Study Of Left Ventricular Hydrodynamics In Patients With Heart Failure With Reduced And Middle-ranged Ejection Fraction By Vector Flow Mapping

BackgroundHeart failure(HF)is the terminal stage of various cardiovascular diseases and the main leading cause of death.The harmonious interaction between myocardium and blood flow is gradually disrupted during the evolution of left ventricular remodeling,causing inappropriate adaptation of the intraventriclar relative pressure spatial and temporal distribution,the intracardiac flow field and flow energy performance,which further aggravated the left ventricular remodeling.Therefore,the assessment of left ventricular hydrodynamics is also an important part of left ventricular function evaluation.Vector flow mapping(VFM)can visually observe the left ventricular flow field and quantitatively evaluate the hydrodynamics.However,no comparative study of left ventricular hydrodynamic changes in heart failure with reduced ejection fraction(HFrEF)and heart failure with middle-ranged ejection fraction(HFmrEF)has been reported.Therefore,in this study,the left ventricular structure,function and hydrodynamics changes in patients with different types of heart failure were comprehensively investigated by using traditional echocardiography and new VFM technology,and the characteristics of intracardiac hydrodynamics changes in patients with heart failure were observed noninvasivelyObjective1.Using VFM technology to analyze intraventricular relative pressure gradient(IVPG),left ventricular flow field and energy loss(EL)during different phases in HFrEF and HFmrEF patients to comprehensively evaluate the changes of left ventricular hydrodynamics.2.Exploring the relationship between left ventricular fluid dynamics and ventricular structure and functionMethods1.Research objectsForty-nine patients with heart failure were enrolled to the HF group,including thirty-three patients in the HFrEF group and fifteen in HFmrEF group.A total of 43 patients without heart failure were selected as the control group.General clinical data such as gender,age,height,weight,BMI,BSA,heart rate,blood pressure,complications,NT-proBNP were recorded2.Echocardiographic examinationThe HITACHI-ALOKA LISENDO 880 echocardiography instrument was used to acquire the images of the parasternal long axis view,apex two-chamber,three-chamber and four-chamber views.Pulsed wave doppler was used to measure mitral valve blood flow during diastole,and tissue doppler was used to measure mitral ring velocity.In apical three-chamber view,VFM mode was selected to determine the isovolumic systolic period(P1),ejection period(P2),isovolumic diastolic period(P3),early diastolic period(P4)and atrial systolic period(P5),then observe the intraventricular flow field at each phase and measure the relative pressure,vortex and energy loss indicators3.Measurement indicatorsWe measured IVS,LVPW,LVEDD,LAD,EDV,ESV,LAV(by two-plain Simpson method)in two-dimensional echocardiography images and calculated LVM,LVMI,SI,LVEF,SV,CO,CI,LAVI.The echo system automatically calculated absolute value of GLS by simplified spot tracing technology when we did the two-plain measurements.We measured E,A,E/A,and DT in color doppler images and e's,e'l in tissue doppler images and calculated the average e' and E/e'.We recorded the intraventricular relative pressure difference(IVPD)and intraventricular relative pressure gradient(IVPG),vortex features and EL during five phases in VFM images.Vortex features included number,location,shape,orientation,maximum area(Al),maximum circulation(Cl)and duration.EL indicators included maximum EL(ELl),mean EL(ELm),and total EL in each phase(ELt).4.Statistical methods SPSS 24.0 was used for analysis,and the measurement data were all tested for normality.Independent sample t test,Wilcxon rank-sum test,Mann Whitney U test or chi-square test were used for comparison between the two groups.One-way ANOVA or Brown-forsythe's test were used for comparison between multiple groups.Spearman correlation analysis was used to study the correlation of two variations,and multivariate linear regression was performed to find the independent correlation factors of IVPD and IVPG.The level of statistical significance was set at P<0.05.Results 1.General clinical data comparison No statistically difference was observed in age,gender,height,weight,BMI,BSA,history of hypertention,smoking,drinking and heart rate between HF and control groups(P>0.05),and no statistically difference among control,HFmrEF,and HFrEF groups as well.There were more people with diabetes mellitus in the HF group than in the control.Patients in the HF group showed lower systolic and diastolic blood pressure and higher serum NT-proBNP than in the control group.Serum NT-proBNP in the HFrEF group was statistically higher than in the control(P<0.05).2.Comparison of two-dimensional and doppler ultrasonic indicators 2.1 Left ventricular size and mass:LVEDD,EDV,ESV,LVM,LVMI increased in the HF group than in the control(P<0.05).Among the three groups,LVEDD,EDV,ESV were highest in the HFrEF group,then in the HFmrEF group and last in the control(P<0.05).HFrEF and HFmrEF groups showed higher LVM and LVMI than control group(P<0.05),but no statistically difference exited between the HF subgroups(P>0.05)2.2 Left atrial size:The HF group showed larger