Peak Torsion Research Articles

Combination effect of Chinese kidney-tonifying granules and platelet-rich plasma gels on enhancing bone healing in rat models with femur defects

BackgroundThe traditional Chinese kidney-tonifying granules, known as Bushen Zhongyao Keli (BSZYKL), have been found to stimulate calcium salt deposition, enhance bone formation, and foster bone growth within the bone matrix at sites of bone defects. On the other hand, platelet-rich plasma (PRP) is enriched with various growth factors capable of facilitating the repair of bone defects and enhancing bone strength following fractures. This study is dedicated to investigating the combined efficacy of BSZYKL and PRP gel (PRP-G) in the treatment of bone defects.MethodsWe established a femur defect model in male Sprague-Dawley (SD) rats and filled the defect areas with autologous coccygeal bone and PRP-G. For 8 consecutive weeks, those rats were given with intragastric administration of BSZYKL. Biomechanical characteristics of the femur were assessed 28 days after intramuscular administration. On day 56, bone formation was examined using X-ray, micro-CT, and transmission electron microscopy. Additionally, we analyzed the expression of bone formation markers, Runx2 and Osterix, in femur tissues through qPCR, Western blotting, and immunohistochemistry.ResultsRats receiving the combined treatment of BSZYKL and PRP-G exhibited drastically enhanced femoral peak torsion, failure angle, energy absorption capacity, and torsional stiffness as compared to control group. This combination therapy also led to marked improvements in bone volume, mass, and microarchitecture, accompanied by elevated expressions of Runx2 and Osterix when compared to control group. Notably, the synergistic effects of BSZYKL and PRP-G in treating bone defects surpassed the effects of either treatment alone.ConclusionsThese findings revealed the potential of BSZYKL in combination with PRP-G in improving bone defects.

Uncertainty Quantification of the ONERA 7A Rotor Performance and Loads Using Comprehensive Analysis

Quantification of blade stiffness uncertainties and sensitivities on rotor power and structural loads for the ONERA 7A rotor is established using the U.S. Army and ONERA rotorcraft comprehensive analysis tools. A stochastic-based approach is implemented to generate probabilistic bounds of the response outputs, including rotor performance and loads due to uncertainties in blade stiffness using 1) a Monte Carlo approach coupled directly with U.S. Army’s rotorcraft comprehensive toolset, and 2) a surrogate of ONERA’s rotorcraft comprehensive analysis solver using polynomial chaos expansions to efficiently predict the response outputs. The analysis showed that uncertainties in blade torsion, flap, and lag stiffnesses impact the predicted rotor power by a quantifiable amount. Significant uncertainties in peak torsion, flap, and chord bending moments are also confirmed. The sensitivities of the stiffness properties on response outputs using Sobol indices are also studied. The results show that total required power is exclusively sensitive to variability in torsion stiffness with no interaction effects with flap and lag stiffnesses. Sensitivities due to independent parameter effects and by combining with other parameters on peak structural loads are also examined. The analysis demonstrates the merits of integrating a stochastic, data-driven approach for uncertainty and sensitivity analyses in rotorcraft aeromechanics predictions.

Modeling Delamination in NSTX-U Inner Leg Using “EKILL”

The possibility of thermal strain–induced delamination was anticipated in the original design of the NSTX-Upgrade (NSTX-U). Current “bunching” at the toroidal field (TF) flag causes nonuniform Joule heating of the TF conductor during a shot. This produced through-thickness tensions beyond the measured capacity of the insulation bond. This however occurred where the torsional shear was at a minimum, and the Upgrade design progressed with the understanding that delamination at the core of the TF flag might occur. During the Recovery project design reviews, concern over the extent of delamination was elevated. In various early simulations, the tensile stresses reached 50 MPa. With more accurate through-thickness insulation modulus and thickness, and at end-of-flattop versus end-of-pulse temperature, the tensile stress goes down to 25 MPa, and possibly lower based on higher-fidelity modeling. Insulation delamination has been predicted analytically in coils in projects other than NSTX-U, and indications of delamination have been observed in some machines. Out-of-plane loads on the NSTX TF coil produce local and global twisting of the tokamak. The inner leg supports part of the torsion as a torque shaft or tube. Peak torsion is at the outside radius of the TF central column, away from the regions that don’t carry current, experience less Joule heat, and develop tension. Testing of the shear and tensile fatigue properties of the CTD-425 system was repeated and was a part of this requalification effort. This paper addresses simulations done in ANSYS based on a simple assumption that when the tension and shear stresses exceed an allowable, the elements are “killed” or considered much less capable of carrying tension and shear loads established by fatigue S-N tests. A competing and complementary method, the Virtual Crack Closure Technique (VCCT) was used to augment and validate the EKILL procedure. Determination of Paris constants to support the VCCT analysis is described Fig. 8.

