Assessment of Regional Myocardial Function in Patients with Hypertrophic Cardiomyopathy by Tissue Strain Imaging

The value of tissue strain imaging （SI） in regional myocardial systolic and diastolic func tion assessment was studied. In 18 patients with nonobstructive hypertrophic cardiomyopathy （HCM） and 20 age-matched healthy subjects, regional myocardial longitudinal peak systolic strain in eject time （represented by εet） was measured at basal, mid and apical segments of septal, lateral and posterior walls of the left ventricle （LV） and compared between groups, εet had no significant difference between segments in control group （P〉0.05）, which displayed a decreasing trend from basal segments to apical ones. εet in the HCM group was significantly decreased （P（0. 05） as compared with that in the healthy group. In the HCM group, εet in the midseptum was significantly less than at the basal and apical septum, and was also less than at the rest LV walls in the same group （P〉0.01）. The systolic reversed εet was noticed in 35% of the hypertrophic segments in HCM group. Significantly negative correlation existed between the absolute value of εet and wall thickness in the midseptum （r= -0.83）. The post-systolic strain（PSS） segment number the and amplitudes in healthy group were significantly less than those in HCM group （P〈0.05）. Both regional myocardial systolic and diastolic functions were impaired in hypertrophic or non-hypertrophic segments in patients with the HCM, especially in hypertrophic segments. Strain imaging technique is a sensitive and accura tool in myocardial dysfunction assessment.

Assessment of Left Ventricular Longitudinal Regional Myocardial Systolic Function by Strain Imaging Echocardiography in Patients with Hypertrophic Cardiomyopathy

To assess the left ventricular longitudinal regional myocardial systolic function by strain imaging （SI） echocardiography and to study the relationship between regional myocardial systolic function and left ventricular structure in patients with hypertrophic cardiomyopathy （HCM）. S1 echocardiography were performed in 18 patients with HCM and 17 healthy subjects. For each wall, regional myocardial systolic strain was analyzed at the basal, mid, and apical level respectively. And the peak systolic strain was measured. Our results showed that the patients with HCM had reduced peak systolic strain at almost each segment of different walls when compared with healthy subjects. There was significant correlation between the mid-septum peak systolic strain and the thickness of IVS, so was the correlation between the mid-septum peak systolic strain and the IVS to LVPW thickness ratio. This study demonstrated that the left ventricular longitudinal regional myocardial systolic function was abnormal in HCM, and this kind of abnormalities existed extensively in hypertrophic and non-hypertrophic cardiac segments. The degrees of left ventricle hypertrophy and asymmetry are related to the myocardial regional systolic function in HCM.

Diagnostic Accuracy of Strain Imaging of the Left Ventricle in Detection of Obstructive Coronary Artery Disease

Background: Speckle tracking echocardiography using average global strain and strain rate (SR) parameters for early detection of high risk patients with coronary artery disease (CAD) has gained a substantial clinical interest. Objective: Assessment of the diagnostic accuracy of strain imaging of the left ventricle in detection of obstructive coronary artery disease. Methods: One hundred patients were enrolled. They were divided into 3 groups: Group I (n = 40 patients) presented with ST segment elevation myocardial infarction (STEMI), Group II (n = 40 patients) presented with non-ST segment elevation myocardial infarction (NSTEMI) or unstable angina (UA) and Group III (n = 20 patients) with normal coronary angiography served as a control group. All patients were subjected to 2D speckle tracking echocardiography (2D STE) to assess LV longitudinal strain and strain rate (SR). Sensitivity, specificity and diagnostic accuracy of 2D STE in prediction of CAD and its severity using Gensini score were assessed. Results: The mean age for Group I, II and III was 52.20 ± 11.83, 51.97 ± 14.53 and 52.75 ± 10.75 respectively. LV average global systolic strain (AGS) was significantly lower in group I and II when compared to group III. AGS and average global systolic SR showed significant direct correlation with Gensini score. The diagnostic accuracy of 2D STE in prediction of significant LAD stenosis was 92.5%, and it was 89.5% in prediction of 3 vessels CAD. Conclusion: Strain imaging using 2D STE can predict the territory and severity of CAD with high diagnostic accuracy and can be used as a simple noninvasive diagnostic tool to identify high risk CAD patients.

