LA Deformation Research Articles

Abstract 13086: Left Atrial Function in Adult With Normally Functioning Bicuspid Aortic Valves

Background: Bicuspid aortic valve is a complicated and heterogeneous disease that has aroused great interest in recent years. Traditionally the greatest attention during a routine echocardiography is paid to the function of the ventricles and aortopathy, much less is known about dysfunction the left atrium. The objective of this study was to characterize left atrial strain (LAS) and functions by two-dimensional speckle tracking echocardiography in adult BAV with normally functioning, and interrogate the risk factors. Methods: This is a prospective cohort study of 52 patients (age 40.23±11.29 years) and 33 healthy volunteers (aged 39.12±12.74 years) were recruited. All subjects included in both groups were in sinus rhythm and no clinical history of cardiovascular diseases. We mainly assessed left atrial reservoir, pump, and conduit function using 2D STE, then determined relationships among indices of segmental aortic stiffening, BAV cusp fusion pattern, LV diastolic function indices and LA deformation. Results: Without adjustment, the indices of LA functions in patients with BAV were significantly decreased compared with controls (LAS 49.41 ± 11.14 vs 59.48 ± 9.53, p<0.001, LAEF 71.56 ± 6.57 vs 76.36 ± 5.72, p=0.001; LAS-passive 29.43 ± 9.42 vs 36.67 ± 9.60, p=0.001, LAEF-passive 43.72 ± 10.78 vs 49.58 ± 6.80, p=0.003). However, after adjustment on age, gender, systolic blood pressure, diastolic blood pressure, BSA ,only the LAS was lowering (p<0.001). With or without adjustment, the ascending aorta of patients with BAV were still stiffer at each segment compared with controls. As parameters of LV diastolic functions, the E/e’ ratio (p=0.01) and e’ value (p=0.01) were significantly altered. The LA volume were increased in BAV patients (59.33 ± 19.12 vs 46.10 ± 9.73). In patients with BAV, LA functions, LV functions and segmental aortic stiffness were not influenced by the Sivere valve types. In multiple regression analysis, the stiffness at the sinus of Valsalva were independently correlated with LAS (adjust R 2 = 0.82, β = -0.33, p<0.001). Conclusion: Left atrial dysfunction is common in adult BAV with normally functioning. LA dysfunction is associated with stiffness index at the sinus of Valsalva, and is independent of LV function.

Right ventricle to pulmonary artery coupling improves early after transcatheter aortic valve implantation and this is related to improved left atrial function

Abstract Background Transcatheter aortic valve implantation (TAVI) improves not only left heart remodeling but also has an upstream effect on the right ventricle and pulmonary vasculature. Right ventricle (RV) to pulmonary artery (PA) coupling, a parameter which integrates RV systolic performance at a given degree of afterload, was associated with all-cause mortality in these patients (pts). Our aim was to evaluate the short-term effect of TAVI on RV-PA coupling and the main determinants of RV-PA coupling in pts with aortic stenosis (AS) undergoing transfemoral TAVI. Methods We have prospectively enrolled 102 consecutive pts (76±8 years, 57 men) with severe AS undergoing TAVI. All pts underwent a comprehensive echocardiogram both before and 30 days after TAVI, including speckle tracking echocardiography (STE) for myocardial deformation analysis. Peak values of global longitudinal left ventricular strain (GLS), left atrial strain (LAε, reservoir function), and late diastolic LA strain rate (ASr, contractile function) were measured. The ratio of tricuspid annular plane systolic excursion (TAPSE) to PA systolic pressure (PASP) was used as an estimate of RV-PA coupling. Results Compared with baseline, there was a significant increase in LV ejection fraction after TAVI (54±12% vs 50±13%, p=0.04), a significant reduction in LV mass (147±35 vs 171±44 g/m2, p<0.001) and increase in absolute GLS values (14±3% vs 12±5%, p=0.007). Indexed LA volumes decreased (49±19 vs 55±19 ml/m2, p=0.03) while both global LAε and ASr improved significantly after TAVI (16±8% vs 13±7%, p=0.01 and −1.2±0.6 vs −0.9±0.6%, p=0.01). A significant improvement of TAPSE/PASP values (0.069±0.026 vs 0.057±0.025 cm/mm Hg, p<0.001) was found after TAVI, indicating an enhanced RV-PA coupling. In multivariable regression analysis global LAε was independently related to RV-PA coupling, both before and after TAVI (R=0.54, p=0.003 and R= 0.39, p<0.001). The increase in RV-PA coupling was significantly related to the increase in LAε (p=0.005). Conclusions Our results confirm that relief of aortic valve obstruction by TAVI has beneficial effects on the RV-PA coupling, that occur early after intervention. This is accompanied by a significant improvement in LV and LA deformation. Moreover, there is a significant correlation between LA function and RV-PA coupling both before and after TAVI. Enhanced RV-PA coupling after TAVI is related to improved LA strain, suggesting the contribution of LA function in modulating right heart function in this setting. Funding Acknowledgement Type of funding source: None

