Radial Strain Values Research Articles

Subclinical anthracycline-induced cardiotoxicity in long-term follow-up of asymptomatic childhood cancer survivors: Assessment by speckle tracking echocardiography.

Survivors of childhood cancer treated with anthracyclines carry the risk for developing late-onset cardiotoxicity. The purpose of this study was to evaluate left ventricular (LV) function in this patient group and compare it with healthy controls by means of conventional and speckle tracking echocardiography (STE) after exposure to chemotherapy. Conventional and STE were performed in 45 childhood cancer survivors (mean age 11±4.6; 26 male) treated with anthracyclines (median cumulative dosage 240mg/m2 ; range, 100-460) and compared with age, gender and body surface area matched healthy controls. Follow-up period after chemotherapy was 21.9±17.8months. Blood samples were taken from survivors and controls to determine brain natriuretic peptide (BNP). Following anthracycline exposure, pediatric cancer survivors had lower longitudinal, radial anteroseptal, and radial anterior strain values compared to controls (P<.05). The calculated global longitudinal and global radial strain values were lower compared to the control group (P<.05). Both groups had normal ejection fraction (EF) and fractional shortening (FS). Brain natriuretic peptide (BNP) levels of both groups were in the normal range. Despite normal EF and FS, children exposed to anthracycline therapy may have late-onset subtle changes of LV strain values measured by STE. Whether these changes of strain can predict future risk of developing heart failure needs to be explored in further studies.

Prognostic implications of global myocardial mechanics in hypertrophic cardiomyopathy by cardiovascular magnetic resonance feature tracking. Relations to left ventricular hypertrophy and fibrosis

BackgroundInterstitial fibrosis, myocardial fiber disarray and non-uniform shortening are common histological features of hypertrophic cardiomyopathy (HCM). The degree of LV hypertrophy and fibrosis are postulated to contribute to the impairment of myocardial shortening. Cardiovascular magnetic resonance myocardial (CMR) feature tracking (CMR-FT) has emerged as a robust method that provides quantitative measurements of myocardial deformation. Our aim was first to evaluate LV strain parameters in HCM by CMR-FT and their dependence on both functional parameters and late gadolinium enhancement (LGE); and secondly we sought to determine their association with major cardiovascular outcomes. Methods and results74 patients with HCM and 75 controls subjects underwent a CMR study including LGE imaging. Global peak longitudinal, circumferential and radial systolic strain values (GLS, GCS, GRS) were measured by CMR-FT. A primary endpoint of all-cause mortality and secondary combined endpoint of hospital admission related to heart failure, lethal ventricular arrhythmias or cardiovascular death were defined. Patients with HCM showed attenuation of all LV strain values (p<0.001). Multivariate analysis showed that both LV hypertrophy and %of LGE were independent predictors of attenuated LV strains. All systolic LV strain parameters were impaired in patients with primary and secondary endpoints (follow up time: 25.6±9.9months, p<0.05 and p<0.01 respectively). Abnormal GLS, GCS and GRS were significantly associated with primary and secondary endpoints. ConclusionBoth LV hypertrophy and fibrosis contribute to the impairment of LV myocardial mechanics in HCM. In this population, reduced LV strain is associated with poor cardiac outcomes, particularly cardiovascular mortality and HF.

Application of Speckle-Tracking Echocardiography in an Experimental Model of Isolated Subendocardial Damage

The subendocardium is highly vulnerable to damage and is thus affected even in subclinical disease stages. Therefore, methods reflecting subendocardial status are of great clinical relevance for the early detection of cardiac damage and the prevention of functional impairment. The aim of this study was to investigate the potentialability of myocardial strain parameters to evaluate changes within the subendocardium. Male 129/Sv mice were injected with isoproterenol (ISO; n=32) to induce isolated subendocardial fibrotic lesions or saline as appropriate control (n=15). Transthoracic echocardiography was performed using a 30-MHz linear-frequency transducer coupled to a high-resolution imaging system, and acquired images were analyzed for conventional and strain parameters. The degree of collagen content within the different cardiac layers was quantified by histologic analysis and serum levels of tissue inhibitor of metalloproteinase-1, abiomarker for fibrosis, were assessed. ISO treatment induced a marked increase in subendocardial collagen content in response to cell loss (control vs ISO, 0.6±0.3% vs 5.8±0.9%; P<.001) and resulted in a moderate increase in left ventricular wall thickness with preserved systolic function. Global longitudinal peak strain (LS) and longitudinal strain rate were significantly decreased in ISO-treated animals (LS, -15.49% vs -11.49% [P=.001]; longitudinal strain rate, -4.81 vs -3.88sec-1 [P<.05]), whereas radial and circumferential strain values remained unchanged. Global LS was associated with subendocardial collagen content (r=0.46, P=.01) and tissue inhibitor of metalloproteinase-1 serum level (r=0.52, P<.05). Further statistical analyses identified global LS as a superior predictor for the presence of subendocardial fibrosis (sensitivity, 84%; specificity, 80%; cutoff value, -14.4%). Assessment of LS may provide a noninvasive method for the detection of subendocardial damage and may consequently improve early diagnosis of cardiac diseases.