Loss of left ventricular rotation is a significant determinant of functional mitral regurgitation

AimTo evaluate insufficient rotational movement of the left ventricle (LV) as a potential novel mechanism for functional regurgitation of the mitral valve (FMR). Methods and resultsWe compared reference subjects and patients with LV dysfunction (LVD, ejection fraction EF < 50%) with and without FMR (regurgitant volume RVol>10 ml). Subjects without structural mitral valve pathology undergoing cardiac MRI were evaluated. Delayed enhancement, global LV remodeling parameters, systolic twist and torsion were measured (using manual and novel automated cardiac MRI tissue-tracking). The study included 117 subjects with mean ± SD age 50.4 ± 17.8 years, of which 30.8% were female. Compared to subjects with LVD without FMR (n = 31), those with FMR (n = 37) had similar clinical characteristics, diagnoses, delayed enhancement, EF, and longitudinal strain. Subjects with FMR had significantly larger left ventricles (EDVi:136.6 ± 41.8 vs 97.5 ± 26.2 ml/m, p < 0.0001) with wider separation between papillary muscles (21.1 ± 7.6 vs 17.2 ± 5.7 mm, p = 0.023). Notably, they had lower apical (p < 0.0001) but not basal rotation and lower peak systolic twist (3.1 ± 2.4° vs 5.5 ± 2.5°, p < 0.0001) and torsion (0.56 ± 0.38°/cm vs 0.88 ± 0.52°/cm, p = 0.004). In a multivariate model for RVol including age, gender, twist, LV end-diastolic volume, sphericity index and separation between papillary muscles, only gender, volume and twist were significant. Twist was the most powerful correlate (beta −2.23, CI -3.26 to −1.23 p < 0.001). In patients with FMR, peak systolic twist negatively correlates with RVol (r = −0.73, p < 0.0001). ConclusionReduced rotational systolic LV motion is significantly and independently associated with RVol among patients with FMR, suggesting a novel pathophysiological mechanism and a potential therapeutic target.

Endovascular reversal of renovascular hypertension blunts cardiac dysfunction and deformation in swine.

Renovascular hypertension (RVH) induces hemodynamic and humoral aberrations that may impair cardiac function, structure and mechanics, including cardiac twist and deformation. Revascularization of a stenotic renal artery can decrease blood pressure (BP), but its ability to restore cardiac mechanics in RVH remains unclear. We hypothesized that percutaneous transluminal renal angioplasty (PTRA) would improve cardiac function and left ventricular (LV) deformation in swine RVH. Seventeen domestic pigs were studied for 16 weeks: RVH, RVH + PTRA and normal controls (n = 5-6 each). Global LV function was estimated by multidetector computed-tomography, and LV deformation by electrocardiographically triggered MRI tagging at the apical, mid, and basal LV levels. Cardiomyocyte hypertrophy, myocardial capillary density, and fibrosis were evaluated ex vivo. BP and wall thickness were elevated in RVH and decreased by PTRA, yet remained higher than in controls. LV myocardial muscle mass increased in RVH pigs, which also developed diastolic dysfunction, whereas cardiac output increased. Furthermore, both apical rotation and peak torsion angle increased in RVH compared with controls. Ex vivo, RVH induced myocardial fibrosis and vascular rarefaction. PTRA restored cardiac function and alleviated hypertrophy, vascular rarefaction, and fibrosis. PTRA also normalized apical rotation and peak torsion angle, and elevated basal peak radial strain and apical peak radial strain compared with RVH. In addition to cardiac LV adaptive hypertrophy and diastolic dysfunction, short-term RVH causes cardiac deformation. Despite only partial improvement in BP, PTRA effectively restored cardiac function and reversed abnormal mechanics. Hence, renal revascularization may be a useful strategy to preserve cardiac function in RVH.

