Factors of Formation of Various Types of Left Ventricular Diastolic Filling in Adolescents with Myocardium Pathology

Abstract

Objective: to study the main components of the formation of impaired left ventricular diastolic filling in adolescents with myocardial pathology. Materials and methods. The study involved 110 adolescents with myocardial pathology aged 13–18 years, of which 40 — with heart rhythm disorder, 40 — with dysplastic cardiomyopathy, 30 — with primary hypertension. Morphological and functional parameters of the heart were studied using ultrasound according to standard procedure. Left ventricular diastolic function has been studied in the pulsed wave Doppler mode with transmitral flow mapping from the apical access of four-chambered heart. For an adequate assessment of left ventricular diastolic function and detection of its earliest disorders, adolescents underwent tests with isometric exercise. Based on these results, adolescents were divided in terms of the E/A ratio. In order to identify common latent factors that explain the correlation between indicators, we have used the factor analysis, namely, the principal component analysis. All statistical procedures were performed using application packages Statgraphics Centurion. Results. On the initial stages of formation of diastolic dysfunction of the left ventricular myocardium in adolescents, a significant role is played by a number of factors, which can be conditionally defined as the geometric, functional and neurohumoral factors consistently included in the pathological process. Thus, during the formation of left ventricular diastolic dysfunction type 1, the number one is neurohumoral factor, namely, the activation of the sympathoadrenal system, then peripheral vascular tone is being involved in the pathological process, and, consequently, a geometric factor — changing the sizes of the left atrium. In the formation of left ventricular diastolic dysfunction type 2, the process consistently involves the renin-angiotensin system, namely, renin, a functional factor is presented by the indices of general peripheral vascular resistance and cardiac output, and geometric one includes left atrial diameter and the left ventricular end-diastolic size. Formation of left ventricular diastolic dysfunction type 3 is influenced by such components of the neurohormonal system, as renin and angiotensin-II, then the process subsequently includes peripheral vascular tone and a geometric factor in the form of left atrial diameter and left ventricular end-diastolic size. Thus, in the initial stages of left ventricular diastolic dysfunction in adolescents with myocardial pathology, a significant role is played by the sympathoadrenal system, peripheral vascular tone and left atrial function, and then sequentially the renin-angiotensin system is being involved, which causes an increase in myocardial stiffness and, as a result, the inclusion in the pathological process not only of the left atrium, but also the structure (end-diastolic volume) and function of the left ventricle (stroke volume).

Keywords

• diastolic function
• left ventricle
• adolescents
• factor analysis