Residual Gradient Research Articles

Abstract 4120743: MEK inhibition for recurring pulmonary valve stenosis in RASopathy patients

Backgound: The RASopathies are developmental syndromes resulting from variants in the RAS/mitogen-activated protein (MAPK) cascade. The vast majority of RASopathy-causing variants lead to a gain of function in RAS-MAPK signaling. This has motivated compassionate use of MEK inhibition (MEKi) for rare, but potentially lethal complications such as hypertrophic cardiomyopathy and lymphatic disease. However, the most recurrent cardiac complication in RASopathies is pulmonary valve stenosis (PVS). PVS may require balloon valvuloplasty (BV) and can recur over time. Research question: Can MEKi be successfully used for recurrent PVS in RASopathy-patients? Aim: To report compassionate use of MEKi (trametinib) in recurring RASopathy-associated PVS. Method: Retrospective, single-center study at CHU Sainte Justine, Montreal, from 2021 to 2024. Results: After informed parental consent for off-label compassionate use of trametinib, four patients with recurrence of severe PVS after balloon valvuloplasty (>= 80 mmHg) had a total of 5 treatment episodes. Three patients were female, and one patient was male. The following genotypes were represented: Case 1, RIT1 A77V; case 2, PTPN11 N308D; case 3, RIT1 F82V, del22q11dist; case 4, PTPN11 Q110G, dup Xp22.13 (VUS), dup 16p11.2. Initial BV was carried out between three weeks and 10 months of age. Recurrence of PVS was noted between 4 days and 6 months after BV. Peak gradients at recurrence measured 72 -96 mmHg, and decreased to 40 – 64 mmHg (Dp -10 to -40 mmHg) at one to three months after treatment. Treatment had to be stopped in three cases for cutaneous side effects, with a rapid second recurrence in one case, which again responded to MEKi. PVS residual gradients at latest follow-up ranged from 30 – 69 mmHg. In all four patients, repeat catheter intervention or surgery could be avoided. In three out of four RASopathy patients with severe recurrent PVS after initial BV, we observe mild or moderate residual PVS. The patient with residual severe PS also carries a del22q11.2dist, which renders her haploinsufficient for LZTR1, a potential disease/treatment modifier within the RAS-MAPK cascade. Conclusion: Our results potentially expand the indications for MEKi in selected cases of RASopathy-associated recurrence of PVS and suggest an alternative to surgery or repeat catheterization. However, this case series is limited by the lack of an adequate contemporaneous, genotyped control cohort and its retrospective nature.

A sex-specific comparison of valve-in-valve transcatheter aortic valve implantation

Abstract Introduction Valve-in-valve (ViV) transcatheter aortic valve implantation (TAVI) is a viable and less-invasive alternative to open heart surgery in selected patients with bioprosthetic valve dysfunction. Since patients receiving initially a new bioprosthetic aortic valve are predominantly male, data on a sex-specific comparison of ViV-TAVI is scarce. Thus, we compared patient characteristics, procedural outcomes, and 1-year outcomes of female (F) versus male (M) patients with failing bioprosthetic aortic valves undergoing ViV-TAVI. Methods A total of 375 Patients at 3 German centres were included in this analysis. The 1-year mortality was the primary outcome measure, secondary outcomes included VARC-3 defined technical and device success and early safety. Results Overall, 160 (42.6 %) women and 215 (57.4 %) men were included. Women were older (F 81 (77; 84), p < 0.001), had a greater surgical risk (STS PROM F: 9.1 (6.1; 13,9) %, p < 0.001) and a higher rate of previous coronary bypass surgery (F: 25.6 % vs M: 40 %, p = 0.004), while presenting mostly failed valve sizes < 20 mm (F: 59.4 % vs M: 33.4 %, p < 0.001) and therefore higher gradients (F: 40 (31; 50) mmHg vs M: 32 (25; 42) mmHg, p < 0.001). Aortic regurgitation was the mode of failure in 7.5 % of F vs. 14.4 % of M. The number of stentless valves was higher in men (F: 8,1 % vs M: 14 %, p = 0.08). Patients received a self-expanding TAVI prostheses in 79.4 % and 75.8 % respectively in F and M patients. The rates of technical success (F: 75.6 % vs M: 83.3 %, p =0.06), device success (F: 52.5 % vs M: 58.2 %, p = 0.27) and early safety (F: 67.5 % vs M: 67 %, p = 0.91) were comparable between genders. Residual mean gradients were higher in F (F: 15 (11;22) mmHg vs M: 15 (10; 20) mmHg, p = 0.03), while the rates of residual regurgitations were greater in M patients (F: 1 (0.6 %) vs M: 11 (5.1 %), p = 0.04). The Kaplan-Meier estimated 30-day mortality rate (F: 2.5% vs M: 3.3%, p = 0.66) and 1-year mortality rates (F: 10 % vs M: 92.6 %, p = 0.37) were comparable between genders. Conclusion: F and M patients treated by ViV-TAVI have comparable short-term outcomes according to VARC-3-defined endpoints and similar mortality rates after 30 days and 1 year. The residual gradients in F and residual regurgitations in M could be explained by structural features of their failed valves. Further large scale studies are needed to determine, if such procedural outcomes are truly sex-specific.