Cross-Domain Collaborative Oscillation Control Strategy for a Hybrid Driveline Based on the Integration of a Notch Filter, PI filter, and Backlash Estimator

Abstract This work studies torque oscillation control of a hybrid driveline, and proposes a new cross-domain collaborative (C2) control strategy that comprises a notch filter, a PI filter, and a backlash estimator. The C2 control strategy is centered on a notch filter, which is built on digitalization of the driveline system and analyses of oscillation elements in the frequency domain. To enhance the performance of the notch filter in the time domain, a PI filter is connected in series to the notch filter. Considering that the driveline is a nonlinear time system during backlash travel, a backlash estimator is developed to handle the torque control target. The notch frequency and backlash travel time are identified through simulations, and the control strategy and selected parameters are evaluated in road tests. The results indicate that this control strategy can reduce the peak torsion speed to 71%.

Left ventricular rotational deformation changes by speckle tracking imaging before and 24hours after transcatheter closure of large secundum atrial septal defects in children.

Large atrial septal defects (ASDs) in children cause increased volume overload of the right side of the heart which in turn lead to impairment of left ventricular (LV) performance. The aim of this study was to evaluate immediate LV rotational deformation changes in children with large ASDs post-device closure and removal of right ventricle (RV) volume overload. Twenty children who underwent transcatheter closure (TCC) of large secundum ASDs were included in the study. LV rotational deformation was assessed pre- and 24hours post-device closure using speckle tracking imaging (STI). 55% were females with mean age 6.1±3.5years. LV peak basal clockwise rotation improved significantly (-6.9±2.6° before vs -10.3±4.1° after TCC, P=.005), and time to peak clockwise rotation (345.1±124.7 milliseconds (ms) before vs 282.2±82.9ms after closure, P=.02). There was no significant difference in apical rotational parameters including peak counterclockwise rotation (P>.05 for both). LV twist (11.3±3.8° before vs 17.5±7.1° after closure, P=.001) and torsion (2.1±0.7°/cm before vs 3.1±1.2°/cm after closure, P=.01) were significantly improved, mainly as the result of improvement of LV basal rotation. LV revealed a significant increase in LV end-diastolic volumes (P=.02) 24hour after TCC with no significant change (P>.05) in end-systolic volumes after closure. Increased peak LV twisting and torsion were attributed to the improved peak systolic clockwise basal rotation after TCC of large ASDs in children.

Biphasic Plating – In vivo study of a novel fixation concept to enhance mechanobiological fracture healing

BackgroundFracture fixation has advanced significantly with the introduction of locked plating and minimally invasive surgical techniques. However, healing complications occur in up to 10% of cases, of which a significant portion may be attributed to unfavorable mechanical conditions at the fracture. Moreover, state-of-the-art plates are prone to failure from excessive loading or fatigue. A novel biphasic plating concept has been developed to create reliable mechanical conditions for timely bone healing and simultaneously improve implant strength. This paper introduces the novel fixation concept and presents preclinical results from a large animal study. MethodsTwenty-four sheep underwent a mid-diaphyseal osteotomy stabilized with either the novel biphasic plate fixator or a control locking plate. Different fracture patterns regarding orientation and localization were investigated. Animals were free to fully bear weight during the post-operative period. After 12 weeks, the healing fractures were evaluated for bone formation using micro-computer tomography and strength and stiffness using biomechanical testing. Additionally, histological evaluation of soft tissue samples with respect to metal wear debris was performed. ResultsNo plate deformation or failures were observed under full weight bearing with the biphasic plate. Defects stabilized with the biphasic plate demonstrated robust callus formation compared to control group. Torsion tests after plate removal revealed no statistical difference in peak torsion to failure and stiffness for the different fracture patterns stabilized with the biphasic plate. However, the biphasic plate group specimens were 45% stronger (p=0.002) and 48% stiffer (p=0.007) than the controls. No histological signs of metal wear due to the biphasic feature could be found. ConclusionsThe biphasic plate concept is aimed at improving the biomechanics of locked plating. The results of this large animal study demonstrate the feasibility and clinical potential of this novel stabilization concept.

