bluuebunny/crossref_metadata_2025 huggingface dataset:
Solving the challenging puzzle of the Grimsel II runner vibration
Authors: Titzschkau M , Dörfler P
Published: October 2022

After 30 years of operation, the runners of the four 100 MW high-head Francis turbines successively developed fatigue cracks starting from the hub-side trailing-edge fillets. Assessment of alternating stress in normal turbine operation revealed that stress levels were not nearly large enough to explain the damages. Consequently, a test campaign comprising start and stop manoeuvres in addition to normal turbine operation was conducted in 2017. Strain gauge signals obtained on-board of the runner blades were recorded together with casing vibration and acoustic signals. Intense high-frequency vibration centred around 611 Hz was detected in three transient conditions of operation: at speed-no-load (SNL), during coast-down and during back-to-back pump start. Common properties of these conditions were very low to no discharge, strong secondary flow in the runner and speed between 50 and 100 %. Due to the extremely narrow bandwidth, three possible ways of excitation were considered and checked: rotor-stator interaction (RSI), rotor-dynamic instability and Von Kármán excitation. RSI was excluded due to speed-independent frequency. Strong sidebands in the stationary-frame frequency spectra - obviously caused by runner shroud deformation shapes ND1 through ND5 - excluded any feedback from runner side chamber pressure; thus leaving Von Kármán excitation as the only possible diagnosis. Accordingly, a very safe profile was selected and implemented for the runner blade trailing edges. Subsequent field-testing at two modified units confirmed that the vibration problem at the harmful operation points had hereby been eliminated.
Numerical Simulation and Experimental Verification of Downstream Fish migration in a Bulb turbine
Authors: Benigni H , Schneider J , Reckendorfer W , Schiffer J , Tuhtan J , Leithner S , Zenz G , Meusburger P
Published: October 2022

Downward migrating fish can be damaged when passing through turbines in the direction upstream to downstream. The overall influence on the fish population is not known yet. In recent decades, many publications with steady-state CFD calculations for the passage of fish have been published. However, transient CFD calculations show that the range in which fish pass the runner itself is not easily predictable but rather random, influenced by the current position of the runner, thus affecting the probability of survival. The pressures, which are also well represented by steady-state CFD calculations, are compared by applying “Live Fish” (typical types for the middle of Europe) as well as “Barotrauma Detections Sensors (BDS)” which were exposed to the area of the turbine intake at different heights and monitored during downstream migration.
The Semi-Air-Cushion Surge Tank: Design Principles and Case Study
Authors: Richter W , Zenz G , Vereide K
Published: October 2022

Surge tanks are required to enable power and frequency governing of hydraulic machines in hydropower plants with pressure tunnels. To improve the hydraulic performance and reduce the construction costs, a new concept of semi-air-cushion surge tank (semi-ACST) is proposed. The semi-ACST can be particularly effective for upgrading and retrofitting of existing hydropower plants, when additional hydraulic machine capacity is added to an existing waterway. The key design element is a crown throttle, constructed as an inverted weir placed in the crown of the chamber. The purpose is to intentionally trap an air pocket during filling of the lower chamber. The air is released slowly through defined air pipes so that the air in practice contributes equivalent to added volume in the upper chamber. Thus, the semi-ACST improves the dampening of mass oscillation, without increasing the surge tank volume. The semi-ACST has been investigated and developed with multiphase 3D CFD simulations with RANS turbulence modelling. The design principles have been tested on the case-study Tonstad hydropower plant (960 MW). In the presented case study, the semi-ACST is proposed as an extension of one of the three exiting hydraulically coupled surge tanks.
1D numerical study of a multistage centrifugal pump during transient operation
Authors: Alerci Aldo , Vagnoni Elena , Nicolet Christophe , Hugo Nicolas , Paolone Mario
Published: October 2022

Hydropower plants (HPPs) are acknowledged to be fundamental assets to provide generation flexibility to power systems hosting substantial amount of stochastic renewable energy sources. Within this context, providing this flexibility enforces HPP units to cross-over transient operating conditions or to operate in off-design conditions. The evaluation of the impact that such transients have on the hydraulic machines is a fundamental step to assess the operating costs in terms of lifetime reduction of the machine structural integrity.

When these assessments are performed on experimental test-rigs featuring a machine’s reduced scale models, testing transient regimes may potentially trigger harmful pressure profiles along the piping system as well as resonant phenomena on the test-rig. Simulating how the several state variables evolve during the experimental tests allows for the prediction of damaging circumstances and, eventually, prevent performing experimental tests in detrimental conditions.

In this regard, this paper illustrates a numerical method able to reliably reproduce the experimental test-rig behavior while preserving the consistency of the scaled similarities with respect to a specific case study HPP: the Veytaux I pumped-storage hydropower plant located in Switzerland.

