Radial dynamics of an encapsulated microbubble with interface energy

In this work a mathematical model based on interface energy is proposed within the framework of surface continuum mechanics to study the dynamics of encapsulated bubbles. The interface model naturally induces a residual stress field into the bulk of the bubble, with possible expansion or shrinkage from a stress-free configuration to a natural equilibrium configuration. The significant influence of interface area strain and the coupled effect of stretch and curvature is observed in the numerical simulations based on constrained optimization. Due to the bending rigidity related to additional terms, the dynamic interface tension can become negative, but not due to the interface area strain. The coupled effect of interface strain and curvature term observed is new and plays a dominant role in the dominant compression behaviour of encapsulated bubbles observed in the experiments. The present model is validated by fitting the experimental data of $1.7\,\mathrm {\mu }$ m, $1.4\,\mathrm {\mu }$ m and $1\,\mathrm {\mu }$ m radii bubbles by calculating the optimized parameters. This work also highlights the role of interface parameters and natural configuration gas pressure in estimating the size-independent viscoelastic material properties of encapsulated bubbles with interesting future developments.

Three and Two-Dimensional Cardiac Mechanic Parameters by Speckle Tracking Echocardiography are Predictors of Outcomes In Chagas Heart Disease

BACKGROUND: Chagas disease (CD) is a neglected infectious disease associated with early mortality and substantial disability. Three-dimensional speckle tracking (3D STE) may play a role in the evaluation of CD. We aim to characterize new echocardiographic variables in patients with CD and to assess the hypothesis that 3D STE may predict outcomes. METHODS: Seventy-two patients with CD were included. Clinical and conventional 2D and 3D STE analysis were performed. Patients were followed up for sixty months. Clinical events were defined as hospitalization for heart failure, complex ventricular arrhythmias, heart transplant and all-cause death. RESULTS: Seventy-two patients were recruited and enrolled in three groups: left ventricular ejection fraction (LVEF) < 0.40 (N=22); 0.40 < LVEF < 0.50 (N=10) and LVEF > 0.50 (N=30). After a Cox model analysis, the top predictors of composite endpoints were 2D LV global longitudinal strain (GLS) ≤ -11.3% (AUC=0.87), 2D LV global circumferential strain (GCS) ≤ -10.1% (AUC=0.79), 3D LV GLS≤ -13% (AUC=0.82), 3D LV area strain ≤ -16% (AUC=0.81) and right ventricle (RV) GLS ≤ -17.2% (AUC=0.78). CONCLUSIONS: Patients with CD and mrLVEF were morphologically similar to the rLVEF patients despite the benign evolution as the pLVEF group. RV GLS, 2D LV GLS, 2D LV GCS, 3D LV GLS, and 3D LV area strain are strong predictors of sixty months outcomes in patients with CD.

Pursuing the non-invasive assessment of cardiac contractility: the added value of pressure-area-strain loop analysis in volume overload-induced heart failure

Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This work was supported by the New National Excellence Programme (ÚNKP-19-3-I) of the Ministry for Innovation and Technology in Hungary, and the Artificial Intelligence Research Field Excellence Programme of the National Research, Development and Innovation Office of the Ministry of Innovation and Technology in Hungary. Background Global longitudinal strain (GLS) by speckle-tracking echocardiography (STE) is a sensitive parameter of left ventricular (LV) systolic function. Nevertheless, GLS is dependent on loading conditions. Through the analysis of pressure-strain loops, myocardial work was recently introduced and tested in different clinical scenarios. Myocardial work incorporates afterload, but still, it neglects changes in preload and LV geometry. Purpose Accordingly, our aim was to test our hypothesis that adding instantaneous LV size to myocardial work calculation can further mitigate the load-dependency of GLS, and therefore, a better correlation with intrinsic myocardial contractility can be achieved. Methods Volume overload-induced heart failure was established by an aortocaval fistula (ACF) in male Wistar rats (n = 12). Age-matched sham-operated animals served as controls (n = 12). STE was performed to assess GLS, which was immediately followed by invasive pressure-volume (P-V) analysis to assess LV pressure and to compute a gold-standard index of cardiac contractility (preload recruitable stroke work [PRSW]). Global myocardial work index (GMWI) was calculated from GLS and the invasively measured LV pressure. To compute GMWI indexed to LV area (GMWIA), the instantaneous power (calculated by multiplying the strain rate and the instantaneous LV pressure) was divided by the instantaneous LV area, and then it was integrated from mitral valve closure until mitral valve opening. Results LV ejection fraction did not differ significantly (ACF vs. controls: 59 ± 4 vs. 65 ± 9%, p = NS), whereas GLS (Figure 1A - representative animals) was slightly decreased in the ACF group (-13.2 ± 2.3 vs. -15.4 ± 1.9%, p &lt; 0.05). In contrast, PRSW, GMWI (Figure 1B - representative animals) and GMWIA (Figure 1C - representative animals) were considerably reduced in ACF compared to controls (57 ± 13 vs. 111 ± 38mmHg, 1383 ± 382 vs. 1928 ± 281mmHg%, 11.6 ± 3.7 vs. 47.9 ± 22.8mmHg%/mm2, all p &lt; 0.01). GLS showed moderate correlation with PRSW (r=-0.550, p &lt; 0.01), whereas GMWI correlated more significantly, but still moderately with the invasively measured LV contractility (r = 0.681, p &lt; 0.001). Correlation between the pressure-area-strain loop-derived GMWIA and P-V analysis-derived PRSW (Figure 1D) was found to be very strong (r = 0.924, p &lt; 0.001). Conclusions In the case of LV volume overload-induced heart failure, our pressure-area-strain loop-derived metric reflected LV contractility better than GLS and even GMWI. Therefore, the incorporation of instantaneous LV size into myocardial work calculation represents a promising clinical tool to assess and monitor intrinsic myocardial function independently of loading conditions. Abstract Figure 1

Association between microvascular dysfunction and impaired myocardial deformation in hypertrophic cardiomyopathy

Funding Acknowledgements Type of funding sources: None. Objective To analyze the relationship between coronary microvascular dysfunction (MCD) and left ventricular (LV) myocardial deformation in hypertrophic cardiomyopathy (HCM). Methods Prospectively inclusion of HCM patients (P). MCD was assessed by CMR, during regadenoson-induced hyperemia. For perfusion assessment, the myocardium was divided into 32 subsegments (16 AHA segments subdivided into an endocardial and epicardial layer). Ischemic burden was calculated as the number of involved subsegments, assigning 3% of myocardium to each subsegment. Epicardial coronary artery disease was excluded by computed tomography or invasive coronary angiography. LV myocardial deformation was evaluated by 2D and 3D speckle-tracking echocardiography (STE), including global longitudinal strain (GLS), peak systolic dispersion (PDS), global circumferential strain (GCS), global radial strain (GRS), area strain, twist and torsion. Results 31 P enrolled (51%male,age57.8 ± 15.5years). Asymmetric septal hypertrophy was seen in 55%, apical in 29%, concentric in 16%,maximal wall thickness (MWT) of 20.5 ± 4.9mm; 26% with LVOT obstruction; LV ejection fraction 67.9 ± 7.9%. In 2DSTE analysis, P with more ischemia (&gt;20%of LV) presented more severe impaired GLS and greater PDS, comparing with patients with ≤20% of ischemia. Similarly, 3DSTE imaging showed worse LV performance in P with greater ischemic burden, expressed by significant difference in GLS, GRS and area strain. GCS also trended to be worse in the presence of &gt;20% of ischemia. The stronger correlation was found between 2D GLS and ischemic burden (Pearson correlation factor 0.545; p = 0.002). Conclusion In HCM, the severity of ischemia secondary to MCD was associated with impairment in LV myocardial deformation evaluated by 2D and 3D STE. Table 1. Echocardiography Ischemic burden (% of LV) 2D parameters ≤ 20% (n = 15) &gt; 20% (n = 16) p-value GLS (%) -15.6 ± 2.7 -12.1 ± 4.7 0.016 PSD (ms) 73.2 ± 25.6 102.1 ± 57.6 0.150 3D parameters GLS (%) -10.3 ± 4.5 -7.3 ± 3.0 0.010 GCS (%) -12.6 ± 3.0 -10.1 ± 4.5 0.079 GRS (%) 30.8 ± 8.5 22.8 ± 11.4 0.035 Area strain(%) -20.8 ± 4.9 -15.8 ± 6.3 0.020 Twist (deg) 6.0 ± 4.8 4.1 ± 4.0 0.175 Torsion (deg/cm) 1.2 ± 0.9 0.8 ± 0.7 0.232