Evaluation of Myocardial Strain in Patients With Amyloidosis Using Cardiac Magnetic Resonance Feature Tracking

PurposeTo study the use of cardiac magnetic resonance (CMR) feature tracking technique in evaluation of myocardial amyloidosis. Materials and MethodsCMR scans of 28 patients with biopsy proven myocardial amyloidosis and 35 controls were reviewed. Conventional short axis, vertical long axis, and 4-chamber cine steady-state free precession images from CMR scans were used to generate radial, circumferential, and longitudinal myocardial strain maps using feature tracking software. Global and regional peak radial, circumferential, and longitudinal strain values were computed. ResultsThere were significant decreases in radial, circumferential, and longitudinal strains in patients with myocardial amyloidosis globally and across layers (all P < 0.001). Strain was relatively preserved for the apex and most affected for the basal level. The area under the receiver operating characteristic curve for base peak radial, circumferential, and longitudinal strain 0.899, 0.884, and 0.866 and cut offs of 22.9, −13.3, and −10.9, respectively, were determined by receiver operating characteristic analysis. CMR feature tracking strain analysis of base-level strain parameters was able to differentiate patients with myocardial amyloidosis from those without myocardial amyloid with high sensitivity (82.5%) and specificity (82.9%) particularly for radial strain. The maximum sensitivity (89.3%) was achieved if any of the 3 parameters were abnormal, and the maximum specificity (88.6%) when all 3 parameters were abnormal. ConclusionMyocardial amyloidosis produces significant changes in regional and global strain parameters, and the peak radial and circumferential strain are the most affected at the basal layer.

Magneto-thermo-mechanical creep behavior of nano-composite rotating cylinder made of polypropylene reinforced by MWCNTs

History of strains, stresses and displacements of a rotating cylinder made of polypropylene reinforced by multi-walled carbon nanotubes (MWCNTs) subjected to magneto-thermo-mechanical loading is investigated using Burgers viscoelastic creep model. By making use of equations of equilibrium, stress-strain and strain-displacement, a constitutive differential equation containing creep strains is obtained which is solved semi analytically. It has been found that radial displacement, tangential strain and absolute values of radial strain are increasing with time at a decreasing rate so that they finally approach the steady state condition. Effective stresses are decreasing at the inner and increasing at the outer surface of the cylinder.

Strain by Nuclear Magnetic Resonance in Hypertrophic Cardiomyopathy

Background: New techniques have been developed for the quantitative analysis of myocardial deformation by cardiovascular magneticresonance from cine-sequences (as feature tracking) or from sequences with myocardial saturation bands (tagging), enabling areliable evaluation of the true systolic function in patients with hypertrophic cardiomyopathy.Objectives: The aim of this study was to assess systolic function expressed as evaluation of ejection fraction and myocardial deformationby new analysis techniques in a population with hypertrophic cardiomyopathy.Methods: Forty patients with hypertrophic cardiomyopathy were retrospectively included in the study between April 2009 and April2016. Wall thickness values were estimated and endocardial and epicardial borders were traced for calculation of ventricular volumesand mass. Four-chamber and short-axis cine and tagging sequences defined the borders to analyze deformation or myocardialstrain by feature tracking and myocardial tagging; values of global longitudinal, circumferential and radial strain were obtained andsegmental strain curves were established.Results: Mean ejection fraction in the overall population was 72%±9%. In the analysis of myocardial deformation by feature-trackingfrom 4-chamber and short-axis cine sequences, mean global longitudinal strain was -9.9%±3%, circumferential strain -14%±5%and radial strain 33%±10%. In the values obtained by myocardial tagging, mean global longitudinal and circumferential strainswere -7%±3% and -17%±3%, respectively.Conclusions: A global preserved ejection fraction was estimated in this population with hypertrophic cardiomyopathy, despite havinga significant decrease in longitudinal, circumferential and radial myocardial deformation. That is why the new analysis techniquesby cardiac MRI allow a deeper understanding of the real systolic function of patients suffering from this disease.