Moreover, in this paper, the developed 1D numerical model of the EPFL Technological Platform for Hydraulic Machines experimental test-rig is presented since some of the characteristic transient sequences of the studied HPP are simulated on this model and compared to the prototype scale 1D numerical results.
Assessments of hydropower plants start-up sequences and equivalent runner damage under transient operation
Authors: Seydoux M , Vagnoni E , Nicolet C , Alligné S , Hugo N , Paolone M
Published: October 2022

With specific reference to the HPP start-up sequence, the conventional process requires to operate the runner in a particular operating regime called Speed-No-Load (SNL) that is detrimental for the runner. Thanks to last decade’s improvements in MW-class power electronics, new generators’ technologies have emerged providing an additional degree of freedom to HPPs control. In this respect, the control of the hydraulic turbine speed can be used to decrease the level of damage induced on the runner by choosing the appropriate trajectory for transient operations. Variable speed is a recent technology and its capability to improve the transient operation of hydraulic machines is not fully addressed in literature and, specifically, for start-up sequences. To fully take advantage of such an added degree of freedom, an in-depth experimental study has been performed at EPFL (PTMH) on a specific speed homologous reduced scale model of the unit 5 of Z’Mutt HPP equipped with a reversible pump-turbine. The paper presents a methodology to (i) investigate different transient sequences to start-up the hydraulic machine, which have been tested on reduced scale model, and to (ii) evaluate the equivalent damage impact on the runner. The results of this study highlight the advantages of leveraging the variable speed technology during the unit start-up.
Variation law of pressure pulsation during variable speed operation of pumped storage units
Authors: Li Yulan , Yang Weijia , Huang Yifan , Ma Weichao , Zhao Zhigao , Yang Jiebin , Yang Jiandong
Published: October 2022

Variable speed operation technology has become an emerging development direction in hydropower industry. Variable-speed pumped storage plants (VSPSPs) constantly undergo various transient processes, and ensuring the amplitude of pressure pulsation within the control range is critical to the safe operation of variable-speed pumped storage units (VSPSUs). However, its extreme value is usually determined by rule of thumb in design stage, and few researches focus on the relationship between pressure pulsation and variable speed operation of VSPSUs. In this paper, characteristic curves of pressure pulsation are plotted by processing model test results with Gridfit function, taking a real VSPSP as an example. The total pressure during transient processes is predicted by simulation of a numerical model. Load rejection conditions (change initial speed) and large load regulation conditions (change speed command and power command) are simulated, and the influence of operating trajectory on pressure pulsation during variable speed operation is analyzed. The results show that with the increase of initial speed or speed command, the value of pressure pulsation increases; the trajectory passes through more high-amplitude pressure pulsation region and gradually shifts to the S-shaped region, causing the pressure oscillation. This study could provide theoretical reference for the operation of VSPSUs.
Dynamic performance and sensitivity of grid-connected hydropower station under uncertain disturbance
Authors: Liu Y , Guo W C , Cao R , Chen Z , Wang L
Published: October 2022

The grid-connected operating condition of hydropower station is a common operation mode to provide electric energy for the load side. This paper investigates the dynamic performance and sensitivity of grid-connected hydropower station (GCHS) under uncertain disturbance. Firstly, the nonlinear uncertain model of GCHS under uncertain disturbance is established. Then, the dynamic performance of GCHS is studied when the governor parameters change under certain step disturbance, periodic disturbance and uncertain random disturbance, respectively. Finally, based on the sensitivity index of the uncertain output obtained from the extended Fourier amplitude sensitivity test method, the sensitivity of the uncertain random disturbance at different input positions is studied. The results indicate that the GCHS under periodic disturbances or random disturbances have more complex dynamic performance than that under certain step disturbance. Under periodic disturbance, the forced oscillations and high frequency resonances are generated in dynamic response of GCHS. Under the uncertain random disturbance, the system of GCHS always presents random oscillation. The state variables q

H
, z, qP, y, x

s
, x

t
, and δ of GCHS are the most sensitive to uncertain disturbances, which are introduced at the generator or surge tank. The uncertain disturbances have significant interaction on the dynamic response of GCHS.
Multifunctional water tower
Authors: Jandourek Pavel , Pochylý František
Published: October 2022

The aim of this article is to present a new technical solution of the multifunctional water tower. The principle of the new designed a water tower is fundamentally based on self-sufficiency and independence of energy sources, either the energy of the sun or the wind is used. To the conversion of this energy into mechanical energy for pumping of water to storage tank is used a ball screw mechanism, which driving a high discharge displacement pump based on the piston principle.
A group theoretic perspective on entanglements of division fields
Authors: Daniels Harris , Morrow Jackson
Published: October 2022

In this paper, we initiate a systematic study of entanglements of division fields from a group theoretic perspective. For a positive integer

n
n

and a subgroup

G
⊆
G

L
2

(

Z

/

n

Z

)

G\subseteq GL_2( \mathbb {Z}/n\mathbb {Z})

with surjective determinant, we provide a definition for

G
G

to represent an

(
a
,
b
)

(a,b)

-entanglement and give additional criteria for

G
G

to represent an explained or unexplained

(
a
,
b
)

(a,b)

-entanglement.

Using these new definitions, we determine the tuples

(
(
p
,
q
)
,
T
)

((p,q),T)

, with

p
>
q
∈

Z

p>q\in \mathbb {Z}

distinct primes and

T
T

a finite group, such that there are infinitely many non-

Q

¯

\overline {\mathbb {Q}}

-isomorphic elliptic curves over

Q

\mathbb {Q}

with an unexplained

(
p
,
q
)

(p,q)

-entanglement of type

T
T

. Furthermore, for each possible combination of entanglement level

(
p
,
q
)

(p,q)

and type

T
T

, we completely classify the elliptic curves defined over

Q

\mathbb {Q}

with that combination by constructing the corresponding modular curve and

j
j

-map.
Randomized placebo-controlled crossover trial of memantine in children with epileptic encephalopathy
Authors: Schiller Katharina , Berrahmoune Saoussen , Dassi Christelle , Corriveau Isabelle , Ayash Taghreed A , Osterman Bradley , Poulin Chantal , Shevell Michael I , Simard-Tremblay Elisabeth , Sébire Guillaume , Myers Kenneth A
Published: October 2022

Memantine is an N-methyl-D-aspartate receptor antagonist, approved for dementia treatment. There is limited evidence of memantine showing benefit for paediatric neurodevelopmental phenotypes, but no randomized placebo-controlled trials in children with developmental and epileptic encephalopathy.