Calculation of intraprocedural hemodynamics with computational functional dynamic in mitral valve edge-to-edge repair

Abstract Background Hemodynamic outcomes in patients undergoing transcatheter edge-to-edge-repair of the mitral valve (M-TEER) are difficult to predict. Computational functional dynamic (CFD) is frequently used in biomedical engineering to simulate blood flow patterns under various conditions. The authors developed a standardized workflow for individualized analyses and investigated the hemodynamic of mitral regurgitation volumes and gradients by using CFD. Methods 20 patients from two high volume centers who suffered from severe mitral regurgitation (MR) and underwent full cycle cardiac computed tomography (CT) prior procedure were enrolled. Baseline computed tomography and intraprocedural data were analyzed. Based on the specific valve morphology, individualized CFD-simulations were performed to calculate MR volumes prior to intervention and estimate hemodynamics after M-TEER. Results CFD-analyses of 20 patients (mean age 80±4 years, 60% male) showed excellent correlation between baseline PISA method-based MR volumes (45±23ml) measured in transesophageal echocardiography (TEE) and CFD-based calculation (45±26ml; R=0.917; P<0.001) as well as between TEE-measured mean baseline effective regurgitant orifice area (EROA; 27±16mm²) and CFD-measured EROA (24±18mm²; R=0.869; P<0.001)). After device implantation, correlation between intraprocedural TEE-measured and CFD-estimated correlation for residual MR volumes (R=0.949; P<0.001) and EROA (R=0.841; P<0.001) remained robust. Post-interventional mean diastolic pressure gradient (TEE) was 3.6±2.8mmHg which was in close correlation with the CFD estimated gradient (3.0±1.8mmHg, R=0.905; P<0.001). Conclusions This is the first study to use a CFD-standardized workflow for predicting hemodynamic changes in patients undergoing M-TEER using data from two different centers. In the future, CFD-based analyses might serve as a key-diagnostic tool for predicting residual MR volumes and gradients for M-TEER-procedures.Comparison of TEE and CFD flow patternBland-Altman-Blots

Microstructure and residual stress gradient evolution mechanism of electronic copper strip for lead frame

The miniaturization of integrated circuits has led to a shift in lead frame fabrication methods from physical stamping to chemical etching. However, this process is highly sensitive to residual stress. We investigated the gradient distribution of residual stress, microstructure, and macroscopic texture in electronic copper foils using a layer-by-layer peeling method, and proposed a novel strategy for evaluating residual stress levels. Our findings reveal that the rolling-induced residual stress exhibits a gradient distribution along the thickness direction. Specifically, from the surface to the central layer, the stress transitions gradually from tensile to compressive, with the stress type primarily influenced by metal flow during rolling. Additionally, we observed gradient variations in the S and Cube texture. Tensile stress favors the formation of Cube-texture, while compressive stress promotes S-texture development. Notably, Cube-texture can lead to strain localization during rolling, directly impacting the local residual stress levels and distribution. Furthermore, quantitative analysis of dislocation density using peak profile methods revealed a consistent trend between {111} plane dislocation density and lateral residual stress. Further investigation highlighted that dislocations and precipitates associated with {111} planes in face-centered cubic metals significantly influence residual stress, with their combined effects determining the overall stress magnitude in relation to texture, dislocations, and precipitates.