Left Ventricular Strain and Rotation by 2-D Speckle Tracking Echocardiography Identify Early Alcoholic Cardiomyopathy

This study assessed whether 2-D speckle tracking echocardiography (STE) derived from left ventricular (LV) strain and rotation is capable of detecting LV dysfunction associated with alcoholic cardiomyopathy. Ninety-two male chronic alcoholic patients were grouped by alcohol intake amount and duration: mild (n = 30; >90 mg ethanol daily, 3–5 d per wk for 5–8 y); moderate (n = 30; >90–150 mg ethanol daily, 3–5 d per wk for 9–20 y); and severe (n = 32; >150 mg ethanol daily, 6–7 d per wk for >10 y). Thirty non-drinkers were recruited as healthy controls. Rotation and twist values were lower in the severe group compared with the other groups (p < 0.05). The moderate and severe alcohol groups demonstrated lower longitudinal, circumferential and radial strain values and early to late filling (E/A) ratios compared with the mild group and non-drinkers (all p < 0.05). 2-D STE–derived strain and rotation are reliable echocardiographic markers for detecting left ventricular dysfunction in patients at risk of developing alcoholic cardiomyopathy.

22 Intra-ventricular myocardial deformation strain analysis in healthy volunteers: regional variation and implications for regional myocardial disease processes

Ejection fraction (EF) is a traditional marker of systolic function. However, it may not detect early, subtle cardiac disease with regional predilection. The aim of this study was to define regional intra-ventricular variation in myocardial strain in a cohort of healthy volunteers using Tissue-tracking cardiac magnetic resonance (CMR). Methods Healthy volunteers were recruited (n = 94, age range 20–79 years, 54% male). CMR at 1.5T was performed. Tissue-tracking software (CVI42, Circle Cardiovascular Imaging Inc.) estimated myocardial strain from the long-axis and the short-axis steady-state free precession (SSFP) cine images (Figure 1). The entire cohort was analysed by two independent readers. Inter-observer variability was also assessed. Myocardial segments were defined in accordance to the American Heart Association 16-segment model. Regional variations in circumferential and radial strain between basal, mid-cavity and apical segments as well as between left ventricle walls were assessed. Statistical analysis was performed using paired t test (p Results Inter-observer reproducibility analyses were excellent for mid-cavity and apical radial and circumferential strain values. On the other hand, reproducibility was not as good for basal segments for both deformation directions. Regional variations in strain (Table 1) revealed a statistically significant increase in deformation of the apical segments compared to the basal and mid-cavity ones for both radial and circumferential strain. Analysis of the different LV walls deformations indicated lowest values in the septum in all subjects, as well as across all age and gender subgroups. Conclusion This is the first study to demonstrate that there is a positive gradient toward the apex in both circumferential and radial strain using CMR-derived myocardial strain analysis. Furthermore, we also showed that the interventricular septum is the segment with lowest deformation values. These findings are important, as a comprehensive understanding of normal intra-ventricular regional variation is needed before this new tool can be implemented in routine clinical practice.

Subclinical Left Ventricular Longitudinal and Radial Systolic Dysfunction in Children and Adolescents with Type 1 Diabetes Mellitus.

