bluuebunny/crossref_metadata_2025 huggingface dataset:
Geochemical factors affecting the solubility of copper in seawater
Authors: Angel Brad M. , Apte Simon C. , Batley Graeme E. , Raven Mark
Published: November 2020

Environmental contextMany trace metals, including copper, are only sparingly soluble in seawater and may exist in both dissolved and particulate forms (e.g. as precipitates). Aquatic organisms may experience different toxic effects from exposure to dissolved and particulate trace metals. This study investigates how concentration, reaction time and changes to precipitate composition/mineral formation affect copper solubility in seawater, thus influencing metal bioavailability and toxicity in the field and laboratory.
AbstractA lack of knowledge on the solubility of metals such as copper affects the ability to predict the forms (dissolved and particulate) that organisms are exposed to in field and laboratory waters. Laboratory tests were conducted where copper (total concentrations of 0.5 to 20mg L−1) was added to natural and artificial seawater (pH 8.15, 22°C), equilibrated for 28 days and dissolved copper monitored at periodic intervals. At 0.5mg L−1, dissolved copper concentrations remained stable over 28 days and no precipitates were detected. However, at higher total copper concentrations, an initial rapid precipitation phase was followed by the establishment of a metastable equilibrium that persisted for periods of days to weeks, and whose solubility concentrations and duration were influenced by the total copper concentration and typically in the range 0.6 to 0.9mg L−1. After 5 to 15 days, a step change decrease in dissolved copper concentration followed by a slow decline was observed in the >2mg L−1 total copper treatments. The minimum solubility measured after 28 days was 0.053mg L−1. Elemental and X-ray diffraction analyses indicated that the copper precipitates comprised similar proportions of amorphous copper hydroxycarbonate and amorphous dicopper trihydroxide chloride after 1 day and transformed to predominantly mineralised dicopper trihydroxide chloride in the clinoatacamite polymorph form after 28 days. These observations have particular relevance for toxicity tests of less sensitive organisms and highlight the need to consider metal solubility, exposure to precipitates and changes in precipitate mineral phases.
Shelf–oceanic dynamics of surface environmental parameters in the Kangaroo Island–Bonney Coast region
Authors: Foo Dahlia , McMahon Clive , Hindell Mark , Goldsworthy Simon
Published: November 2020

The shelf and oceanic waters of the Kangaroo Island–Bonney Coast region are important foraging habitats for top marine predators in the ecosystem; however, the dynamics between the two distinct water types have not been investigated. This study examined the spatial and temporal variability of oceanographic parameters in the southern waters of Australia (36–43°S, 136–141°E) associated with the Bonney Upwelling (shelf) and subtropical front (STF; oceanic). Using satellite data from 1997 to 2016, we found that productive oceanic waters were associated with the STF and eddy activity; they were generally furthest from the shelf break in spring–summer (upwelling season on the shelf) and closest to the shelf break in winter–autumn (downwelling season on the shelf). Inter-annual variabilities of chlorophyll-a concentration (Chl-a), sea-surface temperature and sea surface-height anomaly were generally higher in summer than in winter for both shelf and oceanic waters. El Niño–Southern Oscillation, Southern Annular Mode and Indian Ocean Dipole were cross-correlated with anomalous shelf and oceanic Chl-a at various lagged times (range=15–0 months). This study provides a regional perspective of the spatial and temporal oceanographic variability in southern Australian waters, which may help with understanding apex-predator ecology in the ecosystem.
Association of the vertical and horizontal force‐velocity profile and acceleration with change of direction ability in various sports
Authors: Baena‐Raya Andrés , Soriano‐Maldonado Alberto , Conceição Filipe , Jiménez‐Reyes Pedro , Rodríguez‐Pérez Manuel A.
Published: November 2020

This study aimed to assess the association of the mechanical variables derived from the force‐velocity (FV) profile (i.e. theoretical maximal force [F 0], velocity [V 0] and maximal power output [P max]) with change of direction (COD) performance in soccer, basketball and tennis players. Fifty‐four male athletes (soccer n = 23; tennis n = 16; basketball n = 15) were assessed for the vertical (Vrt) and horizontal (Hzt) FV profiles, COD with the dominant (D) and nondominant (ND) legs, using the modified 505 test, and sprint. Hzt FV profile parameters showed stronger associations with performance than Vrt FV profile in the three sports. Specifically, the Hzt parameter most strongly associated with COD performance was F 0 in tennis (r = −0.83; p<0.001) and P max in soccer and basketball (r = −0.79; p<0.001). Associations between sprint times and COD test ranged from (r = 0.73–0.82) in soccer players, (r = 0.74–0.87) in tennis players and (r = 0.62–0.85) in basketball players, respectively (p<0.05). Considering the whole sample and the random effect of the type of sports, an improvement in sprint acceleration (i.e. one N/kg increase in F 0 and one W/kg in P max) was associated with −0.15 s and −0.04 s to complete the 505 test, respectively. In conclusion, our results suggest the potential usefulness of assessing the Hzt FV profile to maximize acceleration capabilities through training interventions which, in turn, may translate into improved COD performance. However, further longitudinal and experimental research is needed to confirm this hypothesis.
Reviving non-minimal Horndeski-like theories after GW170817: kinetic coupling corrected Einstein–Gauss–Bonnet inflation
Authors: Oikonomou V K , Fronimos F P
Published: November 2020