Altered Biatrial Phasic Function after Heart Transplantation in Children

We used two-dimensional echocardiographic speckle-tracking to investigate whether left and right atrial (LA and RA) phasic function in pediatric heart transplantation (HT) patients is altered and explored the relationship to HT-related clinical variables. Eighty-six subjects (36 HT and 50 normal children) were prospectively enrolled in two centers. Clinical data included age at HT, bypass time, ischemia time, donor age, and incidence of rejection. Atrial deformation indices including strain and strain rates (SRs) were measured using two-dimensional echocardiographic speckle-tracking. Components of phasic atrial function-reservoir (εr, SRr), conduit (εcd, SRcd), and booster (εct, SRct) were calculated. Comparisons with controls were made using t test or Kruskal-Wallis test, and correlations to clinical variables were explored. The mean age and body surface area of HT subjects were 10.2±6.2years and 1.2±0.6m2, respectively. The mean heart rates were higher in HT (96±18 vs 88±21 in controls). There were reductions in RA and LA reservoir (εr, SRr), conduit (εcd, SRcd), and booster (εct, SRct) function in HT compared with controls. There was no relationship of LA and RA deformation indices with mean age at HT, bypass time, or ischemia time. The LA εcd correlated weakly with donor age (r=-0.49, P=.04) and RA SRr, and SRcd showed association with duration of HT (P<.05). Nineteen HT recipients had follow-up studies 0.24±0.18years after the first examination, and deformational indices were not significantly changed. Atrial strain determination is feasible in pediatric HT recipients and demonstrates disruption of reservoir, conduit, and booster function of both atria in this population; we speculate this may be a consequence of ventricular diastolic dysfunction.

570 Myocardial deformation imaging after STEMI: can we better predict one-year mortality and heart failure development?

Abstract Prognosis after STEMI is still challenging. One-year mortality ranges between 10-12% and the incidence of heart failure (HF) is between 4% and 28%. Early and accurate identification of high-risk patients necessitates therapy intensification. Aim this study is a part of PREDICT-VT study (NCT03263949). The aim was to test whether deformation imaging based on spackle tracking echocardiography predict MACE (total mortality, HF hospitalization and NYHA class ≥3 development) better than conventional echocardiography and clinical parameters. Methods in 264 consecutive pts enrolled in PREDICT-VT study early echocardiography (5 ± 2 days after pPCI) was done including LA and multilayer LV deformation analysis with longitudinal (L), radial (R) and circumferential (C) strain (S; %) and strain rate (SR, 1/sec). LV index of post systolic shortening for longitudinal (PSS LS) and circumferential (PSS CS) strain were calculated as average of PSS over 18 LV segments. Results 198 patients completed 1-year follow-up and 22 patients (11.1%) experienced MACE. Significant echo, clinical and laboratory predictors with the ROC analysis are listed in the table according to AUC . Conclusion peak systolic longitudinal and to a lesser degree peak systolic circumferential deformation predict mortality and HF development after pPCI better than conventional echo and even clinical parameters. From diastolic parameters only radial SR during atrial contraction was better MACE predictor compared to conventional echocardiography. AUC p Cut-off Senz Spec Peak systolic LS epicardial layer 0.757 &amp;lt;0.001 -11 75 63 Radial SR during atrial contraction 0.754 &amp;lt;0.001 -0.63 65 80 Peak systolic LS mid-wall layer 0.750 &amp;lt;0.001 -12.58 80 60 PSS LS endocardial layer 0.744 &amp;lt;0.001 0.1409 70 61 Peak systolic CS endocardial layer 0.744 &amp;lt;0.001 -18.08 70 67 Wall Motion Score Index 0.740 0.001 1.53 70 70 Peak systolic CS mid-wall layer 0.730 0.001 -13.66 80 60 Peak radial LV strain 0.722 0.001 14.08 80 60 Creatine kinase peak level 0.698 0.003 2155 64 73 LV EF 0.692 0.004 47.5 67 60 TAPSE 0.685 0.015 1.95 75 60 LA strain 0.676 0.012 18.33 63 64 Killip class 0.644 0.028

