Characterization of Pt-coated twin paraboloidal laboratory capillary high energy X-ray optics.

Novel focusing optics composed of twin paraboloidal capillaries coated with Pt, for laboratory X-ray sources are presented and characterized. The optics are designed to focus the X-rays, resulting in an achromatic focused beam with photon energies up to 40 keV. The performance of the optics under different operational conditions is studied by comparing the energy-photon count spectra of the direct and focused beams. Based on these analyses, the optics gain and efficiency as a function of photon energy are determined. A focal spot of 8.5 µm with a divergence angle of 0.59° is observed. The obtained characteristics are discussed and related to theoretical considerations. Moreover, the suitability and advantages of the present optics for X-ray microdiffraction is demonstrated using polycrystalline aluminium. Finally, possibilities for further developments are suggested.

Understanding repeat hospitalizations in intermediate-to-high risk aortic stenosis patients following transcatheter aortic valve replacement.

OBJECTIVES: We describe the causes, timing and predictors of readmissions and analyze its impact on clinical outcomes in intermediate-to-high-risk patients with severe symptomatic aortic stenosis (AS) who underwent transcatheter aortic valve replacement (TAVR). BACKGROUND: Intermediate-high risk TAVR patients with severe AS have an increased risk for hospital readmissions due to the high burden of comorbidities. METHODS: Patients who underwent TAVR from 2012 to 2018 at a single tertiary cardiac center were included and followed for 1 year. Readmissions were categorized as noncardiovascular (non-CV) and CV. RESULTS: A total of 611 patients (410 with no readmissions, 201 with ≥1 readmissions) were included. There was a total of 317 readmissions (mean: 1.58 ± 1.09 per readmitted patient) with 65 patients having ≥2 readmissions. 64.0% were non-CV and 36.0% were CV. The top three CV causes were pacemaker/implantable cardioverter-defibrillator placement, bleeding, and stroke. About 23% occurred at 1 m, the majority were CV; 45% occurred between 7 and 12 m, the majority were non-CV. Those with ≥1 readmissions had a higher burden of comorbidities including peripheral arterial disease, diabetes, immunosuppression, prior percutaneous coronary interventions, and dialysis. Readmissions were associated with higher 1-year mortality (adjusted hazard ratio: 2.53, 95% confidence interval: 1.40-4.59; p = 0.002). High-risk patients had higher non-CV readmissions (0.37 ± 0.79 vs. 0.25 ± 0.62; p = 0.044) compared to intermediate-risk patients but similar CV readmissions (p = 0.645). CONCLUSIONS: Understanding readmissions post-TAVR will promote the early identification of at-risk groups and the implementation of preventative measures to improve outcomes and reduce the burden and costs of readmissions.

Adjunctive use of fluoroscopy during MitraClip implantation reduces procedural complexity: The parallax technique.

BACKGROUND: During MitraClip implantation sub-valvular correction of trajectory and/or alignment may increase adverse clip or leaflet events. With systematic adjunctive use of fluoroscopy ("Parallax technique"), we aimed to assess parameters that minimize the need for corrective measures and help increase procedural efficiency. METHODS: We retrospectively analyzed 30 patients without (Fl-) and 39 patients utilizing adjunctive fluoroscopy (Fl+) during MitraClip implantation. After establishing trajectory and supra-valvular alignment, the Parallax technique was utilized. Trajectory and alignment are maintained during advancement. RESULTS: All patients had 3 or 4+ MR. There were no differences in baseline demographics. The average number of clips (Fl- vs Fl+) was 1.72 ± 0.8 vs 1.59 ± 0.5, p = .57. For the first clip, the need for sub-valvular alignment (80% vs. 36%, p = .0001), eversion with retraction back to left atrium (23% vs. 10%, p = .001) and the number of grasps (2.3 ± 1.2 vs 1.4 ± 0.9) was reduced. The time from transseptal puncture to first clip deployment (71 ± 21 vs 44 ± 16 min, p = .01) was reduced. Procedural success was achieved in all but one patient in the Fl- group (p = ns). There were no differences noted for in-hospital or 30-day outcomes. CONCLUSIONS: Systematic use of a simple and easy to implement "Parallax technique" was associated with reduced need for sub-valvular manipulation and was associated with improved procedural times. Further larger scale studies are needed to assess the applicability of the technique.

