Diagnostic and Treatment Features in Patients with Carotid Stenoses and Arterial Hypertension

The dissertation examines the diagnostic and treatment characteristics of patients with atherosclerotic carotid stenoses and concomitant arterial hypertension. The study addresses the relationship between the severity of hypertension, the morphological structure of atherosclerotic plaques, the degree of internal carotid artery stenosis, blood lipid parameters, cerebral hemodynamics, and postoperative blood pressure dynamics following carotid endarterectomy. Using duplex ultrasonography, transcranial Doppler imaging, and morphological analysis of surgical specimens, the work demonstrates how hypertension stage influences vascular wall structure, lipid profile, and cerebral blood flow velocity, and it substantiates the role of carotid endarterectomy not only as a means of eliminating cerebral ischemia but also as a method of correcting arterial hypertension in this patient group.

Relevance of the study - Diseases of the circulatory system continue to occupy a leading place in the structure of overall mortality of the adult population in economically developed countries [21,183]. In the Russian Federation, more than half of the population suffers from cardiovascular diseases [39].

Arterial hypertension (AH) is one of the most common cardiovascular diseases (CVD) and at the same time the most important risk factor for acute vascular catastrophes (myocardial infarction and stroke), mortality from which in Russia remains higher than in most developed European countries [53].

Up to 80-95% of all deaths from cardiovascular diseases (CVD) are attributable to coronary heart disease (CHD) and cerebral stroke (CS). These diseases are based on atherosclerosis (A) and arterial hypertension (AH). At present, arterial hypertension (AH) and hypercholesterolemia are considered among the leading risk factors (RF) for atherosclerosis, and they generally develop with age. Thus, starting from 30 years of age, the frequency of stroke increases by 1.5-2 times in each subsequent decade of life - I.V. Damulin, D.A. Parfenov et al., 2001.

The principal site of the atherosclerotic process (65-73.4%) is the ostium of the internal carotid artery (ICA) [40,67]. In recent years, one of the leading mechanisms of acute cerebrovascular disorders has been considered to be arterio-arterial microembolism from the ICA bifurcation zone [17,21,51,52]. However, the significance of the morphological structure and surface character of atherosclerotic plaques (ASP) in these patients has not been adequately reflected in the standards that determine the indications for carotid endarterectomy (CE). Until recently, no studies have been conducted aimed at establishing the relationship between the degree of blood pressure (BP) elevation, lipid profile disturbances, and the morphological structure of atherosclerotic lesions of the carotid arteries.

It is generally recognized that the efficacy of CE in symptomatic patients with ICA stenosis greater than 70% is very high, as it reduces the risk of stroke death by 48% [64]. One of the complex problems in the surgical treatment of occlusive-stenotic lesions of the brachiocephalic vessels is the management of patients with concomitant arterial hypertension (AH). This is especially true for patients suffering from severe forms of AH [203]. The majority of these patients have already experienced ischemic or hemorrhagic stroke [16,21]. When performing carotid endarterectomy in such patients, the risk of intraoperative complications increases: recurrent stroke and cerebral hyperperfusion syndrome, which may also lead to the development of acute cerebrovascular disorders [56]. However, there are no studies devoted to the outcomes of CE in patients with ICA stenosis and concomitant AH.

According to a number of authors, atherosclerotic lesions of the arteries supplying the brain are also one of the causes of elevated blood pressure (BP) [118]. There are publications reporting the presence in the CNS of structures capable, under hypoxic conditions, of secreting biologically active substances with vasoconstrictive action that promote an increase in vascular tone and, consequently, in BP, in order to ensure normal perfusion of brain tissue [191,205]. However, there is no unambiguous opinion regarding the existence of a central mechanism of AH development, and there are no publications proving a hypotensive effect after CE. Therefore, further search for solutions to the problem of treating patients with hemodynamically significant ICA stenosis and concomitant AH is required.

Aim of the study - To investigate the relationship between the severity of AH, the morphological structure of atherosclerotic plaque, and the degree of ICA lesion, blood lipid profile disturbances, cerebral hemodynamic (CH) status, as well as the dynamics of blood pressure after carotid endarterectomy. Objectives of the study

1. To study the features of changes in the structure of the vascular wall according to ultrasound duplex scanning (UDS) data and the morphology of atherosclerotic plaque depending on the stage of arterial hypertension.

