Comprehensive assessment of the functional state of the cardiovascular system in adolescents with nephrogenic arterial hypertension

The dissertation is devoted to a comprehensive assessment of the functional state of the cardiovascular system in adolescents with nephrogenic arterial hypertension. The work examines the prevalence of secondary nephrogenic arterial hypertension in adolescence and young age, the features of the structural and functional state of the left heart compartments and of left ventricular diastolic function, as well as the possibilities of graded exercise testing and 24-hour ambulatory blood pressure monitoring as tools for assessing central hemodynamics and prognosis. A comparison of parameters is carried out between adolescents with nephrogenic and essential arterial hypertension and a control group, including in long-term follow-up, with the aim of identifying early myocardial changes and substantiating approaches to the correction of cardiovascular complications in young people.

Significant attention is currently paid to the problem of AH, due to the fact that AH is the most common CVD, having a considerable number of life-threatening complications leading to disability and mortality (Kushakovsky M.S., 1997; Gogin E.E., 1999; Oganov R.G., 2000 [91]), thus being one of the main risk factors for cardiovascular complications and mortality from them, the share of which in the structure of total mortality is 20-50% (1999 WHO-ISH Guidelines for the Management of Hypertension, 1999). According to selective studies, in modern society up to 20% of the adult population suffers from AH, and in Russia this figure is even higher, at 25-30% [91].

It is known that the younger the age of a patient with AH, the higher the probability of its symptomatic nature [10,34] (Antonova L.T., 1993; Vyshinska T., P. Yanushevich et al., 1998). The frequency of SAH among individuals with elevated BP is within 20-30% [131] (Shastin I.V., Ametov A.S., Simonenko V.B., 2000), and the most common cause of symptomatic AH in adolescence is renoparenchymal AH (up to 34% of cases among all pathology accompanied by an increase in BP [10] (Antonova L.T., 1993). Also, V.A. Almazov and E.V. Shlyakhto (2001) point out that AH in patients with pyelonephritis more often develops in childhood or young age [7].

Recently, the proportion of renal AH has been increasing. Thus, if in the 1960s-1970s their share accounted for 10-15% of cases, then by the beginning of the 1990s the frequency of detection of AH associated with kidney diseases amounted to 30-35% (Gordeev A.V., Sura V.V., Malyshev Yu.M. et al., 1990; Arabidze G.G., 1992 [8]; Williams G.H., Braunwald E., 1995).

According to the literature, there is also an increase in the number of patients with end-stage CKD, including those caused by inflammatory kidney diseases [87,44,70,49]. Over the past 10 years in the USA, the number of patients with CKD has increased threefold. About 20-30% of all patients in need of renal replacement therapy are patients with primary renal pathology or kidney diseases within systemic diseases.

It has been established that a feature of the course of nephritis in children is a latent onset and low-manifest course [66,46] (Zakharova I.N., 2001), and, given that during the pubertal period, a period of active growth and hormonal changes [10] (Antonova L.T., 1993), when the young organism has increased sensitivity and vulnerability to adverse environmental conditions (Arnoldi I.A., 1964; Kalyuzhnaya R.A., 1970; Serdyukovskaya G.N., 1978), a long-existing latent or opportunistic infection can contribute to the development of a new chronic inflammatory pathological process or to the intensification of the activity of an existing one, to the acceleration of the progression of kidney disease, to the aggravation of existing secondary AH, or to its appearance in inflammatory kidney diseases that previously proceeded without it.

One of the factors determining the quality of life and prognosis in adult patients with kidney diseases is the severity of cardiac involvement [22]. Currently, much attention is paid to the study of LVDD, the disorders of which are significant in many CVDs, including AH [146,24,53,54,277].

Analysis of the literature data shows that the conducted studies of LVDD in patients with AH concerned either childhood or older age groups, or adolescent patients were included in the cohort of adult patients without differentiation by sex, while the issues of LVDD in adolescents with nephrogenic AH were not discussed in the available literature. Questions of the diagnosis of disorders of systolic and diastolic heart function at an early stage of renal AH development without the presence of CKD remained open.

