Evaluation Of Left Ventricular Function In Patients With Aortic Stenosis Retained In Ejection Fraction By Vector Flow Mapping

BackgroundValvular heart disease is a kind of common cardiovascular disease that endangers human life and health.Aortic stenosis(AS)is the most common valvular heart disease in people over 65 years old.It is estimated that the incidence of valvular heart disease is as high as 12.4%in the elderly and 13%in people over 75 years old.Its incidence increases with age.Patients with AS have a longer asymptomatic period and clinical symptoms only occur when the valve area is less than 1.0cm2.Typical clinical symptoms include angina pectoris,dyspnea and syncope.In the early stage of AS,the heart is in the compensatory stage,the cardiac function has not been decreased,and the patients may have no obvious symptoms.As the course of the disease progresses,the afterload of the heart increases,resulting in ventricular hypertrophy,cardiac decompensation,decreased cardiac function,heart failure and even death.Therefore,the accurate evaluation of cardiac lesions in patients with AS with preserved ejection fraction is of great significance to the evaluation of left ventricular function,the choice of treatment and the evaluation of prognosis.The vector flow mapping(VFM)technology is based on color Doppler flow imaging and speckle tracking echocardiography.Through the calculation of continuity equation,the blood flow in ventricle and cardiovascular cavity can be studied visually and quantitatively.VFM technology can quantitatively calculate the energy loss caused by blood flow viscous friction in the ventricular cavity,and find the changes of intracardiac hemodynamics by comparison with normal subjects,which provides a more sensitive quantitative index for the change of cardiac function.The application of VFM technology has covered a variety of clinical diseases,including hypertrophic cardiomyopathy,left ventricular diastolic dysfunction,dilated cardiomyopathy,ischemic cardiomyopathy and so on.ObjectiveTo quantitatively evaluate the energy loss in systolic and diastolic cavities of left ventricle in patients with AS with preserved ejection fraction by using VFM technique.MethodsFifty-two patients with AS treated in people's Hospital of Zhengzhou University from March 2018 to October 2019 were selected as case group.According to the?2017 EACVI/ASE Clinical recommendations?,combined with aortic valve area(AVA),aortic valve maximum blood flow velocity(Vmax)and aortic valve mean pressure gradient(PGmean),the patients were divided into three subgroups:mild aortic stenosis(miAS)group(n=17),moderate aortic stenosis(moAS)group(n=15)and severe aortic stenosis(seAS)group(n=20).In the same period,20 healthy people were selected as the control group.The left atrial anteroposterior diameter(LAD),left ventricular end-diastolic diameter(LVEDD),left ventricular ejection fraction(LVEF),peak E and peak A were measured by Japanese Aloka F75 color Doppler echocardiography with UST-52105 cardiac probe.The VFM program was started and the patients were instructed to hold breath after exhalation to collect dynamic color Doppler flow images of standard apical four-chamber,two-chamber and three-chamber sections in three consecutive cardiac cycles.The systolic and diastolic mean energy loss(m-EL)of left ventricle in each group was measured under the energy loss mode of VFM technique.The left ventricular m-EL in isovolumic contraction period(IVCP),rapid ejection period(REP),slow ejection period(SEP),isovolumic relaxation period(IVRP),rapid filling period(RFP),slow filling period(SFP)and atrial systole period(ASP)were obtained.The differences of IVCP,REP,SEP,IVRP,RFP,SFP and ASP left ventricular m-EL among each group were compared.Results1.Comparison of systolic m-EL of left ventricle:The left ventricular m-EL of REP in miAS group was significantly higher than that in control group(P<0.05).The left ventricular m-EL of IVCP,REP and SEP in moAS group were significantly higher than those in control group and miAS group(all P<0 05).The left ventricular m-EL of IVCP,REP and SEP in seAS group was significantly higher than that in control group,miAS group and moAS group(all P<0 05).There was no significant difference in IVCP and SEP left ventricular m-EL between miAS group and control group(P>0.05).2.Comparison of diastolic m-EL of left ventricle:The left ventricular m-EL of RFP and ASP in miAS group was significantly higher than that in control group(P<0.05).The left ventricular m-EL of IVRP,RFP,SFP and ASP in moAS group were significantly higher than those in control group and miAS group(all P<0 05).The left ventricular m-EL of IVRP,RFP,SFP and ASP in seAS group were significantly higher than those in control group,miAS group and moAS group(all P<0 05).There was no significant difference in left ventricular m-EL in IVRP and SFP between the miAS group and the control group(P>0.05).3.Pearson correlation analysis:In AS patients,IVCP,REP,SEP,IVRP,RFP,SFP and ASP left ventricular m-EL were negatively correlated with AVA(r=-0.810,-0.908,-0.835,-0.777,-0.919,-0.816,-0.838,respectively;all P=0.000),positively correlated with Vmax(r=0.815,0.903,0.843,0.782,0.922,0.828,0.873,respectively;all P=0.000);and positively correlated with PGmean(r=0.856,0.924,0.881,0.809,0.928,0.849,0.861,respectively;all P=0.000).There was a negative correlation between left ventricular m-EL and LVEF in IVCP(r=-0.774,P=0.000),REP(r=-0.870,P=0.000)and SEP(r=-0.829,P=0.000)in patients with AS.There was a positive correlation between left ventricular m-EL of RFP and E peak in patients with AS(r=0.852,P=0.000).There was a positive correlation between left ventricular m-EL of ASP and A peak in patients with AS(r=0.879,P=0.000).Conclusion1.Compared with the control group,the left ventricular systolic m-EL was increased in AS patients,suggesting that there were changes in systolic function in AS patients with preserved ejection fraction.2.Compared with the control group,the left ventricular diastolic m-EL was increased in AS patients,suggesting that there were changes in diastolic function in AS patients with preserved ejection fraction.3.Both systolic and diastolic left ventricular m-EL in patients with AS were correlated with AVA,Vmax and PGmean,indicating that systolic and diastolic left ventricular m-EL can be used to evaluate the severity of AS.4.IVCP,REP and SEP left ventricular m-EL in patients with AS were significantly correlated with LVEF,indicating that systolic left ventricular m-EL can be used to reflect left ventricular systolic function in patients with AS.5.There was a significant correlation between RFP left ventricular m-EL and E peak in AS patients,and there was a significant correlation between left ventricular m-EL and A peak in ASP,indicating that diastolic left ventricular m-EL can be used to reflect left ventricular diastolic function in patients with AS.6.The VFM technology provides a new method for the evaluation of left ventricular systolic and diastolic function in patients with AS,and EL is more sensitive than traditional LVEF and E/A in quantitative evaluation of left ventricular systolic and diastolic function.