Pulse Waveform Research Articles

Design and verification of monitoring system of DC microgrid based on Ethernet communication

AbstractReal‐time acquisition of microgrid (MG) operation data and remote control play a crucial role in the safe and stable operation of MG. A design scheme of monitoring system is proposed for the wind/photovoltaic/energy storage islanded direct current MG. The core controllers used in direct current MG system are programmable logic controller and digital signal processor. The monitoring system mainly adopts Ethernet communication, together with serial port communication mode Recommend Standard 232 (RS232) and Recommended Standard 485 (RS485) communication modes. A heterogeneous networking is built with controllers and data display instruments. Different monitoring interfaces are designed, the important information can be real‐time detected, collected and displayed. The multi‐energy and multi‐load dispatching operation control are realized according to scheduling operation plan. The parameters of the inverter can be adjusted, and the output voltage waveform and sinusoidal pulse width modulation waveform of the inverter can be measured. The communication of the proposed monitoring system is reliable, flexible and expandable, and easy to realize remote operation control. Moreover, the detection and control functions can be extended further. Through experiments, the effective control and monitoring of the designed monitoring system is verified, and the intelligent management is realized.

Design of a High-Voltage Arbitrary Waveform Generator Using a Modular Cascaded H-Bridge Topology

As the integration of renewable energy sources into the grid increases, the insulation systems of grid components such as transformers and switchgear encounter significant challenges due to the transients and harmonics generated by power-electronic-based converters. A test generator capable of replicating these component stresses is essential to accurately evaluate these insulation systems under real-grid conditions. This paper proposes a modular cascaded H-bridge-based high-voltage arbitrary waveform generator, prototyped with three stages to generate customized waveforms (triangular, sawtooth, pulse, and complex) up to 8 kV. The H-bridge modules are designed using Si MOSFETs with a maximum blocking voltage of 4.5 kV. The input to the HV H-bridge module is provided by a 10 kV medium-frequency transformer, whose design is described with a focus on the insulation system and winding configuration. This transformer is driven by a zero-voltage switching driver. This arbitrary waveform generator excels in several aspects, including a straightforward design procedure, compact size, high voltage capability, ease of integration, and cost.

Cuff-less wearable biosensor in continuous noninvasive human radial artery pulse waveform and blood pressure measurement using self-mixing interferometry

In this paper, we propose a compact, wearable biosensor for the noninvasive measurement of human radial artery pulse waveform curve (PWC) and blood pressure (BP). In this system, self-mixing interferometry (SMI) technology is employed to measure the weak arterial vascular deformation, enabling accurate PWC retrieval. Based on the reconstructed PWC features, BP values are precisely estimated by means of deep learning method. Here continuous wavelet transform (CWT), enabling visualization of the relationship between the SMI signal temporal frequency components and the PWC characteristics, is highlighted for PWC flipping points seeking and convolutional neural network (CNN) input parameter acquisition. For the first time, a novel deep learning network preprocessing method is proposed that allows direct feature extraction from the CWT scalogram of SMI signal without the complicated PWC reconstruction algorithm. The robustness and accuracy of our device are validated by a series of clinical measurements, mean absolute error (MAE) and standard deviation (STD) values are calculated and compared with the existing models. We approach minimal BP estimation results (MAE ± STD) of 1.41 ± 1.89 mmHg for systolic blood pressure (SBP) and 1.78 ± 2.01 mmHg for diastolic blood pressure (DBP), respectively. The luxuriant novelties and remarkable performance clearly demonstrate our wearable sensor’s great potential in BP monitoring, and other clinical applications.

Arrhythmogenicity of monophasic and biphasic PFA waveforms in a porcine model.

The potential risk of inducing ventricular arrhythmias was explored by employing pulsed field ablation (PFA) through the administration of both monophasic and biphasic waveform deliveries. PFA was applied to specific locations in the right ventricle (RV, n = 5 sites) in swine (n = 2), utilizing identical settings with consistent amplitude, pulse width, and a number of pulses for both monophasic and biphasic waveforms. PFA deliveries were precisely timed in 10-ms intervals across the entire T wave. Using monophasic waveforms, ventricular fibrillation (VF) was induced 7/7 times when PFA pulses were delivered during the T wave. Biphasic waveforms resulted in no ventricular arrhythmias when PFA was delivered across the entire duration of T wave. Our findings indicate that VF can be consistently induced with monophasic pulse waveforms, but not with biphasic pulse waveforms in a porcine model.

Electrodeposition of Sn-Ru Alloys by Using Direct, Pulsed, and Pulsed Reverse Current for Decorative Applications

Pulsed current has proven to be a promising alternative to direct current in electrochemical deposition, offering numerous advantages regarding deposit quality and properties. Concerning the electrodeposition of metal alloys, the role of pulsed current techniques may vary depending on the specific metals involved. We studied an innovative tin–ruthenium electroplating bath used as an anti-corrosive layer for decorative applications. The bath represents a more environmentally and economically viable alternative to nickel and palladium formulations. The samples obtained using both direct and pulsed currents were analyzed using various techniques to observe any differences in thickness, color, composition, and morphology of the deposits depending on the pulsed current waveform used for deposition.

