Ischemic ventricular tachycardia from below the posteromedial papillary muscle, a particular entity: Substrate characterization and challenges for catheter ablation.

Background: In patients with ischemic ventricular tachycardia (VT), substrate may be "protected" by the posteromedial papillary muscle (PMPM), explaining failure of endocardial-only ablation.

Objective: We sought to characterize the arrhythmogenic substrate and ablation approach in patients with ischemic VT mapped to the inferior left ventricle in which endocardial ablation failed because of inaccessible substrate underlying the PMPM.

Methods: We included 10 patients with recurrent ischemic VT, evidence of inferior scar, and failed endocardial ablation.

Septal Coronary Venous Mapping to Guide Substrate Characterization and Ablation of Intramural Septal Ventricular Arrhythmia.

Objectives: This study describes the use of septal coronary venous mapping to facilitate substrate characterization and ablation of intramural septal ventricular arrhythmia (VA).

Background: Intramural septal VA represents a challenge for substrate definition and catheter ablation.

Methods: Between 2015 and 2018, 12 patients with structural heart disease, recurrent VA, and suspected intramural septal substrate underwent a septal coronary venous procedure in which mapping was performed by advancement of a wire into the septal perforator branches of the anterior interventricular vein.

Expeditious, scalable solution growth of metal oxide films by combustion blade coating for flexible electronics.

Metal oxide (MO) semiconductor thin films prepared from solution typically require multiple hours of thermal annealing to achieve optimal lattice densification, efficient charge transport, and stable device operation, presenting a major barrier to roll-to-roll manufacturing. Here, we report a highly efficient, cofuel-assisted scalable combustion blade-coating (CBC) process for MO film growth, which involves introducing both a fluorinated fuel and a preannealing step to remove deleterious organic contaminants and promote complete combustion. Ultrafast reaction and metal-oxygen-metal (M-O-M) lattice condensation then occur within 10-60 s at 200-350 °C for representative MO semiconductor [indium oxide (InO), indium-zinc oxide (IZO), indium-gallium-zinc oxide (IGZO)] and dielectric [aluminum oxide (AlO)] films.

Heating and cooling of ligand-coated colloidal nanocrystals in solid films and solvent matrices.

Ligand-to-nanocrystal heating and subsequent cooling to the environmental medium is investigated with infrared pump, electronic probe (IPEP) spectroscopy. Compared to solid films, solvated nanocrystals show faster ligand-to-nanocrystal heat equilibration (c. 11 ps versus c.

Quintet-triplet mixing determines the fate of the multiexciton state produced by singlet fission in a terrylenediimide dimer at room temperature.

Singlet fission (SF) is a photophysical process in which one of two adjacent organic molecules absorbs a single photon, resulting in rapid formation of a correlated triplet pair (TT) state whose spin dynamics influence the successful generation of uncorrelated triplets (T). Femtosecond transient visible and near-infrared absorption spectroscopy of a linear terrylene-3,4:11,12-bis(dicarboximide) dimer (TDI), in which the two TDI molecules are directly linked at one of their imide positions, reveals ultrafast formation of the (TT) state. The spin dynamics of the (TT) state and the processes leading to uncoupled triplets (T) were studied at room temperature for TDI aligned in 4-cyano-4'-pentylbiphenyl (5CB), a nematic liquid crystal.

Polarization-Dependent Lasing Behavior from Low-Symmetry Nanocavity Arrays.

This paper reports how geometric effects in low-symmetry plasmonic nanoparticle arrays can produce polarization-dependent lasing responses. We developed a scalable fabrication procedure to pattern rhombohedral arrays of aluminum anisotropic nanoparticles that support lattice plasmon modes from both first-order and second-order diffraction coupling. We found that nanoparticle shape can be used to engineer the spatial overlap between electromagnetic hot spots of different lattice modes and dye gain to support plasmonic lasing.

Comparison of the arrhythmogenic substrate between men and women with nonischemic cardiomyopathy.

Background: Outcomes of ventricular tachycardia (VT) ablation in structural heart disease have been reported to differ by sex. Whether this is due to differences in the underlying arrhythmogenic substrates among patients with nonischemic cardiomyopathy (NICM) remains unclear.

Objective: The purpose of this study was to compare the characteristics of arrhythmogenic substrates between women and men with NICM.

Thermal Excitation Control over Photon Emission Rate of CdSe Nanocrystals.

Temperature-dependent photoluminescence lifetimes of electron-hole pairs (excitons) in CdSe nanocrystals are governed by the energetic ordering and spacing of slowly emitting, spin-forbidden "dark" exciton states and rapidly emitting "bright" states. Here, infrared pulses that are resonant with hydrocarbon surface ligand vibrational transitions are shown to offer a route to manipulate the instantaneous emission rate of CdSe nanocrystals at cryogenic temperature. Transient heating of the inorganic nanocrystal core is achieved via resonant excitation of ligand vibrations, followed by heat flow to the nanocrystal lattice.