Clinical Outcomes of Concomitant Secondary Chordal Cutting to Surgical Myectomy in HOCM.

In patients who underwent surgical septal myectomy for hypertrophic obstructive cardiomyopathy (HOCM), additional mitral valve repair may offer additional benefits in terms of further reducing left ventricle outflow tract (LVOT) gradients, systolic anterior motion (SAM) and mitral regurgitation (MR). We performed a systematic review of the literature to evaluate the evidence of surgical myectomy with additional secondary chordal cutting in patients with HOCM. A systematic literature search in MEDLINE and EMBASE was performed until April 2024. The primary outcome studied was postoperative echocardiographic LVOT-gradient. A random effects meta-analysis of means was performed for the primary outcome. The secondary outcomes studied were postoperative residual MR-grade, 30-day new permanent pacemaker implantation, and in-hospital mortality. From 1911 unique publications, a total of 6 articles fulfilled the inclusion criteria and comprised 471 patients with a pooled mean preoperative resting LVOT gradient of 84 mmHg (95% CI: 76-91). The postoperative pooled mean LVOT-gradient was 11 mmHg (95% CI: 10 - 12) with a low heterogeneity (I2 = 44%). The residual LVOT gradient exceeding 30 mmHg was present in 9 (1%) patients. MR-grade 3 or 4 at hospital discharge was present in 7 (1%) patients. The 30-day new permanent pacemaker implantation rate was 7% and the in-hospital mortality was 0.4%. This systematic review and meta-analysis demonstrate that combining surgical septal myectomy with secondary chordal cutting can be performed safely and effectively eliminate LVOT obstruction in HOCM patients. Further studies are needed to determine the additive effectiveness of additional secondary chordal cuttings.

Improvement of gradient microstructure and properties of wire-arc directed energy deposition titanium alloy via laser shock peening

Wire-arc directed energy deposition (WADED) technology has been widely used in the remanufacturing of titanium alloy structural components benefited from with the advantages such as high deposition efficiency and low cost. However, due to the coarse and anisotropic microstructure, the complex internal stresses and processing-induced rough surface significantly reduce fatigue performance and reliability of the remanufactured structural components. In this work, surface modification of titanium alloy WADED repair component was carried out via laser shock peening (LSP), and its gradient structure, microhardness, residual stress and fatigue performance and enhancement mechanism were systematically investigated. Results indicated that the different microstructure of each region led to different responses under the action of LSP, which was related to the change of dislocation density. LSP induced crystal defects such as high-density dislocations, twins and stacking faults on the surface. A variety of crystal defects gradually decreased with the depth from the strengthened surface, formed a gradient microstructure and significantly affected the microhardness and residual stress of the repaired components. The surface hardness and compressive residual stress of the repaired components were greatly increased after LSP and the hardened layer and compressive residual stress depth affected layer were 600 μm and 800 μm, respectively. The average fatigue life of the additive repair component increased by 197 % under the synergistic effect of compressive residual stress and gradient microstructure.

Combined Impact of Residual Mitral Regurgitation and Gradient After Mitral Valve Transcatheter Edge-to-Edge Repair