Assessment of global and regional left ventricular twistand displacement in anterior myocardial infarction using2-dimensional strain imaging

The recent development of 2-dimensional strain(2D strain)imaging can provide a powerful alternative for assessing left ventricular(LV)torsion.This study was conducted to evaluate the global and regional left ventricular twist by 2D strain in patients with anterior wall myocardial infarction(AMI).A total of 55 AMI patients were divided into two groups according to their ejection fraction(EF)values(group A:LVEF≥50%;group B:LVEF<50%),and 35 normal people served as the control group.Using 2-dimensional strain software,global and regional LV rotation and displacement were obtained at two planes.Compared with the control group,patients of group A showed reduced peak LV twist of the anterior and anterior-septal wall(9.26�1.89 vs 10.74�2.67;9.71�1.71 vs 11.36�2.29,both P<0.05),but the radial displacement and global twist were maintained(P>0.05).Differently,regional and global LV twist and radial displacement in patients of group B deceased significantly,especially in the anterior and anterior-septal wall,as compared with patients in the control or group A(both P<0.05).Moreover,a strong correlation was noted between peak twist and radial displacement;the twist-displacement loop was markedly distorted in patients of group B.This study demonstrated that 2D strain has a potential ability for quantification of left ventricular global and segment twist and radial displacement in patients with coronary artery disease.

Quantification of Regional Left Ventricular Systolic Dysfunction in Patients With Coronary Artery Disease by Strain Rate Imaging

Objectives To detect and compare the systolic strain rate (SR) and strain in the infarct and ischemic myocardium by strain rate imaging (SRI), in order to explore the clinical value of SRI in evaluating regional left ventricular systolic dysfunction. Methods Patients with coronary artery disease were divided into angina pectoris (11 cases) and myocardial infarction (21 cases) groups. Twenty age-matched normal subjects served as the control group. Septal, lateral, anterior, inferior, anteroseptal and posterior walls of the left ventricle were respectively scanned using color tissue Doppler imaging (TDI). Then SR and strain curves were derived from TDI for basal, middle and apical segments of each wall. SRI parameters were: Systolic SR (SRsys), systolic strain (εsys) and maximum strain (εmax). Results Compared with normal segments, SRsys, εsys and εmax decreased significantly in the infarct and ischemic segments (P<0.01). Compared with ischemic segments, SRsys, εsys and εmax decreased significantly in the infarct segments (P<0.05). Conclusions SRsys, εsys and εmax measured by SRI can be used to quantitatively analyze regional left ventricular systolic dysfunction in patients with coronary artery disease, and aid in differentiating infarct from ischemic myocardium.

QUANTIFICATION OF RIGHT VENTRICULAR FUNCTION IN ATRIAL SEPTAL DEFECT USING ULTRASOUND- BASED STRAIN RATE IMAGING

Objective To study the validation of ultrasound-based strain rate imaging in the quantitative assessment of right ventricular （RV） function in atrial septal defect （ASD）. Methods Tissue Doppler images （TDI） of RV longitudinal and short axes were recorded from the apical 4-chamber view and the subcostal short-axis view in 18 normal controls, 28 children with ASD and 14 children after Amplazter closure of ASD respectively. Peak systolic velocities （ V）, peak systolic strain rates （SR）, peak systolic strains （S） at the basal segment, middle segment of RV lateral wall and the basal septum from the longitudinal axis, the middle segment of RV free waU from the short axis were quantitatively measured using QLAB^TM tissue velocity quantification software system respectively. Peak dp/ dt from the RV isovolumic contraction determined during the right cardiac catheterization in 28 ASD patients was used as the gold standard of RV contractility. Peak systolic indices were compared against max dp/dt by linear correlation, Results Peak systolic indices at the basal and middle segments of RV lateral wall from the longitudiual axis increased significantly in 28 ASD patients. Peak systolic indices at the basal septum also increased in patient group, but not significantly. Significant decreases in peak systolic indices at the basal and middle segments of RV lateral wall were observed after the Amplatzer closure in 14 ASD patients. There was no significant difference at the middle segment of RV free wall from the short axis between patient group and normal control. A strong correlation was found between max dp/dt and peak systolic indices at the basal and middle segments of RV lateral wal l （ P 〈 0. 05 ）. Conclusion Ultrasound-based strain rate imaging can assess quantitatively RVfunction in CHD. Peak systolic strains determined at the basal and middle segments of RV lateral wall are strong noninvasive indices of RV contractility.

