| Objectives:Quantitative analyze the left ventricular myocardial strain of patients with aortic valve stenosis(AS)of different degrees by using Layer-Specific strain,and to explore the changes of left ventricular myocardial function,so as to provide a reference for staging and selection of appropriate treatment for AS patients in clinical practice.Methods:Selecting 68 cases LVEF≥50% in patients with aortic stenosis as the research object from Hunan Provincial People’s Hospital between January2020 and December 2020.According to the 2017 detailed recommendations from the EACVI and ASE for echocardiographic evaluation of aortic stenosis will be grouped AS patients,including mild AS group of 30 cases,moderate the AS group of 20 cases,18 cases severe AS group.At the same time,33 healthy people of the same period and age suitable for the case group without obvious heart disease were included as the control group.The heart probe with frequency of 1-5MHz of Philips EPIQ 7C color Doppler ultrasound diagnosed instrument was selected to collect and save the relevant dynamic images,and then the Layer-Specific strain software was used for analysis.All the object of study were informed of the operation method and content and obtained informed consent before examination.According to the 2019 ASE guideline,measuring the following parameters:Left ventricular end diastolic dimension(LVEDD),Left ventricular end systolic dimension(LVESD),End diastolic interventricular septal depth(IVSD),End diastolic left ventricular posterior walldepth(LVPWD),Aortic valve mean pressure gradient(MPG)and Aortic systolic peak velocity(Vmax).LVEF was measured by biplanar Simpson method.Application Layer-Specific strain technology to measure the following parameters:systolic peak global endocardial longitudinal strain(GLSendo),systolic peak global midcardial longitudinal strain(GLSmid),systolic peakglobal epicardial longitudinal strain(GLSepi),systolic peak global endocardial circumferential strain(GCSendo),systolic peak global midcardial circumferential strain(GCSmid),systolic peak global epicardial circumferential strain(GCSepi)and circumferential strain at the mitral valve,papillary muscle and apex levels.All parameters were measured three times,which mean values were compared.At the same time,the venous blood of the patients was extracted to obtain NT-pro BNP data,and the correlation analysis was made between the systolic peak global longitudinal and circumferential strain of each layer of myocardium and the degree of NT-pro BNP and valve stenosis.Results:1.Comparison of general informationThere were no noticeable changes in age,sex character,height,heart rate and weight in AS groups at different degrees compared with the control group(P > 0.05).2.Comparison of parameters of conventional echocardiographyCompared with the control group,IVSD,LVPWD,aortic valve MPG and aortic valve peak velocity were increased in mild,moderate and severe AS groups,and those parameters with increasing AS severity(P <0.05).Compared with the control group,there were no noticeable changes in left ventricular systolic and diastolic diameter and LVEF in AS groups at different degrees(P > 0.05).IVST,LVPWT,MPG and Vmax in the moderate AS group were distinctly different from those in the mild AS group(P < 0.05).Patients with severe AS had significantly increased in IVSD,LVPWD,MPG and Vmax compared with both the mild and moderate AS groups(P < 0.05).3.Comparison of layer-specific strain parameters:(1)The systolic peak global longitudinal strain of the myocardium of the left ventricle decreased gradually from the endocardial layer to the epicardial layer in both the control group and the AS groups with different degrees.Compared with the control group,the global peak longitudinal strain in the systolic period of each layer of the AS groups with different degrees decreased,and the differences were statstically significant(P < 0.05).Compared with the AS group,GLSendo decreased in the moderate AS group compared with the mild AS group(P < 0.05).Compared with the mild and the moderate AS group,the global longitudinal strain of peak in systolic period of the severe AS group was lower(P < 0.05).(2)In both the control group and the AS groups with different degrees,the global peak circumferential strain in the systolic period of the left ventricle decreased from the endocardial to the epicardial layer,and increased gradually from the mitral valve to the apex level.Compared with the control group,there were no distinctly differences in the systolic peak global circumferential strain in each layer and segment of the myocardial in the mild AS group(P > 0.05),while the GCSendo,GCSmid and GCSepi in the moderate and severe AS groups were all decreased,with noticeable differences(P < 0.05).Comparison with with the matched group,the mitral valve,papillary muscle and apex level systolic peak circumferential strain both the endocardial layer and middle layer of moderate AS group were reduced(P < 0.05),while in the severe AS group,the peak circumferential strain of systolic myocardium at the mitral valve,papillary muscle and apex level was decreased(P < 0.05).There was no distinctly difference in the global peak circumferential strain of the inner,middle and outer layers between the moderate AS and the mild AS group(P > 0.05).Compared with the mild and moderate AS groups,the global peak circumference strain in the systolic period of the severe AS group was lower,(P < 0.05).Compared with the mild AS group,there was no significant difference in the peak circumferential strain of each segment and layer(P > 0.05).Compared with the mild AS group,endocardial layer and middle myocardial systolic peak circumferential strain of the levels of the mitral valve and papillary muscle in the severe AS group were all decreased(P < 0.05).The systolic peak circumferential strain of endocardial and middle myocardium in apical level of severe AS group was lower than that in moderate AS group(P < 0.05).4.Correlation analysisCompared with the control group,NT-pro BNP increased in mild,moderate and severe AS groups,and gradually increased with the increase of AS severity(P < 0.05).NT-pro BNP was positively correlated with Vmax(r=0.806,P<0.001).GLSendo,GLSmid and GLSepi were negatively correlated with Vmax(r=-0.889,-0.688,-0.680,P <0.001).GCSendo、GCSmid、GCSepi were negatively correlated with Vmax(r=-0.772,-0.728,-0.704,P < 0.001);GLSendo 、 GLSmid 、GLSepiwere negatively correlated with NT-pro BNP(r=-0.825,-0.711,-0.719,P<0.001);GCSendo、GCSmid、GCSepi were negatively correlated with NT-pro BNP(r=-0.698,-0.679,-0.696,P<0.001)。Conclusions:1.layer-specific strain technology can better detection of left ventricular myocardial systolic peak longitudinal strain and circumferential strain.The control group with different levels AS groups are characterized by the longitudinal and circumferential strain by endocardial layer to the epicardial reduce layer by layer,gradually increased levels of mitral valve to apex.2.Aortic stenosis can lead to structural and functional changes of the left ventricle,and with the aggravation of valve stenosis,the global peak longitudinal and circumferential strains of each layer of myocardium in systolic period gradually decreased.The longitudinal strain parameter decreases earlier than the circumferential strain.Left ventricular myocardial function injury gradually developed from endocardial layer to transmural myocardium.3..Before LVEF of conventional echocardiography was changed,the layer-specific strain parameters of the left ventricle had changed,sugge STEng that those parameters were a useful indicator to evaluate the early cardiac function damage of the left ventricle.GLSendo is the earliest indicator of abnormal changes,and can be used for the early and sensitive detection of subclinical left ventricular systolic dysfunction.4.GLSendo combined with NT-pro BNP level can more accurately evaluate the cardiac function status of patients with different degrees of AS,and grade the cardiac function of patients with AS. |
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