2. To evaluate the dynamics of changes in the serum lipid profile in patients depending on the severity of arterial hypertension, CHD, chronic cerebrovascular insufficiency (CCVI), and ICA lesion.

3. To clarify the features of changes in cerebral hemodynamics in patients with carotid stenoses and varying severity of arterial hypertension with concomitant CHD and CCVI.

4. To study the dynamics of BP changes after carotid endarterectomy in patients with varying severity of AH and concomitant CHD and CCVI.

Scientific novelty - For the first time, a comparative study was conducted in patients with atherosclerotic ICA stenosis and concomitant AH, which made it possible to establish the relationship between the degree of blood pressure elevation and the morphological structure of atherosclerotic ICA lesion, blood lipid profile, cerebral hemodynamic (CH) status, and to study the dynamics of blood pressure after carotid endarterectomy.

It has been proved that with increasing severity of arterial hypertension in patients with atherosclerotic ICA lesion of up to and greater than 70%, there is a marked disturbance of the intima-media complex (IMC) differentiation, a change in its thickness, and the presence of ICA deformations. In patients with ICA stenosis greater than 70%, an increase in echonegative plaques to 54% is observed, the number of echopositive plaques decreases twofold (25%), and the number of calcified ASP amounts to 25%, which increases the risk of arterio-arterial embolism.

A pattern has been revealed consisting in the fact that with increasing severity of AH, significant disturbances of lipid metabolism are recorded. The greatest changes in the quantitative content of total cholesterol (TC), high-density lipoproteins (HDL), and low-density lipoproteins (LDL) in blood plasma are observed in patients with stage II AH and ICA stenosis up to 70% with concomitant CHD. The identified lipid changes indicate the activity of the atherosclerotic process in this group of patients. High levels of total cholesterol and LDL against the background of decreased HDL were observed in 85% of patients with stage II AH and in 50% of patients with stage III AH.

The study of blood flow velocity parameters in the carotid arteries using transcranial Doppler ultrasonography made it possible, for the first time, to establish that in individuals with an identical degree of ICA stenosis, an increase in AH severity is accompanied by an increase in blood flow velocity. Concomitant CHD does not exert a significant influence on cerebral blood flow velocity parameters. The leading role in increasing blood flow through the internal carotid arteries belongs to arterial hypertension.

It has been proved for the first time that CE in patients with atherosclerotic ICA stenosis greater than 70% is not only an etiotropic method for eliminating cerebral ischemia, but also a highly effective means of treating the cerebroischemic form of AH. The hypotensive effect after carotid endarterectomy is recorded in all groups of patients regardless of the severity of chronic cerebrovascular insufficiency (CCVI) and contralateral ICA lesion, and is especially pronounced in individuals with stage III AH.

Practical significance

The studied features of the vascular wall structure and atherosclerotic plaque morphology, the dynamics of changes in the serum lipid profile, and cerebral hemodynamics in patients with carotid stenoses and varying severity of arterial hypertension prove the necessity of performing ultrasound duplex scanning (UDS) of the brachiocephalic arteries in this category of patients, which will enhance the effectiveness of differentiated rehabilitation treatment. It has been shown that the greatest number of echonegative plaques is recorded in patients with ICA stenosis greater than 70% and stage III AH, therefore they constitute a group at increased risk of ischemic stroke. In the majority of patients with atherosclerotic ICA stenosis less than 70% and stage II AH, the most pronounced changes and disturbances of the serum lipid profile are recorded, indicating the activity of the atherosclerotic process specifically in this group of patients. Timely diagnosis of the carotid artery status and correction of lipid metabolism disturbances in this category of patients will contribute to more effective therapeutic and preventive measures. It has been proved that with increasing severity of AH in patients with atherosclerotic ICA stenosis, an increase in blood flow velocity is recorded. The detection by UDS of elevated blood flow velocity parameters in the carotid arteries requires special attention, as this may indicate the formation of atherosclerotic changes in the vascular wall. Early diagnosis of carotid artery stenoses makes it possible to prevent the complicated course of AH and to delay or eliminate the need for carotid endarterectomy.