After the recent GW170817 event of the two neutron stars merging, many string corrected cosmological theories confronted the non-viability peril. This was due to the fact that most of these theories produce massive gravitons primordially. Among these theories were the ones containing a non-minimal kinetic coupling correction term in the Lagrangian. In this work we demonstrate how these theories may be revived and we show how these theories can produce primordial gravitational waves with speed

c

T

2

=
1

in natural units, thus complying with the GW170817 event. As we show, if the gravitational action of an Einstein–Gauss–Bonnet theory also contains a kinetic coupling of the form ∼ξ(ϕ)G

μν
∂
μ

ϕ∂
ν

ϕ, the condition of having primordial massless gravitons, or equivalently primordial gravitational waves with speed

c

T

2

=
1

in natural units, results to certain conditions on the scalar field dependent coupling function of the Gauss–Bonnet term, which is also the non-minimal coupling of the kinetic coupling. We extensively study the phenomenological implications of such a theory focussing on the inflationary era, by only assuming slow-roll dynamics for the scalar field. Accordingly, we briefly study the case that the scalar field evolves in a constant-roll way. By using some illustrative examples, we demonstrate that the viability of the theoretical framework at hand may easily be achieved. Also, theories containing terms of the form ∼ξ(ϕ) □ ϕg

μν
∂
μ

ϕ∂
ν

ϕ and

∼
ξ

(

ϕ

)

g

μ
ν

∂

μ

ϕ

∂

ν

ϕ

2

are also lead to the same gravitational wave speed as the theory we shall study in this paper, so this covers a larger class of Horndeski theories.
Thermodynamic identities with sunray diagrams
Authors: Kim Joon-Hwi , Nam Juno
Published: November 2020

One of the hurdles in teaching undergraduate thermodynamics is a plethora of complicated partial derivative identities. Students suffer from difficulties in deriving, justifying, or interpreting the identities, misconceptions about partial derivatives, and a lack of in-depth understanding of the meanings of identities. We propose a novel diagrammatic method for the calculus of differentials and partial derivatives called the ‘sunray diagram’ that resolves the difficulties above. The sunray diagram technique relates a partial derivative with ‘arrow sliding’, which enables an aesthetic and intuitive manipulation of partial derivative expressions in the form of successive arrow slidings. Furthermore, the sunray diagram is more than an ad hoc or abstract machinery but is based on the symplectic structure of thermodynamics; the sunray diagram admits a direct physical interpretation on the P–V (or T–S) plane. We elaborate on such physical semantics of the sunray diagram by taking Maxwell’s approach to the geometry of thermodynamic structures—reinterpreted in terms of differential geometry—as a reference point. We anticipate that our discussion introduces the geometry of thermodynamics to learners and enriches the graphical pedagogy in physics education.
Oscillatory magnetic fields for neutron resonance spin-echo spectroscopy
Authors: Jochum J K , Hecht A , Soltwedel O , Fuchs C , Frank J , Faulhaber E , Leiner J C , Pfleiderer C , Franz C
Published: November 2020

The generation of high frequency oscillatory magnetic fields represents a fundamental component underlying the successful implementation of neutron resonant spin-echo spectrometers, a class of instrumentation critical for the high-resolution extraction of dynamical excitations (structural and magnetic) in materials. In this paper, the setup of the resonant circuits at the longitudinal resonant spin-echo spectrometer RESEDA is described in comprehensive technical detail. We demonstrate that these circuits are capable of functioning at frequencies up to 3.6 MHz and over a broad bandwidth down to 35 kHz using a combination of signal generators, amplifiers, impedance matching transformers, and a carefully designed cascade of tunable capacitors and customized coils.
A comparative study on atomic transport properties of liquid less-simple metals
Authors: Gosh R C , Bin Noor Sohrab , Mohaiminul Islam M A
Published: November 2020

We have studied the atomic transport properties of liquid less-simple metals namely Bi, Cd, Pb, Sb, Sn and Tl using universal scaling laws and hard sphere (HS) theories of liquid. Effective interionic interaction in metals has been derived from both Brettonet–Silbert (BS) and Ashcroft’s empty core pseudopotential models. For structure calculation, variational modified hypernetted chain integral equation theory has been considered. Excess entropy and effective HS diameter are the basic ingredients of the study. Obtained ingredients are found to be close with experimental data than any other available literature values when BS model has been chosen. Comparing with experimental data, obtained results for transport coefficients suggest that Faber’s HS theory is excellent for diffusion coefficient and is reasonably good for viscosity coefficient along with BS pseudopotential than any other combinations employed in this study. The probable reason may be the hybridization of s and d electrons exists in the concerned systems.
On the stability and stationarity of the Super H-mode combined with an ion transport barrier in the core
Authors: Knolker M , Evans T E , Snyder P B , Grierson B , Hanson J , Jaervinen A , Jian X , McClenaghan J , Osborne T , Paz-Soldan C , Solomon W , Wilks T
Published: November 2020