Some authors consider AH to be the primary cause of the development of LVDD, finding a high degree of correlation between the BP level and diastolic dysfunction [127]. These data were also obtained during examination of the adult contingent of patients (in the presence of long-existing AH in them, which influenced the changes in the myocardium).

In recent years, great importance has been attached to 24-hour blood pressure monitoring (ABPM) in patients with AH [151,137,203,206,220,238,244,282,288,289,293]. The established data on the relationship of certain LVDD parameters with ABPM parameters in essential AH [146] are also contradictory in the literature (Philips R. C et al., 1987; Parati G., 1992), and are not reflected in adolescents with nephrogenic AH.

Up to the present time, the features of the contractile and diastolic function of the left ventricle in adolescents with nephrogenic AH, their relationship with the features of the circadian BP rhythm and with hemodynamic parameters during graded exercise tests have not been studied. The assessment of systolic heart function during dynamic follow-up of these patients has also not been carried out to date.

Many researchers note a significant increase in the risk of cardiovascular complications in the presence of chronic kidney disease [49,57,78,97,113,218]. Analysis of the literature shows that the data presented were obtained for patients of older age groups, or there are single works concerning pediatric patients. Studies of the state of the cardiovascular system in adolescents are few and contradictory, and in adolescents with nephrogenic AH, as the most common cause of arterial hypertension at a young age [10,72], they have not been studied. The study of structural and functional changes in the myocardium, the assessment of left ventricular diastolic function and central hemodynamic parameters at the onset of SAH in patients with chronic kidney diseases and during dynamic follow-up remains relevant, with the aim of identifying prognostically significant parameters.

This comprehensive study will help in adequately assessing the prognosis of the disease and developing an optimal strategy for the correction of cardiovascular complications in young people.

All the above made it possible to formulate the aim and objectives of the study. Aim of the study:

The aim of the present work is a comprehensive assessment of the functional state of the CVS in adolescents with nephrogenic AH.

OBJECTIVES OF THE STUDY:

1. To study BP parameters and CH parameters in adolescents with symptomatic nephrogenic AH in comparison with the control group and young men with EAH, and also to assess the dynamics of these parameters in the long-term periods of SAH development.

2. To assess structural and functional changes in the state of the left heart compartments in adolescents with renoparenchymal AH and EAH and the features of the dynamics of these changes in the long-term periods of SAH development.

3. To assess the features of the type of hemodynamic response and physical working capacity during graded exercise in young men with nephrogenic AH in comparison with the control group and EAH.

4. To determine the most sensitive parameters of LVDD changes in adolescents with renoparenchymal AH. To identify the features of the LVDD state in adolescents with nephrogenic AH at the onset of the disease and in the long-term period.

5. To compare the 24-hour BP profile in young people with long-existing and recently existing nephrogenic AH, as well as in adolescents with SAH and EAH.

6. To determine the correlation relationships between LVDD parameters and ABPM parameters in adolescents with nephrogenic AH.

Scientific novelty:

For the first time, a detailed comprehensive assessment of the state of the CVS in adolescents with renoparenchymal AH and the dynamics of these changes in the long-term periods using available examination methods has been carried out.

The features of the type of hemodynamics in various nosological forms of arterial hypertension in adolescence, namely nephrogenic and essential, as well as the dynamics of these changes in the long-term periods of SAH, have been studied in detail.

For the first time, the negative effect of elevated BP on the diastolic function of the heart in young men with renoparenchymal AH has been shown.

For the first time, the dynamically changing LVDD parameters in young people with nephrogenic AH have been determined.

Practical significance:

1. A comprehensive assessment of the functional state of the CVS in adolescents with nephrogenic AH will allow evaluating the initial changes in the heart and CH parameters, which will help in assessing the prognosis of the disease and correcting cardiovascular complications.

2. A dynamic study of systolic heart function and CH parameters in adolescents with nephrogenic AH will reveal the main parameters of involvement, which will indicate the directions of drug correction of these changes.

3. The assessment of LVDD and ABPM parameters in adolescents with nephrogenic AH will be able to identify important and earliest indicators of myocardial changes and the 24-hour BP profile.