In this randomized double-blind placebo-controlled crossover trial (Trial registration: https://clinicaltrials.gov/ct2/show/NCT03779672), patients with developmental and epileptic encephalopathy received memantine and placebo, each for a 6-week period separated by a 2-week washout phase. Electroencephalography, seizure diary, patient caregivers’ global impression, serum inflammatory markers and neuropsychological evaluation were performed at baseline and after each treatment phase. The primary outcome measure was classification as a ‘responder’, defined as ≥2 of: >50% seizure frequency reduction, electroencephalography improvement, caregiver clinical impression improvement or clear neuropsychological testing improvement.

Thirty-one patients (13 females) enrolled. Two patients withdrew prior to initiating medication and two (twins) had to be removed from analysis. Of the remaining 27 patients, nine (33%) were classified as responders to memantine versus two (7%) in the placebo group (P < 0.02). Electroencephalography improvement was seen in eight patients on memantine compared to two on placebo (P < 0.04). Seizure improvement was observed in eight patients on memantine and two on placebo (P < 0.04). Caregivers reported overall clinical improvement in 10 patients on memantine compared to seven on placebo (not significant). Statistical analysis of neuropsychological evaluation suggested improvements in symptoms of attention-deficit hyperactivity disorder and autism.

Memantine is a safe and effective treatment for children with developmental and epileptic encephalopathy, having the potential to improve both seizure control and cognitive function.
Urine Tenofovir Levels Strongly Correlate With Virologic Suppression in Patients With Human Immunodeficiency Virus on Tenofovir Alafenamide-Based Antiretroviral Therapy
Authors: Johnson Kelly A , Okochi Hideaki , Arreguin Mireya , Watabe Joseph , Glidden David V , Chattopadhyay Anindita , Imbert Elizabeth , Hickey Matthew D , Gandhi Monica , Spinelli Matthew
Published: October 2022

We found that urine tenofovir (TFV) levels >1500 ng/mL strongly predict virologic suppression among people with human immunodeficiency virus taking tenofovir alafenamide (odds ratio, 5.66; 95% confidence interval, 1.59–20.14; P = .007). This suggests an existing point-of-care assay developed for tenofovir disoproxil fumarate will support adherence monitoring for patients on all TFV-based antiretrovirals.
circSMAD4 Promotes Experimental Colitis and Impairs Intestinal Barrier Functions by Targeting Janus Kinase 2 Through Sponging miR-135a-5p
Authors: Zhao Jie , Lin Zhiliang , Ying Pu , Zhao Zhibin , Yang Haojun , Qian Jun , Gong Yu , Zhou Yan , Dai Yi , Jiao Yuwen , Zhu Weiming , Wang Honggang , Tang Liming
Published: October 2022

Background

Numerous studies have explored the association between circular RNAs [circRNAs] and Crohn’s disease [CD]. However, the pathological role, biological functions, and molecular mechanisms of circRNAs in CD have not been fully elucidated.

Methods

The circRNA microarray analysis was performed to identify deregulated circRNAs in colon tissues. The identified circRNAs were verified through quantitative real-time polymerase chain reaction [qRT-PCR]. In vivo and in vitro functional studies were performed to verify the role of circSMAD4 in CD and investigate the mechanisms involved.

Results

We found that circSMAD4 was the most significantly upregulated circRNA. The expression level of circSMAD4 was positively correlated with levels of inflammatory factors. Overexpression of circSMAD4 impaired tight junction [TJ] proteins and enhanced apoptosis of epithelial cells. These effects were reversed by treatment with miR-135a-5p mimic. Mechanistic studies showed that circSMAD4 exerts its effects on CD by ‘sponging’ miR-135a-5p to regulate Janus kinase 2 [JAK2]. Si-circSMAD4 delivery through microspheres ameliorated experimental colitis and protected the intestinal barrier function in IL-10 knockout mice.

Conclusion

This study shows that circSMAD4 regulates the progression of experimental colitis via the miR-135a-5p/JAK2 signalling axis and it may be a potential therapeutic target.
A validated score to predict one-year and long-term mortality in patients with significant tricuspid regurgitation
Authors: Hochstadt Aviram , Maor Elad , Ghantous Eihab , Merdler Ilan , Granot Yoav , Rubinshtein Ronen , Banai Shmuel , Segev Amit , Kuperstein Rafael , Topilsky Yan
Published: October 2022

Aims

Most patients with significant (defined as ≥ moderate) tricuspid regurgitation (TR) are treated conservatively. Individual mortality rates are markedly variable. We developed a risk score based on comprehensive clinical and echocardiographic evaluation, predicting mortality on an individual patient level.