Retrieval of a MitraClip from the left atrium using a two-snare technique: Case report and review of the literature.

MitraClip is used for reduction of mitral insufficiency in patients who are not good surgical candidates, but with expanding indications, the use of MitraClip and the number of complications will increase. Here is presented a case of a single leaflet device attachment that worsened the patient's mitral insufficiency, as well as the technique for stabilizing the valve followed by retrieval of the device. A special focus is placed on removing the using a two-snare technique to avoid the need for a surgical cutdown and repair.

Transseptal access for left heart structural interventions in the setting of prior atrial septal defect closure.

A transseptal puncture is critical for "left-sided" structural heart interventions. Procedures such as transcatheter edge-to-edge repair (MitraClip) and left atrial appendage (LAA) closure (Watchman) require precise puncture of the interatrial septum (IAS), and the presence of a prior atrial septal defect (ASD) closure device poses a challenge. We aim to present a successfully completed case of MitraClip and Watchman in the presence of ASD closure device in two different patients. A review of the literature will be reported, and pertinent clinical and technical considerations will be discussed in depth to achieve procedural success. In summary, transseptal puncture for left heart structural interventions is feasible in the presence of a prior ASD/patent foramen ovale closure device. A detailed understanding of the anatomical considerations as well as the use of multimodality imaging to evaluate the IAS will aid in improving procedural success rates.

Metrology of a Focusing Capillary Using Optical Ptychography.

The focusing property of an ellipsoidal monocapillary has been characterized using the ptychography method with a 405 nm laser beam. The recovered wavefront gives a 12.5×10.4µm2 focus. The reconstructed phase profile of the focused beam can be used to estimate the height error of the capillary surface. The obtained height error shows a Gaussian distribution with a standard deviation of 1.3 µm. This approach can be used as a quantitative tool for evaluating the inner functional surfaces of reflective optics, complementary to conventional metrology methods.

Intraprocedural direct left atrial and wedge pressure correlation during transcatheter mitral valve repair: Results from a single center registry.

OBJECTIVES: This study investigates the correlation of occlusive wedge pressure (WP) with direct left atrial (LA) pressure in patients with severe mitral regurgitation (MR) undergoing transcatheter mitral valve repair (TMVr) with MitraClip. BACKGROUND: There is interest in acquiring objective hemodynamic parameters for intraprocedural guidance in patients undergoing MitraClip. METHODS: The study included 94 patients with severe MR at prohibitive surgical risk who underwent MitraClip at the University of California Davis Medical Center between 2014 and 2016. RESULTS: An average of 1.8 ± 0.7 clips were used to achieve MR grade of 2+ or less in 99% of patients. Correlation analysis of all (n = 236) pre-clip, inter-clip, and final-clip WP and LA pressures yielded a Pearson's R (r) of 0.85 and 0.79 for mean WP vs mean LA and WP V vs LA V, respectively. Median LA V to mean LA ratio (LAV:mLA) was 1.75 (IQR 1.5-1.9). 79% (n = 74) of patients had LAV:mLA ratio ≥ 1.5 with associated WP V vs LA V correlation (r) of 0.83. In patients with LAV:mLA ratio < 1.5, the correlation (r) was 0.69. Baseline characteristics were not significantly different between patients with LAV:mLA ratio ≥ 1.5 and patients with LAV:mLA ratio < 1.5. Post-procedure, median LA V: mean LA ratio decreased from 1.75 to 1.4, P = 0.0001. CONCLUSIONS: Correlation between WP and direct LA pressure in patients with severe MR undergoing Mitraclip is modest. Caution is advised when using WP to approximate LA pressure intraprocedurally, especially in patients with baseline low LAV:mLA ratios.

Initial clinical experience with the FlexPoint Steerable Transseptal Needle in left-sided structural heart procedures.