1038 Comparative assessment of phasic left atrial and regional left ventricular strain in patients with cardiac amyloidosis and LV hypertrophy

Abstract Background Echocardiographic hallmarks of cardiac amyloidosis (CA), such as increased wall thickness of the LV and sparkling appearance of the myocardium, are limited by a reduced diagnostic accuracy. Purpose We sought to evaluate the diagnostic value of phasic left atrial strain alterations and of regional global longitudinal systolic LV strain (LVGLS) reductions in patients with CA and with other forms of LV hypertrophy. Methods Standard apical 4-chamber views were stored for offline analysis (Vivid E9, GE, Vingmed, Horton) in 54 patients who underwent endomyocardial biopsy for unclear LV hypertrophy. We then analyzed LVGLS as well as LA reservoir, conduit, and contraction strain using 2D speckle tracking echocardiography (2DSTE; EchoPAC software, GE). To assess regional LVGLS, the average of apical strain values / (average of mid + basal LV strain values) was calculated (relative apical sparing; RELAPS). Receiver operating characteristic (ROC) curve analyses and a multivariate logistic regression analysis were performed to investigate the diagnostic value of the respective LA and LV deformation analysis. Results CA was bioptically confirmed in 34 patients (13 TTR, 1 AA, 20 AL amyloidosis). In 18 patients, myocardial biopsy revealed other forms of LV hypertrophy, such as hypertensive heart disease (n = 2), hypertrophic cardiomyopathy (n = 12), and inflammatory myocardial diseases (n = 4). Mean septal wall thickness (17.7 ± 2.9 mm and 17.9 ± 4.3 mm) and left atrial volume index (43.8 ± 12.2 and 44.1 ± 17.2) were not different between groups. RELAPS was significantly higher in patients with CA (1.37 ± 0.94 vs. 0.86 ± 0.29, p&amp;lt;.007). Phasic atrial mechanics were significantly worse in CA (LA reservoir, conduit, and contraction strain 10.0 ± 5.2%, -6.5 ± 3.5%, and -5.0 ± 4.1%, respectively, in CA; and 22.7 ± 7.8%, -13.9 ± 5.2%, and -13.0 ± 5.5%, in LVH, respectively; p&amp;lt;.001). With an area under the curve (AUC) of 0.91, and a sensitivity and specificity of 91.2 and 84.2% for a cut-off value of &amp;lt;15.8%, LA reservoir strain showed a higher diagnostic accuracy in discriminating CA from LVH than the parameter RELPAS (AUC 0.74, sensitivity and specificity 60% and 71% for a cut-off of &amp;gt;1.0; p&amp;lt;.05). LA conduit and contraction strain performed significantly better than RELAPS as well (AUC 0.87 for conduit, and AUC 0.86 for contraction function; p&amp;lt;.001 each). Of all echocardiographic parameters, LA reservoir strain remained significantly associated with CA in a multivariate regression model. Conclusions LA strain during all three phases of the atrial cycle was significantly reduced in patients with CA compared to other forms of LVH, and showed a markedly higher diagnostic accuracy than regional LV strain analysis, with LA reservoir strain showing highest discriminative value. The assessment of LA strain, as part of a comprehensive echocardiographic assessment, may be useful to rule-in the possible diagnosis of CA in patients with unclear LV hypertrophy.

The effectiveness of therapy with valsartan and hydrochlorothiazide and its effect on the left atrial myocardium condition in women with arterial hypertension in postmenopause

Purpose - to evaluate the effectiveness of the combination of valsartan and hydrochlorothiazide and its effect on the structural and functional parameters of the left atrial myocardium in postmenopausal women with arterial hypertension.Materials and methods. An open prospective controlled study included 100 postmenopausal women with uncomplicated arterial hypertension. Transthoracic and speckle tracking echocardiography was performed on a Vivid E9 XDClear Console 4D Expert 100 ultrasound scanner (General Electric, USA) with ECG-synchronization. Ambulatory blood pressure monitoring was performed using the device ABPM-04 (Meditech, Hungary). After 6 months of treatment with the antihypertensive combination of valsartan and hydrochlorothiazide, all women were re-examined in full. Statistical analysis of the results was performed using the Statistica 13.0 software package. All tests were two-way, statistically significant considered differences at P < 0.05.Results. As a result of our study, office systolic and office diastolic blood pressure in postmenopausal women with arterial hypertension significantly decreased (P < 0.001) due to a 6-month treatment with valsartan and hydrochlorothiazide. The target level of blood pressure, according to office measurements, was reached by 64 % of patients. A significant decrease of the SBP time index in the daytime in 1.6 times (P = 0.012), morning rise of SBP (P = 0.021) and the average pulse blood pressure (P = 0.012) was observed. Analysis of the LA deformation dynamics under the 6-month antihypertensive therapy did not reveal significant changes in the longitudinal strain of the LA in postmenopausal women with AH, unlike left ventricular strain.Conclusions. Combined antihypertensive therapy with valsartan and hydrochlorothiazide in postmenopausal women is effective, safe and well-tolerated. The use of this therapy for 6 months does not significantly affect the size and deformation properties of the left atrium, in contrast to the positive structural and functional remodeling of the left ventricle.

