Evolution of natural myocardial shear wave behavior in young hearts: determinant factors and reproducibility analysis

Abstract

BackgroundMyocardial diastolic function assessment in children by conventional echocardiography is challenging. Recent high frame rate (HFR) echocardiography facilitates the assessment of myocardial stiffness (MS) -a key factor of diastolic function- by measuring the propagation velocities of myocardial shear waves (SWs). However, normal values of natural SWs in children are currently lacking. ObjectivesTo explore the behavior of natural SW among children and adolescents, their reproducibility, and the factors affecting SW velocities from childhood into adulthood. Methods106 healthy children (2-18 years) and 62 adults (19-80 years) were recruited. HFR images were acquired using a modified commercial scanner. An anatomical M-mode was drawn along the ventricular septum, and propagation velocities of natural SWs after mitral valve closure (MVC) were measured in the tissue acceleration coded M-mode display. ResultsThroughout life, SW velocities after MVC exhibited pronounced age dependency (r= 0.73; P<0.001). Among the pediatric population, SW velocities correlated significantly with measures of cardiac geometry (septal thickness and left ventricular end-diastolic dimension), local hemodynamics (systolic blood pressure), as well as with echocardiographic parameters of systolic and diastolic function (global longitudinal strain (GLS), mitral E/e’, isovolumetric relaxation time and mitral deceleration time) (P <0.001). In a multivariate analysis including all these factors, the predictors of SW velocities were age, mitral E/e’, and GLS (r= 0.81). ConclusionsNatural myocardial SW velocities in children can be detected and measured. SW velocities showed significant dependence on age and diastolic function. Natural SWs could be a promising additive tool for assessment of diastolic function among children.