Reducing the Optical Gain Threshold in Two-Dimensional CdSe Nanoplatelets by the Giant Oscillator Strength Transition Effect.

Two-dimensional CdSe nanoplatelets are promising lasing materials. Their large lateral areas reduce the optical gain threshold by increasing the oscillator strength and multiexciton lifetimes but also increase the gain threshold by requiring multiple band-edge excitons (>2) to reach the optical gain. We observe that the optical gain threshold of CdSe nanoplatelets at 4 K is ∼4-fold lower than that at room temperature.

Synthesis of Type I PbSe/CdSe Dot-on-Plate Heterostructures with Near-Infrared Emission.

Zero-dimensional PbSe quantum dots are heterogeneously nucleated and grown onto two-dimensional zincblende CdSe nanoplatelets. Electron microscopy shows ad-grown dots predominantly decorate edges and corners of the nanoplatelets. Spectroscopic characterizations relate type I electronic alignment as demonstrated via photoluminescence excitation spectroscopy enhancement of near-infrared emission.

Microenvironment control of porphyrin binding, organization, and function in peptide nanofiber assemblies.

To take peptide materials from predominantly structural to functional assemblies, variations in cofactor binding sites must be engineered and controlled. Here, we have employed the peptide sequence c16-AHX3K3-CO2H where X3 represents the aliphatic structural component of the peptide design that dictates β-sheet formation and upon self-assembly yields a change in the overall microenvironment surrounding the Zn protoporphyrin IX ((PPIX)Zn) binding site. All peptides studied yield β-sheet rich nanofibers highlighting the materials' resiliency to amino acid substitution.

Spatially defined molecular emitters coupled to plasmonic nanoparticle arrays.

This paper describes how metal-organic frameworks (MOFs) conformally coated on plasmonic nanoparticle arrays can support exciton-plasmon modes with features resembling strong coupling but that are better understood by a weak coupling model. Thin films of Zn-porphyrin MOFs were assembled by dip coating on arrays of silver nanoparticles (NP@MOF) that sustain surface lattice resonances (SLRs). Coupling of excitons with these lattice plasmons led to an SLR-like mixed mode in both transmission and transient absorption spectra.

Papillary muscle ventricular arrhythmias in patients with arrhythmic mitral valve prolapse: Electrophysiologic substrate and catheter ablation outcomes.

Background: Mitral valve prolapse (MVP) is a common valve condition and has been associated with sudden cardiac death. Premature ventricular contractions (PVCs) from the papillary muscles (PMs) may play a role as triggers for ventricular fibrillation (VF) in these patients.

Objectives: To characterize the electrophysiological substrate and outcomes of catheter ablation in patients with MVP and PM PVCs.

Charge Transfer Dynamics of Phase-Segregated Halide Perovskites: CHNHPbCl and CHNHPbI or (CHNH)(CHNH) Pb I Mixtures.

Lead halide perovskites present a versatile class of solution-processable semiconductors with highly tunable bandgaps that span ultraviolet, visible, and near-infrared portions of the spectrum. We explore phase-separated chloride and iodide lead perovskite mixtures as candidate materials for intermediate band applications in future photovoltaics. X-ray diffraction and scanning electron microscopy reveal that deposition of precursor solutions across the MAPbCl/MAPbI composition space affords quasi-epitaxial cocrystallized films, in which the two perovskites do not alloy but instead remain phase-segregated.

High Internal Quantum Efficiency Ultraviolet Emission from Phase-Transition Cubic GaN Integrated on Nanopatterned Si(100).

Ultraviolet emission characteristics of cubic (c-) GaN enabled through hexagonal-to-cubic phase transition are reported. Substrate patterning and material growth are shown to affect phase purity and emission characteristics of c-GaN as studied by electron backscatter diffraction, and photo- and cathodoluminescence, respectively. Raman study shows a tensile strain in the c-GaN.

Photoinduced, reversible phase transitions in all-inorganic perovskite nanocrystals.

Significant interest exists in lead trihalides that present the perovskite structure owing to their demonstrated potential in photovoltaic, lasing, and display applications. These materials are also notable for their unusual phase behavior often displaying easily accessible phase transitions. In this work, time-resolved X-ray diffraction, performed on perovskite cesium lead bromide nanocrystals, maps the lattice response to controlled excitation fluence.

Infrared-pump electronic-probe of methylammonium lead iodide reveals electronically decoupled organic and inorganic sublattices.