P1950How to improve early prediction of heart failure development after STEMI in clinical arena-is there a place for myocardial deformation imaging?

Abstract Heart failure (HF) development after myocardial infarction with ST segment elevation (STEMI) in the modern era varies greatly (between 4% and 28%), with the highest incidence in the first year. Since, HF still carries substantial morbidity and mortality, accurate and early identification of high-risk patients for HF development after pPCI allows for targeted use of intensive therapy. Aim The current study is a sub-study of PREDICT-VT study (NCT03263949). Its aim is to define multi-parametric model for early HF prediction in STEMI patients treated by pPCI, based on three data sets: clinical data, conventional echocardiographic data and data from myocardial deformation analysis obtained by early speckle tracking echocardiography. Methods In 264 consecutive pts enrolled in PREDICT-VT study early echocardiography (5±2 days after pPCI) was done and included LA and multilayer LV deformation analysis with longitudinal (L), radial (R) and circumferential (C) strain (S; %) and strain rate (SR, 1/sec). LV index of post systolic shortening for longitudinal strain (PSS LS) and for circumferential strain (PSS CS) were calculated for the purpose of this study as average of PSS over 18 LV segments. Results From 195 patients who completed 1-year follow-up, 17 (8.7%) develop HF NYHA class 3 or 4, 60 (30.8%) NYHA class 2 and remaining 118 patients (60.5%) were in NYHA class I. Significant univariate predictors of NYHA were: from clinical parameters – female gender (β=0.169, p=0018), Killip class on admission (β=0.253, p&lt;0.001) and previous atrial fibrillation (β=0.205, p=0.004); from conventional echocardiographic parameters – LV WMSI (β=0.223, p=0.0072), LVEF (β=−0.256, p&lt;0.001), LAVI (β=0.174, p=0.020) and TAPSE (β=−0.263, p=0.001); from parameters of longitudinal LV deformation – LS at the epicardial level (β=0.242, p=0.001) and PSS LS (β=0.360, p&lt;0.001); from parameters of LV circumferential deformation – CS at epicardial level (β=0.225, p=0.001) and PSS CS at epicardial level (β=0.124, p=0.004); from left atrial mechanics – LA strain (β=−0.199, p=0.007). In multivariable stepwise regression model 5 variables were further identified as independent predictors that significantly increased model power to predict HF development (R square from 0.134 to 0.270, p&lt;0.001). They are: PSS LS (β=0.255, p=0.002), previous atrial fibrilation (β=0.205, p=0.008), TAPSE (β=−0.176, p=0.031), female gender (β=0.165, p=0.032) and PSS CS (β=0.155, p=0.047). Conclusion Independently from and above classical clinical and echocardiographic parameters, amount of left ventricular post-systolic deformation in longitudinal and circumferential direction, expressed as LV indexes of post-systolic shortening, significantly improved early prediction of HF development after pPCI.

P2459Do left atrial strain measurements provide information independent from left ventricular function parameters?

