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Objective:To explore alterations of myocardial mechanics in mice models of physiological aging.Methods:Mice aged from 3 weeks to 24 months were chosen(n=50). Conventional echocardiography and layer speckle tracking echocardiography(LS-STE)were applied to evaluate alterations of myocardial mechanics in different ages(each for 10 mise). Pathological myocardial alterations in the aging process were detected using HE and Masson's trichrome staining.Results:Clear age-dependent changes in mice of different ages were observed when assessed using parameters of conventional echocardiography( P<0.05 for all). Values from parameters of LS-STE also showed that longitudinal, circumferential and radial strain in both the endocardium and the epicardium gradually decreased during physiological aging( P<0.05 for all). Compared with the 3-weeks old group, longitudinal strain in the endocardium was significantly reduced in the 14-months old group[(-23.49±2.32) vs.(-17.19±2.28), P<0.05]; Compared with the 3-weeks old group, radial strain, longitudinal strain in the endocardium, longitudinal strain in the epicardium, circumferential strain in the endocardium and circumferential strain in the epicardium were significantly reduced in the 24-months old group[(32.90±5.01) vs.(21.80±5.54), (-23.49±2.32) vs.(-15.44±2.27), (-13.23±3.19) vs.(-7.59±2.21), (-25.93±4.09) vs.(-20.31±4.08), (-9.30±1.92) vs.(-6.01±1.04), P<0.05)]; HE and Masson's trichrome staining of the myocardium indicated increases in the cross-sectional area of cardiomyocytes and fibrosis during the aging process. Conclusions:LS-STE can accurately detect early cardiac dysfunction and pathological myocardial alterations associated with aging in mice and may serve as an effective tool in evaluating anti-myocardial aging.
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Objective To assess the left ventricular systolic function after renal sympathetic denervation(RSD) in beagles with heart failure by layer-specific two-dimensional speckle tracking imaging.Methods Twenty-three beagles were randomly divided into control group (8 dogs),URSD group (8 dogs)and RSD group (7 dogs).Control group was implanted with pacemakers without pacing,URSD group was implanted with pacemakers and underwent 3 weeks of rapid right ventricular pacing,and RSD group underwent catheter-based RSD bilaterally and was simultaneously implanted with pacemakers.All standard measurements were obtained from the left ventricular short-axis views at the levels of mitral annulus,papillary muscle and apex,and apical four-chamber,two-chamber,and long-axis views.The peak systolic longitudinal strain and circumferential strain of each layer of the left ventricle were measured by layerspecific two-dimensional speckle tracking imaging.Results After 3 weeks,all of the dogs in both the URSD and RSD groups showed lower left ventricular diastolic and systolic function compared with those in the control group,however,the dogs in the RSD group had a higher LV ejection fraction (LVEF) than the dogs in the URSD group(P ＜ 0.05).Compared with the control group,the global longitudinal strain,circumferential strain and radial strain all decreased significantly in URSD and RSD groups.The longitudinal strain of endo-and mid-cardium and the circumferential strain in endo-cardium were significantly higher in RSD group than those in URSD group(P ＜0.05).Conclusions Myocardial systolicfunction is impaired in dogs with heart failure,layer-specific two-dimensional speckle tracking imaging can provide effective tools to assess the left ventricular systolic function.Renal sympathetic denervation can improve the myocardial systolic function in dogs with heart failure.
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Objective To evaluate the impact of maintenance hemodialysis(MHD) on left ventricular(LV) strains via layer-specific speckle-tracking imaging (LSTI).Methods Twenty-eight MHD patients and 28 matched controls were enrolled in the study.Conventional echocardiography and LSTI were performed on patients before and shortly after one hemodialysis session,as well as on controls.Results LV end-diastolic volume (LVEDV) were markedly reduced after one session of HD [(52.3±22.4)ml/m2 vs (55.0±15.3)ml/m2,P=0.033],but still larger than the control group (47.4±6.4) ml/m2.LV ejection fraction (LVEF) decreased in MHD patients after HD [(62.5±8.1)% vs (64.6±7.3)%,P=0.06],which was similar to those in the control group (66.0±4.2)% and in MHD patient before HD (P=0.391).The three layer circumferential and longitudinal strains decreased in the order of the control group,patients before HD and after HD [CS-endo:(-26.3±3.6)% vs (-22.2±4.7)% vs (-19.2±5.4)%;CS-mid:(-19.0±2.7)% vs (-15.3±3.5)% vs (-13.0±3.8)%;CS-epi:(-11.1±2.3)% vs (-8.0±2.6)% vs (-6.5±2.3)%;LS-endo:(-23.7±3.0)% vs (-18.6±3.6)% vs (-16.4±4.5)%;LS-mid:(-20.9±2.7)% vs (-16.3±3.1)% vs (-14.0±4.1)%;LS-epi:(-18.4±2.4)% vs (-14.1±2.8)% vs (-12.0±3.6)%;all P<0.01],while the synchrony index,standard deviation of times to peak longitudinal strain,increased in these three groups [(3.6±1.0)% vs (6.3±1.5)% vs (7.5±2.2)%,all P<0.01].Linear correlation analysis showed ultrafiltration volume was negatively related with the difference of longitudinal strains before and after HD (difference of LS-endo:r=-0.428,P=0.023;difference of LS-mid:r=-0.423,P=0.025;difference of LS-epi:r=-0.422,P=0.025).Conclusions One session of HD may have injurious effects on LV strains and systolic synchrony.The reduction of ultrafiltration volumes may be helpful to protect cardiomyocytes.
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Objective To quantitatively evaluate the difference in global longitudinal strain(GLS)and global circumferential strain (GCS)of three-layers of cardium between diabetes mellitus (DM)patients using layer-specific speckle-tracking imaging.Methods Fifty-seven DM patients and sixty matched controls were enrolled in the study.GLS and GCS of three-layer cardium were assessed using layer-specific speckle-tracking imaging,available by GE Vivid E9 and EchoPac workstation.Results GLS of three-layer cardium in DM patients were significantly lower than those in normal controls (all P 0.05 ).GLS and GCS of three-layer cardium was highest in endo-cardium and lowest in epi-cardium.Conclusions GLS of three-layer cardium may be a sensitive indicator of early left ventricular systolic dysfunction in DM patients with normal ejection fraction.