BackgroundReducing mitral regurgitation (MR) during mitral transcatheter edge-to-edge repair (M-TEER) may come at the cost of increased mitral valve gradient (MVG). The combined impact of residual MR and MVG on clinical outcomes after M-TEER is unknown. ObjectivesThis study sought to evaluate the impact of postprocedure MR and MVG on clinical outcomes after M-TEER. MethodsEXPANDed is a pooled, patient-level cohort of the EXPAND (A Contemporary, Prospective Study Evaluating Real-world Experience of Performance and Safety for the Next Generation of MitraClip Devices) and EXPAND G4 studies, which were designed to evaluate real-world safety and effectiveness of the third- and fourth-generation MitraClip TEER Systems. Subjects were categorized by echocardiographic core laboratory (ECL) assessments into 4 groups according to 30-day MR grade and mean MVG: 1) MR ≤1+/MVG <5 mm Hg; 2) MR ≤1+/MVG ≥5 mm Hg; 3) MR ≥2+/MVG <5 mm Hg; and 4) MR ≥2+/MVG ≥5 mm Hg. ResultsA total of 1,723 subjects had evaluable echocardiograms at 30 days: 72% had MR ≤1+/MVG <5 mm Hg, 18% had MR ≤1+/MVG ≥5 mm Hg, 7% had MR ≥2+/MVG <5 mm Hg, and 3% had MR ≥2+/MVG ≥5 mm Hg. MR≤1+ was sustained through 1 year in 93% of patients who achieved 30-day MR≤1+. MVG decreased from 30 days to 1 year in subjects with MVG ≥5 mm Hg (6.7 ± 4.0 to 5.5 ± 2.5 mm Hg MR ≤1+/MVG ≥5 mm Hg and 6.5 ± 1.5 to 5.5 ± 1.7 mm Hg MR ≥2+/MVG ≥5 mm Hg). One-year rates of all-cause mortality and heart failure hospitalization were lower for subjects who achieved MR ≤1+ at 30 days, regardless of MVG. ConclusionsReduction of MR to mild or less after M-TEER with the latest-generation MitraClip systems was associated with clinical benefit regardless of MVG.

Supra-Annular Self-Expanding Versus Balloon-Expandable Valves for Valve-in-Valve Transcatheter Aortic Valve Replacement

Self-expanding (SE) and balloon-expandable (BE) transcatheter heart valves (THVs) have not been extensively studied in valve-in-valve transcatheter aortic valve replacement (ViV-TAVR). We compared outcomes of supra-annular SE and BE THVs used for ViV-TAVR via a retrospective analysis of institutional data (2013-2023) including all patients undergoing ViV-TAVR (TAVR in previous surgical AVR). Unmatched and propensity-matched (1:1) comparisons of clinical and echocardiographic outcomes were undertaken between SE and BE THV along with Kaplan-Meier survival analysis. A total of 315 patients undergoing ViV-TAVR were included of which 73% received a SE THV. Median age was 77 years and women comprised 42.5% of the population. Propensity-score matching (1:1) yielded 81 matched pairs. Implanted aortic valve size was comparable between the groups (23 mm [23-26] vs. 23mm [23-26], p=0.457). At 30 days following ViV-TAVR, the SE group had a lower mean aortic valve gradient (14 mmHg [11-18] vs. 17.5 mmHg [13-25], p=0.007). A higher number of BE patients had severe prosthesis-patient mismatch (PPM) (16% vs. 6.2%, p=0.04). At one-year follow-up, the SE group had a lower aortic valve gradient (14.0 mmHg [9.6-19] vs. 17 mmHg [13-25], p=0.04) compared to the BE group. 30-day mortality was 2.7% while one-year mortality was 7.5% and comparable between the groups. Survival and stroke incidence were similar in both groups up to 5 years. In conclusion, both SE and BE THVs had comparable survival following ViV-TAVR. The higher residual aortic valve gradients in BE THVs are likely due to valve design and warrant long-term evaluation for potential structural valve degeneration.

Impact of three-dimensional imaging and printing on septal myectomy results-single centre's experience.