Abstract Introduction LA strain has been proposed to be a reliable and independent prognostic marker, as well as a useful surrogate of LA function. Purpose To assess if LA deformation measurements add independent information to standard echocardiographic measurements. Methods We included 66 normals and patients with a wide range of pathology and diastolic dysfunction grade from the echo data base of our hospital if image quality was sufficient for both LA and LV strain analysis. Patients with a mobile interatrial septum, arrhythmias and more than mild valvular regurgitation were not considered. Standard echocardiographic measurements including LA and LV volumes were performed according to current guidelines. LA and LV longitudinal strains were assessed by 2D speckle tracking in the same cardiac cycle in apical 4 and 2 chambers views using peak R as time reference. Peak LA and LV strain as well as LA and LV strain at onset of LA contraction were measured to calculate the strain components of all three phases of the cardiac cycle (systolic, early diastolic and late diastolic). Results In our cohort, the ratio of LA and LV systolic strain was directly and strongly related to the volume ratio of the two chambers (R2=0,894, slope=-1.001, p&lt;0.0001, see Figure 1). This was confirmed by a multivariate regression analysis, where systolic LA strain proved to be strongly dependent on systolic LV strain, LA volume and LV volume (R2=0.872, p&lt;0.0001 for the final model). For early diastolic strain, confounders were LV early diastolic strain, LA volume, LV volume and lateral wall E' tissue velocity (R2=0.784, p&lt;0.0001); while LA late diastolic strain was dependent on LV late diastolic strain, LA volume, LV volume and lateral wall A' tissue velocity (R2=0.823, p&lt;0.0001). Strain ratio vs volume ratio Conclusions Our data suggest that systolic LA strain (reservoir strain) is strictly dependent on systolic LV strain and the volume ratio of both chambers and, therefore, its measurement cannot provide additional information beyond classical measurements. Diastolic LA strain components show a less strict dependence on LV function and may therefore provide additional information.

Association of the plasma aldosterone concentration, left atrial deformation and ambulatory blood pressure in never-treated early hypertensive patients

ABSTRACTLeft atrial (LA) strain is known to exhibit an early progressive reduction in hypertensive patients with diastolic dysfunction. However, an association of the renin-angiotensin-*aldosterone system (RAAS) with LA deformation has not been found in these patients. We aimed to investigate the association of plasma aldosterone concentration (PAC) and 24-hour ambulatory blood pressure monitoring (ABPM) with LA and left ventricle (LV) deformation in never-treated early hypertensive patients. This cross-sectional study included 101 never-treated subjects who were registered in a working group at The Catholic University of Korea. The patients were divided into a hypertension group (n = 71), which was defined as having a systolic blood pressure (BP) ≥130 mm Hg and/or a diastolic BP ≥80 mm Hg based on ABPM, and a control group (n = 30). Enrolled patients underwent conventional and speckle tracking echocardiography, ABPM, and measurement of pulse wave velocity, PAC, and plasma renin activity. Compared with the control group, the hypertension group had significantly increased PAC, global longitudinal strain (GLS), atrial reservoir strain, atrial pump strain, and atrial systolic strain rate. LA pump strain was independently associated with nighttime systolic BP. PAC was correlated with GLS but not LA deformation in hypertensive patients without clinically apparent target organ damage. The raised LV pressure secondary to the nocturnal systemic pressure overload might be more strongly associated with LA deformation than with the RAAS.

Left atrial deformation analysis by speckle tracking echocardiography to predict exercise capacity after myocardial infarction

IntroductionLeft atrial (LA) size and function are associated with outcome after myocardial infarction (MI). In this study we aimed to assess the impact of LA function as a predictor of exercise capacity through speckle tracking echocardiography. MethodsA total of 94 patients (mean age 54.8±11.0 years; 82% male) were enrolled one month after MI. Echocardiography was used to assess LA volumes and various indices of LA conduit, contraction and reservoir function. LA deformation was assessed by two-dimensional speckle tracking to calculate strain and strain rate at different phases of the cardiac cycle. Exercise capacity was assessed by oxygen uptake (VO2) on cardiopulmonary exercise testing. ResultsIncreased LA volumes, especially LA volume before atrial contraction, were correlated with reduced peak VO2 and reduced VO2 at anaerobic threshold. Decreased peak VO2 was associated with reduced LA conduit function (ρ=0.24; p=0.02), but not with LA booster function (ρ=-0.07; p=0.53). Lower peak atrial longitudinal strain was associated with worse exercise capacity (ρ=0.24; p=0.02). ConclusionsAfter MI, increased LA volumes were markers of decreased functional capacity that was associated with decreased LA conduit function, but not with LA contractile function. In these patients, LA longitudinal strain analysis may be useful to predict reduced exercise capacity.

