Pathogenesis of arterial hypotension
Last reviewed: 23.04.2024
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The most difficult and insufficiently studied are the pathogenesis of arterial hypotension. There are several theories of the origin of the disease: constitutional-endocrine, vegetative, neurogenic, humoral.
Constitutional-Endocrine Theory
In accordance with this theory, arterial hypotension arises from the primary reduction of vascular tone due to insufficient function of the adrenal cortex. In subsequent studies, it was found that with arterial hypotension, the mineralocorticoid, glucocorticoid and androgenic functions of the adrenal gland decrease. In children of primary school age with stable arterial hypotension, the glucocorticoid function of the adrenal cortex is reduced, and in children of the senior school age, glucocorticoid and mineralocorticoid.
Vegetative Theory
According to the autonomic theory, the emergence of arterial hypotension is associated with an increase in cholinergic function and a decrease in the function of the adrenergic system. Thus, in most patients with arterial hypotension, an increase in the content of acetylcholine and a decrease in the level of catecholamines in blood plasma and daily urine are detected. It is known that the lack of synthesis of norepinephrine and its predecessors contributes to a decrease in diastolic and mean arterial pressure. Variability of the synthesis of these neurotransmitters is typical for the pre- and pubertal period. Hypofunction sympathic-adrenal system leads to variability in blood supply to the brain and central circulation, violation of external respiration, reducing oxygen consumption. In recent years, it has been established that in the origin of arterial hypotension, it is not so much a decrease in the tone of the sympathetic-adrenal system that is important, but rather a change in the sensitivity of the alpha and beta adrenoreceptors to the neurotransmitters.
Neurogenic theory
This theory of the emergence of arterial hypotension is now recognized by most researchers. Violation of the neurogenic pathway of regulation of arterial pressure is the main link in the development of arterial hypotension. According to this theory, under the influence of psychogenic factors, the neurodynamic processes in the cerebral cortex change, the correlation between the processes of excitation and inhibition in both the cortex and subcortical autonomic centers of the brain (ie, there is a peculiar form of neurosis). Because of this, hemodynamic disorders occur, the most important of which is dysfunction of capillaries with a decrease in the total peripheral resistance. In connection with the emerging functional disorders compensatory mechanisms come into play that lead to an increase in the impact and minute volume of blood. More than 1/3 of adult patients with stable arterial hypotension in the cerebral cortex, inhibition processes predominate over the processes of excitation, typical dysfunction of the upper sections of the brain stem, with functional tests, the a-index decreases on the background electroencephalogram.
In most cases, with arterial hypotension using existing instrumental and biochemical methods, it is not possible to detect specific causes of the disease. Nevertheless, there is no doubt that in hypotonic illness, a reduction in blood pressure is associated with a complex interaction of genetic factors, as well as a violation of physiological regulatory mechanisms.
At an arterial hypotension mechanisms of autoregulation are broken. There is a discrepancy between cardiac output and total peripheral vascular resistance. In the early stages of the disease, cardiac output is elevated, whereas the overall peripheral vascular resistance is reduced. As the disease progresses and systemic arterial pressure is established at a low level, the overall peripheral vascular resistance is steadily reduced.
Humoral theory
In recent years, in connection with the study of the problem of the regulation of arterial pressure, interest has increased in the study of humoral factors of a depressive nature. According to the humoral theory, arterial hypotension is caused by an increase in the level of kinins, prostaglandins A and E, having a vasodepressor effect. A definite value is attached to the content of serotonin and its metabolites in the blood plasma involved in the regulation of the blood pressure level.
Systemic arterial pressure begins to decrease with the inclusion of antihypertensive homeostatic mechanisms (renal excretion of sodium ions, aortic and major arterial baroreceptors, kallikrein-kinin system, dopamine release, natriuretic peptides A, B, C, prostaglandins E 2 and I 2, nitric oxide, adrenomedulin , taurine).
Thus, the primary arterial hypotension is currently considered as a special form of neurosis of the vasomotor center with impaired function of peripheral depressor apparatus and a secondary change in the function of the adrenal glands.
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