Methods and results

The cohort included 1701 consecutive patients with significant TR, half with isolated TR, admitted to a single hospital, treated conservatively. We derived a scoring system predicting 1-year mortality and validated it using k-fold cross-validation and with external validation on another cohort of 5141 patients. Score utility was compared with matched patients without significant TR. One-year mortality rate was 31.3%. The risk score ranged 0–17 points and included 11 parameters: age (0–3), body mass index ≤ 25 (0–1), history of liver disease (0–2), history of chronic lung disease (0–2), estimated glomerular filtration rate (0–5), haemoglobin (0–2), left-ventricular ejection fraction (0–1), right-ventricular dysfunction (0–1), right atrial pressure (0–2), stroke volume index (SVI) (0–1) and left-ventricular end-diastolic diameter (0–1). One-year mortality rates increased from 0 to 100%, as the score increased up to ≥16. Areas under the receiver operating curves were 0.78, 0.70, and 0.73, for the original, external validation, and external validation with SVI measured cohorts. The score remained valid in subpopulations of patients with quantified RV function, quantified TR and isolated TR. Significant TR compared to no TR, affected 1-year mortality stronger with higher scores, with a significantly positive interaction term.

Conclusion

We suggest a robust risk score for inpatients with significant TR, assisting risk stratification and decision-making. Our findings underscore the burden of TR providing benchmarks for clinical trial design.
Effect of Motexafin lutetium-mediated ultrasound-guided red laser photodynamic therapy on endothelial dysfunction using a new automatic ultrasound image processing software
Authors: Mehrad H
Published: October 2022

Background

As is well recognized, the majority of atherosclerosis start with an inflammatory process, resulting in endothelial dysfunction.

Purpose

In this study, we developed an experimental photosensitizer Motexafin lutetium (Lu-Tex)-mediated photodynamic therapy system, and investigated its effectiveness on endothelial dysfunction improvement in an animal model of balloon dilation injury, using a new automatic ultrasound image processing software.

Methods

Briefly, Golden Syrian hamsters' femoral artery underwent balloon dilatation injury. After four weeks, femoral arteries of the treatment group at the lesion region, treated using Motexafin lutetium - mediated fiber optic catheter-based red low level laser (742 nm, 150 J/cm2) photodynamic therapy. In order to evaluate endothelial-dependent relaxation, acetylcholine-mediated dilation (AMD) was measured during the infusion of acetylcholine at a rate of 0.5 μg/kg/min and endothelial independent relaxation was evaluated by measuring nitroglycerin mediated dilation (NMD) during the infusion of nitroglycerin at a rate of 5μg/kg/min. For off-line analysis, a computerized analysis method for evaluating instantaneous changes in the wall of the hamster femoral artery was used. For automatic measurement of the mean wall thickness and the lumen diameter from longitudinal B-mode ultrasound images, two algorithms, i.e., maximum gradient and dynamic programming were composed and implemented. Reference points and cost function were based on dynamic programming and maximum gradient, respectively.

Results

Results from computerized B-mode ultrasound image processing software showed significant differences in AMD between the treated and the non-treated hamsters (p<0.05), whereas there were no significant differences in NMD between the treatment and normal groups (p>0.05).

Conclusion

Cytotoxic and anti-inflammatory effect of Motexafin lutetium, induced by red laser photodynamic therapy accompanied by photobiomodulation effect of red laser, can cause to reduce the immune cells in intimal layer and improve the endothelial dysfunction via increasing the endothelial nitric oxide synthase function. Furthermore, it is concluded that the new automatic method enables accurate and repeated evaluation of the endothelial dysfunction using photodynamic therapy in this model.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Mehrad Research Lab
LA strain helps identifying the cardioembolic etiology of transient ischemic attacks
Authors: Arnautu D A , Vacarescu C , Arnautu S F , Gaita L , Cozma D
Published: October 2022

Background

Patients who have transient ischemic attacks (TIA) often suffer from asymptomatic and paroxysmal atrial fibrillation (AF). Due to the fact that AF is located in the atria, we sought to determine whether abnormalities in left atrial (LA) structure and function could help identify the cardioembolic cause of TIA in patients with sinus rhythm but with documented episodes of paroxysmal AF.

Methods

The research included 190 individuals with TIA and classified them into two groups based on the presence (group I) or absence (group II) of confirmed paroxysmal AF. The diagnosis of paroxysmal AF was established by an assessment of medical records. To prevent assessing atrial stunning, cardiac ultrasonography was conducted in sinus rhythm at least 14 days following the initiation the TIA.

Results

The results indicated that patients in group I were older, more often female, had a history of stroke or TIA, and had a higher CHA2DS2-VASc score. Additionally, they exhibited increased LA volumes, a decreased LA emptying fraction, and markedly altered LA deformation patterns. Three factors were found as being independently associated with paroxysmal AF using multivariate logistic regression: age, LA reservoir strain, and LA emptying fraction (P<0.0001). The variables had as cut-off values: age >55 years, LA reservoir strain<−17%, and LA emptying fraction <51%.

Conclusion

The current research establishes that LA strains are independently associated with paroxysmal AF in patients with TIA and may aid in determining the cardioembolic origin of these events.

Our findings have considerable clinical implications because, until now, LA 2D-STE was not included in the usual evaluation of TIA patients, but it may be the ideal next step in this regard.

Funding Acknowledgement

Type of funding sources: None.
Global longitudinal strain assessment in long-term survivors of childhood acute lymphoblastic leukemia
Authors: Gonzalez-Manzanares R , Pericet-Rodriguez C , Fernandez-Ruiz A , Fernandez-Aviles C , Heredia-Campos G , Resua-Collazo A , Castillo-Dominguez J C
Published: October 2022

Background

The role of global longitudinal strain (GLS) in the long-term cardiac evaluation of childhood acute lymphoblastic leukemia (ALL) survivors is not clearly defined.