The Super H-mode, a regime with high pedestal pressure and stored energy, is explored on DIII-D and combined with an ion transport barrier in the plasma core to increase performance. A significant improvement of ion temperatures and confinement is facilitated by favorable conditions such as high rotational shear and high ion pedestal temperatures. As a result of a rise in density and simultaneous decrease in rotation, the ion transport barrier disappears during the discharge evolution, leading to a transition from a very high confinement state at early times, to a reduced but still high confinement phase. Additionally, in many discharges, a global magnetohydrodynamic (MHD) event consistent with the coupling of a destabilized internal mode to an edge localized mode causes a large energy loss and leads to a reorganization of the plasma into a lower temperature, higher density state. Depending on the magnitude of the global MHD event, the plasma edge collisionality can increase significantly and shift the operational boundary from the peeling to the ballooning side, which can be understood as a drop out of the Super H-mode channel into standard H-mode. Hence, in Super H-mode discharges with ion transport barriers, both the improved pedestal height and rotational shear contribute to the high stored energy. At very low levels of rotation, the confinement factor for SH modes is still expected to exceed standard H-mode by 20%–30%. With their overall stationarity and high-performance levels, Super H-mode discharges provide an attractive regime for ITER and may enable a more compact design of future fusion power plants.
A comparative study on GaSb epilayers grown on nominal and vicinal Si(100) substrates by molecular beam epitaxy
Authors: Arpapay Burcu , Suyolcu Y Eren , Çorapçıoğlu Gülcan , van Aken Peter A , Gülgün Mehmet Ali , Serincan Uğur
Published: November 2020

The direct growth of GaSb buffer layers on Si substrates is attracting considerable interest in the integration of group III-Sb based device structures on lower-cost Si substrates. Here, we present the effect of various growth steps on the defect types and defect density that are crucial for advancing high crystal quality GaSb buffer layer on nominal/vicinal Si substrate. As a growth step, the applied thermal annealing at an intermediate step provided a decrease in the threading dislocation (TD) density down to 1.72 × 108 cm−2, indicating a more effective method compared to post-growth annealing. Additionally, the importance of period number and position of GaSb/AlSb superlattice layers inserted in GaSb epilayers is demonstrated. In the case of the GaSb epilayers grown on vicinal substrates, the APB density as low as 0.06 µm−1 and TD density of 1.98 × 108 cm−2 were obtained for the sample grown on 4° miscut Si(100) substrate.
Sideways force due to coupled rotating kink modes in tokamaks
Authors: Pustovitov V.D. , Rubinacci G. , Villone F.
Published: November 2020

The possibility of generation of the rotating sideways force on the wall by the kink modes is analytically investigated. The approach is basically the same as that developed earlier in (Mironov and Pustovitov 2017 Phys. Plasmas
24 092508) for the locked modes, but now their rotation is allowed. Its main elements are ∂b/∂t ≠ 0 (described by the growth rate γ and angular rotation frequency ω of the magnetic perturbation b), resistive dissipation in the wall, and the requirement of zero sideways force on the plasma. These make the approach greatly different from those resulting in the so-called Noll’s formula. The result is also different; it predicts a force an order of magnitude smaller. Nevertheless, such a force can be dangerous at the resonance frequency of the vacuum vessel. The derived relations show that the rotating force must be maximal at ωτ
w = O(1), where τ
w is the resistive wall time. For the faster modes it decreases roughly as ∼1/ω.
Assessment of Risks Associated With Severe Acute Respiratory Syndrome Coronavirus 2 Experimental Human Infection Studies
Authors: Kuiper Vincent P , Rosendaal Frits R , Kamerling Ingrid M C , Visser Leonardus G , Roestenberg Meta
Published: November 2020

Controlled human infection (CHI) models for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been proposed as a tool to accelerate the development of vaccines and drugs. Such models carry inherent risks. Participants may develop severe disease or complications after deliberate infection. Prolonged isolation may negatively impact their well-being. Through secondary infection of study personnel or participant household contacts, the experimental virus strain may cause a community outbreak. We identified risks associated with such a SARS-CoV-2 CHI model and assessed their likelihood and impact and propose strategies that mitigate these risks. In this report, we show that risks can be minimized with proper risk mitigation strategies; the residual risk, however, should be weighed carefully against the scientific and social values of such a CHI model.
Coronary computed tomography versus stress echocardiography-guided management of stable chest pain patients: a propensity matched analysis
Authors: Vamvakidou A , Danylenko O , Pradhan J , Kelshiker M , Jones T , Whiteside D , Sethi A , Senior R
Published: November 2020

Background

Recent recommendations by national and international societies advocate the use of coronary computed tomography (CCT) as the first-line test for the assessment of low-risk patients with suspected stable angina. However limited real-life data exist regarding its relative clinical value versus stress echocardiography (SE)-guided management.

Purpose

We aimed to assess in a real-life setting the clinical value of stress echocardiography (SE)-guided versus CCT-guided management in patients presenting with stable chest pain and no prior history of coronary artery disease (CAD).

Methods

We compared the relative feasibility, efficacy and the proportion of patients undergoing downstream testing including revascularisation and their impact on outcome (mortality and myocardial infarction) when CCT versus SE were used as the first line test for the assessment of stable chest pain.

Of the patients who underwent CCT (N=2192) or SE (N=2081) between October 2013 and October 2014 only those with suspected stable angina and without previous CAD were selected. The population was propensity-matched (total 1980 patients-990 patients each group) to account for differences in the baseline cardiovascular risk factors.

