Characteristic And Z Score Equations For Left Ventricular Myocardial Strain In Normal Children At Different Body Surface Area Stages

Objective:To evaluate the characteristic of left ventricular myocardial strain which were obtained by real-time three-dimensional speckle tracking imaging in normal healthy children at different body surface area,The normal reference value and the Z-score of the left ventricular myocardial strain in normal healthy children were determined.To provide a normal reference for the clinical assessment of early left ventricular dysfunction in children.Methods:a total of 173 children aged 4~18 years old were selected,Full-volume three-dimensional dynamic image were obtained and analyzed by off-line Tom Tec workstation,three-dimensional left ventricular global and each segments longitudinal,radial,and circumferential strain parameters were acquired.The normal children were divided into 3 groups according to body surface area(BSA).Group A(>0.6m~2,≤1.0m~2),group B(>1.0m~2,≤1.4m~2)and group C(>1.4m~2,≤1.8m~2).The differences of three dimensional strain parameters between different BSA groups were compared,and to determine the characteristics of three-dimensional strain parameters in normal children,those with significant changes in trend were further analyzed.Taking BSA as independent variables,three dimensional strain parameters were used as dependent variables to establish multiple regression models,and the best regression equation was determined,and Z-score was calculated.Results:1.The global longitudinal strain(GLS)and global radial strain(GRS)value of the three groups showed a decreasing trend with BSA,the difference was statistically significant(P<0.05).The 16-segment of longitudinal strain(LS)and most segment of radial strains(RS)showed a decreasing trend,and the difference was statistically significant(p<0.05).The difference of global circumferential strain(GCS)value between three groups was not statistically significant(P>0.05).Most segment of the circumferential strains(CS)had no statistically significant differences among the groups(P>0.05).2.There was significant nonlinear associations between body size variables(age,height,weight,and BSA)and LS,adjusting for BSA was better than adjusting for age,weight,and height.The best model of 13 LS parameters were the quadratic model,the best model of 1 LS parameter was the logarithmic model,and the best model of 1LS parameter was the square root model,the residuals of the two LS parameters were abnormal distribution,therefore,there were no suitable model matching.The regression equation between LS and BSA were established,and Z-score were calculated.3.There was significant nonlinear associations between body size variables(age,height,weight,and BSA)and RS,adjusting for BSA was better than adjusting for age,weight,and height.The best model of the 7 RS parameters were the quadratic model,the best model of the 2 RS parameters was the square root model,and the others have no suitable model matching.The regression equation between the reciprocal of RS and BSA were established,and Z-score were calculated.Conclusion:1.The left ventricular myocardial function of normal children in different BSA groups was inhomogeneity.The LS and RS decreased with the increase of BSA.CS did not change significantly with the increase of BSA.2.The influence of age,height,weight,and BSA on LS and RS was significant in pediatric echocardiograph,BSA was the most significant factor.The establishment of Z-score model between LS、RS and BSA can reduce the risk of misjudgment due to the normal change of the strain in the growth process.