Purpose

To assess the prevalence of subclinical left ventricular systolic dysfunction (SLVD) in long-term survivors of ALL. We also aimed to compare echocardiographic measurements with a control group.

Methods

Patients <18 years of age diagnosed with ALL between 1985–2015 at our center were enrolled. Healthy siblings willing to participate were conformed the control group. GLS was measured with an automated software (AutoStrain, Tomtec). SLVD was defined as GLS<18.5% (absolute value) based on the lower limit of the 95% confidence interval in the control group. Group differences were accounted with nverse probability of treatment weighting.

Results

Of the 90 survivors included (37.8% female, time from diagnosis 18 [11–26] years), 24 (26.6%) had SLVD. Left ventricular systolic but not diastolic measurements were reduced compared to the control group (Table 1). Predictors of GLS in the survivors were smoking (p=0.004) and history of hematopoietic stem-cell transplantation (p=0.042) (Table 2).

Conclusions

Over ¼ of childhood ALL survivors had abnormal GLS values after a median follow-up of 18 years. Left-ventricular systolic parameters were reduced compared to a control group.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Sociedad Española de Cardiología. Sociedad Andaluza de Cardiología.
Changes in right ventricular two-dimensional echocardiographic speckle-tracking indices in adult LVAD population: a prospective clinical study
Authors: Stapor M , Pilat A , Gorkiewicz-Kot I , Kleczynski P , Zmudka K , Legutko J , Kapelak B , Wierzbicki K , Gackowski A
Published: October 2022

Objective

Preserved right ventricular (RV) function is crucial in patients supported with left ventricular assist devices (LVAD). The use of strain derived from speckle tracking echocardiography (STE) is recommended by recent guidelines to evaluate intricate RV contractility. The data regarding long-term RV observation in LVAD patients using STE are limited. Thus, the study aimed to determine RV systolic function by STE in the remote period after LVAD implantation.

Methods

Patients with implanted third-generation LVADs with hydrodynamic bearing were prospectively enrolled (NCT05063006). The RV STE indices were analyzed before and after LVAD implantation, both at rest and during the cycle ergometer exercise test.

Results

We included 22 patients, the mean age was 58.4±7 years, 95.5% were men, and 45.5% had dilated cardiomyopathy. Stress tests were conducted 7 months postoperatively. The RV strain analysis was feasible in all subjects both in rest and exercise. The RV free wall strain (RVFWS) worsened from −13% (IQR, −17.3 to −10.9) to −11.3% (IQR, −12.9 to −6; p=0.033) after LVAD implantation with the particular decline in the apical RV segment [−11.3% (IQR, −16.4 to −6.2) vs −7.8% (IQR, −11.7 to −3.9; p=0.012)]. The RV four-chamber longitudinal strain (RV4CSL) remained unchanged [−8.5% (IQR, −10.8 to −6.9) vs −7.3% (IQR, −9.8 to −4.7; p=0.184)]. Neither RVFWS (−11.3% (IQR, −12.9 to −6) vs −9.9% (IQR, −13.5 to −7.5; p=0.077) nor RV4CSL [−7.3% (IQR, −9.8 to −4.7) vs −7.9% (IQR, −9.8 to −6.3; p=0.548)] changed during cycle ergometer stress test.

Conclusion

The RVFWS worsens after LVAD implantation presumably due to impaired apical contractility. In LVAD-supported patients during the cycle ergometer stress test, the detailed RV strain analysis is feasible and its indices remain unchanged.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): 1. Cor Aegrum Foundation of Cardiac Surgery Development in Cracow2. Medtronic Poland sp. z o.o.
Could echocardiographic left atrial characterization have additive value for detecting risks of atrial arrhythmias and stroke in patients with hypertrophic cardiomyopathy?
Authors: Al Wazzan A , Galli E , Lacout M , Paven E , L'official G , Schnell F , Oger E , Donal E
Published: October 2022

Background

Atrial arrhythmia (AA) is considered a turning point for prognosis in hypertrophic cardiomyopathy (HCM) patients. Prediction of AA and associated stroke risk in patients with HCM is an important clinical challenge as these events can occur in young subjects and significantly impact their quality of life. (1) (2)

Purpose

We sought to assess whether an echocardiographic evaluation focused on the left atrial (LA) characterization could estimate the occurrence of AA and stroke in HCM patients.

Methods

216 HCM-patients (52±16 years old) were enrolled between 2016 and 2019. All patients underwent transthoracic echocardiography for the evaluation of left atrial volume (LAV), left ventricular global longitudinal strain (LV-GLS), peak left atrial strain (PLAS) and peak atrial contraction strain (PACS) by speckle-tracking imaging. A composite endpoint was defined as a history of AA and/or a history of stroke or peripheral embolism and/or occurrence of AA.

