Evaluate The Left Ventricular Function Of Hypertrophic Cardiomyopathy By Vector Flow Mapping(VFM) And Speckle Tracking Imaging

Hypertrophic cardiomyopathy(HCM)is the most common cardiomyopathy with an age-related prevalence ranging from 0.02% to0.23%(ie,1 in 500)in adults.In about 60% of cases,it is transmitted as an autosomal dominant trait mainly caused by mutations in cardiac sarcomere protein genes,while in a smaller proportion(5%–10%)of adult cases,HCM is caused by other genetic disorders(eg,inborn errors of metabolism,neuromuscular diseases,mitochondrial disease).Patients typically present with an increased left ventricular(LV)wall thickness,not otherwise explained by abnormal loading conditions.The anatomical and functional features include myocytes disarray,interstitial fibrosis,abnormal coronary microcirculatory function,and electrocardiographic abnormalities.The diagnosis of HCM is based on the detection of increased LV wall thickness(?15 mm in one or more LV myocardial segments)by any imaging modality.Standard echocardiographic examination represents a pivotal tool in prompt evaluation and quantification of LV wall thickness and identification of specific details,such as systolic anterior motion(SAM)of the mitral valve and latent LV outflow tract obstruction(LVOTO).However,it lacks diagnostic accuracy for the identification of early myocardial impairment and for differential diagnosis underlying this condition.The evolution of newer ultrasound-based technologies,such as vector flow mapping(VFM),2D speckle tracking,3D speckle tracking,has revolutionized the assessment of cardiac performance with a more sophisticated evaluation of global and regional cardiac function.VFM can evaluate the left ventricular hemodynamic status,such as left ventricular energy loss,wall shear stress and circulation,etc.Layer-specific quantification of myocardial deformation(subendocardial,midmyocardial,and subepicardial layer),may disclose the subclinical systolic dysfunction and synchronicity.3D speckle tracking imaging can evaluate the systolic and twist function of left ventricle from the perspective of the three-dimensional.These advances are progressively becoming a pivotal tool in clinical workup of affected patients,allowing us to refine differential diagnosis in HCM.This research includes three parts:Part ? Left ventricular energy loss and wall shear stress assessed by vector flow mapping in patients with hypertrophic cardiomyopathyObjective: The aim of this study was to assess left ventricular(LV)summation of energy loss(EL-SUM),average energy loss(EL-AVE)and wall shear stress(WSS)using vector flow mapping(VFM)in patients with hypertrophic cardiomyopathy(HCM).Methods: Forty HCM patients,and 40 controls were evaluated by transthoracic echocardiography.Conventional echocardiographic parameters,summation and average of energy loss(EL-total,EL-base,EL-mid and EL-apex),and WSS in each segment were calculated at different phases.Results: Compared with controls,conventional diastolic measurements were impaired in HCM patients.HCM patients also showed increased EL-SUM-total and EL-AVE-total at the peak of LV rapid ejection period as well as decreased EL-SUM-total and EL-AVE-total at the end of early diastole.In controls,EL-SUM and EL-AVE showed a gradual decrease from the basal segment to the apex,this regularity was not observed in HCM patients.Compared with controls,HCM patients showed increased WSS at the peak of the LV rapid ejection period and the atrial contraction period as well as decreased WSS at the end of early diastole(all p < 0.05).WSS was increased slightly at the peak of the LV rapid filling period in HCM patients(p=0.055).Conclusion: EL and WSS values derived from VFM are novel flow dynamic parameters that can effectively evaluate systolic and diastolic hemodynamic function in HCM patients.Part ? Layer-specific quantification of myocardial deformation may disclose the subclinical systolic dysfunction and synchronicity in patients with hypertrophic cardiomyopathyObjective: To evaluate the global and regional myocardial systolic function in different myocardial layers and synchronicity in the patients with hypertrophic cardiomyopathy(HCM)by using layer-specific quantification of myocardial deformation.Methods: Myocardial imaging of 40 HCM patients(HCM group)and 40 healthy subjects(control group)was collected.The apical long-axis,four-and twochamber views and parasternal short-axis at the basal,middle,apical levels were acquired by echocardiography.The peak systolic longitudinal and circumferential strain of the subendocardial,midmyocardial,and subepicardial layers was measured using two-dimensional speckle tracking echocardiography(2D STE).The standard deviation of time to peak longitudinal strain(PSD)in 17 segments of left ventricle were calculated.The data were compared and analyzed between the two groups.Results: The longitudinal and circumferential strain were decreased gradually from the subendocardial to the midmyocardial to the subepicardial layer in both HCM group and control group(p<0.05).Compared with healthy subjects,the absolute value of layer and global longitudinal strain was significantly lower in HCM group(p<0.01).The interventricular septum thickness at end-diastole positively correlated with the peak longitudinal systolic strain of the subendocardial,the midmyocardial,and the subepicardial layers from the bull-eye view of longitudinal myocardial strain.Compared with healthy subjects,the global circumferential strain and circumferential strain in apical level of midmyocardial and subepicardial layers was significantly lower in HCM group(p<0.01).Compared with controls,the global longitudinal and circumferential strain was significantly lower in HCM group(-20.44±1.58 vs-13.21±2.78,p<0.01;-17.99±3.18vs-14.08±1.93,p<0.01,respectively).The circumferential transmural gradient(?LS=LPSEndo-LPSEpi)is obvious than the longitudinal transmural gradient(18.70±1.84v5.74±0.71 s,P<0.01).PSD of HCM group was larger than that of control group(83.77±34.34 vs 29.33±3.78,P<0.01)?Conclusion: Layer-specific quantification of myocardial deformation can assess left ventricular global and regional function,providing another useful equipment.Part ? Evaluation of systolic and twist function of left ventricle in hypertrophic cardiomyopathy using 3D speckle tracking imagingObjective: To evaluate the longitudinal,circumferential,area,radial strain and twist,torsion of left ventricle in the patients with hypertrophic cardiomyopathy(HCM)using 3D speckle tracking imaging.Methods: 4D full-volume imaging of 40 HCM patients(HCM group)and 40 healthy subjects(control group)was collected.Longitudinal,circumferential,area,radial strain and twist,torsion of left ventricle were measured respectively.The data were compared and analyzed between the two groups.Results: Compared with controls,the longitudinal strain,area strain,radial strain was significantly lower in HCM group(p<0.01,respectively).Circumferential strain was also lower in HCM group,but no significant difference was found between two groups(p>0.05).Compared with controls,left ventricular twist was significantly higher in HCM group(p<0.05).The rotation at the base and apex(RotB,RotA),torsion of left ventricular(Tor)in HCM group was higher,but no significant difference was found between two groups(p>0.05).Compared with 2D speckle tracking,the measurement of longitudinal was lower,circumferential strain and radial strain were higher using 3D speckle tracking.The measurement time was significantly reduced using 3D speckle tracking.Conclusion: 3D speckle tracking is a useful method to assess LV systolic function and torsional deformation and may make the assessment more available in clinical and research cardiology.