Results

The mean age of the population was 59±13.2 years and 949 (47.9%) patients were male. Inconclusive tests were 6% versus 3% (p<0.005) in CCT versus SE. Severe (>70%) luminal stenosis on CCT and inducible ischemia on SE detected obstructive CAD by invasive coronary angiography in 63% versus 57% patients (p=0.33). Over the entire follow-up period (median 717 (IQR 93–1069) days) significantly more patients underwent invasive coronary angiography (21.5% versus 7.3%, p<0.005) and revascularisation (33.5% versus 3.5%, p<0.005) respectively in the CCT versus the SE group. Following their initial assessment 336 (33.9%) patients in the CCT and 86 (8.7%) in the SE group underwent further functional testing (SE, stress cardiac MRI, exercise electrocardiography) (p<0.005) (Figure 1A). There was no difference in all-cause mortality (p=0.26) or death and myocardial infarction (p=0.16) between the two groups (Figure 1B).

Conclusions

SE when used for the assessment of patients with stable angina and no prior CAD resulted in more conclusive tests, similar detection of obstructive CAD, less overall invasive coronary angiography and revascularization and less subsequent functional tests compared with CCT.

Figure 1

Funding Acknowledgement

Type of funding source: None
The distribution and relationship between 3D LVEF and 3D strain in a general population
Authors: Ericsson F , Tayal B , Zaremba T , Schnohr P , Jensen G , Mogelvang R , Soegaard P
Published: November 2020

Introduction

Three-dimensional (3D) echocardiography (3DE) is currently extensively used to estimate left ventricle (LV) morphology and heart valves. However, it is underutilized in the assessment of LV function. Most likely, it is due to limited knowledge of the normal reference intervals. In order to fill this knowledge gap, studies which investigates the 3DE reference ranges in a larger cohort of a general population are needed. The objective of the current study was to study the relationship and distribution of 3D LV ejection fraction (EF) and its corresponding strain values in subjects enrolled in Copenhagen City Heart Study (CCHS).

Methods

The echocardiograms were acquired from CCHS subjects from 2011–2014 by using GE Vivid E9 (GE Medical, Copenhagen, Denmark), during four consecutive heart beats. Exclusion critera were missing data or measurements in 3D, poor image quality or frame rate (<12 fps) and, based on visual evaluation of the echocardiograms, inappropriate tracking of three or more myocardial segments in the strain analysis. The echocardiograms were analysed in 2019 on EchoPacTM v. 201 (GE Medical, Copenhagen, Denmark).

Results are presented in means, interquartile ranges (IQR) and as adjusted correlation values (r2). R2 values equal to or above 0.64 (equals to r=0.8) were considered as strong correlation. LV function parameters included were LVEF, global longitudinal strain (GLS), global circumferential strain (GCS) and area strain (AS). LVEF and strain results are presented as percentages (%). The distribution and relationship between 3D LVEF, GLS, GCS and AS are visualized as scatter plots and box-whiskers plots. The statistical analysis and the visualisation of the data was performed in RStudio v. 3.5.1. P-values <0.005 were considered as markers for statistical significance.

Results

There were 2955 subject with available 3DEs in CCHS among which 1202 subjects had sufficient image quality for evaluation. The mean 3D LVEF was 54.6% (IQR: 50–60%), 3D GLS −14.5% (IQR: −13 to −16), 3D GCS −13.4% (IQR: −11 to −15) and AS −24.7% (IQR: −22 to −27).

The adjusted correlation values between LVEF with strain parameters were: 0.04 (GLS), 0.37 (GCS) and 0.26 (AS), which was poor.

Conclusion

This study provides valuable data of the distribution of 3D LVEF and its corresponding 3D strain values in a general population. The 3D strain values are lower than the reference interval described in literature for two-dimensional echocardiography. Moreover, correlation was also found to be poor between LVEF and different strain parameters.

3D LVEF vs. 3D Strain (GLS, GCS, AS)

Funding Acknowledgement

Type of funding source: None
Non-invasive assessment of right ventriculo-arterial coupling in dilated cardiomyopathy – insights from 3D echocardiography
Authors: Vijiiac A.E , Guzu C , Scarlatescu A , Onciul S , Iancovici S , Petre I , Zamfir D , Pascal A.M , Onut R , Stoian M , Dorobantu M
Published: November 2020

Background

Right ventricular-pulmonary artery coupling (RVPAC) reflects the mechanical efficiency of the interaction between the right ventricle (RV) and the pulmonary circulation unit. Although it has been traditionally assessed with right heart catheterisation (RHC), modern imaging techniques enable the non-invasive estimation of the RVPAC, which proved to correlate well with measurements derived from RHC.

Methods

We used three-dimensional (3D) echocardiography to study 88 consecutive patients (60.4±13.4 years, 69 men) with dilated cardiomyopathy (DCM) and left ventricular ejection fraction<40% and we measured the RV volumes and RV ejection fraction (RVEF) using dedicated software. 15 healthy individuals served as controls. RVPAC was estimated non-invasively as the ratio between the RV end-systolic volume and stroke volume. Right-sided heart failure was defined as either elevated jugular venous pressure, pedal oedema or congestive hepatomegaly.

