Reference Values of Noninvasive Myocardial Work Indices Measured by Echocardiography in Healthy Children

Abstract

BackgroudNoninvasive myocardial work, estimated by left ventricular (LV) pressure-strain loop (PSL), has been introduced for assessing LV myocardial performance. Based on both blood pressure and speckle-tracking derived strain data, noninvasive myocardial work is considered to be less load-dependent than global longitudinal strain (GLS). In some conditions, such as hypertension or aortic coarctation, the increased afterload will affect strain measurements, and myocardial work can serve as a more robust metric.ObjectiveWe prospectively recruited healthy children to explore the relationship between myocardial work indices and body size parameters, and to determine the reference values of noninvasive myocardial work indices in healthy children.Methods183 healthy children (aged 1–18 years, males: 52.5%) were enrolled in the study. Global work index (GWI), global constructive work (GCW), global wasted work (GWW), global work efficiency (GWE), were assessed by LVPSL and compared according to age and sex.ResultsThe mean for GWI was 1,448.7 ± 265.0 mm Hg%, 1,859.8 ± 290.7 mm Hg% for GCW, and the median (interquartile range) for GWW was 54.0 (33.0–82.0) mm Hg% and 97.0 (95.0–99.0) % for GWE. male had greater GWI and GCW) than female (1,572.5 ± 250.2 mm Hg% vs. 1,312.2 ± 208.7 mm Hg% and 1,944.3 ± 299.2 mm Hg% vs. 1,766.6 ± 251.5 mm Hg%, respectively, all P < 0.001). GWI and GCW were significantly correlated with baseline parameters, including age, height, weight, BSA, body mass index, heart rate, and blood pressure. After indexed to BSA, GWI (BSA), GCW (BSA) remained significantly negatively correlated with age (P < 0.001).Conclusionswe proposed the normal reference values and regression equations for GWI and GCW based on age and BSA in healthy children. This might provide a basis of reference for the evaluation of cardiac function in children with cardiopulmonary disease.

Normal Values for Echocardiographic Myocardial Work in a Large Pediatric Population

“…Speckle tracking echocardiog-raphy analysis was performed in semiautomatic fashion with manual correction. Global LV longitudinal strain (LVGL) and regional (basal, mid, and apical) values were automatically derived from all views measured with a standard 6-segment model (e.g., 6 segments for each view, 18 segments globally) [1][2][3][4][5]. Left ventricular ejection fraction was calculated by the biplane Simpson's method in a semi-automated fashion with manual correction.…”

“…One can be plotted against the other, and a pressure-strain loop emerges for the cardiac cycle beginning as the mitral valve opens and the ventricle fills, proceeding through isovolumic contraction, ventricular ejection, and finally isovolumic relaxation [1,2]. Myocardial work calculations incorporate the area of the pressure-strain loop during LV ejection [1][2][3][4][5]. Dynamic pressure-strain loops can be created from echocardiographic measurements of myocardial strain in three apical views and a noninvasive cuff blood pressure measurement performed at the same time.…”

“…Wasted work (WW) is work performed during segmental elongation and reversed during isovolumetric relaxation. Finally, work efficiency is the fraction of constructive work divided by constructive work plus wasted work [1][2][3][4][5][6]. Myocardial strain-LV loop analysis furthermore allows for differentiation between constructive and wasted work and provides data on energy consumption [1][2][3][4][5].…”

“…Finally, work efficiency is the fraction of constructive work divided by constructive work plus wasted work [1][2][3][4][5][6]. Myocardial strain-LV loop analysis furthermore allows for differentiation between constructive and wasted work and provides data on energy consumption [1][2][3][4][5]. Adult studies showed how MW may provide additional and complementary information for the analysis of LV function compared to myocardial strain which is influenced by the afterload [6].…”

“…Normal values for MW have been derived in adults [6][7][8][9][10][11]. The few studies on normal MW parameters in children [1][2][3][4][5] used limited sample size (150 to 212 subjects) and mostly evaluated children above 6 years [3][4][5]. Data on younger children are limited [2], and data in neonates and infants are absent.…”