Results

The patients were followed for 2.9 years. Among the 216 patients, 78 (36%) met the composite endpoint. These patients were older (50.3±16.7 vs. 57.1±14.4 years, p=0.0035), had a higher prevalence of arterial hypertension (42.3% vs. 62.3%; p=0.005) and had higher NT-proBNP levels. LAV (37.2±15.7 vs. 47±20 ml/m2, p=0.0001) was significantly higher in patients who met the composite endpoint, whereas PLAS and PACS were significantly impaired (26.6±9.12 vs. 19.3±9.54%; p<0.0001 and 13.1±6.3% vs. 8.8±6.5%; p<0.0001, respectively). After adjustment, PLAS and PACS remained independently associated with events with an odds ratio (OR) of 0.42 for PLAS (95% CI, [0.29–0.61]; p<0.0001). Stroke occurred in 67% of the patients without any clinical AA. PLAS with a cut-off of under 15.5% provided event detection with 91% specificity and demonstrated a predictive value for new-onset of AA. Although there was a high correlation between PLAS and LV-GLS, LV-GLS was not associated with the events.

Conclusion

The impairment of LA function assessed by 2D speckle-tracking echocardiography was strongly associated with AA and the risk of stroke, even in patients without any documented AA. Its value for guiding the management of HCM-patients requires further investigation.

Funding Acknowledgement

Type of funding sources: None.
Could premature ventricular contractions lead to atrial remodeling?
Authors: Keles N , Kahraman E , Parsova E , Bastopcu M , Karatas M , Yelgec N S
Published: October 2022

Background

Premature ventricular contraction (PVC) is a frequent kind of arrhythmia that affects around 1% of the general population. While PVC most frequently impairs ventricular function in structurally normal hearts, retrograde ventriculo-atrial conduction can occur in people with PVC. These retrograde atrial activations may mimic pulmonary vein-derived atrial ectopies. As a result, PVC may raise the risk of AF by retrograde ventriculo-atrial conduction.

The Four-Dimensional Automated Left Atrial Quantification (4D Auto LAQ) tool is a left atrial analytical approach that utilizes three-dimensional volume data to quantify the volume, as well as LA longitudinal and circumferential strain. The purpose of this study was to determine if clinical diagnosis of PVC is connected with abnormal LA functions as determined by LA strain evaluation utilizing a 4D Auto LAQ compared to the normal population.

Methods

58 patients with frequent PVCs were enrolled in the research, along with 53 healthy volunteers as a control group. Imaging was performed using the GEvivid E95 ultrasonic diagnostic instrument (GE Healthcare; Vingmed Ultrasound, Horten, Norway) equipped with an M5S probe (frequency range: 1.5–4.6 MHz) and a 4V probe (frequency range: 1.5–4.0 MHz). Images were imported into and selected for analysis using the EchoPAC203 software (GE Healthcare). The analysis mode was selected, followed by the volume and 4D Auto LAQ submodes. Following that, the sample point was positioned in the center of the mitral orifice in each of the three planes. The'review' function was used to acquire the LA parameters measured by 4D Auto LAQ, including volume and strain parameters.

Results

The maximum left atrial volume (LAVmax) and minimal left atrial volume (LAVmin) were signifcantly higher in patient group (38.91±9.72 vs. 46.31±10.22, 17.75±4.52 vs. 23.10±7.13 respectively, all p values <0.001).On the other hand left atrial reservoir longitudinal strain (LASr), conduit longitudinal strain (LAScd), contraction longitudinal strain (LASct), reservoir circumferential strain (LASr-c), conduit circumferential strain (LAScd-c), and contraction circumferential strain (LASct-c) were signifcantly lower in patient group (26.64±5.64 vs. 19.16±4.58, −19.53±3.72 vs. −11.28±3.47, −10.34±1.56 vs. −4.59±1.49, 30.72±4.04 vs. 19.31±2.60, −19.91±1.78 vs. −13.38±2.85, −15.89±6.37 vs. −9.24±1.63, respectively all p values <0.001).

Conclusion

The present study found that premature ventricular contractions can lead to atrial remodeling as well as ventricular remodeling in patients with PVC and 4D LAQ technology can quantitatively evaluate atrial myocardial function and detect these changes early.

Funding Acknowledgement

Type of funding sources: None.
Right ventricular mechanics among beta-thalassemia major patients
Authors: Patsourakos D , Aggeli C , Gatzoulis K , Delicou S , Xydaki A , Koukos M , Gialleli F , Dimitroglou Y , Tsioufis K
Published: October 2022

Introduction

Right ventricular function among β-thalassemia (β-TM) patients is affected by both pulmonary circulation pressure and primary iron deposition on right ventricular myocardium.

Purpose

In our study we aimed to detect the presence of impaired right ventricular function and right ventricle to pulmonary circulation (RV-PC) coupling by applying novel echocardiographic techniques among these patients.

Methods

47 β-TM patients (mean age 39.02±8.76 years, 48.9% male sex) and 24, age and sex matched, healthy controls were examined by transthoracic echocardiography. Conventional echocardiographic parameters were estimated (LVEF, E/e' ratio, left atrial volume index (LAVI), right ventricular systolic pressure (RVSP), S' wave of tricuspid annulus), alongside with deformation indices (left atrial strain at reservoir phase (LASr), right ventricular free wall (RVfw) and 4 chamber (RV4c) strain), as well as RV-PC coupling expressed as S'/RVSP, RVfw/RVSP and RV4c/RVSP. T2* was calculated by cardiac magnetic resonance imaging in β-TM patient group.

Results

E/e' ratio, LVEF, LAVI, RVSP, LASr, RVfw, RV4c, S'/RVSP, RVfw/RVSP and RV4c/RVSP differed significantly between patients and controls (Table 1). T2* did not correlate with either right ventricular deformation indices or RV-PC coupling indices. A correlation was found regarding LASr with both S'/RVSP (r=0.383, p=0.008) and RV4c/RVSP (r=−0.388, p=0.007) but not with RVfw/PVSP (Table 2).