To assess changes in the results of septal myectomy (SM) following introduction of three-dimensional (3D) imaging and 3D printing in surgical interventions planning and performing in the single-centre settings. Between January 2007 and March 2022, 268 consecutive symptomatic patients with hypertrophic obstructive cardiomyopathy and peak pressure gradient at obstruction area ≥50 mmHg underwent conventional SM (n = 112) or SM with heart 3D modelling (n = 156). For comparative analysis, we used propensity score matching (PSM) by 14 variables and there were formed group 1PSM (conventional SM, n = 77) and group 2PSM (3D-modelled SM, n = 77). It was noted for group 2PSM: larger mean resected myocardium mass [10.0 (standard deviation 4.3) vs 5.2 (standard deviation 2.7) g], P < 0.001, no mitral valve replacement cases [0 vs 28 (36.4%), P < 0.001], no iatrogenic ventricular septal defects cases [0 vs 6 (7.8%), P = 0.028], lower rate of major complications [6 (7.8%) vs 17 (22.1%), P = 0.011], smaller residual peak systolic gradient at the obstruction level [7.0 (5.0-9.0) vs 11.0 (7.0-16.0) mmHg, P < 0.001]. During the long-term follow-up, it was noted for group 2PSM as compared to group 1PSM: lower 5-year cumulative incidence of major adverse cardiovascular events [3.8% (95% confidence interval 0.7-11.7%) vs 16.9% (9.5-26.1%), P = 0.007] and cardiac-related death [3.8% (95% confidence interval 0.7-11.7%) vs 13% (95% confidence interval 6.6-21.6%), P = 0.05]. SM based on 3D virtual and printed heart models is more effective than conventional SM.

Prognostic implications of residual mild coarctation gradient after interventional repair.

There is limited data on the prognostic implications of residual mild coarctation (RMC) in patients with repaired native coarctation of the aorta (CoA). To explore the association of RMC with mid-term comorbidities in post-interventional patients, and the predictive value of the residual pressure gradient. The authors retrospectively analyzed 79 native CoA patients who received successful intervention at our hospital between October 2010 and June 2023. The outcomes of the study were late arterial hypertension (either raised blood pressure or commencement of hypotensive medications) only in normotensive patients at early follow-up and the composite mid-term comorbidities including new-onset aortic injury, re-stenosis, and re-intervention. At a median follow-up of 60months, late hypertension and mid-term comorbidities occurred in 16 (28.1%) and nine (11.4%) patients, respectively. Multivariate Cox proportional hazard regression analysis identified invasive peak systolic CoA pressure gradient (PSPG) as the best independent predictor of both outcomes. The maximally selected rank statistics indicated 10mm Hg as the best PSPG cut-off value for predicting late hypertension. Compared to patients with PSPG<11mm Hg, the cumulative event rates of both outcomes were higher in those with PSPG≥11mm Hg (log-rank test, p<.001 for both endpoints). PSPG≥11mmHg was proved to be the independent predictor of late hypertension with a significantly increased risk. In patients with non-surgical CoA repair, the post-interventional RMC and PSPG ≥11mm Hg are important predictors of clinical comorbidities at mid-term follow-up.

Effect of compound surface modification of shot peening and DLC coating on surface integrity and fatigue properties of gear steel 16Cr3NiWMoVNbE

We conducted a study on the surface compound modification of shot peening and pure carbon DLC coating to simultaneously meet the requirements of wear resistance and fatigue resistance of spline structure. The effects of surface compound modification were investigated on the surface morphology, residual stress profile, microstructure, and nano-indentation hardness of 16Cr3NiWMovNbE gear steel, and conducted a comparative study on fatigue performance. The results show that the surface compound modification inherits the surface morphology and compressive residual stress gradient of shot peening, while the surface residual stress is slightly smaller than that of shot peening. In addition, surface compound modification still reflects the characteristics of high hardness and high fracture resistance of DLC coatings. Under the bending load based on spline tooth root, compared to the original specimen, the fatigue life after shot peening, pure carbon DLC coating, and surface compound modification is increased by 3.68, 2.35, and 3.36 respectively. Although the compound modified surface still maintains the shot peening morphology with a increasing surface roughness and stress concentration coefficient, the 100 μm-depth compressive residual stress profile and the subgrain refinement layer introduced, as well as the hard surface layer with good load-bearing capacity, have played the role of fatigue strengthening.