Experiment and evaluation of wrinkling strain in a corner tensioned square membrane

Prediction of wrinkling characteristics is strongly correlated with the strain perpendicular to wrinkling direc- tion. In this paper, the strain field of wrinkled membrane is tested by VIC-3D system based on the digital image correlation technique. Experimental results are validated by the tension wrinkling simulation. The experimental strain perpendicular to wrinkling direction is analyzed in depth. The wrinkling strain of a square wrinkled membrane under corner tension is extracted from experimental strain perpendicular to wrinkling direction. A quantitative characterization format of the experimental wrinkling strain is proposed. A modified prediction method of wrinkling amplitude is presented based on the experimental wrinkling strain. The re- sults show that the precision of modified prediction model has improved 13.2% compared with the classical prediction model. The results reveal that the modified model can give an accurate prediction of the wrinkling amplitude.

Early Detection of Regional and Global Left Ventricular Myocardial Function Using Strain and Strain-rate Imaging in Patients with Metabolic Syndrome

Background：Strain and strain-rate imaging （SRI） have been found clinically useful in the assessment of cardiac systolic and diastolic function as well as providing new insights in deciphering cardiac physiology and mechanics in cardiomyopathies,and identifying early subclinical changes in various pathologies.The aim of this study was to evaluate the regional and global left ventricular （LV） myocardial function in metabolic syndrome （MS） with SRI so that we can provide more myocardial small lesions in patients with MS,which is robust and reliable basis for early detection of LV function.Methods：Thirty-nine adults with MS were enrolled in the study.There was a control group of 39 healthy adults.In addition to classic echocardiographic assessment of LV global functional changes,SRI was used to evaluate regional and global LV function.Including：Peak systolic strain （S）,peak systolic strain-rate （SR-s）,peak diastolic strain-rate （SR-e）.Results：There were no statistically significant differences between MS and controls in all traditional parameters of LV systolic function.On the other hand,significant differences were observed between MS and the control group in most of the parameters of S,SR-s,SR-e in regional LV function.Multiple stepwise regression analyses revealed that S and SR significantly were negatively correlated with blood pressure,waist circumference,fasting plasma glucose,uric acid,suggesting that risk factories were relevant to regional systolic dysfunction.Conclusion：In MS with normal LV ejection fraction,there was regional myocardial dysfunction,risk factors contributed to the impairment of systolic and diastolic function of the regional myocardium.Assessment of myocardial function using SRI could be more accurate in MS patient evaluation than conventional echocardiography alone.

Characteristics of myocardial postsystolic shortening in patients with coronary artery disease assessed by strain rate imaging