P780 Left ventricular torsion in severe valvular disease

Abstract Introduction Left Ventricular (LV) torsion is an important component of LV performance. With the development of speckle tracking echocardiography, it became possible and feasible to measure rotation and twisting with a high degree of accuracy. No standard normal values are defined for peak torsion, although mean values around 10° are found in normal subjects with a slight increase with age. Purpose In this study we aimed to evaluate torsion in the different types of severe valvular disease. Methods We conducted a retrospective, observational study including patients with severe valvular disease with suitable images for torsion analysis. We included 61 patients (21 with severe aortic stenosis (AS), 20 with severe aortic regurgitation (AR) and 20 with severe mitral regurgitation (MR). Circumferential basal and apical strain was performed, and peak torsion was calculated. Results were compared between groups and were related with echocardiographic parameters, including left ventricle ejection fraction (LVEF). Results Mean age was 70.3 ± 13.6 years with a male preponderance (66%). Mean LVEF was within normal range in the aortic valve disease group; no significant difference was found in LVEF between AS and AR patients (57 ± 7.7% vs 55 ± 9.7%, p = 0.57). In comparison with the aortic disease group, MR patients had a reduced LVEF (48 ± 17.3% vs 56 ± 8.7%, p = 0.05). Mean peak torsion was 8.9 ± 5.1° in AS, 12.6 ± 4.9° in AR and 7.9 ± 3.2° in MR (p = 0.004). Comparing with aortic valve disease patients, MR patients had a reduced mean peak torsion (7.9 ± 3.2° vs 10.7 ± 5.3°, p = 0.03). In relation with patients with AS, those with AR had a higher peak torsion (12.6 ± 4.9° vs 8.9 ± 5.1°, p = 0.024) and a higher left ventricle end-diastolic volume (87.3 ± 29.1 mL.m-² vs 64.5 ± 24.9 mL.m-², p = 0.011). Circumferential apical strain showed a negative correlation with peak torsion (r²=0.203, p = 0.006) and with LVEF (r²=0.290, p &amp;lt; 0.001). Peak torsion did not demonstrate any significant correlation neither LVEF nor circumferential basal strain. Conclusion LV function and peak torsion are more associated with apical than basal circumferential movement. Aortic valve disease is responsible for LV torsion variations in patients with normal ejection fraction, showing an increase in AR and a reduction in AS. In MR patients a reduced LVEF could entails a decrease in peak torsion.

P319 Evidence for abnormal deformational reserve in hypertrophic cardiomyopathy on exercise: is it a game-changer?

Abstract Funding Acknowledgements None Hypertrophic obstructive cardiomyopathy (HOCM) is characterized by muscle hypertrophy and fibrosis, interfering with force generation and relaxation. Abnormal ventricular (LV) myocardial deformation have been demonstrated in patients with HOCM at rest, but there is lack of data regarding the deformational mechanics in exercise. AIMS: We wanted to assess the adaptability of LV deformational behaviour to physical exercise in HCM patients as compared to healthy control subjects. METHODS 24 obstructive HOCM (age 51.2 ± 14.2yrs; 16 men, LVOT-obstruction 56 ± 19mmHg at rest or on Valsalva maneuver) and 32 control subjects (50.9 ± 6.8 yrs, 19 men from the MAGYAR-PATH Registry) underwent supine bicycle stress echocardiography (ESE) with measurements of 2D- and Doppler, 2D-Speckle Tracking Tracking Imaging and 3D-Full Volume Analysis. Beyond conventional LV/RV functional measurements; peak longitudinal (LS), circumferential (CS) Strain values; peak Twist and Torsion angles; post-systolic shortening index (PSS) and diastolic phase indices (Untwisting time - UTT and rate - UTR) calculated; the UTR/Twist ratio was given as "coupling index". The LV/RV-EF calculated by 3D-Full Volume Analysis off-line by TomTec Arena™ software both at rest and on submaximal ESE. RESULTS The HOCM group had lower resting LS (-14.6 ± 4.5 vs 18.4 ± 2.6%, p &amp;lt; 001) but higher CS (-32.9 ± 5.1 vs 28.8 ± 2.3%, p &amp;lt; 0.001) and Twist angles (9.9 ± 2.6 vs 6.1 ± 2.2º, p &amp;lt; 0.01) than control subjects. Exercise induced an increase in all strains in control subjects, but much less in HOCM (LS: -21.4 ± 3.5 vs 15.1 ± 3.0% and CS: -33.9 ± 3.6 vs 34.1 ± 4.2% in HOCM, p &amp;lt; 0.02 in controls, NS in HOCM); the increase of Twist angle was minimal in HOCM (Δ1.2 ± 1.2 vs Δ3.6 ± 2.3º in controls, p &amp;lt; 0.01). The PSS was more pronounced on ESE in HOCM than in controls (46.6 ± 12 vs 21.2 ± 9.6% in controls, p &amp;lt; 0.001). Peak UTR was slower (118 ± 2.1 vs 133.1 ± 14.1 º/s) during ESE and occured later (141 ± 19 vs 121 ± 9.1% of systolic time, p &amp;lt; 0.02) in HOCM than in controls. There was significant relationship between the Twist and UTR in control subjects (β=-0.0807, p &amp;lt; 0.001), but not in HOCM (β=-0.0046, p = 0.05). The UTR/Twist ratio diminished only in HOCM but not in controls (-8.0 ± 0.6 vs -13.1 ± 2.5 1/s, p &amp;lt; 0.02). CONCLUSIONS The HOCM patients had significantly impaired strain-adaptability; developed post-systolic shortening and no LV Torsional reserve was found on exercise. Also, I detected decreased and delayed UTR indices in the HOCM group. These findings support evidence for reduced systolic-diastolic coupling efficiency, assessed by Twist-Untwist mechanics in HOCM patients, which can contribute to the development of exercise-related symptoms and the dynamic LVOT-obstruction. This unique pattern of deformational behaviour to exercise can help in the differential diagnostic workup in patients with LV hypertrophy of unknown aetiology and also would hold additional value in the risk stratification process for patients with HCM-phenotypes.