Results

Patients with DCM showed larger RV end-diastolic volume (163±60.9 ml vs. 91.3±13.2 ml; p<0.0001), as well as larger RV end-systolic volume (97.3±43.2 ml vs. 39.8±7.2 ml; p<0.0001) than healthy controls. The patients in the study group showed lower RVEF: 41.5±8.5% vs. 56.5±3.6% (p<0.0001). Non-invasive RVPAC was 1.53±0.60 in DCM patients vs. 0.78±0.11 in controls (p<0.0001). RVPAC had an excellent negative correlation with RVEF, both in DCM patients (r=−0.96, p<0.0001) and in controls (r=−0.99, p<0.0001). Patients with no signs of right-sided heart failure had lower RVPAC (1.38±0.45) than patients with at least one sign of right heart failure (1.90±0.72, p=0.03). Patients with mild symptoms of heart failure (NYHA classes 1 or 2) showed lower RVPAC (1.37±0.48) than DCM patients with severe heart failure (NYHA classes 3 or 4): 1.79±0.68 (p=0.003).

Conclusions

3D echocardiography provides useful insights in the functional assessment of the cardiopulmonary unit. Non-invasive RVPAC is impaired in patients with DCM, and it is more impaired when signs of right-sided heart failure are present. Severe symptoms are associated with more pronounced decoupling of the RV and the pulmonary circulation. The prognostic significance of non-invasive RVPAC in a disease primarily involving the left ventricle remains to be clarified.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): This work was supported by CREDO Project - ID: 49182, financed through the SOP IEC -A2-0.2.2.1-2013-1 cofinanced by the ERDF
Mechanical systolic dyssynchrony assessed with 3-D echocardiography and its association with global strain
Authors: Espinola-Zavaleta N.G , Antonio-Villa N.E , Garcia-Diaz J.A , Escudero-Salamanca M , Alvarez-Santana R , Alexanderson-Rosas E
Published: November 2020

Background

The evaluation of global longitudinal strain using 2-D velocity vector imaging, is an accurate automatized tool for assessment of ventricular function, nevertheless its correlation with systolic synchrony by 3D echocardiography, remains unclear.

Aims

To evaluate the correlation between global longitudinal strain and systolic synchrony index (SSI). In addition, identify which ventricle has the global longitudinal strain with the best odds ratio for detecting systolic dyssynchrony (SSI ≥6.0 ms).

Methods

We evaluate left (LV-GS, LA-GS) and right (RV-GS; RA-GS) global longitudinal strain using automatized 2-D velocity vector imaging. SSI was measured using 17 segments according to guidelines.

Results

We included 420 subjects. Characteristics of study population are presented in table 1. We found a positive and significant correlation with LV-GS (r=0.152, 95% CI: 0.052–0.247), RV-GS (r=0.119, 95% CI: 0.02–0.215), LA-GS (r=0.160, 95% CI: 0.290,0.212) and RA-GS (r=0.249, 95% CI: 0.355,-0.136) (Figure 1). Decreased values of RV-GS (OR: 1.06, 95% CI: 1.01–1.10) had the better association with mechanical systolic dyssynchrony after adjusted for covariates.

Conclusion

Automated measurement of the global longitudinal deformation of the left and right chambers correlates with the systolic synchrony index. The quantification of RV-GS could be an ideal tool to detect systolic dyssynchrony using an automated approach

Funding Acknowledgement

Type of funding source: None
Hemodynamic heterogeneity of inadequate cardiac output increase identified by 2-dimensional volumetric exercise echocardiography: slow, stiff or weak heart?
Authors: Bombardini T , Zagatina A , Ciampi Q , Cortigiani L , D'Andrea A , Borguezan Daros C , Zhuravskaya N , Wierzbowska-Drabik K , Kasprzak J.D , De Castro E Silva Pretto J.L , Djordjevic-Dikic A , Beleslin B , Ostojic M , Kovacevic-Preradovic T , Picano E
Published: November 2020

Background

Two-dimensional (2-D) volumetric exercise stress echocardiography (ESE) provides an integrated view of preload reserve through end-diastolic volume (EDV) and left ventricular contractile reserve (LVCR) through end-systolic volume (ESV) changes.

Purpose

To assess the dependence of stroke volume (SV) and cardiac output (CO) upon LVCR EDV changes and heart rate (HR) during ESE.

Methods

We prospectively performed semi-supine bicycle or treadmill ESE in 1,344 patients (age 59.8±11.4 years; 550 female; ejection fraction = 62.5±8%) referred for known or suspected coronary artery disease in 20 quality controlled laboratories of 16 countries from 2016 to 2019. SV was calculated at rest and peak stress from raw measurement of LV EDV and ESV by biplane Simpson rule, 2-D echo. LVCR was the stress-rest ratio of force (systolic blood pressure by cuff sphygmomanometer/ESV, abnormal values <2.0 identify a “weak” heart). Preload reserve was defined by an increase in LV EDV. Abnormal values (lack of EDV increase, peak EDV ≤ rest EDV) identify a “stiff” heart. Cardiac output was calculated as SV * HR (measured with standard EKG). HR reserve (stress/rest ratio) <1.85 identifies a “slow” heart with chronotropic incompetence.

Results

By selection, all patients had negative SE by wall motion criteria. Of the 1,344 patients included in the study, 448 belonged to the lowest tertile of CO increase. Of them 326 (73%) achieved HR reserve <1.85; 220 (49%) had a blunted LVCR and 374 (83%) a reduction of preload reserve, with 348 patients (78%) showing ≥2 abnormalities. The more the abnormal criteria, the worse the CO response, which was lowest in slow, stiff and weak hearts: see figure.