LAD,LAV and LAV than the control(P<0.05).These three indicators were larger in the HF subgroups than in the control(P<0.05)but no statistically difference exited between the HF subgroups(P>0.05)2.3 Left ventricular spherical index:SI was significantly larger in the HF group than in the control(P<0.05).The HFrEF group showed larger SI than the control(P<0.05),but no significant difference with HFmrEF group(P>0.05)2.4 Left ventricular systolic function index:LVEF,GLS,SV,CO,CI were reduced in HF group compared with the control group(P<0.05).Among the three groups,LVEF,GLS were lowest in the HFrEF group,then in the HFmrEF group and last in the control(P<0.05).The HFrEF and HFmrEF groups had lower SV than the control(P<0.05)and the HFrEF group had lower CO and CI compared with the control group(P<0.05)2.5 Left ventricular filling indicators:E/A and E/e' were higher in HF group than in the control(P<0.05).HFrEF group had higher E,E/A and E/e' compared with HFmrEF and control groups(P<0.05).HFmrEF group had higher A than the other two groups(P<0.05).3.Comparison of VFM relative pressure indicatorsThe normal intraventricular relative pressure presented a regular stratified distribution increasing or decreasing along the long axis,indicating that the normal left ventricular IVPG had an obvious longitudinal orientation,which was lost in failing heart.In iso volumetric systole and ejection phases,IVPG directed from the left ventricular apex to the base.While in isovolumetric diastole,early diastole and atrial systolic phases,IVPG directed from the base to the apex.In all five phases,IVPD and IVPG in HF group were lower than the control(P<0.05),and it was more obvious in isovolumetric diastole and atrial systole phases.In addition,there was a decreasing trend for IVPD and IVPG in the control,HFmrEF,and HFrEF groups(P<0.05)4.Comparison of VFM left ventricular flow field and vortex indicatorsIn the control group,the blood flow formed two vortices on both sides of the anterior and posterior leaflets of the mitral valve during the rapid filling period.As the ventricular filling,the anterior clockwise vortex gradually increased and moved to the center of left ventricle to form a larger regular vortex that lasted till the early part of the ejection phase and contributed to be the outflow jet.There was no significant difference in the number of vortices between the HF and control groups(P>0.05)However,patients with heart failure showed a looser and larger clockwise vortex during diastole which was closer to the apex.Meanwhile,there were several small vortices that varied in sizes,locations and direction of rotation in the left ventricle The maximum area of the vortex(Al)in isovolumetric diastole and atrial systole phases were statistically different(P<0.05).There was no significant difference in Cl in five phases(P>0.05).No significant difference was found in left ventricular blood flow pattern between the HFrEF and HFmrEF groups.5.Comparison of VFM energy loss indicatorsELm-P2,ELt-P2 and ELm-P3 in HF group were lower than in control(P<0.05),while EL1-P5,ELm-P5 and ELt-P5 in atrial systole phase were higher(P<0.05).Among HFrEF,HFmrEF and control groups,ELm-P2 and ELm-P3 in HFrEF group were lower than in control(P<0.05).ELm-P4 in HFrEF group was higher than the other two groups(P<0.05).There was no significant difference of EL indicators in other phases among the three groups(P>0.05).6.Correlation analysis6.1 IVPD and IVPG in five phases were to different degrees negatively correlated with LVEDD,LVMI,ESV and positively correlated with LVEF and GLS(P<0.05)IVPG-P3 had the strongest correlation with LVEF and GLS(r=0.745,0.690,P<0.05)6.2 EL1-P4 and ELm-P4 were highly positively correlated with E(r=0.735,0.724,P<0.05).EL1-P5 and ELm-P5 were highly positively correlated with A(r=0.567,0.590,P<0.05).(r=0.735,0.724,P<0.05)?6.3 ELI and ELm in P1,P2 and P3 were positively correlated with IVPD and IVPG in the same phase(P<0.05).ELI and ELm in P3 and P4 were positively correlated with Al and Cl in the same phase(P<0.05).ELt in five phases were positively correlated with Cl in the same phase(P<0.05)6.4 Among all objects,IVPG in five phases were all independently associated with LVEF(P<0.05).In addition,IVPG-P1 was independently associated with LVL(P<0.05)and IVPG-P2 was independently associated with LVEDD(P<0.05).Among all patients with heart failure,IVPG-P1,IVPG-P2 and IVPG-P3 well independently associated with GLS(P<0.05).Conclusions1.In patients with heart failure,IVPD and IVPG lost the strict base-apex longitudinal orientation in five phases of cardiac cycle,and are lower than the normal heart2.IVPD and IVPG in five phases are correlated with the left ventricular structural and functional parameters.IVPD and IVPG decrease as the progression of left ventricular reconstruction.3.In the heart failure group,the main diastolic vortex were loosely arranged and enlarged,and there were small vortices in different directions and sizes in diastole period,causing a significant increase in energy loss in atrial systole phase4.VFM technology can be combined with two-dimensional echocardiography to comprehensively assess the left ventricular structure,intraventricular relative pressure distribution and intraventricular blood fluid dynamics changes in patients with heart failure of different degrees.