There are few studies of subclinical systolic dysfunctions in children and adolescents with type 1 diabetes mellitus (DM), and so the available data are limited. The aim of this study was to determine early echocardiographic signs of LV systolic dysfunction in children and adolescents with type 1 DM using two-dimensional speckle tracking echocardiography (2DSTE). The study included 84 children and adolescents with type 1 DM and 32 sex-, age-, and body mass index-matched healthy subjects. The LV functions were assessed using conventional echocardiography, tissue Doppler imaging, and 2DSTE. The results showed LV diastolic dysfunction as reflected by significantly increased A-wave velocity, decreased E/A ratio, and increased early filling deceleration time in the patients with diabetes (P = 0.02, P = 0.029, and P = 0.04; respectively). Compared with the control group, patients with diabetes showed significantly lower values for longitudinal systolic strain and strain rate in most segments of the LV; for radial strain values of the LV; for lateral circumferential strain and posterior and anterolateral circumferential strain rate of the LV; and for global longitudinal and radial strain of the LV. Global longitudinal and radial strain values of the LV were significantly lower among patients with poor glycemic control than in the control group. In addition to diastolic dysfunction, LV longitudinal and radial function was found to be impaired in asymptomatic children and adolescents with type 1 DM who have normal LV ejection fraction by 2DSTE. Glycemic control may be the main risk factor for alteration of myocardial function.

Comprehensive left ventricular mechanics analysis by speckle tracking echocardiography in Chagas disease.

BackgroundChagas disease (CD) is a frequent cause of dilated cardiomyopathy (CMP) in developing countries, leading to clinical heart failure and worse prognosis. Therefore, the development and evolution of this CMP has always been a major topic in numbers of previous studies. A comprehensive echocardiographic study of left ventricular (LV) mechanics, fully assessing myocardial contraction, has never been done before. This could help characterize and improve the understanding of the evolution of this prevalent CMP.MethodsA total of 47 chagasic and 84 control patients were included in this study and allocated in groups according to LV ejection fraction. 2D-Echocardiogram was acquired for LV mechanics analysis by speckle tracking echocardiography.ResultsMean age of chagasic individuals was 55y and 16 (34 %) were men. Significant difference was found in global longitudinal velocity analysis, with lower values in indeterminate form. In the group with severe systolic dysfunction, a paradoxical increase in longitudinal and apical radial displacements were demonstrated. In parallel, segmental analyzes highlighted lower values of radial displacement, strain and strain rate into inferior and inferolateral walls, with increase of these values in septal and anterior walls.ConclusionChagasic CMP has a vicarious pattern of contraction in the course of its evolution, defined by reduced displacement and strain into inferior and posterior walls with paradoxical increase in septal and anterior segments. Also, lower longitudinal velocities were demonstrated in CD indeterminate form, which may indicate an incipient myocardial injury.

Simple Screening Test for Sarcopenia is a Useful Tool to Predict Future Adverse Events in Male Patients with Cardiovascular Risk

effect of CPAP on LV function in treated hypertensives with OSA. Methods: Fifty moderate to severe (apnea hypopnea index S 15) OSA patients (65.069.9 yrs.) were classified into two groups, based on the medication with and without C-PAP as follows; CPAP group (34 patients) and Non-CPAP group (16 patients). Longitudinal, radial and circumferential strain values (%) of LV elucidated by speckle tracking imaging and various conventional markers of echocardiography were compared before medication with follow-up period (2.260.6 yrs.). Results: Show the Table. Conclusion: CPAP improves the longitudinal systolic function significantly, and diastolic function such as E/e and left atrial dimension also decreased.

Advanced Parameters of Cardiac Mechanics in Children with CKD: The 4C Study.

Newer parameters of cardiac mechanics provide additional insights on cardiac dysfunction in adult patients with CKD. The aim of this study was to identify prevalence of subclinical abnormalities in cardiac function through the analysis of novel indices of cardiac mechanics in a large population of children with CKD. Between 2009 and 2011, the prospective observational Cardiovascular Comorbidity in Children with CKD Study enrolled patients with CKD ages 6-17 years old with eGFR=10-45 ml/min per 1.73 m(2) in 14 European countries. Cardiac morphology and function were assessed through echocardiography. The analysis presented encompasses global radial, longitudinal, and circumferential strains as well as time to peak analysis. Data were compared with 61 healthy children with comparable age and sex. Data on 272 patients with CKD with complete echocardiographic assessment are reported (age =12.8±3.5 years old; 65% boys). Patients with CKD showed mildly higher office BP values and higher prevalence of left ventricular hypertrophy, but no differences were observed among groups in left ventricular ejection fraction. Strain analysis showed significantly lower global radial strain (29.6%±13.3% versus 35.5%±8.9%) and circumferential strain components (-21.8%±4.8% versus -28.2%±5.0%; both P<0.05) in patients with CKD without significant differences observed in longitudinal strain (-15.9%±3.4% versus -16.2%±3.7%). Lower values of global radial strain were associated with lower circumferential endocardial-to-epicardial gradient (r=0.51; P<0.01). This association remained significant after adjusting for BP, eGFR, and presence of left ventricular hypertrophy. Eventually, patients with CKD also showed higher delay in time to peak cardiac contraction (58±28 versus 37±18 milliseconds; P<0.05). A significant proportion of children with CKD show impaired systolic mechanics. Impaired systolic function is characterized by lower radial strain, transmural circumferential gradient, and mild cardiac dyssynchrony. This study suggests that analysis of cardiac strain is feasible in a large multicenter study in children with CKD and provides additional information on cardiac pathophysiology of this high-risk population.

