The Value Of Speckle Tracking Echocardiography And Serum Myocardial Enzymes In Hyperthyroid Cardiomyopathy In Rabbits

Objective:1.To evaluate the left ventriclar systolic function of different geometicpatterns in rabbits with hyperthyroid cardiomyopathy by speckle trackingechocardiography(STE).2.To study the correlation between the level of serum myocardial enzymes and leftventriclar systolic function of different geometic patterns in rabbits with hyperthyroidcardiomyopathy.Methods:Part one:Thirty New Zealand purebred rabbits were randomly dividedinto two groups:control group (n=10) and experimental group (n=20). Hyperthyroidismanimal model was established by peritoneal injection of Levothyroxine(L-Thy) for fourweeks in experimental group.STE and conventional echocardiographic parameters wereobtained at the4thweek in two groups,these parameters were as follow:left ventricularend diastolic diameter(LVDd), interventricular septal thickness at enddiastole(IVSTd),left ventricular inferolateral wall thickness at end diastole(IWTd),leftventricular ejection fraction(LVEF),left ventricular fraction shortening(LVFS),curvesand peak values of systolic radial strain (RS) and circumferential strain (CS).Accordingto the formula,calculate left ventricular mass(LVM),left ventricular massindex(LVMI),relative wall thickness(RWT).According to the ultrasound parameterchanges,the ventricular geometries of experimental group were divided into twogroups:concentric hypertrophy(CH) subgroup and eccentric hypertrophy(EH) subgroup.Part two:The animal,group and heart function parameters were the same as the partone.Hitachi7600automatic biochemical analyzer and diagnostic kits were used todetect myocardial enzymes in rabbits with hyperthyroid cardiomyopathy.Results:Part one:Compared with control group,LVDd,IVSTd,IWTd and LVMI inEH subgroup increased significantly(all P<0.01),and LVEF and LVFS in EH subgroup decreased significantly(all P<0.01).Compared with control group,IVSTd, IWTd,RWTand LVMI in CH subgroup increased significantly(all P<0.01).There were no statisticaldifferences in LVDd,LVEF and LVFS between control group and CH subgroup(allP>0.05).Compared with CH subgroup,LVDd and LVMI in EH subgroup increased(allP<0.05) and RWT,LVEF and LVFS decreased significantly(all P<0.01).Compared withcontrol group,RS values decreased significantly in anterior interventricular septums andanterior segments of CH subgroup,CS values decreased significantly in anteriorinterventricular septums,anterior segments and posterior interventricular septums inpapillary muscle of left ventricle level(all P<0.01).RS and CS curves of EH subgroupwere disordered,RS and CS values were evidently1ower than control group in papillarymuscles of left ventricle level(all P<0.01).Compared with CH subgroup,RS and CSvalues decreased significantly in anterolateral segments,inferolateral segments andinferior segments of EH subgroup,CS values of EH subgroup were decreasedsignificantly in posterior interventricular septums in papillary muscles of left ventriclelevel(all P<0.01).Part two:The blood CK-MB in EH subgroup was conspicuously higher than that incontrol group and CH subgroup(P<0.01).The blood CK-MB in CH subgroup was notchange significantly than that in control group(P>0.05).Other serum myocardialenzymes were also not change significantly among three groups(all P>0.05).Thepathological examination showed that the damage in EH subgroup was severer than thatin CH subgroup.LVEF and LVFS were negatively correlated with the bloodCK-MB(r=-0.393,P<0.05;r=-0.423,P<0.05).Conclusion:1.STE can assess accurately the left ventricle systolic function ofdifferent geometic patterns in rabbits with hyperthyroid cardiomyopathy.2.The blood CK-MB in rabbits with hyperthyroid cardiomyopathy in EH subgroupincreases obviousely,and not change in CH subgroup.The elevation of the bloodCK-MB is associated with the degree of pathological injury and is correlated with leftventriclar systolic function.