Assessment of left ventricular torsion in long axis view in patients with chronic stenosis of coronary arteries.

Background:Left ventricular torsion is one of the most important biomechanical parameters of heart that routinely is measured in short axis view. A review of the literature has indicated that assessment of left ventricular torsion in short axis view has some limitations. In the present study, we evaluated whether torsion angle assessment in long axis view can be used as a diagnostic biomechanical marker in patients with coronary artery disease (CAD).Methods:We assessed 20 males and 15 females who suffered from CAD and 24 healthy males and females. Two dimensional echocardiography images were scanned in cine loop format position throughout four cardiac cycles at basal and apical levels in the long axis view (4CH). Peak torsion angle in long axis view was obtained by speckle tracking method under block matching algorithm.Results:In long axis view, peak torsion angle and time of peak torsion angle were similar in female (34.87±5.8˚, 287±18ms) and males (33.26±5.60˚, 295 22ms) while they were significantly decreased and increased in CAD patients (female: 24.91±3.5˚, 345±26ms and male: 24.15±2.16˚, 358±24 ms) in comparison to healthy subjects. The peak torsion angle reduction in CAD patients was a subsequent of reduced rotation angle of basal and apical levels (P<0.001).Conclusion:The results showed that sex difference did not influence torsion angle of the left ventricle. It is concluded that left ventricular torsion assessment in long axis view has the potential to distinct patients with CAD from healthy subjects in routine echocardiography evaluation.

Simultaneous determination of dynamic cardiac metabolism and function using PET/MRI

BackgroundCardiac metabolic changes in heart disease precede overt contractile dysfunction. However, metabolism and function are not typically assessed together in clinical practice. The purpose of this study was to develop a cardiac positron emission tomography/magnetic resonance (PET/MR) stress test to assess the dynamic relationship between contractile function and metabolism in a preclinical model. MethodsFollowing an overnight fast, healthy pigs (45-50 kg) were anesthetized and mechanically ventilated. 18F-fluorodeoxyglucose (18F-FDG) solution was administered intravenously at a constant rate of 0.01 mL/s for 60 minutes. A cardiac PET/MR stress test was performed using normoxic gas (FIO2 = .209) and hypoxic gas (FIO2 = .12). Simultaneous cardiac imaging was performed on an integrated 3T PET/MR scanner. ResultsHypoxic stress induced a significant increase in heart rate, cardiac output, left ventricular (LV) ejection fraction (EF), and peak torsion. There was a significant decline in arterial SpO2, LV end-diastolic and end-systolic volumes in hypoxia. Increased LV systolic function was coupled with an increase in myocardial FDG uptake (Ki) during hypoxic stress. ConclusionPET/MR with continuous FDG infusion captures dynamic changes in both cardiac metabolism and contractile function. This technique warrants evaluation in human cardiac disease for assessment of subtle functional and metabolic abnormalities.