Conclusion

Patients with normal CO reserve during exercise usually have a fast, compliant and strong heart. Abnormal CO reserve is associated with heterogeneous hemodynamic responses, with slow, stiff and/or weak hearts. The clarification of underlying hemodynamic heterogeneity is the prerequisite for a personalized treatment, and can be easily extracted from a standard 2-D volumetric SE. Hearts with normal CO are all alike; every heart with abnormal CO is abnormal in its own way.

CO % changes in subsets (*p<0.001)

Funding Acknowledgement

Type of funding source: None
Better diastolic function in CRT candidates is associated with improved survival after CRT implantation
Authors: Galli E , Smiseth O.A , Aalen J , Duchenne J , Larsen C , Sade E , Hubert A , Anilkumar S , Penicka M , Hernandez A , Leclercq C , Voigt J.-U , Donal E
Published: November 2020

Background

The relationship between diastolic dysfunction (DD) and outcome after CRT is debated.

Purpose

Purpose of this study was to evaluate the role of DD in predicting all-cause mortality in heart failure patients undergoing CRT.

Methods

One-hundred ninety-three patients (age: 67±11 years, QRS width: 167±21 ms, LVEF 28±8%) were included in this multicentre prospective study. Mitral filling pattern, mitral tissue Doppler velocity, tricuspid regurgitation velocity, and indexed left atrial volume were used to classify DD from grade I to III according to the 2016 recommendations of the American Society of Echocardiography/European Association of Cardiovascular Imaging. A reduction of LV end-systolic volume >15% at 6-month follow-up (FU) identified CRT-responders and was observed in 132 (68%) patients.

Results

During a median 35 months FU, 29 (15%) patients died. Through multivariable analysis, coronary artery disease, NYHA functional class and grade I DD were shown to be independent predictors of prognosis (Table 1). Grade I DD was associated with a longer survival rate in both responders and non responders (Figure 1). Non responders with grade II-III DD had the worse outcome (HR 12.5 [3.56–44.04], p<0.0001).

Conclusions

Better diastolic function at baseline is associated with an improved survival after CRT implantation, independently of CRT-response.

Funding Acknowledgement

Type of funding source: None
Obstructive and restrictive ventilatory patterns are differentially associated with cardiac structure and function in late-life
Authors: Ramalho S , Claggett B.L , Kitzman D.W , Chang P.P , Cipriano Junior G , Solomon S.D , Skali H.L , Shah A.M
Published: November 2020

Background

Pulmonary and cardiac function both decline with age. However, few data exist regarding the associations of obstructive and restrictive spirometric patterns with cardiac structure and function in late-life.

Purpose

Determine the associations of reduced percent predicted forced vital capacity (ppFVC) and forced expired volume in 1 second (FEV1)/FVC with cardiac structure and function in late life.

Methods

In the Atherosclerosis Risk in Communities longitudinal cohort study, 3,854 heart failure free participants underwent echocardiography and spirometry at the fifth study visit (2011–2013). Relationships were examined using multivariable linear regression. Models adjusted for demographics and clinical risk factors (Table legend).

Results

Mean age was 75±5 years, 40% were male, 19% black, and 6% current smokers. Mean FEV1/FVC was 72±8, and ppFVC was 98±17%. In adjusted analyses, lower FEV1/FVC was associated with higher pulmonary arterial pressure (PASP) but not with measures of left ventricular (LV) structure or function (Table). In contrast, lower ppFVC, was associated with greater LV mass, worse LV strain, higher E/e' ratio, greater left atrial volume index, and higher PASP (all p<0.01; Table).

Conclusion

In late life, reductions in both FEV1/FVC and ppFVC are associated with higher pulmonary pressure, but only ppFVC was associated with worse LV structure and function.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): National Heart, Lung, and Blood Institute, National Institutes of Health, Department of Health and Human Services
New expectations for diastolic function assessment in TTE based on a semi-automated computing of strain-volume loops
Authors: Hubert A , Le Rolle V , Galli E , Bidaut A , Hernandez A.I , Donal E
Published: November 2020

Background

Early diagnosis of heart failure with preserved ejection fraction (HFpEF) by determination of diastolic dysfunction is challenging. Strain-volume loop (SVL) is a new tool to analyze left ventricular function.

Purpose

We propose a new semi-automated method to calculate SVL area and explore the added value of this index for diastolic function assessment.

Methods

50 patients (25 amyloidosis, 25 HFpEF) were included in the study and compared with 25 healthy control subjects. All patients underwent standard echocardiography. SVL area were also assessed.

Results

Left ventricular ejection fraction was preserved and similar between groups. Classical indices of diastolic function were pathological in HFpEF and amyloidosis groups with greater left atrial volume index, greater mitral average E/e' ratio, faster tricuspid regurgitation (p<0.0001 compared with controls). SVL analysis demonstrated a significant difference of the global area between groups, with the smaller area in amyloidosis group, the greater in controls and a mid-range value in HFpEF group (37 vs 120 vs 72 ml.%, respectively, p<0.0001) (Table 1). Applying a Linear Discriminant Analysis (LDA) classifier, results show a mean area under the curve (AUC) of 0.89 for the comparison between HFpEF and amyloidosis groups (Figure 1).

