Left ventricular myocardial hypertrophy and strain changes in children with hypertrophic cardiomyopathy

Abstract

Introduction. An assessment of the relationship between the severity of hypertrophy and changes in the myocardial strain at which systolic disfunction is detected in children with hypertrophic cardiomyopathy (HCM) is clearly essential.Aim. To assess the relationship between hypertrophy and the myocardial strain in children with hypertrophic cardiomyopathy (HCM).Materials and methods. 61 patients aged between 7 and 17 years with a primary form of HCM underwent an ultrasound examination of the heart using standard techniques. An assessment of the left ventricular systolic function performed using of-line the two-dimensional (2D) speckle-tracking mode with analysis parameters that included global and segmental longitudinal, circumferential, and radial myocardial strains. The analysis of hypertrophy of myocardial segments carried out taking into account the absolute values of the thickness of the left ventricular myocardium in systole and diastole, depending on age, in terms of standard deviation units in the population (Z-score factor).Results. A decrease in longitudinal strain below the relevant values, an increase in radial strain, and no changes in circular strain were observed when the thickness of the left ventricular myocardium increased over 2.48Z. A further decrease in radial strain was observed when myocardial thickness was over 4.24Z, and circular strain was over 3.16Z. The relationship between myocardial hypertrophy and longitudinal strain had an inverse linear relationship: the lower the strain values, the greater the thickness of the myocardium. With increasing thickness of the myocardium, the radial strain first tended to increase in a compensatory manner, but it decreased when myocardial thickness increased over 4.24Z. The circular strain, as well as longitudinal one, has an inverse linear relationship, but with longer preservation of normal values when myocardial hypertrophy increases.Conclusion. Children with HCM demonstrate various types of relationships between hypertrophy and myocardial strain, which detection is important for the assessment of the left ventricular systolic function to improve the prognosis and therapeutic approach to the disease. A comprehensive approach to the assessment of myocardial strain in children with HCM should include not only a routine identification of global strain, but also assessment of the segmental strain to detect early signs of myocardial dysfunction. Comparison of measures of various types of strain and the thickness of the left ventricular myocardium has a very important diagnostic value for understanding the degree of changes in its kinetics.