fatty substances. The same results were obtained when feeding animals with foodstuffs containing large amounts of cholesterol - chicken egg yolks, animal fats, and brain matter.
It is especially easy to obtain atherosclerotic changes in the arteries in experiments with the introduction of cholesterol or the feeding of food rich in it in such species of animals that, during their usual diet, do not receive cholesterol at all or receive it in a relatively small amount. On the contrary, in animals that constantly consume food rich in cholesterol, atherosclerotic lesions of the arteries are much more difficult to induce. To reproduce the disease, in addition to the introduction of large amounts of cholesterol, they had to cause an artificial decrease in the general metabolism. The latter was easily achieved by the introduction of certain drugs that lower the function of the thyroid gland, as one of the most important organs that regulate the metabolism in the body.
Probably, in the origin of atherosclerosis, metabolic shifts associated with the disruption of the activity of other organs of internal secretion are also important, but in this regard, little indisputable data have been obtained.
Based on the results of the experiments just mentioned, it could be assumed that in humans, an essential point in the development of atherosclerosis of the arteries is a decrease in metabolism, leading to the accumulation of cholesterol and other fats in the body. A number of facts support this assumption.
Atherosclerosis of the arteries, as shown by statistics, is more common and more pronounced in well-fed people, especially in obese subjects. On the contrary, in people with reduced nutrition, this disease is less common and less pronounced.
In the same way, various conditions affect, leading to a decrease in nutrition and metabolism in the body. For example, a decrease in thyroid function is especially often accompanied by the development of atherosclerotic changes in the arteries.
Further, observations indicate that these changes are less common in people engaged in physical labor, physical exercise, living in good hygienic conditions, in a word, in those cases when the body is in a state of normal metabolism. The inhibitory effect of physical activity on the development of arterial atherosclerosis has also been shown in experiments on animals fed with cholesterol. On the contrary, in people leading a sedentary lifestyle, atherosclerosis occurs more often, especially in unfavorable emotional states - nervous shocks, experiences, prolonged fatigue.
The great importance of fatty substances, in particular cholesterol, for the occurrence of arterial atherosclerosis in humans also follows from the fact that often in patients suffering from this disease, expressed in a sharp form, an increase in the level of cholesterol in the blood is determined, which, of course, contributes to its deposition in arterial walls and the occurrence of disease.
In addition to an increase in the content of cholesterol in the blood, some shifts in the ratios of cholesterol and other fatty substances, as well as protein substances in the blood, are quite characteristic of atherosclerosis.
If, moreover, we recall that the only reliable way to experimentally obtain atherosclerosis in animals is to feed them with food containing cholesterol, then a whole series of weighty data are obtained that testify to the important role of cholesterol in the development of atherosclerosis. However, one should not think that an increase in cholesterol in the body is the only factor leading to the development of arterial atherosclerosis. Recent studies have shown that other fatty substances also play some role in the formation of atherosclerotic lesions.
 In addition, attention was drawn to the fact that cholesterol in the blood and deposited in the walls of the arteries is always associated with the protein substances of the blood. Thus, the role of the latter in the origin of cholesterol deposits in the walls of arteries cannot be rejected either.
Establishing the important role of metabolic factors in the development of atherosclerosis is essential for understanding the essence of this disease. In previous years, atherosclerosis (arteriosclerosis) was considered only a disease of the arteries, now atherosclerosis should be considered as a violation of metabolism and nutrition of the whole organism. The defeat of the arteries is the most essential and practically the most important manifestation of this metabolic disease, especially the metabolism of fatty substances.
Let us now proceed to consider the question of what significance all the data presented here have for medical practice. First of all, it should be noted that the attribution of arterial atherosclerosis to the group of diseases of nutrition and metabolism has completely changed the view of doctors on the nature and origin of the disease described. This, in turn, has found a vivid reflection in both the prevention and treatment of atherosclerosis. Much attention was paid to the state of nutrition and metabolism in such patients, as well as in the elderly, predisposed to this disease.
Who can be attributed to this category, which people are most prone to arterial atherosclerosis? First of all, those who are already hereditarily burdened in the sense that their parents or relatives suffered from diseases that are a manifestation of atherosclerosis, for example angina pectoris, myocardial infarction.
Further, a very important moment for the disease and intensifying it is the state of arterial hypertension, that is, an increase in blood pressure in the arteries. Arterial hypertension can appear as separate outbreaks (the so-called hypertensive crises), and exist continuously for a long time, representing the main symptom of hypertension. Currently, there is no disagreement on the issue that hypertension is the most important condition contributing to the development of arterial atherosclerosis. Some even believe that chronic arterial hypertension and atherosclerosis are a single disease, depending on the malfunctioning of those parts of the brain that regulate both metabolic processes in the body and the reactions of the arterial system.
The next important point, predisposing to the disease of atherosclerosis, are various intensified or perverted reactions from the higher nervous activity. The latter consist in states of increased tension, frequent affects, various breakdowns of nervous activity, leading to a state of neurosis and affecting the entire body, its state of metabolism and vascular reactions. Often, such pathological conditions of the nervous system are also the basis of hypertension.
We have pointed out the main features and essence of lesions of the arteries that form the basis of atherosclerosis. From all the data presented, it is easy to understand in which direction the issues of diagnosis, prevention and therapy of this disease are being developed.
Diagnosis of atherosclerosis is based mainly on the detection of those secondary changes in organs that arise as a result of damage to the arteries in this disease. However, for a long time, atherosclerotic lesions of the arteries remain difficult to recognize for a doctor, until they manifest themselves in the form of disturbances in the blood supply to vital organs: the heart, brain, or do not make themselves felt as a picture of insufficient blood supply to the lower extremities. The presence of these diseases is relatively easily detected by doctors on the basis of both conventional and some enzymes that appear in the blood in an increased amount already in the early stages of myocardial infarction. On the basis of all these diagnostic techniques, practitioners for the most part correctly recognize atherosclerotic changes in the arteries that underlie the violation of the activity of internal organs.
N. N. Anichkov - Diseases of the arteries
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