OBJECTIVES: The purpose of this study is to describe the initial clinical experience with a steerable transseptal needle (STSN) for left-sided structural heart procedures. BACKGROUND: Targeted transseptal (TS) puncture is required for many structural heart procedures, and the use of a steerable needle has not previously been described. METHODS: Consecutive patients undergoing structural heart interventions with targeted TS puncture under transesophageal echocardiographic (TEE) and fluoroscopic guidance were studied. The STSN was used in all patients with a standard commercial TS sheath. Deflection of the needle was performed "real time" to achieve localization of the TS puncture site. RESULTS: Twenty-seven patients underwent STSN puncture of the interatrial septum. In all cases, the needle could be deflected in vivo to achieve optimal tenting and localization of the puncture site without having to remove or reshape the needle. The needle was deflected to match a wide range of right atrial diameters (width 4.3 ± 0.9 cm and length 6.0 ± 0.9 cm in the 4-chamber view). In two patients with prior mitral valve surgery and a fibrotic septum, assisted crossing was achieved using the piercing stylet in one patient, and Bovie energy in the other. There were no procedural complications, and all patients had successful completion of the intended structural heart procedure. CONCLUSIONS: The STSN needle can be used to target the intended puncture location on the interatrial septum with real-time adjustable deflection without the need to remove and reshape the needle. In all cases crossing was successful and there were no complications.

X-ray fluorescence at nanoscale resolution for multicomponent layered structures: a solar cell case study.

The study of a multilayered and multicomponent system by spatially resolved X-ray fluorescence microscopy poses unique challenges in achieving accurate quantification of elemental distributions. This is particularly true for the quantification of materials with high X-ray attenuation coefficients, depth-dependent composition variations and thickness variations. A widely applicable procedure for use after spectrum fitting and quantification is described. This procedure corrects the elemental distribution from the measured fluorescence signal, taking into account attenuation of the incident beam and generated fluorescence from multiple layers, and accounts for sample thickness variations. Deriving from Beer-Lambert's law, formulae are presented in a general integral form and numerically applicable framework. The procedure is applied using experimental data from a solar cell with a Cu(In,Ga)Se2 absorber layer, measured at two separate synchrotron beamlines with varied measurement geometries. This example shows the importance of these corrections in real material systems, which can change the interpretation of the measured distributions dramatically.

Elemental fingerprinting of materials with sensitivity at the atomic limit.

By using synchrotron X-rays as a probe and a nanofabricated smart tip of a tunneling microscope as a detector, we have achieved chemical fingerprinting of individual nickel clusters on a Cu(111) surface at 2 nm lateral resolution, and at the ultimate single-atomic height sensitivity. Moreover, by varying the photon energy, we have succeeded to locally measure photoionization cross sections of just a single Ni nanocluster, which opens new exciting opportunities for chemical imaging of nanoscale materials.

Sustained Intraprocedural Cardiac Arrest During BASILICA TAVR.

The bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction (BASILICA) procedure allows patients with severe aortic stenosis and anatomical challenges from aortic leaflet orientation, positioning of coronary ostia, and height of sinuses of Valsalva to undergo TAVR. We present a case of intraprocedural cardiac arrest secondary to iatrogenic left main coronary artery obstruction following a successful BASILICA procedure.

Assembly of amorphous clusters under floating monolayers: a comparison of in situ and ex situ techniques.

We report synchrotron X-ray scattering studies of biomimetic crystallization of hydroxyapatite (the primary constituent of bone), using monolayers of fatty acid molecules floating on simulated body fluid (SBF) as well as aqueous solutions of calcium phosphate. A ∼10 Šthick film of amorphous material is observed to form immediately at the molecular monolayer, consistent with the proposed formation of "Posner clusters". This layer becomes denser but not significantly thicker as the subphase concentration and the temperature approach physiological conditions. The amorphous films do not crystallize within 24 h, in contrast to prior reports of more rapid crystallization using electron microscopy on ex situ samples. However, crystallization occurs almost immediately after our films are transferred onto solid substrates. These results illustrate the importance of in situ measurements for model biomineralization experiments.

Micro X-ray fluorescence reveals pore space details and spatially-resolved porosity of rock-based microfluidic devices.

Characterization of microscopic details of the fabric of mudstones and shales (i.e., structure and composition) is important to understand their storage and transport properties. Current characterization methods struggle to probe reliably multiple scales of interest (e.g., pore and fracture) and measure properties at the finest resolution under representative in situ conditions. Micro X-ray fluorescence (µXRF) is a high-performance imaging technique that produces elemental images at sub-10 µm spatial resolution and could offer insight into a diversity of shale properties, such as mineral composition, porosity, and in situ pressure gradients. This study designed and carried out a porosity mapping protocol using model and real-rock microfluidic devices and contrast fluids. Etched silicon micromodels with real-rock pore network patterns served as ideal models to establish a proof of concept. Measurements were performed on a novel µXRF microscope not powered by synchrotron radiation. We registered the µXRF datasets with the binary rock masks used for micromodel fabrication and applied segmentation algorithms to compare porosities. We assessed expected advantages and limitations through a sensitivity analysis and beam study. µXRF is an important new imaging technique for microfluidic applications.

