Electrical Engineering and Computer Science

PurposePolymeric heart valves (PHVs) offer the potential to combine the durability of mechanical valves with the favorable hemodynamics of bioprosthetic valves; however, establishing clear relationships between polymer properties and valve-level function remains a key challenge. This study evaluates polycarbonate-based polyurethanes as candidate scaffold materials for polymeric mitral valves through a multiscale structure–function approach.MethodsTwo aromatic polycarbonate-based thermoplastic polyurethanes, Carbothane AC-4095A (CB95-AC) and QuadraSil ARCS 90A (Qsil), were characterized using rheological, mechanical, and spectroscopic analyses. Trileaflet valve scaffolds were fabricated and evaluated using particle image velocimetry (PIV), pressure–flow measurements, and accelerated wear testing (AWT) up to 50 million cycles. Preliminary in vivo performance was assessed following implantation of a CB95-AC valve in an ovine model.ResultsQsil exhibited higher solution viscosity, lower storage modulus, and improved elastic recovery, indicating a more compliant response, whereas CB95-AC demonstrated greater stiffness and tear resistance. Both materials maintained stable valve function, with preserved projected orifice area and repeatable pressure waveforms after AWT. PIV analysis showed physiologic pulsatile inflow and intraventricular vortex formation for both valves, with Qsil producing slightly broader vorticity patterns and CB95-AC exhibiting more localized flow structures. Evaluation of the CB95-AC valve in vivo demonstrated preserved transmitral inflow with low pressure gradients and no evidence of obstruction.ConclusionPolycarbonate-based polyurethanes provide promising performance as polymeric mitral valve scaffolds, with material-dependent differences influencing leaflet mechanics and flow organization while maintaining structural integrity during comparative accelerated wear testing. These findings provide a multiscale framework for evaluating associations between polymer properties, mechanical behavior, and valve-level performance in next-generation polymeric and hybrid tissue-engineered heart valves.

PurposeEarly detection of right ventricular (RV) dysfunction is essential in pulmonary arterial hypertension (PAH) but remains challenging using conventional echocardiography. This study investigates the feasibility of a noninvasive, physics-based framework using three-dimensional (3D) echocardiography that integrates myocardial strain and volumetric flow analysis to characterize RV mechanical performance across stages of PAH.MethodsA prospective pilot study (N = 15) enrolled healthy controls, PAH patients with preserved RV size, and PAH patients with RV dysfunction. Deformation was evaluated by principal strain analysis and by conventional (longitudinal, circumferential) components. Hemodynamic metrics included hemodynamic forces and energetic properties that were derived using a physics-informed volumetric echocardiographic particle image velocimetry (V-Echo-PIV) method applied to contrast-enhanced acquisitions.ResultsDeformation analysis revealed that longitudinal strain was significantly reduced even in PAH patients with preserved RV dimensions, while second principal (secondary) strain showed a distinctive sign reversal, indicating a paradoxical systolic lengthening, early in the disease. The analysis of hemodynamic forces showed a marked reduction in systolic propulsion across all PAH stages. In contrast, energetic abnormalities were predominantly observed at later stage of the disease.ConclusionsThe integration of 3D myocardial strain with fluid dynamics provides a comprehensive physiological assessment of RV remodeling. While strain and systolic propulsion appear as sensitive markers for early dysfunction, diastolic energetics may support disease staging. This noninvasive framework shows promise for early detection and longitudinal monitoring of PAH patients.