Conclusion

Strain-volume loops area is efficient to identify patients with a diastolic dysfunction. This new semi-automated tool is very promising for future development of automated diagnosis with machine-learning algorithms.

Figure 1

Funding Acknowledgement

Type of funding source: None
Assessment of left ventricular filling pressure: left atrial reservoir strain is an excellent replacement for missing tricuspid regurgitation velocity
Authors: Khan F , Inoue K , Remme E.W , Andersen O.S , Gude E , Skulstad H , Chetrit M , Garcia-Izquierdo Jaen E , Ha J.W , Klein A.L , Kikuchi S , Ohte N , Nagueh S.F , Smiseth O.A
Published: November 2020

Background

When evaluating left ventricular filling pressure (LVFP) according to current guidelines, tricuspid regurgitation (TR) velocity is often not available.

Purpose

In the present study we investigate if left atrial (LA) reservoir strain may be used instead of TR velocity for evaluation of LVFP.

Methods

We performed a prospective, multicenter, multinational and multivendor study in an all comer population of 322 patients with suspected heart failure or other cardiovascular disease where LVFP was measured by right- or left heart catheterization, as pulmonary capillary wedge pressure or pre-A LV diastolic pressure, respectively. Echocardiography was performed within 1 day of catheterization.

101 patients classified as special populations in the 2016 ASE/EACVI recommendations (i.e. non-cardiac pulmonary hypertension, atrial fibrillation, hypertrophic and restrictive cardiomyopathies) were excluded. Of the remaining 221 patients, 118 patients had EF ≥50% and 103 patients had EF <50%. Regression analysis was performed for LA reservoir strain and TR velocity against LVFP. LA reservoir strain at a cut-off value of <18% was applied instead of TR velocity in the 2016 ASE/EACVI algorithm and compared with the current algorithm.

Results

LA reservoir strain correlated better with LVFP than TR velocity, r=0.62 vs 0.40 (p<0.01) (Figure 1). When replacing TR velocity with LA reservoir strain, the feasibility of the ASE/EACVI 2016 algorithm increased from 91.8% to 98.1%. The accuracy of the algorithm was not significantly altered (80% vs 79%).

An accuracy of 80% for the algorithm is lower than what has been reported in earlier publications, this may be due to inclusion of patients without suspected heart failure and no assessment of clinical data, which in turn may have influenced the accuracy of the algorithm.

Conclusion

LA reservoir strain has better correlation to LVFP than TR velocity, and can be used in the ASE/EACVI 2016 algorithm for estimation of LVFP as a replacement when TR velocity is missing.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): South-Eastern Norway Regional Health Authority
Identification of the intermittent nature of trace mitral and/or aortic regurgitation: long-term longitudinal echocardiogram study in children with Dravet syndrome treated with fenfluramine
Authors: Agarwal A , Galer B , Wong P , Farfel G , Keane M.G , Lai W.W
Published: November 2020

Background

Previous studies have identified the presence of trace valvular regurgitation; however, these studies are typically cross-sectional assessments at a single point in time and provide no information regarding the natural history of trace aortic or mitral regurgitation (AR, MR). To our knowledge no study has assessed valve function in growing children with longitudinal echocardiogram (ECHO) assessments.

Purpose

To monitor cardiac valve function with regular, standardized ECHOs in patients with Dravet syndrome (DS) treated with fenfluramine for up to 3 years.

Methods

Patients with DS who completed either of two double-blind Phase 3 clinical trials were eligible to enroll in the open label extension (OLE) study. Patients were to be excluded from entry into the double-blind trials if they exhibited any degree of AR or MR, including trace; or pulmonary artery hypertension (PAH). However, trace MR or AR were not exclusion criteria for continuation into the OLE study. All patients had an ECHO prior to initiation of treatment in the double-blind study, after 6 to 8 weeks of treatment, and at the end of that study. In the OLE study, ECHOs were performed at study week 4, 5, or 6, and every 3 months thereafter. Valve morphology was also examined.

Results

As of September 1, 2019 a total of 330 patients had enrolled in the OLE study and received at least one dose of fenfluramine. The average age of patients at enrollment was 9.0±4.6 years, 27.6% were <6 years old, and 54.5% were male. The median duration of treatment with fenfluramine in the OLE study was 631 days (min, max; 7, 1086 days), and a total of 2,691 ECHOs had been performed. The point prevalence of trace MR was 10.6% at OLE study entry and ranged from 2.8% to 12.9% thereafter. All instances of trace MR were transient events that reverted to absent or oscillated between trace and absent at later study visits. Four patients demonstrated trace AR at one or more visits and all had reverted to absent at their most recent examination. No changes in valve morphology were observed.

Conclusions

In this long-term longitudinal ECHO study in DS children treated with fenfluramine, we identified that trace MR and AR were intermittent and not predictive of future valve disease. In all cases trace reverted to absent regurgitation at subsequent ECHOs. No valve morphological changes were seen. The intermittent and transient nature of trace regurgitation observed in this study is consistent with current ECHO guidelines, which consider trace regurgitation to be a normal physiologic phenomenon.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Zogenix, Inc.
Demographic characteristics, aortic valve intervention rates and all-cause mortality in 4 flow-gradient sub-types of severe aortic stenosis
Authors: Saeed S , Vamvakidou A , Yakupoglu H.Y , Senior R , Khattar R.S
Published: November 2020

Introduction

Severe aortic stenosis (AS), defined as aortic valve area (AVA) <1.0 cm2, can be divided into 4 categories based on flow status and mean gradient. Stroke volume index <35 ml/m2 has classically been used to define low flow, but recent data suggest that flow rate (FR) <200ml/sec may be a more accurate and robust marker of low flow.