Conclusions

Right ventricular deformation indices were found to be impaired in β-TM patients compared to controls, but they do not seem to be associated with myocardial iron load (T2* index). RV-PC coupling was also found to be impaired among patients and a correlation was found between RV-PC indices and left atrial strain. The latter suggests that the presence of atrial cardiomyopathy in β-TM patients could be associated with the impaired RV-PC coupling.

Funding Acknowledgement

Type of funding sources: None.
The impact of left atrial mechanics on adverse events and clinical outcome after cardiac surgery
Authors: Dalos D , Haaser S S , Hofer F , Kazem N , Koller L , Hammer A , Steinlechner B , Laufer G , Hengstenberg C , Niessner A , Sulzgruber P
Published: October 2022

Objectives

Post-operative atrial fibrillation (POAF) represents a common complication after cardiac surgery that is associated with unfavorable clinical outcome. Identifying patients at risk for POAF is crucial but challenging.

Purpose

This study aimed to investigate the prognostic potential of speckle tracking echocardiography (STE) on POAF and fatal adverse events from a long-term perspective.

Methods

A total of 124 patients undergoing elective cardiac surgery were prospectively enrolled and underwent pre-operative STE. Patients were followed prospectively for the occurrence of POAF within the entire hospitalization and reaching the secondary endpoints cardiovascular (CV) and all-cause mortality.

Results

Within the study population 43.5% (n=53) of enrolled individuals developed POAF. After a median follow-up of 3.9 years, 25 (20.2%) patients died. We observed that patients presenting with POAF had lower global peak atrial longitudinal strain (PALS) values compared to the non-POAF arm (POAF: 14.8% [95% CI: 10.9–17.8] vs. non-POAF: 19.4% [95% CI: 14.8–23.5], p<0.001). Moreover, global PALS was a strong and independent predictor for POAF (adjusted Odds Ratio per 1-SD: 0.37 [95% CI: 0.22–0.65], p<0.001), and independently associated with mortality (adjusted Hazard Ratio per 1-SD: 0.63 [95% CI: 0.40–0.99], p=0.048). CART analysis revealed a cut-off value of <17% global PALS as high-risk for both POAF and mortality.

Conclusion

Global PALS is associated with the development of POAF following surgery in an unselected patient population undergoing CABG and/or valve surgery. Since patients with global PALS <17% face a poor long-term prognosis, routine assessment of global PALS needs to be considered in terms of proper secondary prevention in the era of personalized medicine.

Funding Acknowledgement

Type of funding sources: None.
Incremental value of global longitudinal strain in long-term risk prediction after acute coronary syndrome. A SWEDEHEART registry based echo study
Authors: Lenell J , Lindahl B , Erlinge D , Spaak J , Jernberg T , Baron T
Published: October 2022

Background

Global longitudinal strain (GLS) by 2D speckle tracking echocardiography has emerged as a new method for assessing left ventricular (LV) function, however its added value in long-term risk prediction after Acute Coronary Syndrome (ACS) has not been clearly established. This study aimed to investigate GLS as a predictor of death and heart failure re-hospitalization after ACS in relation to more established echocardiographic measures.

Method

1385 consecutive patients with acute coronary syndrome (47% STEMI, 45% NSTEMI, unstable angina 3.6% and unspecified ACS 4.5%), admitted between 2008 and 2014 to the three participating Swedish university hospitals were reported to the SWEDEHEART registry and underwent routine echocardiography during their hospital stay. The echo data was retrospectively collected from each study site and reviewed at a Core Lab. The prognostic value of systolic left ventricular function parameters (LVEF and GLS) regarding all-cause mortality and heart failure (HF) hospitalizations (median follow-up 6.8 years) was studied using the Cox proportional Hazards model. A nested model comparison was performed with C-statistics.

Results

In the 942 patients remaining after exclusion (median age 65 years, 77% men) median LVEF was 55% (inter quartile range (IQR) 47–60) and median GLS −14.8% (IQR −17.8–11.8). The combined endpoint of HF hospitalization and all-cause death was reached in 17.7% of the patients, 12.1% of the patients died and 8.7% were re-admitted due to HF. After adjustment for baseline characteristics, both LVEF and GLS were individual independent predictors of the combined endpoint, HR 0.964 (95% CI 0.949–0.980, p<0.001) and HR 1.042 (95% CI 1.002–1.084, p=0.042) respectively. The C-statistics increased from 0.752 (95% CI 0.712–0.792) to 0.755 (95% CI 0.706–0.785) when GLS entered the model with clinical data and LVEF.

Conclusion

In a large cohort of patients with ACS and normal or near-normal ejection fraction, GLS emerged as an independent long-term risk predictor of all-cause mortality and heart failure hospitalizations. The incremental predictive value of GLS on top of clinical background and LVEF was statistically significant, but of limited clinical significance.