Global and regional myocardial deformation mechanics of microvascular obstruction in acute myocardial infarction: a three dimensional speckle-tracking imaging study

Microvascular obstruction (MVO) and transmural infarct size are prognostic factors after acute myocardial infarction (AMI). We assessed the value of myocardial deformation patterns using 3D speckle tracking imaging (3DSTI) in detecting myocardial and microvascular damage after AMI. One hundred patients with first ST-segment elevation MI from the REMI Study were prospectively included. Transthoracic echocardiography with 3DSTI and CMR were performed within 72 h after revascularization therapy. Global (3DG) and segmental (3DS) values of LV longitudinal (LS), circumferential and radial area strain were obtained. Late gadolinium enhancement (LGE) and MVO was quantified as transmural (>50%) or non-transmural (<50%). Predictive performance was assessed by area under the receiver operating curve characteristic (AUC). Mean LVEFCMR was 45.8 ± 9.2 % with 22.2 ± 12.7% transmural LGE. MVO was present in 55 patients (MVO transmural extent 11.4 ± 11.8%). In global analysis, all 3DG strain values were correlated with LVEFCMR and infarct size, with the best correlation obtained for 3DGAS (r = -0.678; p < 0.0001). All 3DG strain values, with the exception of LS, were significantly different between patients with and without MVO. In segmental analysis, all 3DS strain values were significantly lower in transmurally infarcted segments than in non-infarcted segments, and all 3DS values except 3DSRS were significantly lower in non-transmural infarcted segments than in non-infarcted segments. The best 3DS strain for detecting non-viable segments with MVO (MVO > 75%) was 3DSAS [AUC 0.867 (0.849-0.884), 78.0% sensitivity and 81.1% specificity for 3DSAS = -16.1%]. Importantly, 3DSRS and 3DSAS were associated with an increase in diagnostic accuracy of both transmural LGE and MVO over 3DSLS (all increase in AUC > 0.04, all p < 0.01). The newly developed 3DSTI, especially 3DSAS, is a sensitive and reproducible tool to predict and quantify the transmural extent of scar. This new early imaging strategy improve the prediction of MVO while enabling to assess the success of reperfusion and the risk of late systolic remodeling in STEMI.

Early Detection of Bi-ventricular and Atrial Mechanical Dysfunction Using Two-Dimensional Speckle Tracking Echocardiography in Patients with Sarcoidosis.

Sarcoidosis is a systemic inflammatory disease with unknown etiology involving several organs. Myocardial involvement, pericarditis, severe rhythm abnormalities, and heart valve disease due to papillary muscle dysfunction are some of the cardiac manifestations. Conventional echocardiographic methods remain insufficient for the determination of subclinical myocardial dysfunction in patients with sarcoidosis. In our study, we investigated the impact of sarcoidosis on bi-ventricular and atrial functions using two-dimensional (2D) speckle tracking echocardiography (STE). Forty patients with sarcoidosis and 20 age and sex-matched controls were recruited into study. All subjects underwent a transthoracic echocardiography for the evaluation of ventricular and atrial functions with 2D STE. Left ventricular (LV) dimensions, LV ejection fraction, and right ventricular (RV) systolic velocity were similar between the two groups. Left atrial (LA) diameter was significantly higher in sarcoidosis patients than controls. Eighteen (45%) patients in the sarcoidosis group and 1 (5%) patient in the control group had LV diastolic dysfunction. LV global longitudinal, radial, circumferential strain, twist, untwists, and RV global longitudinal strain values were significantly lower in sarcoidosis patients compared to controls. LA and RA reservoir functions were also significantly lower in sarcoidosis patients than controls. Although impaired LV diastolic function was detected using conventional parameters, only novel advanced echocardiographic modalities demonstrated impaired bi-ventricular and atrial mechanical functions in patients with sarcoidosis.