Iatrogenic Atrial Septal Defect Closure Through the Steerable Guide Catheter: Description of Technique and Single-Center Experience.

OBJECTIVES: To introduce a novel method of direct iatrogenic atrial septal defect (iASD) closure through the MitraClip steerable guide catheter (SGC). BACKGROUND: MitraClip implantation requires transseptal puncture and the creation of an iASD. There are relatively rare instances, such as hemodynamically significant shunting or concerns for embolus, where iASD must be closed during index procedure. In these instances, it may be beneficial to not give up access to left atrium. METHODS: We retrospectively reviewed all iASD closures during MitraClip implantation at our institution from 2015 to 2020. Cases where an ASD occluder was deployed directly through SGC were included. RESULTS: Eleven patients had immediate iASD closure through the SGC. Indications for using this method included concern for paradoxical embolus, large defect size and/or significant shunting. Closure device sizes ranged from 8 to 22 mm. Mean time from removal of clip delivery system to occlusion of iASD was 14.6 minutes. There were no procedural complications related to iASD closure using this method. CONCLUSION: Closure of iASD intra-procedurally directly through transseptal guide sheath via the method described was safe and allowed for continuous left atrium access.

Reverse self-assembly: (111)-oriented gold crystallization at alkylthiol monolayer templates.

It has long been known that thiol-terminated molecules self-assemble as commensurate monolayers on Au(111) surfaces. By spreading floating octadecanethiol monolayers on aqueous solutions of chloroauric acid (HAuCl4) and using x rays to reduce the gold ions as well as to probe the structure, we have observed the nucleation of (111)-oriented Au nanoparticles at thiol surfaces. This process may be similar to the formation of biogenic gold by bacteria. The thiol monolayer acts as a "soft template," changing its structure as Au crystals form so that there is a sqrt[3]×sqrt[3] commensurate relationship.

How water meets a very hydrophobic surface.

Is there a low-density region ("gap") between water and a hydrophobic surface? Previous x-ray and neutron reflectivity results have been inconsistent because the effect (if any) is subresolution for the surfaces studied. We have used x-ray reflectivity to probe the interface between water and more hydrophobic smooth surfaces. The depleted region width increases with contact angle and becomes larger than the resolution, allowing definitive measurements. Large fluctuations are predicted at this interface; however, we find that their contribution to the interface roughness is too small to measure.

Control of thin liquid film morphology during solvent-assisted film deposition.

Liquid films of different silicate esters were deposited from volatile solvents on hydroxylated and hydrogen-passivated silicon surfaces. We show that adsorption of silicate ester molecules and the resulting structural morphology of the liquid films not only are determined by attractive van der Waals forces with contributions from electrostatic interactions between the silicone ester moieties and oxide surface sites but also can be tuned by modifying the substrate surface or by changing the liquid-solvent interactions. Our results also show the importance of the conformational properties of liquid molecules and their rearrangements at the liquid/solid interface for controlled solvent-assisted film deposition.

Technical Considerations for TAVR in the Treatment of Stentless Bioprosthetic Aortic Valve Insufficiency in LVAD Patients.

An 80-year-old man with a history of bicuspid AV complicated by severe AI presented with progressive NYHA class III symptoms and severe bioprosthetic AV insufficiency. Transcatheter aortic valve replacement was planned via transfemoral approach. We encountered several technical challenges and describe them herein.

Structural signal of a dynamic glass transition.

Pentaphenyl trimethyl trisiloxane is an isotropic liquid at room temperature with a dynamic glass transition at 224 K. Using x-ray reflectivity, we see surface density oscillations (layers) develop below 285 K, similar to those seen in other metallic and dielectric liquids and in computer simulations. The layering threshold is approximately 0.23 times the liquid-gas critical temperature. Upon cooling further, there is a sharp increase at 224 K in the persistence of the surface layers into the bulk material, i.e., an apparently discontinuous change in static structure at the glass transition.