Echocardiographic assessment of the left atrial function in patients with mitral valve disease by two-dimensional speckle tracking

Abstract Objectives: Comparing effects of mitral stenosis and mitral regurgitation on LA deformation using twodimensional speckle tracking echocardiography. Methods: Fifty patients with isolated

Left atrial remodelling may predict exercise capacity in obstructive sleep apnoea patients

Background: Left atrial volume (LAV) and LA deformation has been proposed as a good marker of exercise performance in patients with diastolic dysfunction (DD). As DD is more prevalent in obstructive sleep apnoea (OSA) we aimed to evaluate the influence of LAV and LA deformation parameters on exercise performance in varying severity of OSA. Materials and methods: OSA was diagnosed after polysomnography. Fifty-five OSA patients were enrolled in the study. OSA patients were divided into two groups with apnoea-hypopna-index (AHI) > 30 and <30. LAV was calculated. LA strain and LA strain rates were assessed with speckle tracking echocardiography (STE). Exercise capacity was evaluated by treadmill exercise test. Results: MET values were lower in group II compared to group I (p < .05). Echocardiographic findings: Comparison within groups: In both groups E/E’, LA stain, LA strain rate S and LA strain rate E were higher after exercise than before (p < .05). In group I LA strain rate A was higher after exercise than before (p < .05). Comparison between groups: LA strain, LA strain rate S, LA strain rate E and LA strain rate A were lower and E/E’ and LAVI were higher in group II compared to group I before and after exercise (p < .05). Correlation with METs: AHI, LVEDV, E/E’ and LAVI were negatively and LA strain was positively correlated with METs (p < .05). Conclusions: Left ventricular diastolic dysfunction is more prevalent in severe OSA and is associated with impaired exercise performance. Additionally, LA remodelling may predict exercise capacity in this subgroup of patients.

Left and right atrial feature tracking in acute myocarditis: A feasibility study

PurposeThe present study aims at evaluating the feasibility and reproducibility of cardiac magnetic resonance (CMR) feature tracking (FT) derived strain and strain rate (SR) parameters of the left and right atrium (LA, RA) in patients with acute myocarditis as well as their potential to detect diastolic dysfunction. In addition, the diagnostic value of LA and RA strain parameters in the setting of acute myocarditis is investigated. MethodsCMR cine data of 30 patients with CMR-positive acute myocarditis were retrospectively analyzed. 25 age- and gender-matched healthy individuals served as a control. Analysis of longitudinal strain and SR of both atria was performed in two long-axis views using a dedicated FT-software. LA and RA deformation was analyzed including reservoir function (total strain [εs], peak positive SR [SRs]), conduit function (passive strain [εe], peak early negative SR [SRe]) and booster pump function (active strain [εa], peak late negative SR [SRa]). Intra- and inter-observer reproducibility was assessed for all strain and SR parameters using Bland-Altman analyses, intra-class correlation coefficients (ICCs) and coefficients of variation (CV). ResultsFT analyses of both atria were feasible in all patients and controls. Reproducibility was good for reservoir and conduit function parameters and moderate for booster pump function parameters. Myocarditis patients demonstrated an impaired LA reservoir and conduit function when compared to healthy controls (LA εs: 32±17 vs. 46±13, p=0.019; LA SRs: 1.5±0.5 vs. 1.8±0.5, p=0.117; LA SRe: −1.3±0.5 vs. −1.9±0.5, p<0.001), while LA booster pump function was preserved. In logistic regression and ROC-analyses, LA SRe proved to be the best independent predictor of acute myocarditis (AUC 0.80), and using LA SRe with a cut-off of −1.6s−1 resulted in a diagnostic sensitivity of 83% and a specificity of 80%. Changes in RA phasic function parameters showed a tendency to parallel those of the LA and showed no additional effect with respect to the diagnostic potential in acute myocarditis. ConclusionsMyocarditis patients exhibit an impaired atrial reservoir and conduit function, what might be indicative of ventricular diastolic dysfunction. LA SRe was the best predictor for the presence of acute myocarditis in our study, pointing towards the discriminative power of atrial strain analysis in the CMR-based diagnosis of acute myocarditis.

Left atrial mechanics in patients with acute STEMI and secondary mitral regurgitation: A prospective pilot CMR feature tracking study