Incremental value of resting three-dimensional speckle-tracking echocardiography in detecting coronary artery disease

The aim of the present study was to investigate the incremental value of resting three-dimensional speckle-tracking echocardiography (3D-STE) in the detection of early-stage left ventricular dysfunction in patients with coronary artery disease (CAD). A total of 110 patients suspected of having CAD were recruited. All patients underwent 3D-STE and coronary artery angiography (CAG). They were divided to a CAD group and a normal group according to the results of CAG. Using 3D-STE software, the peak values of longitudinal strain (LS), circumferential strain (CS), radial strain (RS) and area strain (AS) and the time to peak value of these strains (T-LS, T-CS, T-RS and T-AS) were measured. A receiver operator characteristic curve (ROC) was used to analyze the sensitivity of these strains for the diagnosis of CAD. ROC analysis indicated that T-LS and composite indices combining the peak strain value and time to peak of LS, CS and AS have diagnostic value for the early detection of CAD; the area under the curve (AUC) values were 0.667, 0.692, 0.621 and 0.672 respectively (P<0.005). The composite index of longitudinal strain demonstrated the highest diagnostic value for CAD with 62% sensitivity and 76% specificity. These results indicate that 3D-STE has incremental value for the diagnosis of CAD in patients at rest.

A comparison of cardiac motion analysis software packages: application to left ventricular deformation analysis in hypertensive patients

Background Although myocardial function is clinically assessed with global measurements (ventricular volumes, ejection fraction), recent research has shown that regional measurements, such as wall-thickening, strain, and torsion, could provide earlier sub-clinical markers to examine left ventricular (LV) dysfunction and myocardial diseases. Cardiovascular Magnetic Resonance myocardial feature tracking (CMR-FT) technique is used to post-process cine CMR images to provide a quantitative assessment of LV motion deformation parameters. It derives myocardial motion deformation from image features such as myocardium-blood cavity boundary and pixel intensities, and relies only on standard cine images to extract motion deformation. The main objective of this study is to compare two current feature tracking software packages in hypertensive patients. Methods 29 hypertensive subjects were prospectively recruited from a tertiary hypertension clinic and enrolled to undergo CMR examinations. All images were acquired using a 1.5T scanner (Siemens Medical Imaging, Germany), and a cardiac surface coil. LV function was assessed with cine acquisitions in the following planes: 2-chamber, 4-chamber and short-axis slices (basal, mid and apical levels). LV deformation was analysed using: 2D Cardiac Performance Analysis, MR (TomTec Imaging Systems, Munich, Germany) and CVI42 (Circle Cardiovascular Imaging Inc. Calgary, Canada). Endocardial and epicardial LV contours were drawn manually at the end diastolic phase in order to achieve best tracking results; the software packages then allow semi-automated analysis to provide quantitative measurement of global and regional deformation parameters. Results Results of circumferential, radial, and longitudinal strains are given in table 1. Statistical analysis was performed using the student’s paired t-test for dependent sample in order to assess the difference between the two software packages.All radial strain mean values obtained with CVI42 were higher than with Tomtec and the difference was statistically significant for all short-axis circumferential strains. This was also the case for shortaxis apical and 4-chamber radial strains. In total five parameters (short-axis apical and 4-chamber radial strains, all 3 short-axis slices circumferential strains) were statistically different and 5 were not. Conclusions From our results, there is a trend in circumferential strain in short-axis (apical, mid, and basal) where there is a significant difference in the values obtained by the two software packages, whereas radial and longitudinal strain values showed no clear trend. Therefore, there is a clear need for a gold standard validation to assess the accuracy of cardiac motion analysis software packages.

Left ventricular mechanical dysfunction in diet-induced obese mice is exacerbated during inotropic stress: a cine DENSE cardiovascular magnetic resonance study.