Differential Effects of Isoproterenol on Regional Myocardial Mechanics in Rat Using Three-Dimensional Cine DENSE Cardiovascular Magnetic Resonance

The present study assessed the acute effects of isoproterenol on left ventricular (LV) mechanics in healthy rats with the hypothesis that β-adrenergic stimulation influences the mechanics of different myocardial regions of the LV wall in different ways. To accomplish this, magnetic resonance images were obtained in the LV of healthy rats with or without isoproterenol infusion. The LV contours were divided into basal, midventricular, and apical regions. Additionally, the midventricular myocardium was divided into three transmural layers with each layer partitioned into four segments (i.e., septal, inferior, lateral, and anterior). Peak systolic strains and torsion were quantified for each region. Isoproterenol significantly increased peak systolic radial strain and circumferential-longitudinal (CL) shear strain, as well as ventricular torsion, throughout the basal, midventricle, and apical regions. In the midventricle, isoproterenol significantly increased peak systolic radial strain, and induced significant increases in peak systolic circumferential strain and longitudinal strain in the septum. Isoproterenol consistently increased peak systolic CL shear strain in all midventricular segments. Ventricular torsion was significantly increased in nearly all segments except the inferior subendocardium. The effects of isoproterenol on LV systolic mechanics (i.e., three-dimensional (3D) strains and torsion) in healthy rats depend on the region. This region dependency is also strain component-specific. These results provide insight into the regional response of LV mechanics to β-adrenergic stimulation in rats and could act as a baseline for future studies on subclinical abnormalities associated with the inotropic response in heart disease.

High-Intensity Interval Training Improves Left Ventricular Contractile Function.

Improved myocardial contractility is a critical circulatory adaptation to exercise training. However, the types of exercise that enhance left ventricular (LV) contractile and diastolic functions have not yet been established. This study investigated how high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) influence LV mechanics during exercise. Fifty-four healthy sedentary men were randomized to engage in either HIIT (3-min intervals at 40% and 80% of V˙O2max, n = 18) or MICT (sustained 60% of V˙O2max, n = 18) for 30 min·d, 5 d·wk for 6 wk or to a control group (n = 18) that did not engage in exercise intervention. LV mechanics during semiupright bicycle exercise tests were measured by two-dimensional speckle-tracking echocardiography. Before the interventions, acute bicycle exercise increased (i) peak basal/apical radial and circumferential and peak longitudinal strains and strain rates, (ii) peak basal/apical rotations and torsion, and (iii) peak systolic twisting and early diastolic untwisting velocities in the LV. After the interventions, the HIIT group exhibited greater LV mass and diastolic internal diameter as well as higher ratio of E wave to A wave and early diastolic propagation velocity than did the MICT group. Despite decreased peak apical rotation and torsion, HIIT enhanced peak apical radial strain and strain rate as well as shortened the time to reach peak untwisting velocity in the LV during exercise. However, the LV mechanics during exercise were unchanged in the control group. HIIT but not MICT induces eccentric myocardial hypertrophy. Moreover, HIIT effectively improves the LV mechanics during exercise by increasing contractile and diastolic functions.

Left Ventricular Torsion Deformation in Atrial Septal Defect Patients Undergoing Transcatheter Device Closure

Introduction: Atrial septal defects (ASD) considered being one of the known congenital heart diseases. ASD causes increased volume overload of the right heart. The purpose of this study was to evaluate left ventricular (LV) torsion deformation in ASD patients undergoing transcatheter device closure.Methods: All adult patients who underwent transcatheter device closure with ostium secundum ASD were included in the study. We assessed LV torsion in ostium secundum ASD patient’s pre and post device closure by using speckle tracking echocardiography.Results: A total of 37 patients (22 females and 15 males) were included in this study. The average age was 28 ± 19 years. LV peak basal rotation improved significantly (P = 0.028) in post transcatheter closure. LV torsion (2.88 ± 0.99˚/cm before vs. 3.40 ± 1.41˚/cm after closure, P = 0.009) and twisting (15.12 ± 4.69˚ before vs. 17.95 ± 6.21˚ after closure, P = 0.005) were statistically significant in post transcatheter closure. Volumetric assessment of LV including end-diastolic volume and systolic volume showed significant improvement (P = 0.02, P < 0.01) post device closure.Conclusions: The increased peak LV twisting and torsion was mainly attributed to the improved peak systolic clockwise rotation after ASD device closure. The LV twisting at a younger age was improved after the closure of ASD.

Speckle tracking imaging as a predictor of left ventricular remodeling 6 months after first anterior ST elevation myocardial infarction in patients managed by primary percutaneous coronary intervention.