BACKGROUND: Mitral annular calcification (MAC) is common and associated with increased cardiovascular risk and, when severe, mitral stenosis (MS). MAC-related MS differs anatomically and hemodynamically from rheumatic MS (RMS), challenging standard diagnostic methods. This study compares structural and flow characteristics, including  kinetic energy losses, across MAC-related MS, RMS, and normal mitral valves, and evaluates the applicability of conventional diagnostic metrics in MAC. METHODS: Three-dimensional transesophageal echocardiographic data sets from 70 patients (22 normal mitral valves, 26 RMS valves, 22 MAC valves) were used to obtain linear, area, and volumetric measurements for valve comparison. Representative valves from each group were converted into 3-dimensional silicone models for in vitro testing in a heart flow simulator. Transmitral flow was assessed with particle image velocimetry, flow energetics were quantified, and coefficients of contraction were derived from geometric and effective orifice areas. RESULTS: Compared with RMS, MAC-related MS had smaller anteroposterior dimensions, reduced valve volume, and lower coefficients of contraction. MAC demonstrated the highest transmitral velocities and energy dissipation in vitro. Unlike the normal model, neither MAC nor RMS produced a consistent transmitral vortex ring. Despite having a larger geometric orifice, MAC MS produced a greater pressure drop than RMS, likely due to increased flow disruption and lower coefficients of contraction. CONCLUSIONS: MAC-related MS represents a unique pathophysiological entity, characterized by distinct structural and hemodynamic features. These findings underscore the necessity for disease-specific diagnostic frameworks and multimodality imaging strategies to inform clinical decision making and guide emerging therapeutic approaches.

Mitochondrial transplantation has emerged as a promising cardioprotective strategy for ischemia-reperfusion injury, aiming to restore bioenergetic function by delivering healthy mitochondria to damaged tissue. However, conflicting reports exist regarding whether mitochondria can survive exposure to the calcium-rich extracellular environment, such as the bloodstream, prior to cellular uptake. Resolving this question is essential for advancing the therapeutic use of mitochondria in clinical settings. Isolated mitochondria from L6 rat skeletal muscle cells were incubated with physiologic (1.3  mM), sub-physiologic (0.65  mM), and supraphysiologic (2.6  mM) concentrations of calcium. Mitochondrial membrane potential was assessed using MitoTracker™ Red FM fluorescence, and structural integrity was evaluated using impedance-based Coulter counter analysis over a 12-hour time course. Mitochondria exposed to 1.3  mM calcium retained 90-95 % membrane potential by 12 h, while 2.6  mM calcium caused progressive loss of function and integrity, approaching levels seen in freeze-thawed controls. Coulter counter measurements revealed more extensive mitochondrial loss across all calcium-treated groups than fluorescence assays alone, suggesting that dye-based methods may underestimate structural damage. Nonetheless, a substantial proportion of mitochondria remained both structurally and functionally intact at physiologically relevant calcium levels. These findings demonstrate that a substantial number of mitochondria can retain membrane potential and structural integrity after exposure to extracellular calcium concentrations approximating those found in blood. This supports the feasibility of intracoronary mitochondrial transplantation and underscores the need for further in vivo studies to optimize survival and efficacy of mitochondria delivered in calcium-rich environments.

PURPOSE: To evaluate changes in myocardial blood flow (MBF) and coronary flow reserve (CFR) over time in a swine model fed a Western diet (WD) using a novel low-dose myocardial CT perfusion technique. MATERIALS AND METHODS: Ten swine with low-density lipoprotein receptor mutations were fed a WD starting at week 0 and imaged after 12, 16, 17, 18, 19, or 23 weeks of WD exposure (mean ± SD: 17.1 ± 3.25 weeks; range 12-23 weeks) using a 320-slice CT scanner under rest and adenosine-induced stress (240 μg/kg/min). Peripheral contrast injection (370 mgI/mL, 0.5 mL/kg, 5 mL/s) with a diluted chaser (30:70 contrast/saline) was followed by bolus tracking and a single-volume scan acquired at peak aortic enhancement (100 kVp, 200 mA). A first-pass analysis model derived MBF (mL/min/g) from bolus-tracking and scan data. Rest and stress MBF were used to compute CFR. Correlations between WD duration and both stress MBF and CFR were assessed. Reproducibility was evaluated through paired repeated scans. The CT dose index was recorded. RESULTS: Starting at 12 weeks post-WD, stress-induced MBF and CFR were strongly correlated with WD duration: MBFstress = -0.05 T + 2.56 (r = -0.93) and CFR = -0.13 T + 4.30 (r = -0.76). Reproducibility between repeated MBF measurements was high (MBF2 = 0.97MBF1 + 0.05; r = 0.99; RMSE = 0.06 mL/min/g). The average CT dose index was 7.4 mGy. CONCLUSION: Prolonged Western diet consumption in this swine model was associated with a progressive decline in stress-induced MBF and CFR, indicating the development of diet-related myocardial microvascular dysfunction. These results suggest that the low-dose single-volume CT perfusion technique can detect early perfusion impairments before overt disease, offering a promising tool for early risk stratification in coronary artery disease. SUMMARY STATEMENT: A novel low-dose, single-volume CT perfusion technique enables early detection of coronary microvascular dysfunction associated with Western diet exposure, providing a non-invasive and radiation-efficient method for assessing myocardial blood flow and coronary flow reserve before the development of significant epicardial stenosis.