Funding Acknowledgement

Type of funding sources: None.
Echocardiographic assessment of left ventricular radial strain to differentiate cardiac amyloidosis from Fabry disease
Authors: Steudel T , Mattig I , Romero Dorta E , Barzen G , Frumkin D , Laule N , Al Daas M , Spethmann S , Knebel F , Canaan-Kuhl S , Stangl K , Hahn K , Brand A
Published: October 2022

Background

Left ventricular (LV) wall thickening is a typical echocardiographic finding in infiltrative cardiomyopathies like cardiac amyloidosis (CA) and Fabry disease (FD). The discrimination of both infiltrative diseases remains challenging by standard as well as 2D speckle tracking echocardiography (2DSTE)-based analysis of longitudinal LV strain patterns. Over the recent years, a constant development in image quality and data processing provided better possibilities to analyse layer specific myocardial deformation indices. With regards to FD, specific layer LV strain patterns may be useful to rule-in FD in patients with suspected infiltrative cardiomyopathy.

Purpose

The aim of the present study was to investigate differences and the diagnostic value of layer specific 2D STE-based radial LV strain indices in CA and FD.

Methods

Next to standard parameters of a comprehensive echocardiographic assessment (Vivid E9 or E95, GE Vingmed, Horton, Norway, with an M5S 1.5–4.5MHz transducer), we retrospectively analysed the transmural radial LV strain (GSradial), the subendocardial radial LV strain (GSendo), the subepicardial radial LV strain (GSepi), and the strain gradient (GSendo − GSepi) (EchoPAC software, GE) in FD patients and CA patient from the amyloidosis registry at our study site. A Receiver operating curve (ROC) analysis was used to assess the diagnostic value of the respective LV strain values and the layer-specific strain gradient to discriminate FD and CA.

Results

A total of 38 FD and 40 CA patients were included in our analyses. In patients with FD, GSepi showed a marked impairment. LV radial and layer strain were significantly reduced in CA compared to FD patients [GSradial −12.0 (−16.2 to −9.9) in CA vs. −17.7 (−20.5 to −14.6) in FD; p<0.001); GSendo (−20.6 (−27.0 to −15.7) in CA vs. −30.0 (−32.0 to −25.6) in FD; p<0.001); and GSepi (−7.4 (−8.9 to −4.8) in CA vs. −9.1 (−11.86 to −7.6) in FD; p<0.001)]. The gradient of GSendo and GSepi was significantly lower in patients with CA compared to FD (−14.0±5.6 in CA vs. −19.4±4.3 in FD respectively; p<0.001). GSendo held the highest diagnostic accuracy to discriminate CA and FD (area under the curve [AUC] 0.83, 95% confidence interval [CI] 0.73–0.92). The layer-specific strain gradient GSendo − Gsepi showed an AUC of 0.79 (CI 0.69 to 0.89).

Conclusion

Layer-specific strain analysis demonstrated significantly reduced strain values in CA patients compared to FD. The analysis of GSendo held a high diagnostic accuracy to discriminate FD and CA in patients. The integration of layer-specific LV strain indices into the diagnostic work-up may improve the management of patients with an unclear thick heart pathology in future.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Alnylam Pharmaceuticals (Cambridge, MA, USA)
Global longitudinal strain improvement after iron replacement in stable heart failure patients – FER-Strain study
Authors: Benavent Garcia C , Romero Valero A , Garcia Suarez A , Peris Castello F , Rodriguez Santiago F M , Del Rio Lopez M , Vicente Ibarra N , Garcia Honrubia A , Valero Medrano M C , Quintana Aguilar M M , Martinez Moreno M , Gomez Martinez M , Castilla Cabanes E , Tamayo Obregon A S , Morillas Blasco P
Published: October 2022

Background

Iron deficiency in patients with heart failure with reduced left ventricular ejection fraction (LVEF) confers a poor prognosis in terms of hospital admissions and mortality, worsening functional class and quality of life. Its replacement with ferric carboxymaltose (FCM) has demonstrated to improve clinical parameters, however, the way it is achieved remains unclear. Improvement of myocardial contractility is proposed as possible hypothesis and global longitudinal strain (GLS) could behave as an early and high sensitive parameter to assess this improvement in myocardial deformation due to increased iron availability after replacement of iron deficiency.

Purpose

Evaluate the effect of replacement of iron deficiency with FCM on left ventricular global longitudinal strain in patients with stable heart failure with left ventricular ejection fraction <50%.

Methods

Observational, analytical, longitudinal and prospective study that enrolled 45 patients with stable heart failure with LVEF <50% who presented iron deficiency without anemia defined as serum ferritin <100 μg/L or between 100 and 300 μg/L and the transferrin saturation <20%. Transthoracic echocardiogram, 3D, tissue Doppler imaging and strain were performed, by the same cardiologist, before and four weeks after the iron deficiency replacement with FCM.

Results

The study population's median age was 71 years, 67% were men, 76% had high blood pressure, 62% dyslipemia and 33% diabetes. At baseline they presented LVEF 32% ±8.75%, LV systolic volume index 62.3ml±29.56ml and LV GLS −9.09%±3.44%. Four weeks after iron deficiency replacement, they had a significant improvement in LVEF (difference 2.51%; 95% confidence interval [CI], 1.74% to 3.29%; P<0.0001), LV systolic volume index (difference −6.68ml; 95% CI −1.91ml to −11.45ml; P=0.007) and LV GLS (difference −1.11%; CI 95%, −0.4% to −1.81%; P=0.003), with a relative benefit in LV GLS of 10.57%. Other echocardiography parameters didn't show significant differences.

Conclusion

In patients with stable heart failure and LVEF <50%, replacement of iron deficiency with FCM improves systolic parameters, especially left ventricular global longitudinal strain.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Fundaciόn Fisabio (Fomento de la Investigaciόn Sanitaria y Biomédica de la Comunidad Valenciana)