Acute myocardial infarction (AMI) remains a leading cause of morbidity and mortality worldwide. LV remodeling is an important factor in the pathophysiology of advancing heart failure (HF).Aim of the workTo evaluate the value of speckle tracking imaging as a predictor of left ventricular remodeling 6 months after first anterior STEMI in patients managed by primary PCI.MethodologyEighty-five patients with first acute anterior STEMI underwent primary PCI. Patients were followed up for 6 months. Echocardiographywas done within 48 h [1] Standard transthoracic 2D echocardiographic examination: LV internal dimensions and volumes, Left Ventricular EF, and Wall Motion Score Index: [2] LV peak systolic global longitudinal strain and Torsion dynamics were assessed. Echocardiography was repeated at 6 months LV volumes and EF were calculated. LV remodeling was defined as an increase in LV EDV ≥ 20% 6 months after infarction as compared to baseline data. Patients were then classified into Group I: did not develop LV remodeling. Group II: developed LV remodeling. Both groups were studied to determine predictors of LV remodeling.ResultsAt baseline echocardiographic evaluation there was no statistically significant difference between both groups regarding both LVEDD and LVEDV, while there was statistically significant increase in both LV ESD and LV ESV, with statistically significant lower Ejection Fraction, in LV remodeling group. There was also statistically significant higher LV peak systolic GLS values in LV remodeling group, the best cut-off value was >−12.5 (Sensitivity 87%, Specificity 85%) and LV torsion was also statistically significantly lower in the LV remodeling group, with the best cut-off value for LV torsion was <9.5°, [Sensitivity 91%, Specificity 85%].Independent predictors of LV remodeling after AMI: baseline WMSI > 1.8, baseline LV EF < 40, GLS > −12.5%, LV torsion < 9.5°, CK-MB > 500 U/L, baseline Thrombus grade > 4 and total ischemic time.ConclusionAverage peak systolic GLS and LV torsion at echocardiography done early after myocardial infarction are independent predictors of LV remodeling after anterior STEMI and can be used to predict occurrence of LV remodeling after 6 months.

Automated three-dimensional tracking of the left ventricular myocardium in time-resolved and dose-modulated cardiac CT images using deformable image registration

BackgroundAssessment of myocardial deformation from time-resolved cardiac computed tomography (4D CT) would augment the already available functional information from such an examination without incurring any additional costs. A deformable image registration (DIR) based approach is proposed to allow fast and automatic myocardial tracking in clinical 4D CT images. MethodsLeft ventricular myocardial tissue displacement through a cardiac cycle was tracked using a B-spline transformation based DIR. Gradient of such displacements allowed Lagrangian strain estimation with respect to end-diastole in clinical 4D CT data from ten subjects with suspected coronary artery disease. Dice similarity coefficient (DSC), point-to-curve error (PTC), and tracking error were used to assess the tracking accuracy. Wilcoxon signed rank test provided significance of tracking errors. Topology preservation was verified using Jacobian of the deformation. Reliability of estimated strains and torsion (normalized twist angle) was tested in subjects with normal function by comparing them with normal strain in the literature. ResultsComparison with manual tracking showed high accuracy (DSC: 0.99±0.05; PTC: 0.56mm±0.47 mm) and resulted in determinant(Jacobian)>0 for all subjects, indicating preservation of topology. Average radial (0.13 mm), angular (0.64) and longitudinal (0.10 mm) tracking errors for the entire cohort were not significant (p > 0.9). For patients with normal function, average strain [circumferential, radial, longitudinal] and peak torsion estimates were: [-23.5%, 31.1%, −17.2%] and 7.22°, respectively. These estimates were in conformity with the reported normal ranges in the existing literature. ConclusionsAccurate wall deformation tracking and subsequent strain estimation are feasible with the proposed method using only routine time-resolved 3D cardiac CT.

Improvement of continuous subcutaneous insulin infusion on patients with type 2 diabetes mellitus by 3-dimensional speckle tracking echocardiography.

