27.14 What strategy allocate during development compensatory hypertrophies of heart? Give their characteristic.

On dynamics of changes of an exchange, structure and function of a myocardium in development compensatory hypertrophies of heart allocate three basic stages.

1. An emergency stage. Develops directly after increase of loading, it is characterized by a combination of pathological changes in a myocardium (disappearance of glycogen, decrease in a level of creatinphosphate, reduction of the maintenance endocellular potassium and increase of the maintenance of sodium, mobilization glykolisis, accumulation lactate) with mobilization of reserves of a myocardium and an organism as a whole. In this stage raise loading on unit of muscular weight, intensity of functioning of structures IFS, there is fast, within weeks, an increase in weight of heart due to the strengthened synthesis of fibers and thickenings of muscular tissues.

2. A stage of the ending of hypertrophy and concerning steady hyper function. In this stage process of a hypertrophy is completed, the weight of a myocardium is increased by 100-120 % and does not increase any more, IFS was normalized. Pathological changes in an exchange and structure of a myocardium do not come to light, consumption of oxygen, formation of energy, the maintenance microergical connections do not differ from norm. Were normalized hemodinamic infringements. The hypertrophied heart has adapted to new conditions of loading and for a long time compensates them.

3. A stage of a gradual exhaustion and progressing cardiosclerosis. It is characterized by deep exchange and structural changes which gradually collect in elements, which makes energy and constrict elements of cells of a myocardium. The part of muscular fibred perishes and is replaced with a connecting tissue, IFS again increases. The regulatory device of heart is destroyed.. The progressing exhaustion compensatory reserves leads to occurrence of chronic insufficiency of heart, and in the further - to insufficiency of blood circulation.

27.15 What features of the hypertrophied heart are the precondition of its development of decompensation?

The hypertrophied heart differs from normal in a number of metabolisms, functional and structural attributes which, on the one hand, allow it to overcome long time the raised loading, with another, - create preconditions for occurrence of pathological changes.

1. Cell membrane. The increase in weight of heart occurs due to a thickening of each muscular fiber that is accompanied by change of a parity of endocellular structures. Thus, the volume increases proportionally to a cube of the linear sizes, and a surface - absorption of oxygen, nutrients, deducing of products of a metabolism, an exchange of water and electrolytes. By virtue of the listed changes conditions for deterioration of supply of a muscular fiber, especially its central departments are created.

2. Sarcoplasmatical reticulum. The cellular membrane plays the important role in carrying out of excitation and the reduction, carried out through tubular system and sarcoplasmatical reticulum. As growth of these formations at a hypertrophy of a muscular fiber also lags behind, preconditions for infringement of processes of reduction and a relaxation cardiomiocytes are created: owing to delay of an output of ions of calcium in sarcoplasm reduction in summary difficulties of the return transport of ions of calcium sarcoplasmatical reticulum - a relaxation, can sometimes arise local structures separate cardiomiocytes worsens.

3. Nucleus. At a hypertrophy the increase in volume of a cell occurs in a greater degree than volume of a nucleus. Ability of nucleuses highly-differenced cells to division is sharply limited. Thus increase only linear the sizes of nucleuses due to increase in number of chromosomes that is accompanied by some increase of the maintenance of DNA. And as the role of a nucleus consists in maintenance of aluminous synthesis, and consequently, and processes of restoration of endocellular structures relative reduction of a nucleus can lead to infringement of synthesis of fibers and deterioration of plastic maintenance of a cell.

4. Mitochondrias. During development of a hypertrophy the weight of mitochondria in the beginning increases quickie, than weight of the contracttioning fibers, creating conditions for sufficient power maintenance and good indemnification of functions of vessels. However, in the further, in process of aggravation of process, the increase in weight mitochondria starts to lag behind growth of weight of cytoplasm. Mitochondria start to work with a maximum load, destructive changes develop in them, efficiency of their work decreases, is broken oxidative phosphorilizing. It conducts to deterioration of power maintenance of the hypertrophied cell.

5. Blood vessels. The increase in weight of muscular fibers frequently is not accompanied by adequate increase of number of the capillary vessels, especially in cases of fast development of insufficiency of heart. Large coronal arteries do not possess necessary adaptive growth. Therefore during loading vascular maintenance of the hypertrophied myocardium worsens.

6. Innervation. At development of a hypertrophy of a myocardium the nervous device of heart is necessarily involved in process. The strengthened functioning intracardial and extracardial nervous elements are observed. However growth of the nervous ends lags behind increase in weight of the contracted myocardium. There is an exhaustion of nervous cells, trophy influences are broken, the maintenance noradrenalin in a myocardium that conducts to its deterioration constricted properties, to difficulty of mobilization of its reserves decreases. Hence, it is broken and reticular maintenance of heart.

7. Functional reserve. The hypertrophied heart due to increase in its weight constricted and energetic securing the device is capable long time to perform much greater work, than heart normal, keeping thus a normal metabolism. However ability to adapt to a changing loading, a range of adaptable opportunities at the hypertrophied heart is limited. The functional reserve is reduced. It does the hypertrophied heart by virtue of specified above imbalance of endocellular and tissue structures by more vulnerable under various adverse circumstances.