Five-Year Outcomes of Measured and Predicted Prosthesis-Patient Mismatch following Transcatheter Aortic Valve Implantation

BackgroundData on the long-term outcomes of prosthesis-patient mismatch (PPM) after transcatheter aortic valve implantation (TAVI) remain controversial. ObjectivesThe aim of this study was to investigate the incidence and clinical outcomes of measured PPM (PPMM) and predicted PPM (PPMP) in patients undergoing TAVI. MethodsThis is a retrospective analysis of 3,016 patients who underwent TAVI at a large Healthcare System between 2012 and 2021. Effective orifice area indexed to body surface area (EOAi) was measured at discharge using the continuity equation. EOAi was predicted according to the published predictive tables for each model and size of the valve. Primary endpoint was 5-year survival rate. ResultsMean age was 80 years and 55.6% were male. The mean STS risk score was 4.66%. 74.9% of patients received a BEV and 25.1% received a SEV. The incidence of severe PPM was markedly lower when defined by predicted vs. measured EOAi (0.8% vs. 6.3%, P < 0.001) and when assessed in SEV vs. BEV (5.3% vs. 6.6%, p= 0.02). Neither severe PPMp nor severe PPMM was associated with 5-year mortality (HR=1.26, 95% CI= 0.96-1.66, p=0.095; HR=1.03, 95% CI= 0.42-2.49, p=0.954, respectively), irrespective of the presence of high residual pressure gradient. Neither BEV nor SEV was associated with an increased 5-year mortality, irrespective of PPM definition or severity. ConclusionsIn this large healthcare system analysis, neither severe PPMP nor severe PPMM was associated with five-year all-cause mortality. There was no difference between BEV and SEV in terms of mortality, irrespective of the definition or severity of PPM.

Optimized estimation of marine deflection of the vertical from multibeam laser altimeter data of ICESat-2

SUMMARY Satellite altimetry data, with its increasing density and quality, has become the primary source for marine deflection of the vertical (DOV) and gravity anomaly modelling. Limited by orbital inclinations, the precision of the meridian component of the gridded deflection of the vertical (GDOV) calculated by traditional altimetry satellites is significantly better than that of the prime vertical component, and the excessive precision difference between these two components restricts the inversion precision of marine gravity anomaly model. The study of cross-track deflection of the vertical (CTDOV) is enabled by the multibeam synchronous observation mode of the new laser altimetry satellite, Ice, Cloud and Land Elevation Satellite-2 (ICESat-2). Based on the remove-restore method, residual geoid gradients are first calculated in this paper using three approaches: along-track (A-T), cross-track (C-T) and an integration of along-track and cross-track. Vertical deflections are then computed on a 1′ × 1′ grid using the least squares collocation (LSC) method, and the precision is verified against the SIO V32.1_DOV model. An optimized combination is proposed to address the issue of precision differences between the meridian and prime vertical components, and to enhance the precision of DOV inversion. A new DOV combination is formed by combining the meridian component from along-track deflection of the vertical (ATDOV) with the prime vertical component from cross-track deflection of the vertical (CTDOV) based on the remove-restore method. The Philippine Sea (0°–35°N, 120°–150°E) is selected as the test area to verify the feasibility of the optimized combination. The results indicate that the optimized combination of the meridian and prime vertical components achieved test precision of 2.63 and 3.33 μrad, respectively, when compared against the SIO V32.1_DOV model. The precision gap between the components is effectively narrowed by this approach, which maintains the precision of the meridian component and enhances that of the prime vertical component, thereby achieving optimal inversion precision for gravity anomalies.

Posterior Leaflet Mitral Valve Repair with Septal Myectomy For Hypertrophic Cardiomyopathy

Posterior Leaflet Mitral Valve Repair with Septal Myectomy For Hypertrophic Cardiomyopathy

Pictorial rendition of author’s observations on balloon valvuloplasty/angioplasty procedures: Aortic stenosis