This paper presents a multi-team collaboration strategy based on Hamilton’s rule from ecology that facilitates resource allocation among multiple teams, where agents are considered as shared resource among all teams that must be allocated appropriately. We construct an algorithmic framework that allows teams to make bids for agents that consider the costs and benefits of transferring agents while also considering relative mission importance for each team. This framework is applied to a multi-team coverage control mission to demonstrate its effectiveness. It is shown that the necessary criteria of a mission evaluation function are met by framing it as a function of the locational coverage cost of each team with respect to agent gain and loss, and these results are illustrated through simulations.

Purpose of ReviewTo provide the most up-to-date clinical evidence of intracoronary optical coherence tomography (OCT), and clinical implications to guide future imaging research in cardiology.Recent FindingsIntracoronary OCT has demonstrated advanced system performance and high reproducibility in analyzing atherosclerotic lesions. It is an attractive tool due to its capability for functional classification and superior imaging resolution, enabling precise and reliable tissue assessments. Compared to traditional angiography, OCT has been associated with improved long-term clinical outcomes and serves as an effective tool for optimizing stent selection and post-intervention evaluation. The development of OCT variations and the combination of various intravascular imaging modalities further enhance its diagnostic capabilities, allowing a comprehensive assessment of complex vulnerable lesions and improving risk stratification for patients. SummaryCurrent and evolving system development presents a hopeful path for treating coronary artery disease by addressing the challenges of the intracoronary OCT technique. Future studies focusing on utilizing OCT system extensions, integrated multimodality imaging systems, and Artificial Intelligence (AI) derived image analysis will improve clinical endpoints and streamline the process.

CXL shared memory and persistent memory allow the contents of memory to persist beyond crashes. Stores to persistent or CXL memory are typically not immediately made persistent; developers must manually flush the corresponding cache lines to force the data to be written to the underlying storage. Correctly using flush and fence operations is known to be challenging. While state-of-the-art tools can find missing flush instructions, they often require bug-revealing test cases. No existing tools can ensure the absence of missing flush bugs. In this paper, we present PMRobust, a compiler that automatically inserts flush and fence operations to ensure that code using persistent memory is free from missing flush and fence bugs. PMRobust employs a novel static analysis with optimizations that target newly allocated objects. We have evaluated PMRobust on persistent memory libraries and several persistent memory data structures and measured a geometric mean overhead of 0.26% relative to the original benchmarks with hand-placed flush and fence operations.

Abstract

We implement a paraxial azimuthally-radially polarized beam (ARPB), a novel class of structured light beams that can be optimal chiral (OC), leading to maximum chirality density at a given energy density. By using vectorial light shaping techniques, we successfully generated a paraxial ARPB with precise control over its features, validating theoretical predictions. Our findings demonstrate the ability to finely adjust the chirality density of the ARPB across its entire range by manipulating a single beam parameter. Although our experimental investigations are primarily focused on the transverse plane, we show that fields whose transverse components satisfy the optimal chirality condition are optimally chiral in all directions, and our results highlight the promising potential of OC structured light for applications in the sensing and manipulation of chiral particles. We show that helicity density is more general than the concept of handedness. This work represents a significant advancement toward practical optical enantioseparation and enantiomer detection at the nanoscale.