Background and objectiveLeft atrium (LA) is an important biomarker of adverse cardiovascular outcomes and cerebrovascular events. This study aimed to evaluate LA myocardial deformation using cardiac magnetic resonance feature tracking (CMR-FT) in patients with acute ST-segment elevation myocardial infarction (STEMI) and secondary mitral regurgitation (MR). Additionally, to assess interobserver and intraobserver variability of the technique. Materials and methodsTwenty patients with STEMI underwent CMR with a 1.5Tesla MRI scanner. According to the presence of MR patients were divided into two groups: MR(+) and MR(−). Total LA strain (ɛs), passive LA strain (ɛe), and active LA strain (ɛa) were obtained. Additionally, total, passive and active strain rates (SRs, SRe, and SRa) were calculated. To assess interobserver agreement data analysis was performed by second independent observer. ResultsLA volumetric and functional parameters were similar in both groups. All LA strain values were significantly higher in patients with MR: ɛs (27.67±10.25 for MR(−) vs. 32.80±6.95 for MR(+); P=0.01), ɛe (15.29±7.30 for MR(−) vs. 19.22±6.04 for MR(+); P=0.01) and ɛa (12.38±4.23 for MR(−) vs. 14.44±5.19 for MR(+); P=0.03). Only SRe significantly increased in patients with MR (−0.57±0.24 for MR(−) vs. −0.70±0.20 for MR(+); P=0.01). All LA deformation parameters demonstrated high interobserver and intraobserver agreement. ConclusionsConventional volumetric and functional LA parameters do not detect early changes in LA performance in patients with STEMI and secondary MR. In contrast, LA reservoir, passive and active strain are significantly higher in patients with MR. Only peak early negative strain rate substantially increases during secondary MR. LA deformation parameters derived from conventional cine images using CMR-FT technique are highly reproducible.

Analytic study of the onset of plastic necking instabilities during biaxial tension tests on metallic plates

Abstract In this article, we study the onset of the development of plastic necking instabilities during dynamic tension tests on metallic plates biaxially loaded in their plane. This model applies whatever the thickness. The material is supposed to be homogeneous, isotropic, incompressible, elastoviscoplastic, to satisfy Von Mises' plasticity criterion and normality flow rule (damage and heat conduction are neglected). As Dudzinski and Molinari did in 1988 for static tests on very thin plates in the framework of generalized plane stress theory (thickness is supposed to vary slowly and slightly along loading directions) (Instabilite de la deformation viscoplastique en chargement biaxial, 1988, Compte Rendu a l'Academie des Sciences de Paris 307, serie 2, pages 1315–1321), we carry out a linear stability analysis. The flow is viewed as the sum of the mean homogeneous flow of the perfect plate, and of small perturbations δ v → of the velocity field, periodic along the x1− and x2− loading directions, growing exponentially. We search for the most unstable pair of wavelengths ( λ 1 ( d ) , λ 2 ( d ) ) and for the associated growth-rate θ(d) (the dominant mode). Plastic deformation concentrates preferably along zero rate extension lines for non positive velocity gradient ratio α = D 22 / D 11 (D denoting deformation rate tensor), and along lines parallel to minor principal stress direction for biaxial stretching (α > 0). For sufficiently viscous materials, inertia plays a negligible role (maximum plastic strain-rate considered in this paper equals 20 s−1, and thickness does not exceed 2 cm), the wavelength associated with the dominant mode is much greater than thickness, and Dudzinski and Molinari's model gives the associated growth-rate very accurately. This growth-rate is a root of a polynomial equation, that we re-establish starting from the equations of our 3D model. For non viscous materials, inertia is no longer negligible for non positive values of α.

2D SPECKLE STRAIN IMAGING IDENTIFIES DEPRESSED LEFT ATRIAL FUNCTION IN HYPERTENSIVE PATIENTS WITH DIASTOLIC DYSFUNCTION: 3C.07

Background: Assessment of LA deformation obtained by 2D Speckle Strain Imaging (2DSI) has been recently proposed as an alternative method of exploring LA function. The aim of this study was to analyze LA function with 2DSI in hypertensive patients and normal controls. Methods: 39 HTN with grade 1–2 diastolic dysfunction (76 ± 14years; 72%women) and 66 healthy volunteers (NLS; 44 ± 16; 55%women) underwent standard echocardiography with complete evaluation of diastolic function and atrial 2DSI. LA volume was calculated by the area-length method. The ratio of E/e' (filling pressure) to LA 2DSI (strain) was used as an index of LA stiffness. Results: HTN patients were older and more often women as compared to NLS (both p < 0.05). In analysis of covariance with means adjusted for differences in age and gender among groups, HTN showed lower E/A ratio, paired with higher E/e' and LA volume (all p < 0.01). HTN also showed a reduction in LA 2DSI (23.8 ± 8.2% vs 43.0 ± 11.1%; p < 0.001) paired with a marked increase in LA stiffness (0.52 ± 0.09 vs 0.21 ± 0.11%; p < 0.001).As shown in Figure, LA 2DSI was negatively associated with LA volume (p < 0.001; r = -0.51) with no significant association found with other indices of left ventricular diastolic function (including e' and E/A ratio). In a subgroup analysis of 14 randomly selected HTN and 14 age and gender matched controls, both LA 2SDI and LA stiffness were significantly impaired in HTN as compared to NLS also after further correction for differences among groups in LA volume and E/e' ratio. Conclusion: LA function by 2DSI is significantly reduced in HTN with diastolic dysfunction as compared to normal controls. Lower atrial strain is related to higher LA stiffness and LA dilation but is independent of other indices of left ventricular diastolic function.

