Assessment Of Left Ventricular Longitudinal Systolic Function Of Congenital Hypothyroidism By Two-dimensional Speckle Tracking Imaging

Congenital hypothyroidism (CH) is a common endocrine diseases ofpediatrics, clinical manifestations is thyroid hormone level in permanent ortemporary decrease and postnatal Thyroid stimulating hormone (TSH) levelincrease. The heart is an important target organ of thyroid hormones, thyroidhormone plays an important role in maintaining cardiac function. Thyroidhormone can regulate the transcription of many genes in myocardial cells, thethyroid hormones T3and nuclear receptors combining can increase the synthesisof protein, thus affecting the transport of amino acids and sugars on the cellmembrane, and thyroid hormones also affect calcium absorption on thesarcoplasmic reticulum and the activity of ATP enzyme. In addition, thyroidhormone has extranuclear effects, such as short-term changes of T3can changechannel characteristics of sodium and calcium ion in the cardiac, that can affectthe cardiac systolic and rhythm. Expression of myocardial adrenergic receptorgene and sensitivity sympathetic-adrenergic system are enhanced by thyroidhormone, thyroid hormone also can reduce the resistance of peripheral vascularwhile improve cardiac output. Laboratory studies have been show by Heron MIthat thyroid hormone has a certain effect on the growth of coronary arteriole,hypothyroidism can control the growth of small arteries, but hyperthyroidism hasthe opposite effect. Animal experiments suggest that the decrease of thyroidhormone can make the expression of transport protein of the myocardial calciumabnormally, which inhibit the enzyme activity directly and lead to the Ca2+inmyocardial intracellular overloaded, resulting in systolic and diastolic functiondecreased.Objective: To further evaluate the change of left ventricular global andregional systolic function with hypothyroidism, this study use two-dimensional speckle tracking technology to detect left ventricular longitudinal systolic functionin children with hypothyroidism and to explore its clinical value.Methods: Two-dimensional speckle tracking imaging technology (2D-STI)is based on the two-dimensional and select the a certain interest region in theVentricular wall, with the heartbeat cycle, analysis software according gray scaleautomatic frame-by-frame to track the interest region of cardiac muscle tissue’sposition and motion, while compared with the first frame image position tocalculate the deformation of every segment of Ventricular wall.2D-STItechnology compared with the traditional technique is not affected by the anglebetween the direction of the beam and wall motion direction and no angledependence that can more accurately reflect the regional systolic and diastolicfunction of myocardium. Automatic functional imaging (AFI) in this study is afast, practical simple analysis software of speckle tracking imaging can quicklyacquire and analyze the abnormalities of ventricular wall motion and leftventricular segmental analysis diagram.This study selected35children with hypothyroid and30age-matchednormal children. Two groups of subjects were excluded other diseases.Longitudinal peak systolic strain of left ventricular（LPSS) and the Global leftstrain (GLS), the Global left strain average(GLS-Avg) of18segments of thestrain curve and left ventricular segmental analysis diagram are detected by AFI.Results:(1) Compared with the common parameters of left ventricularsystolic function:Left ventricular ejection fraction (LVEF) and left ventricularfractional shortening (LVFS%) of CH compared with the normal control group,the difference was not statistically significant (P>0.05).(2) Left ventricularpeak systolic longitudinal strain (LPSS): Anterior basal segment, the side wall ofthe apical segment, septal basal section, middle section, the posterior wall of thelongitudinal peak systolic strain were significantly different between those ofcontrol group(P<0.05).(3) The section of left ventricular whole strain andaverage strain: Global left ventricular systolic strain (GLS) was significantly lower than the normal group (P<0.05).Conclusion: AFI technology can accurate and rapid detection myocardialsystolic function changes in the present study, and also has very good thefeasibility and accuracy, which is an effective means for the assessment of leftventricular function in clinical. The research results show that patients withhypothyroidism have left ventricular whole and local systolic function change,AFI can detect the early changes of cardiac function in children and feedback tothe clinical timely, it has a great significance to guide the clinical medication andis worth to popular widely.