Three-dimensional speckle tracking echocardiography (3D-STE) was used to evaluate the improvement of continuous subcutaneous insulin infusion on the left ventricular (LV) systolic function of patients with type 2 diabetes mellitu (T2DM). We recruited T2DM patients (38 cases, diabetic group) and healthy volunteers (35 cases, control group) to collect LV full volume imaging. TomTec software was used for calculating LV global longitudinal strain (LVGLS), global circumferential strain (LVGCS), peak twist (LVTW), peak apical rotation (LVPAR), ejection fraction (LVEF), and torsion (LVT). All indices were re-tested 2weeks later after intensive treatment of insulin pump. LVGLS, LVGCS, LVTW and LVPAR in diabetic group were significantly decreased than control group. LVGLS and LVGCS in pre-treatment diabetic group were significantly increased than post-treatment. LVGLS, LVGCS, LVTW and LVPAR had correlations among control, pre-treatment and post-treatment diabetic groups. There were no significant differences in LVEDV, LVESV, LVEF, LVT and R-R. LV systolic function of patients with T2DM complicated with microangiopathy was improved after treatment of continuous subcutaneous insulin infusion. In addition, therapeutic effect could be accurately evaluated by 3D-STE which had vital clinical application.

Left Ventricular Rotational and Twist Mechanics in the Human Fetal Heart

The authors investigated left ventricular (LV) rotational indices, twist, and torsion in a large cohort of fetuses using two-dimensional speckle-tracking echocardiography. Pregnant women (N=102) were prospectively recruited for fetal two-dimensional speckle-tracking echocardiography. Because of variable fetal position, ventricular orientation was established using the location of the liver and LV position in relation to the right ventricle. Twist measurements required correction to account for fetal position, reconciling directionality across all fetal orientations. Peak apical and basal rotations, global longitudinal strain, global circumferential strain (GCS), longitudinal strain rate, circumferential strain rate (CSR), twist, and torsion were reported and tested for associations with gestational age (GA) and estimated fetal weight (EFW). Measurement of rotational indices was feasible in 175 examinations (73%). The mean maternal age was 31±6years, the mean GA 24±6weeks, and the EFW 1.0±1.0kg. Mean peak apical rotation, basal rotation, twist, and torsion were 9.5±2.0°, -4.4±1.1°, 13.1±2.3°, and 7.9±3.4°/cm, respectively. Mean global longitudinal strain, GCS, longitudinal strain rate, and CSR were -22.3±4.3%, -25.0±6.1%, -1.4±0.5sec-1, and -1.6±0.5sec-1, respectively. Absolute GCS, CSR, apical rotation, and twist declined moderately with GA and EFW (P<.05). There were strong negative nonlinear correlations of torsion with GA and EFW: torsion=1,104×GA-1.591 (r2=0.760, P<.001); torsion=115.88×EFW-0.427 (r2=0.772, P<.001). Determination of fetal LV rotational mechanics is feasible and reproducible using two-dimensional speckle-tracking echocardiography. Basal rotation, longitudinal strain, and strain rate vary little with EFW and GA. Interpretation of LV apical rotation, twist, torsion, GCS, and CSR, however, must take GA or EFW into account. These data form the basis for comparison with findings in fetuses with abnormal cardiacanatomy and function.

Blade tip vortex measurements on actively twisted rotor blades

Active rotor control concepts, such as active twist actuation, have the potential to effectively reduce the noise and vibrations of helicopter rotors. The present study focuses on the experimental investigation of active twist for the reduction of blade–vortex interaction (BVI) effects on a model rotor. Results of a large-scale smart-twisting active rotor test under hover conditions are described. This test investigated the effects of individual blade twist control on the blade tip vortices. The rotor blades were actuated with peak torsion amplitudes of up to $$2^\circ$$ and harmonic frequencies of 1–5/rev with different phase angles. Time-resolved stereoscopic particle image velocimetry was carried out to study the effects of active twist on the strength and trajectories of the tip vortices between $$\psi _\text {v}= 3.6^\circ$$ and $$45.7^\circ$$ of vortex age. The analysis of the vortex trajectories revealed that the 1/rev active twist actuation mainly caused a vertical deflection of the blade tip and the corresponding vortex trajectories of up to $$1.3\%$$ of the rotor radius R above and $$-1\%R$$ below the unactuated condition. An actuation with frequencies of 2 and 3/rev significantly affected the shapes of the vortex trajectories and caused negative vertical displacements of the vortices relative to the unactuated case of up to $$2\%R$$ within the first $$35^\circ$$ of wake age. The 2 and 3/rev actuation also had the most significant effects on the vortex strength and altered the initial peak swirl velocity by up to $$-34$$ and $$+31\%$$ relative to the unactuated value. The present aerodynamic investigation reveals a high control authority of the active twist actuation on the strength and trajectories of the trailing blade tip vortices. The magnitude of the evoked changes indicates that the active twist actuation constitutes an effective measure for the mitigation of BVI-induced noise on helicopters.