BackgroundObesity is a risk factor for cardiovascular disease. There is evidence of impaired left ventricular (LV) function associated with obesity, which may relate to cardiovascular mortality, but some studies have reported no dysfunction. Ventricular function data are generally acquired under resting conditions, which could mask subtle differences and potentially contribute to these contradictory findings. Furthermore, abnormal ventricular mechanics (strains, strain rates, and torsion) may manifest prior to global changes in cardiac function (i.e., ejection fraction) and may therefore represent more sensitive markers of cardiovascular disease. This study evaluated LV mechanics under both resting and stress conditions with the hypothesis that the LV mechanical dysfunction associated with obesity is exacerbated with stress and manifested at earlier stages of disease compared to baseline.MethodsC57BL/6J mice were randomized to a high-fat or control diet (60 %, 10 % kcal from fat, respectively) for varying time intervals (n = 7 – 10 subjects per group per time point, 100 total; 4 – 55 weeks on diet). LV mechanics were quantified under baseline (resting) and/or stress conditions (40 μg/kg/min continuous infusion of dobutamine) using cine displacement encoding with stimulated echoes (DENSE) with 7.4 ms temporal resolution on a 7 T Bruker ClinScan. Peak strain, systolic strain rates, and torsion were quantified. A linear mixed model was used with Benjamini-Hochberg adjustments for multiple comparisons.ResultsReductions in LV peak longitudinal strain at baseline were first observed in the obese group after 42 weeks, with no differences in systolic strain rates or torsion. Conversely, reductions in longitudinal strain and circumferential and radial strain rates were seen under inotropic stress conditions after only 22 weeks on diet. Furthermore, stress cardiovascular magnetic resonance (CMR) evaluation revealed supranormal values of LV radial strain and torsion in the obese group early on diet, followed by later deficits.ConclusionsDifferences in left ventricular mechanics in obese mice are exacerbated under stress conditions. Stress CMR demonstrated a broader array of mechanical dysfunction and revealed these differences at earlier time points. Thus, it may be important to evaluate cardiac function in the setting of obesity under stress conditions to fully elucidate the presence of ventricular dysfunction.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-015-0180-7) contains supplementary material, which is available to authorized users.

Intraobserver and interobserver reproducibility for radial, circumferential and longitudinal strain echocardiography.

Objectives: Strain echocardiography (StE) promises to be a new tool for quantitative assessment of cardiac function. Analysis of intra- and interobserver reliability is an important aspect in the process of developing these novel techniques from theory to the implementation into daily routine diagnostics.The purpose of the study was to estimate reliability of the segmental StE.Methods: Left ventricular strain analysis for radial strain (RS), circumferential strain (CS) and longitudinal strain (LS) was performed in 21 healthy volunteers. RS and CS values were obtained in the parasternal short axis at the level of the papillary muscles. LS values were determined in the apical 2-, 3- and 4-chamber views. Cine-loops were recorded and quantitative analyses were conducted on an off-line workstation.Results: Intraobserver reproducibility was highest using LS in the 4-chamber view (9 ± 13.6 % mean deviation, rho = 0.624, p = 0.003), followed by CS (13.3 ± 8.3 %, rho = 0.406, p = 0.068) and lowest in RS (26.3 ± 30.1 %, rho = 0.391, p = 0.080). Interobserver analyses of LS derived from 3-chamber view showed lowest deviation (11.9 ± 9.5 %, rho = 0.513, p = 0.017), followed by CS (15.2 ± 12.0 %, 0.263, p = 0.249) and the least consistent measurements in RS (35.9 ± 46.3 %, rho 0.382, p = 0.088).Conclusion: This study shows that the clinical utility of StE depends on the regional differences of LV wall motion and image quality. LS-values showed promising intra- and interobserver reproducibility values. For quantitative follow-up studies LS should be preferred.