Background Postsystolic shortening （PSS） has been proposed as a marker of myocardial dysfunction. Strain rate imaging （SRI） is a novel ultrasonic technique, allowing reliable and noninvasive measurement of myocardial deformation. The purpose of this study was to investigate the characteristics of myocardial longitudinal PSS by SRI in ischemic and infarct myocardium in patients with coronary artery disease, and to explore its clinical applicability. Methods Eleven patients with angina pectoris, 21 patients with myocardial infarction and 20 healthy subjects were included in the study. Apical four-, three- and two-chamber views were displayed; and septal, lateral, anteroseptal, posterior, anterior and inferior walls of the left ventricle were scanned, respectively. PSS strain （εpss）, the ratio of εpss and systolic strain （εpss/εsys）, the ratio of εpss and maximum strain （εpss/εmax） and the duration of PSS （Tpss） in ischemic, infarct and normal myocardium were analyzed. Results PSS was found more frequent in the ischemic and infarct segments compared with the normal segments （39% vs 22% and 56% vs 22%, respectively; both P〈0.01）. It was even more frequent in the infarct segments than in the ischemic segments （56% vs 39%, P〈0.01 ）. The absolute magnitude of εpss, εpss/εsys, εpss/εmax were significantly larger and mpss significantly longer in the ischemic and infarct segments compared with that in the normal myocardium （P〈0.01）. εpss/εsys, εpss/εmax were even larger and Tpss even longer in the infarct than in the ischemic segments （P〈0.01）. Conclusions PSS is a common and important feature of the ischemic and infarct myocardium. εpss, εpss/εsys, εpss/εmax and mpss as measured by SRI may be promising markers for the quantitative assessment of regional myocardial dysfunction in patients with coronary artery disease. εpss/εsys, εpss/εmax and mpss may be helpful in differentiating infarct from ischemic myocardium.

Strain rate imaging in assessing the size of acute ischemic myocardium in dogs

Background Since the size of ischemic myocardium is closely related with both global and regional function of the myocardium, it is of great significance to measure the size of ischemic myocardium with non-invasive methods. Methods Eleven mongrel dogs were subjected to occlusion of the left anterior descending coronary artery for acute ischemia. Strain rate imaging had M-mode of strain-rate （CAMM） curve pointed from the basal segment of the anterior wall to the basal segment of the inferior wall to detect the border of ischemia size. The strain rate （SR） defined the cut-off value of ischemic myocardium in a two-chamber apical view, and marked by the anterior and inferior wall on two-dimensional images respectively. Along the endocardium and epicardium, the ischemic size was curved on two-dimensional images by the trackball method and then compared with the pathologically ischemic size. And then longitudinal strain rates were compared in the cut-off value, adjacent non-ischemic and ischemic segments at which the cut-off point was defined by changing the curve M-mode of strain rate after ischemia. Results Linear correlation existed between pathology and strain rate ischemic size （r=0.884, P 〈0.001）. The SR parameters were lower in ischemia and cut-off point than in non-ischemic segments. The peak SRs of systole （SSR）, early diastole （EsR）, late diastole （ASR）, strain during ejection time （εet）, and the maximum length change during the entire heart cycle （Emax） in ischemic segments lowered （P〈0.05）. Time to onset of regional relaxation （TR） was prolonged （P=0.012）. Conclusion SR imaging can accurately assess the size of ischemic myocardium. Chin Med J 2009; 122（2）： 193-198

Magnetic resonance imaging： a valuable method for diagnosing chronic lumbago caused by lumbar muscle strain and monitoring healingprocess

Background Magnetic resonance imaging （MRI） is the most sensitive technique for evaluating the healing process and should be performed before the patients return to their exercise routines. The aim of this research was to diagnose chronic lumbago associated with lumbar muscle strain and to monitor healing process by MRI. Methods Sixty-five symptomatic cases of chronic lumbago caused by lumbar muscle strain were collected from March 2009 to October 2011. MRI was used to examine, diagnose and monitor the healing process. The control group included 65 random cases of asymptomatic volunteers. MRI methods included routine sequences of GRE TlWl, TSE T2WI and special sequences of T2-STIR-FS, combined with DWI. We compared the MRI characteristics of symptomatic cases before and after healing and with asymptomatic controls. Results The important MRI characteristics of chronic lumbago with lumbar muscle strain included： （1） The low back muscle showed edema. （2） The low back intermuscular spaces showed edema and/or fluid. （3） The low back spaces beside the spinous process showed edema and/or fluid. （4） The low back vertebral articular process fossae or transverse process fossae showed fluid. Of these image characteristics, the intermuscular space edema provided the best diagnostic sensitivity, Se=83%, with Y1=0.63, Tr=74%. The low back muscle edema provided the best diagnostic specificity, Sp=100%, with Y1=0.66, Tr=83%. And the spaces edema beside the spinous process provided the best diangnostic accuracy, Tr=86%, with YI = 0.71, Se=80%, Sp=91%. The diagnosis accurate could be improved by combining multiple MRI characteristics. The diagnostic accuracy could achieve n=93%, with Y1=0.86, Se=100% and Sp=86% when two characteristics were combined. After rehabilitation care, the edema disappeared on the repeated MRI. Conclusions MRI may well be a useful diagnostic method for lumbago with lumbar muscle strain. Combining routine sequences with T2-STIR-FS and DWI sequences could demonstrate the pathological changes of lumbar muscle strain and monitor the healing.

