Prognostic Value of Feature-Tracking Circumferential Strain in Dilated Cardiomyopathy Patients with Severely Reduced Ejection Fraction Incremental to Late Gadolinium Enhancement

Myocardial fiber deformation measurements have been reported to be associated with adverse outcomes in patients with acute heart failure and those with myocardial infarction.However,few studies have addressed the prognostic value of global circumferential strain(GCS)in dilated cardiomyopathy(DCM)patients with severely impaired systolic function.This study aimed to evaluate the prognostic value of cardiac magnetic resonance(CMR)-derived GCS in DCM patients with severely reduced ejection.Consecutive DCM patients with severely reduced ejection fraction(EF<35%)who underwent CMR were included.GCS was calculated from CMR cine images.The clinical endpoint was a composite of all-cause mortality,heart transplantation,implantable cardioverter defibrillator(ICD)implantation and aborted sudden cardiac death(SCD).A total of 129 patients with a mean EF of 15.33%(11.36%–22.27%)were included.During a median follow-up of 518 days,endpoint events occurred in 50 patients.Patients with GCS≥the median(−5.17%)had significantly reduced event-free survival as compared with those with GCS<the median(P<0.01).GCS was independently associated with adverse events after adjusting for clinical and imaging risk factors including extent of late gadolinium enhancement(LGE)(P<0.05).Adding GCS into the model including the extent of LGE resulted in significant improvements in the C-statistic(from 0.706 to 0.742;P<0.05)with a continuous net reclassification improvement(NRI)of 29.71%.It was concluded that GCS derived from CMR could be useful for risk stratification in DCM patients with severely reduced EF,which may increase common imaging risk factors including LGE.

Speckle-tracking echocardiography for detecting myocardial dysfunction in sepsis and septic shock patients:A single emergency department study

BACKGROUND:Septic cardiomyopathy(SCM)occurs in the early stage of sepsis and septic shock,which has implications for treatment strategies and prognosis.Additionally,myocardial involvement in the early stages of sepsis is difficult to identify.Here,we assess subclinical myocardial function using laboratory tests and speckle-tracking echocardiography(STE).METHODS:Emergency department patients diagnosed with sepsis or septic shock were included for analysis.Those with other causes of acute or pre-existing cardiac dysfunction were excluded.Transthoracic echocardiography(TTE),including conventional echocardiography and STE,were performed for all patients three hours after initial resuscitation.Samples for laboratory tests were taken around the time of TTE.RESULTS:Left ventricular functions of 60 patients were analyzed,including 21 septic shock patients and 39 sepsis patients.There was no significant difference in global longitudinal strain(GLS),global circumferential strain(GCS),or global radical strain(GRS)between patients with sepsis and septic shock(all with P>0.05).However,GLS and GCS were significantly less negative in patients with abnormal troponin levels or in patients with abnormal left ventricular ejection fraction(LVEF)values(all with P<0.05).There were also moderate correlations between GLS and levels of cTnI(r=0.40,P=0.002)or N-terminal pro-B-type natriuretic peptide(NT-proBNP)(r=0.44,P=0.001)in sepsis and septic shock patients.CONCLUSION:Myocardial dysfunction,e.g.,lower LVEF or less negative GLS in patients with sepsis or septic shock,is more affected by myocardial injury.GLS could be incorporated into mainstream clinical practice as a supplementary LVEF parameter,especially for those with elevated troponin levels.

Evaluation of the propensity of strain burst in brittle granite based on post-peak energy analysis

The increasing demand for resources and depletion of near ground mineral resources caused deeper mining operations under highstress rock mass conditions.As a result of this,strain burst,which is the sudden release of stored strain energy in the surrounding rock mass,has become more prevalent and created a considerable threat to workers and construction equipment.It is,therefore,imperative to understand how strain burst mechanism and stored excess strain energy are affected due to the high confinement in deep underground conditions.For this purpose,post-peak energy distributions for brittle rocks were investigated using a newly developed energy calculation method associated with acoustic emission(AE).A series of quasi-static uniaxial and triaxial compression tests controlled by the circumferential expansion were conducted.Snap-back behaviour known as Class-II behaviour associated with energy evolution and the material response under self-sustaining failure were analysed on granites under a wide range of confining pressures(0–60 MPa).The experimental results underline that the energy evolution characteristics are strongly linked to confinement.Stored elastic strain energy(dUE),energy consumed by dominating cohesion weakening(dUCW)and energy dissipated during mobilisation of frictional failure(dUFM)showed a rising trend as the confining pressure was increased.An intrinsic ejection velocity was proposed to express the propensity of strain burst that was purely determined by the excess strain energy released from Class II rock.

Mechanical Analysis and Strength Checking of Current Collector Failure in the Winding Process of Lithium-Ion Batteries

The current collector fracture failure of lithium-ion batteries(LIBs)occurs during its winding production process frequently,and the consequent damages are usually large,but little research has been conducted on this phenomenon.This work stems from the difficulty and obstacles in the winding process of actual production of LIBs.The fracture failure of the current collectors is easily caused by the evolution and mutation of the mechanical behavior during the winding process,resulting in safety hazards and poor efficiency.The purpose of this work is to reveal the evolution and distribution mechanism of circumferential strain of the current collectors on the fracture failure under the constraint of winding process.Experimental tests,finite element calculations and theoretical model are used to study the evolution and distribution of circumferential strain.The dynamic evolution process of circumferential strain is tested accurately,and the mechanism of fracture failure of current collectors is revealed.The criterion for current collector strength is proposed based on the results of strain analysis and SEM observation.