الفهرس 
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Abstract
The anatomy of the adult human left ventricle (LV) is the result of its complex interaction with its environment. from the fetal to the neonatal to the adult form, the human LV undergoes an anatomical transformation that finally results in the most complex of the four cardiac chambers. In its adult form, the human LV consists of two muscular helixes that surround the mid ventricular circumferential layer of muscle fibers. Contraction of these endocardial and epicardial helixes results in a twisting motion that is thought to minimize the transmural stress of the LV muscle. In the healthy myocardium, the LV twist response to stimuli that alter preload, afterload, or contractility has been described and is deemed relatively consistent and predictable. Conversely, the LV twist response in patient populations appears to be a little more variable and less predictable, yet it has revealed important insight into the effect of cardiovascular disease on LV mechanical function. (1)
There is marked heterogeneity in results between studies and no standardization yet for normal reference value and change of these values with age and in different diseases.
Several elegant animal studies have shown that LV twist mechanics are sensitive to changes in LV loading conditions, and thus it must be emphasized that LV twist mechanics cannot be considered load-independent indicators of contractility or lusitropy. Gibbons et al. (11) showed that alterations in loading conditions change LV apical rotation in dogs and concluded “LV twist is primarily a function of volume.”
Echocardiographic speckle tracking imaging (STI) permits rapid and accurate assessment of LV twist mechanics and has been validated with cardiac MRI techniques (10) that was limited due to its higher cost and lower temporal resolution in contrast to speckle tracking echocardiography with its lower cost and higher frame rates with resultant higher temporal resolution.
Aim of the work:
Assessment of left ventricular twist and untwist mechanics in patients with congenital Lt to Rt shunt (ASD, VSD, PDA)
Patients and Methods: A Single center study enrolled 160 children aged less than 6 years were included in the STE analyses for LV twist mechanics. Exclusion of patients aged less than 3 months due to heterogeneous results of their twist and untwist parameters that may affect the final results, good speckle tracking and reliable measurements of twist parameters were possible in 107 children, all aged ≥ 3 month, who finally comprised the study population for analysis.
Study population were divided into 4 groups matching in age and sex:
PDA group: (20 patients)
VSD group: (24 patients)
ASD group: (20 patients)
Control group: (43 normal children)
All study participants underwent full history taking, general examination, local cardiac examination, 12- lead electrocardiogram, Conventional echocardiography (including assessment of IVSd, IVSs, LVIDd, LVIDs, LVPWd, LVPWs, EDV, ESV, SV, EF, FS, LA dimensions, aortic root diameter, E, A, e, a, E/e, IVRT) and 2D-STE (including assessment of longitudinal, circumferential and radial strains), different systolic and diastolic twist parameters (apical and basal rotation, peak twist, time to peak twist, peak twist rate, peak untwist rate, time to peak twist rate, time to peak untwist rate, torsion, peak torsion velocity, amount of untwist during isovolumic relaxation time, isovolumic untwist recoil rate).