Speckle tracking echocardiography in the diagnosis of early left ventricular systolic dysfunction in type II diabetic mice.

sBackgroundThe leptin receptor-deficient db/db mouse is a well-established type II diabetes animal model used to investigate diabetic cardiomyopathy. Previous reports have documented diabetic cardiomyopathy is accompanied by cardiac structural and functional abnormalities. To better elucidate early or subtle changes in cardiac performance in db/db mice, we used speckle tracking echocardiography to assess systolic myocardial strain in vivo with diabetic db/db mice in order to study early changes of left ventricle contractile function in type II diabetes model.MethodsMale diabetic db/db mice and age-matched control mice from C57BL/6J strain at 8,12 and 16 weeks of age were subjected to echocardiography. At the midpapillary level in the parasternal left ventricular short-axis view, end diastolic and systolic left ventricular diameter, interventricular septal thickness and posterior wall thicknesses, ejection fraction, fractional shortening were determined by M-mode echocardiography. Using speckle-tracking based strain analysis of two-dimensional echocardiographic images acquired from the parasternal short-axis views at the mid-papillary level, systolic global radial and circumferential strain values were analyzed.ResultsThere was no significant difference in interventricular septal thickness, posterior wall thicknesses, end diastolic and systolic left ventricular diameter, ejection fraction and fractional shortening between db/db and age-matched control mice at 8,12 or 16 weeks of age (P > 0.05). At 8 and 12 weeks of age, there was no significant difference in left ventricular radial strain and circumferential strain between db/db mice and age-matched controls (P > 0.05). But at 16 weeks of age, the left ventricular radial strain and circumferential strain in db/db mice were lower than in control mice (P < 0.01).ConclusionThe present study shows that speckle tracking echocardiography can be used to evaluate cardiac functional alterations in mouse models of cardiovascular disease. Radial and circumferential strain are more sensitive and can be used for detection of early left ventricular contractile dysfunction in db/db type II diabetic mice.

FEATURE TRACKING-BASED STRAIN ANALYSIS PREDICTS THE PRESENCE OF MYOCARDIAL FIBROSIS AMONG PATIENTS WITH NON-ISCHEMIC CARDIOMYOPATHY

Abnormal myocardial deformation has been described in the presence of regional fibrosis, as detected by late gadolinium enhancement (LGE) cardiac magnetic resonance imaging (CMR) in patients with previous infarction, Fabry’s disease and hypertrophic cardiomyopathy. Mid-wall striae pattern fibrosis on LGE imaging has been shown to predict adverse cardiovascular outcomes among patients with non-ischemic cardiomyopathy. However, macroscopic mid-wall fibrosis is a late pathologic finding and requires administration of gadolinium based contrast agent. Non-contrast dependent markers heralding adverse remodeling are desired. In this study we describe a novel strain analysis tool employing feature tracking to predict the presence of mid-wall fibrosis in patients with non-ischemic cardiomyopathy. CMR imaging was performed in 117 patients with idiopathic non-ischemic cardiomyopathy, defined as a left ventricular ejection fraction (LVEF) <55% by CMR with no prior history of myocardial infarction and no CMR findings of ischemic or other specific cardiomyopathy states (ie. hypertrophic cardiomyopathy, amyloidosis, sarcoidosis). Blinded quantitative analysis was performed using a prototype version of a commercial software (cvi42, version 4.1.5 M192, Calgary, Alberta, Canada). Left ventricular regional strain analysis was performed to obtain both radial and circumferential strain of a mid-ventricular short axis slice cine image (Figure 1). Volumetric analysis of sequential short axis cine images was also performed. LGE images were visually scored for the presence of mid-wall striae fibrosis. Mean age was 57.8 +/- 14.5 years and 60 % of patients were male. CMR characteristics are summarized in Table 1. Mid-wall striae fibrosis was identified in 48 patients (41 %). These patients had greater indexed LV end diastolic and systolic volumes and total scar volume with lower LV and RV ejection fraction. Compared to patients without midwall striae fibrosis, radial and circumferential strain values were significantly lower in the mid anteroseptal segments among patients with midwall striae fibrosis despite corresponding anterolateral strain values being similar (Table 1). On multivariate analysis, patients with midwall striae fibrosis had a significantly lower anteroseptal to anterolateral strain ratio (AASR) for both radial (0.61±0.41 vs. 0.37±0.32, p=0.024) and circumferential strain (0.66±0.36 vs. 0.42±0.29, p=0.015). Of note, 15 (22%) patients had a low AASR despite having no midwall striae fibrosis on LGE imaging. AASR is strongly associated with the presence of midwall striae fibrosis in patients with non-ischemic cardiomyopathy. The prognostic utility of this novel imaging marker warrants future study within a prospective multi-centre study.View Large Image Figure ViewerDownload (PPT)