Organic-inorganic hybrid perovskites such as methylammonium lead iodide (CHNHPbI) are game-changing semiconductors for solar cells and light-emitting devices owing to their defect tolerance and exceptionally long carrier lifetimes and diffusion lengths. Determining whether the dynamically disordered organic cations with large dipole moment benefit the optoelectronic properties of CHNHPbI has been an outstanding challenge. Herein, via transient absorption measurements employing an infrared pump pulse tuned to a methylammonium vibration, we observe slow, nanosecond-long thermal dissipation from the selectively excited organic mode to the inorganic sublattice.

Electrophysiologic Substrate, Safety, Procedural Approaches, and Outcomes of Catheter Ablation for Ventricular Tachycardia in Patients After Aortic Valve Replacement.

Objectives: This study sought to investigate the substrate, procedural strategies, safety, and outcomes of catheter ablation (CA) for ventricular tachycardia (VT) in patients with aortic valve replacement (AVR).

Background: VT ablation in patients with AVR is challenging, particularly when mapping and ablation in the periaortic region are necessary.

Methods: We identified consecutive patients with mechanical, bioprosthetic, and transcatheter AVR who underwent CA for VT refractory to antiarrhythmic drugs and analyzed VT substrate, approach to LV access, complications, and long-term outcomes.

Long-term outcome and mode of recurrence following noninducibility during noninvasive programmed stimulation after ventricular tachycardia ablation.

Background: Noninducibility of ventricular tachycardia (VT) at noninvasive programmed stimulation performed shortly following ablation (negative NIPS) predicts low risk of the medium-term recurrence. This study aimed to evaluate long-term rate and mode of recurrence following negative NIPS.

Methods: We extended follow-up on patients in whom no VT could be induced at NIPS following ablation between 2008 and 2010.

Feasibility of complex transfemoral electrophysiology procedures in patients with inferior vena cava filters.

Background: The presence of inferior vena cava filters (IVCFs) has been considered a relative contraindication to electrophysiology (EP) procedures that require transfemoral venous placement of multiple catheters and/or long sheaths. There are inadequate data related to complex EP procedures in this population.

Objective: The purpose of this study was to describe the experience of a single high-volume center with respect to complex EP procedures in patients with IVCFs.

Utility of ripple mapping for identification of slow conduction channels during ventricular tachycardia ablation in the setting of arrhythmogenic right ventricular cardiomyopathy.

Background: Ripple mapping displays every deflection of a bipolar electrogram and enables the visualization of conduction channels (RMCC) within postinfarction ventricular scar to guide ventricular tachycardia (VT) ablation. The utility of RMCC identification for facilitation of VT ablation in the setting of arrhythmogenic right ventricular cardiomyopathy (ARVC) has not been described.

Objective: We sought to (a) identify the slow conduction channels in the endocardial/epicardial scar by ripple mapping and (b) retrospectively analyze whether the elimination of RMCC is associated with improved VT-free survival, in ARVC patients.

A Nurse-Led Limited Risk Factor Modification Program to Address Obesity and Obstructive Sleep Apnea in Atrial Fibrillation Patients.

Background Obesity and obstructive sleep apnea ( OSA ) are associated with atrial fibrillation ( AF ), yet these conditions remain inadequately treated. We report on the feasibility and efficacy of a nurse-led risk factor modification program utilizing a pragmatic approach to address obesity and OSA in AF patients. Methods and Results AF patients with obesity (body mass index ≥30 kg/m) and/or the need for OSA management (high risk per Berlin Questionnaire or untreated OSA ) were voluntarily enrolled for risk factor modification, which comprised patient education, lifestyle modification, coordination with specialists, and longitudinal management.

Anatomical proximity dictates successful ablation from adjacent sites for outflow tract ventricular arrhythmias linked to the coronary venous system.

Aims: Catheter ablation of outflow tract ventricular arrhythmias (OTVAs) with the earliest activation within the coronary venous system (CVS) can be challenging. When ablation from the CVS is not feasible or ineffective, an approach from anatomically adjacent site(s) can be considered. We report the outcomes of an anatomical approach for OTVAs linked to the CVS.

Heat Transfer at Hybrid Interfaces: Interfacial Ligand-to-Nanocrystal Heating Monitored with Infrared Pump, Electronic Probe Spectroscopy.

The transfer of thermal energy from the ligand passivating layer to the inorganic core of colloidal nanocrystals is observed using infrared-pump, electronic-probe (IPEP) spectroscopy. Inorganic nanocrystals are excellent model systems for organic-inorganic hybrid interfaces as they have much larger surface-to-volume ratios than bulk solids, which facilitate spectroscopic measurements of weak signals. Such interfaces between disparate materials are challenging to probe by traditional methods.