Balloon aortic valvuloplasty (BAV) effectively decreases peak pressure gradients through the aortic valve both at the time of the procedure and during follow-up. This paper presents the author&amp;rsquo;s observations on the utility of BAV in treating congenital aortic valve stenosis (AVS). Previous work by the author noted intermediate-term restenosis and late-onset aortic insufficiency (AI). Factors contributing to restenosis include age under 3 years and post-balloon residual aortic valve gradients exceeding 30 mmHg. Repeat balloon valvuloplasty has been found to address restenosis effectively. However, the onset of AI at late follow-up is a significant disadvantage of BAV. Despite this, BAV is currently considered a beneficial treatment option for managing AVS in children, adolescents, and young adults. In contrast, seniors with calcific AVS do not experience relief from obstruction with BAV and are candidates for aortic valve replacement through transcatheter methodology, a procedure not reviewed in this paper. BAV provides relief of obstruction across the aortic valve and functions as an alternative to surgical intervention. Consequently, BAV is considered a preferred choice in addressing aortic stenosis in the pediatric patient.

Supra-Annular Versus Intra-Annular Self-Expanding Valves in Small Aortic Annulus: A Propensity Score-Matched Study

BackgroundTranscatheter aortic valve replacement (TAVR) with self-expanding valves (SEVs) may have different outcomes with supra-annular valves (SAVs) or intra-annular valves (IAVs) in patients with small aortic annuli (SAA), but this topic remains underexplored. We aimed to evaluate outcomes between different SEVs, namely SAVs (CoreValve/Evolut R/PRO/PRO+/FX) vs. IAVs (Portico/Navitor). MethodsSingle-center data with patients with SAA (maximum diameter <23 mm) who underwent TAVR from 2013 to 2023 with SEVs, followed by 1:1 propensity score matching (PSM). ResultsWe obtained 86 PSM pairs with median age of 83.0 years (SAVs) and 82.0 years (IAVs), with women representing 77.6% of the PSM cohort. After TAVR, we did not find statistically significant differences for the following outcomes: Valve Academic Research Consortium-3 periprocedural mortality, technical success, device success, clinical efficacy, and rates of paravalvular leak were not statistically significantly different, but we found higher rates of permanent pacemaker implantation in the IAV group (1.2 vs. 8.1%; p = 0.029). Despite the larger indexed effective orifice area with SAVs (median 1.0 vs. 0.8 cm2/m2, p = 0.001), we did not find statistically significant differences between the groups in terms of residual mean gradients >20 mmHg (0.0 vs. 2.3%, p = 0.155), and severe prosthesis-patient mismatch (2.3 vs. 5.8%, p = 0.390). No statistically significant difference was observed in survival (log-rank p = 0.950) and stroke (p = 0.6547) between patients who received SAVs and IAVs. For patients with SAA, TAVR with SEV devices is safe. ConclusionsIAVs and SAVs are associated with comparable device performance in terms of hemodynamic structural and nonstructural dysfunction. Randomized data are needed to validate these findings and guide informed device selection.

Backside metallization affects residual stress and bending strength of the recast layer in laser-diced Si

Thin Silicon dies separated by laser dicing form a thin layer via redeposition of ablated silicon known as recast layer. This work analyzed the influence of the recast layer microstructure and nanoscale residual stress gradients on the bending strength of bare and metalized silicon dies <100 μm. Scanning and transmission electron microscopy revealed an intricate microstructure of ablated silicon and elements of the wafer backside metallization within the recast layer. Refined silicon grains decorated by nanoscopic metallic precipitates at their grain boundaries were observed. Cross-sectional synchrotron X-ray nanodiffraction revealed that the altered microstructure increased the tensile residual stress from 200 to 295 MPa for bare and metalized dies, respectively. Additionally, the metalized die exhibited gradients in residual stress and grain size between the die front- and backside. Despite their similar frontside bending strengths of ∼340 MPa, observed in 3-point bending experiments, a considerable strengthening of the backside from 425 up to 957 MPa was measured for bare and metalized die, respectively. The origins of the tensile residual stress and the influence of the backside metallization on the die bending strength are discussed.

A study of stress, composition and grain interaction gradients in energy-dispersive X-ray stress analysis on materials with cubic symmetry.