490 Total atrial activation time: New echocardiographic tool for identifying patients with an atrial substrate vulnerable for AF

=0.306; s=0.053; p=0.026), ejection fraction (r 2 =0.223; s=0.472; p=0.027), left ventricular end-diastolic dimension (r 2 =0.205; s=-0.453; p=0.026), nonsustained ventricular tachy- cardia (r 2 =0.180; s=-0.424; p=0.049). After a multivariate model, we ob- served a significant, negative correlation between LA strain and PR interval (p=0.02; s=-0.580). Conclusions: LA properties, analysed by S/SR analysis, correlate signifi- cantly to morphologic and electric properties of left atrium and ventricle. An independent correlation between LA deformation properties and PR interval may suggest a more impaired left atrial deformation and functional proper- ties in patients with atrio-ventricular conduction delays. 1 ; A. Rea 1 ; T. Miele 1 ;

Mechanical size effects in 2d granular media

We present a critical analysis of experiments on 2d regular packings of cylinders submitted to a uniaxial vertical pressure, by studying finite size effects. The role of the disorder of contacts is emphasized. The influence of the walls, especially the frictions, is discussed; the ratio of the transmitted to the applied force has been measured. We have tested the influence of the size of the samples by increasing width, height or both simultaneously. Conclusions are partly supported by photoelasticity measurements. The role of a characteristic length larger than the grain size is put into evidence Analyse de la deformation uniaxiale d'empilements reguliers de cylindres a 2d. On souligne le role du desordre de contact, et l'influence des parois. Etude des effets de la taille des echantillons

Electron mechanism for the tilting transition in La2-x SrxCuO4

It is shown that the tilting deformation is couplet to the electrons through the tilting induced variation of the Umklapp matrix elements. The latter are important only for small concentrations of Sr if the electron-electron interaction, (which are assumed to be repulsive), are reasonably small. The leading term in the resulting deformation energy is quadratic in the tilting deformation and leads to the critical devease of the tilting mode frequency when the temperature is lowered. The resistivity, although enhanced by Umklapps, is continuous through the tilting transition. The model bears some ressemblence to that developed previously for 4 k f deformations in organic superconductors. Some consequences of the model for the high T c superconductivity are briefly discussed Description de la transition a la phase ondulee en termes d'interactions electroniques (couplage de la deformation aux electrons par l'intermediaire de la variation des elements de matrice Umklapp). Consequences pour la supraconductivite a T c elevee

The effects of damping on the interpretation of geophysical measurements

Measurements of damping in situ as a function of strain are described. Three different methods were used: hammer damping, resonance of an embedded pipe and hysteresis due to cyclic loading. All three methods show distinct values of damping in boulder clay which indicate clearly that anelastic behaviour must be taken into account. There is some evidence that damping is dependent on time as well as strain. When moduli derived from shear wave velocities are used to calculate settlements of loaded pads corrections involving time dependence proportional to damping are required. Theoretically the logarithmic creep rate at a given strain is proportional to (2/nXl/β)- These measurements were used to produce two class A predictions of the time-dependent settlement of loaded pads that were within 20% of the observed values. Suitable viscoelastic models are considered. L'article décrit des mesures d'amortissement in situ en fonction de la déformation. On a utilisé trois méthodes différentes, c'est-à-dire l'amortissement d'un mouton, la résonance d'un tuyau enrobé et l'hystérésis due au chargement cyclique. Les trois méthodes donnent des valeurs différentes pour l'amortissement dans l'argile à blocaux, ce qui indique clairement qu'il faut tenir compte du comportement inélastique. Il apparaît que l'amortissement dépend du temps aussi bien que de la déformation. Lorsque des modules déterminés à partir des vitesses d'onde de cisaillement sont employés pour calculer les tassements des supports chargés, il faut apporter des corrections qui prennent en compte une dépendance du temps proportionnelle à l'amortissement. Théoriquement la vitesse logarithmique de fluage pour une déformation donnée est proportionnelle à (2/π)(1/Q)- Ces mesures ont été utilisées pour produire deux prédictions de classe A du tassement des supports chargés en fonction du temps qui correspondaient aux valeurs observées à 20% près. L'article présent des modèles viscoélastiques corrects.