Methods

We prospectively collected demographic, echocardiographic, aortic valve intervention (AVI) and all-cause mortality data on 1562 patients with symptomatic severe AS from 2010 to 2017 with a mean follow up period of 35±22 months. Patients were divided into 4 flow-gradient sub-groups based on a FR threshold of 200ml/s and mean pressure gradient of 40mmHg. Comparative analyses were performed among the 4 groups using analysis of variance.

Results

The prevalence of normal flow high gradient (NFHG) severe AS was 30%, NF low gradient (NFLG) 21%, low flow HG (LFHG) 18% and LFLG 31% (Table). Across these 4 sub-groups, there was a graded reduction in LVEF and FR, and an increase in age and all–cause mortality.

Conclusions

Classification of aortic stenosis based on flow-gradient patterns, shows important differences in the demographic profile and clinical outcome among the 4 groups. Classical NFHG AS was associated with the highest rate of AVI and lowest all-cause mortality compared to the 3 discordant flow-gradient subtypes. The LFLG group had the lowest AVI rates and worst outcome.

Funding Acknowledgement

Type of funding source: None
Flow rate and stroke volume index as predictors of mortality in patients undergoing transcatheter aortic valve implantation
Authors: Abdelrazek S , Hein M , Sopira M , Neumann F.-J , Jander N , Minners J
Published: November 2020

Background

Reduced flow rate and stroke volume are a common finding in patients with severe aortic stenosis. The aim of this study was to assess their impact on mortality in patients undergoing transcatheter aortic valve implantation (TAVI).

Methods

A total of 1080 patients with severe aortic stenosis who underwent TAVI between 2007 and 2017 were followed for a mean of 2.4±1.6 years. Patients were allocated into two groups according to flow rate (cut-off 200mL/s), 805 patients had a normal flow rate and 275 patients had reduced flow rate. Long-term survival was summarized using Kaplan-Meier curves and Cox-regression models.

Results

Patients with reduced flow rate were older (83.8±5.5 years; P<0.01) with more diabetics (36.7% P=0.02). Kaplan-Meier survival curves demonstrated inferior survival for patients with reduced flow rate (global log rank, P<0.01), Multivariable Cox-regression analysis (adjusted for age, creatinine, diabetes, hemoglobin and presence of atrial fibrillation) confirmed flow rate as an independent risk factor of all-cause mortality (HR: 0.998; 95%-CI: 0.997–0.999; P<0.01). Similar results were obtained for stroke volume index (SVI).

Conclusion

Patients with a reduced flow rate exhibit an increased mortality even after TAVI (similar to patients with reduced SVI) and should therefore be carefully evaluated in the heart-team.

PostTAVI survival according to flow rate

Funding Acknowledgement

Type of funding source: None
The prognostic value of novel myocardial deformation parameters for sudden events in hypertrophic cardiomyopathy
Authors: Zegkos T , Parcharidou D , Panagiotidis T , Ntelios D , Katranas S , Rouskas P , Vassilikos V , Karvounis H , Efthimiadis G
Published: November 2020

Background

Data about the implications of two-dimensional (2D) speckle tracking myocardial deformation parameter for predicting sudden arrhythmic events in hypertrophic cardiomyopathy (HCM) are limited.

Purpose

The aim of our study was to prospectively evaluate the predictive value of novel myocardial deformation parameters with regard to 2D speckle tracking echocardiography in patients with HCM.

Methods

This was a prospective study that included HCM patients without concomitant severe valvular heart disease, without prior myocardial infarction and with sinus rhythm at index evaluation. A total of 317 patients were screened and 67 subjects were excluded. Finally, the study sample consisted of 250 patients (mean age 50.8±15.8, 67.2% male). Global longitudinal strain (GLS), left atrial (LA) strain, radial strain, circumferential strain, and mechanical dispersion of the left ventricle ((MD)-the standard deviation of time to peak negative strain in 18 left ventricular segments) were examined. The primary outcome of the study was sudden arrhythmic events including sudden cardiac death, sustained ventricular tachycardia, resuscitated cardiac arrest and appropriate impantable cardioverter defibrillator discharges.

Results

During a mean follow-up of 2.4±1.2 years, 19 patients suffered a sudden arrhythmic event. GLS, LA strain, MD and radial strain significantly predicted sudden events among our cohort. The optimal cut-off values obtained from receiver-operator characteristic curves were for GLS >−14%, for LA strain <12%, for radial strain <21% and for MD >67ms. However, only GLS >−14% and LA strain <12% displayed a significant additive predictive value on top of the European Society Of Cardiology risk score (HCMRisk-SCD) (C statistic from 0.757 to 0.831, p=0.03 including GLS >−14% in the survival model and to 0.839, p=0.009 including LA strain <12% in the model). (Table)

Conclusion

GLS and LA strain conferred a significant additional prognostic value to HCMRisc-SCD score for predicting sudden arrhythmic events in HCM patients.

Funding Acknowledgement

Type of funding source: None