الفهرس 
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Abstract
Echocardiography is usually the first tool used in diagnosis of congenital heart diseases. Various new echocardiographic modalities have been introduced to help the clinician in the diagnosis of different conditions. One of these modalities is Tissue Doppler Imaging (TDI) which has great benefit in the early detection of systolic and diastolic dysfunction of the heart.
There are many methods used in conventional echocardiography to diagnose both systolic and diastolic dysfunctions. However, there are many problems encountered such as the ―pseudo-normalization pattern‖ seen in grade two diastolic dysfunction, in which the usual pulsed wave Doppler is almost normal while there is a real problem. The Tissue Doppler Imaging (TDI) can avoid these fallacies. Moreover, TDI has been used, with great accuracy, to assess left and right ventricular systolic function by means of mitral annular plane systolic excursion (MAPSE) and tricuspid annular plane systolic excursion (TAPSE).
Tissue Doppler Imaging has been used for long time in adult population and there are established normal values for the TDI parameters for the adult population. However, this isn‘t true if we come to the pediatric practice. Few studies have investigated the normal values of TDI in pediatric population and there were also subjected to much criticism as regard the methodologies and the sample size.
The aim of the work was to set new pediatric reference values and Z scores for the tissue Doppler parameters for Egyptian children.
Summary
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We studied 206 children recruited from the pediatric cardiology clinic at Menoufia university hospital during the period (December 2017 to December 2018). Children were referred by the pediatricians and primary care physicians for exclusion of structural heart problem. After thorough history taking and complete clinical examination, a comprehensive echocardiographic study was done. Two-dimensional echocardiography, color flow mapping and Doppler interrogation were done according to strict protocols. M-mode measurements were also obtained.
Children with structurally normal were chosen to complete the tissue Doppler study. We first started with TDI measurements at the interventricular septum (IVS). Myocardial velocities and time intervals were measured, then the myocardial performance index (MPI) or the Tei index was calculated. Then the same measurements were obtained at the lateral mitral annulus.
We calculated the mean, median and range of each measured parameter. All the parameters were subjected for correlation with the independent variables, age, body surface area and heart rate (due to the variability of heart rate in children, we tried to eliminate its effect on the measured time intervals using the Bazett formula).
Multiple univariate linear regression was done for each measured parameter with the previously mentioned independent variables. Based on the results of linear regression, we hypothesized a formula that correlate between the parameter and the most predicting independent variable with demonstration of the relation coefficient (R²) that indicates the strength of relationship between the two variables.
Summary
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Based on the linear regression modules, the best predictor variable was chosen to draw the Z score figures. The figure showed the relation between the measured TDI parameter on the Y axis and the best predictor variable on the X axis. Each figure showed the mean and the (-1, -2, +1, +2) Z scores. Normal values should lie anywhere between -2 and +2 Z scores
Results: We found that most TDI parameters correlated in a positive manner with age and body surface area. Conversely, they were correlated negatively with heart rate. There were no significant differences in both sexes. Time intervals generally showed higher degrees of correlation with the three parameters: age, body surface area and heart rate. The correlation of the time intervals with the heart rate was blunted to some extent after correcting the time intervals using the Bazett correction.
Our findings were partially consistent with some investigators. There were also points of differences which may be attributed to the different age and ethnic groups.
Conclusion: We introduced normal values and Z score figures for most of the left sided tissue Doppler parameters. This is probably the first Egyptian study done on a large group of healthy children to address the normal values of left side TDI. We hope this study would be of great benefit for all pediatric cardiologists and pave the way for future studies.
Recommendation: Tissue Doppler imaging (TDI) should be a part of routine practice in echocardiography when dealing with children with congenital or acquired heart diseases. This will greatly improve the accuracy of the study and will avoid multiple fallacies.