Features of Constructing Recrystallization Curves of the 2nd and 3rd Types for High-Alloy Alloys of Various Structural Classes VZH159 and 14Cr17Ni2

The features of methods for constructing recrystallization curves of the second and third kind and the dependence “average grain size (area) - strain intensity – temperature” are given. For alloys of various structural classes VZH159 and 14Cr17Ni2 using the above methods, a recrystallization curve and the recrystallization dependence for a temperature of 1100℃ are constructed. The advantages and disadvantages of the above methods are considered.

Pilot study to predict future cardio-vascular events by novel 3D- echocardiography Global area strain in STEMI patients managed by primary PCI

Background Three-dimensional speckle tracking echocardiography (STE) is an ideal modality for accurate assessment of myocardial deformation, the Novel 4D-Global Area strain (GAS) is a very sensitive parameter in detection of subtle changes involving the myocardium as it encompasses both global longitudinal and global circumferential strains . Objectives To investigate the predictive value of four dimensional (4D) strain echocardiography for major adverse cardio-vascular events (MACE) in ST-elevation acute myocardial infarction (STEMI) after successful reperfusion by primary PCI. Methods 171 patients who underwent successful primary PCI were enrolled and properly examined by 2D and 4D echocardiography with 4D strain parameters evaluation then followed up all-over a year for the occurrence of Major adverse Cardiovascular Events (MACE) . Results Thirty two MACE were recorded in 170 patients who completed the follow-up period for one year, compared with those without MACE, patients with MACE had PTCA done during the index Primary PCI intervention, had multi-vessel CAD affection, higher LVEDD, higher LVESD, lower 2D- LVEF, higher WMSI, higher baseline HR, higher EDV and ESV, lower 3D- LVEF, higher 3D-GLS, 3D-GCS and 3D-GAS with lower 3D-GRS, all with p-values &lt; 0.005. Multi-variant logistic regression analysis showed that GAS was the most powerful predictor for MACE among our study population with the best cut-off value of 3D-GAS&gt; -17, with p-value of (0.008) OR (20.668), CI (2.227-191.827) with relative risk of adverse events of 18.205 (95% CI 6.976- 47.506 – P value &lt; 0.001). Conclusion Our data supports the superiority of 4D strain echocardiography parameters specially GAS for prediction of adverse clinical events among patients managed by successful primary PCI .

P1400 Improving ischemia diagnosis: 3D speckle-tracking stress echocardiography

Background 2D stress echocardiography (SE) is based in the visual analysis of wall motion abnormalities and it requires a trained operator. This operator-dependence has promoted the search for a semiautomatic method to reduce SE limitations and improve test accuracy. The aim of this study was to evaluate the value of 3D speckle tracking (3DSTE) in SE in patients with chest pain. Methods 44 consecutive patients with chest pain and pathological findings on CCTA (&gt;50% stenosis or high calcium score (&gt;400 HU) with undetermined severity) were included. These patients underwent SE with acquisition of 3DSTE at rest and at peak stress. Results Mean age was 63.9 ± 9.9 years. 90% were men. The images of the 44 patients were processed with automatic tracking and manual corrections. 11 patients developed inducible ischaemia during SE. Patients with ischaemic response showed significant reductions in 3D area strain (AS) compared to resting values. The 33 patients without inducible ischaemia showed, however, a significant increase in this parameter. Results are shown in table 1. Conclusion 3D area strain SE could help to identify patients with inducible ischemia. However, further studies are need to confirm these data. Ischemia + (n = 11) Ischemia - (n = 33) P 2D LVEF rest 57.2; 5.5 61.4; 6.0 0.04 2D LVEF peak stress 56.9; 11.7 70.0; 9.0 &lt;0.01 3D LVEF at rest 54.3; 6.9 64.3; 9.7 0.17 3D LVEF peak stress 51.9; 22.5 66.0; 8.6 0.17 AS rest 38.3; 5.1 40.4; 5.7 0.29 AS peak stress 37.2; 11.3 43.6; 7.2 0.03 LVEF: left ventricle ejection fracion; AS: area strain.