The influence of various combinations of residual stress, composition and grain interaction gradients in polycrystalline materials with cubic symmetry on energy-dispersive X-ray stress analysis is theoretically investigated. For the evaluation of the simulated sin2ψ distributions, two different strategies are compared with regard to their suitability for separating the individual gradients. It is shown that the separation of depth gradients of the strain-free lattice parameter a 0(z) from residual stress gradients σ(z) is only possible if the data analysis is carried out in section planes parallel to the surface. The impact of a surface layer z* that is characterized by a direction-dependent grain interaction model in contrast to the volume of the material is quantified by comparing a ferritic and an austenitic steel, which feature different elastic anisotropy. It is shown to be of minor influence on the resulting residual stress depth profiles if the data evaluation is restricted to reflections hkl with orientation factors Γ hkl close to the model-independent orientation Γ*. Finally, a method is proposed that allows the thickness of the anisotropic surface layer z* to be estimated on the basis of an optimization procedure.

Routine postdilation after 23 mm Sapien 3 Ultra implantation in the aortic position.

Residual transprosthetic gradient (TG) after transcatheter aortic valve replacement (TAVR) with balloon-expandable valves (BEV) may be due to suboptimal valve expansion. To compare hemodynamics after TAVR with small BEV according to postdilation strategy. This observational, retrospective cohort study included 184 consecutive patients from a single center treated with 23 mm Sapien 3 Ultra (Edwards Lifesciences) BEV implantation in the aortic position and enrolled between January 2020 and April 2023. Patients treated with routine postdilation (RP, n = 73) were compared to patients treated according to local standard practice (SP, n = 111). Primary endpoint was 30-day mean TG. Secondary endpoints were incidence of 30-day prosthesis-patient mismatch (PPM), technical success and device success. Thirty-day mean TG was lower in RP versus SP (12.3 ± 4.6 mmHg vs. 14.1 ± 5.7 mmHg, p = 0.031), and incidence of PPM was less common with RP versus SP (47.3% vs. 71.0%, p = 0.006). Technical success (98.6% vs. 99.1%, p = 0.637) and device success (93.1% vs. 90.1%, p = 0.330) did not differ between groups. Differences in 30-day mean TG were driven by patients at normal flow (12.1 ± 4.0 mmHg vs. 15.0 ± 5.5 mmHg, p = 0.014), while no differences were evident among patients at low flow (12.5 ± 5.5 mmHg vs. 11.7 ± 5.5 mmHg, p = 0.644). RP decreased height and increased width of BEV, and a linear regression established that final BEV width could predict 30-day mean TG (r = -0.6654, p < 0.0001). RP after TAVR with small BEV was associated with more favorable forward-flow hemodynamics than SP.

Optimization of tensile properties and anisotropy in a cryogenically treated laser additively manufactured high entropy alloy

Repetitive deep cryogenic soaking treatment (DCT) of laser metal deposition (LMD) processed CrMnFeCoNi high entropy alloy (HEA) significantly enhances its strength without compromising ductility. This is attributed to the compressive stress induced nanotwin formation, which in turn facilitates twin induced plasticity. In this work, a parametric study on the effect of the residual stress profile and the DCT cycles on the tensile properties of the HEA, along the build and scan directions is conducted. Towards this end, builds fabricated with 5 different laser powers, 1100, 1400, 1700, 2000 and 2300 W, are examined and the ones with highest and lowest residual stress gradient are considered for further DCT treatments. Results indicate that the build fabricated with 1400 W laser power, which has the highest gradient in initial residual stresses, exhibits a greater enhancement in dislocation and twin density with increasing number of DCT treatments. Compared to its as-built state the peak yield and tensile strength of the HEA (along the scanning direction) increases to 592 ± 13 and 778 ± 15 MPa, without significant decrease in its ductility after 12 DCT cycles. However, the enhancement in the dislocation, twin density and therefore, the strength, is minimal after it is treated to 15 DCT cycles. Anisotropy in both strength and ductility, which is of the order of 20-25 %, is also observed in the DCT treated builds along the build and scan directions. These observations were rationalized on the basis of dislocation and twin evolution and distribution during DCT and deformation of the build when deformed in different directions. Implications of these results in the context of employing DCT for strengthening LMD fabricated HEA components are discussed.