Meso-mechanical Interfacial Behavior of Elbow Steel Fiber Reinforced Concrete

The strain distributions near the interface when the elbow steel fiber is pulled out from the half-mould concrete matrix are directly measured using a combined method of single fiber pull-out test and digital image correlation. Meanwhile, the real-time processes of the bonding, debonding and sliding at the interface are observed. The micro-mechanism of the strain localization in the failure process of interface when debonding occurs and the strengthening mechanism at the imbedded fiber are discussed. The experimental results show that the meso-scale strain localization gives rise to the localization of shear damage near the fiber interface. This strain localization characterized by the debonding process near the interface occurs, develops and moves gradually at an apparently regular interval. At the elbow part of the imbedded fiber, the peak value of the shearing stress occurs. But the primary debonding does not occur at this place because the strength of the shear damage is increased at the local area of the elbow part in the concrete, displaying an apparent reinforced effect at the end of the fiber.

Assessment of cardiac function in absence of congenital and acquired heart disease in patients with Down syndrome

Background:Extra genetic material in patients with Down syndrome(DS)may affect the function of any organ system.We evaluated cardiac functions using conventional tissue Doppler and two-dimensional speckle tracking echocardiography in patients with DS in the absence of congenital and acquired heart disease in patients.Methods:A total of 115 patients with DS between 6 and 13 years of age with clinically and anatomically normal heart and 55 healthy children were included in this cross-sectional study.DS was diagnosed by a karyotype test.Patients with mosaic type were not included in this study.Systolic and diastolic functions were evaluated by echocardiography.Results:Pulsed waved Doppler transmitral early/late inflow velocity(E/A),tissue Doppler mitral annular early/late diastolic peak velocity(Ea/Aa),transtricuspid E/A and tricuspid valve annulus Ea/Aa,pulmonary venous Doppler systolic/diastolic(S/D)wave ratio were lower in patients with Down syndrome than in the control group(P=0.04,P=0.001,P<0.05,P<0.001,P<0.001,respectively).Mitral and tricuspid annular Ea were lower in patients with DS(P<0.001).The right and left ventricular myocardial performance indexes were higher in patients with DS than in the controls(P<0.01).They had significantly higher left ventricular mass,ejection fraction,the mitral annular plane systolic excursion values.However,the Down syndrome group compared with the controls had a lower strain values examined by two-dimensional longitudinal speckle-tracking strain echocardiography.Conclusion:These findings suggest conventional tissue Doppler and two-dimensional longitudinal speckletracking strain echocardiography were useful methods of investigating ventricular function and identifying a higher incidence of biventricular dysfunction in patients with Down syndrome compared with the healthy controls.

Elastic deformation behavior of CuZrAlNb metallic glass matrix composites with different crystallization degrees

The room temperature brittleness has been a long standing problem in bulk metallic glasses realm.This has seriously limited the application potential of metallic glasses and their composites.The elastic deformation behaviors of metallic glass matrix composites are closely related to their plastic deformation states.The elastic deformation behaviors of Cu48-xZr48Al4Nbx（x=0,3at.%）metallic glass matrix composites（MGMCs）with different crystallization degrees were investigated using an in-situ digital image correlation（DIC）technique during tensile process.With decreasing crystallization degree,MGMC exhibits obvious elastic deformation ability and an increased tensile fracture strength.The notable tensile elasticity is attributed to the larger shear strain heterogeneity emerging on the surface of the sample.This finding has implications for the development of MGMCs with excellent tensile properties.