Three-Phase Bridge Fully-Controlled Rectifier Circuit Design Based On Digital Integrated Circuits

This paper aims to design and analyze a three-phase fully controlled bridge rectifier circuit. The paper first introduces the basic principles and advantages of the three-phase fully controlled bridge rectifier circuit and then elaborates on five key aspects of the design: transformer design, thyristor selection, thyristor protection design, trigger circuit design, and trigger circuit power supply design. During the design process, parameters such as the motor’s rated power, voltage, current, and resistance were considered to ensure that the selection of thyristor parameters and protective measures meet the needs of practical applications. In addition, the paper discusses the design of synchronous transformers, phase selection, the application of the KJ004 trigger circuit, and the design of the trigger circuit power supply. Finally, the circuit was simulated using Matlab simulation tools, the circuit design was optimized, and satisfactory pulse waveforms and output waveforms were obtained by adjusting the experimental time. The research in this paper provides theoretical basis and practical guidance for the optimized design of three-phase fully controlled bridge rectifier circuits.

Temporal dissipative soliton with controllable morphology in a time-delayed coupled optoelectronic oscillator.

A temporal dissipative soliton (TDS) with controllable morphology is demonstrated in a time-delayed coupled optoelectronic oscillator (OEO) driven by two optical carriers with different wavelengths. The morphology of the TDS is controlled by the power difference between the two optical carriers and the delay difference induced by the group-velocity dispersion (GVD) in the OEO loop. When the delay difference is small, the OEO operates in a single-soliton state. With the increase of the wavelength interval between the two optical carriers, the delay difference becomes significant so that various compound TDS structures are observed, where the TDS interval is equal to the delay difference. The morphology of the compound TDSs can be switched between a pulsating TDS packet and a stable compound TDS structure by further tuning the power difference between the two optical carriers. This discovery not only facilitates the investigation of novel soliton dynamics but also provides a method for generating customized pulse waveforms.

Empaglifozin modifies the arterial stiffness in type-2 diabetic patients: a preliminary report.

Abstract Background Sodium-glucose cotransporter-2 (SGLT2) inhibitors demonstrated beneficial effects on cardiovascular and renal events in patients with type 2 diabetes mellitus. The mechanisms underlying these effects are not fully elucidated. Aim of this study was to investigate whether empagliflozin is able to modify the arterial stiffness in type 2 diabetic patients. Methods Pulse wave velocity (PWV) and other parameters of arterial stiffness were assessed before and after adding empagliflozin to a traditional antidiabetic treatment in 16 consecutive T2DM outpatients folowed for 3 months. Arterial stiffness were evaluted using SphygmoCor ECEL measuring the pulse waveform of the arterial pulse moving from tha descending aorta to the femoral artery (PWV). Data obtained from the diabetic population has been compared to 16 T2DM outpatients not treated with SGLT2 inhibitors. Results In the two groups differences according gender distribution or duration of diabetes mellitus did not emerge. However the empagliflozin group was younger compared to controls (64.1±8.68 vs 74.45±8.13, P < 0.05). Empagliflozin treatment significantly decreased HbA1c after 12 weeks of treatment (7.9±0.78 vs 7.04±1.09%, P < 0.008.). After 12 weeks’ treatment, empagliflozin significantly improved PWV compared to controls not treated with SGLT2-i (ΔPWVV -0.68±1.1 vs 0.89±1,6 p <0.004, P = 0.0065 with age and HbA1c as covariates). Moreover body weight significantly decreased in the empagliflozin group (86.75±16.16 vs 81.71±16.5 kg, p =0.001) compared to controls (in whom remained unchanged) as long as BMI (30.48±5.4 versus 28.75±5.66 kg/m2, P < 0.002) compared to controls (in whom remained unchanged). Estimated glomerular filtration rate (eGFR) remained unchanged in the two groups during the study whereas urine Albumin to Creatinine ratio significantly improved using empagliflozin (17.8±46.8 vs 12.2±35.7 mg/mmol, P = 0.049). Conclusion In this ‘real clinical practice’ experience, the potential effect of empagliflozin treatment on arterial stiffness in T2DM patients was extensively investigated. Arterial stiffness was significantly decreased adding empaglifozin to the traditional treatment and this result has been obtained after 3-month. Significantly improvement in urine Albumin to Creatinine ratio might suggest an amelioration of endothelial function in those patients that could be involved in reducing arterial stiffness.

Undiagnosed impaired glucose tolerance/diabetes mellitus and relationship with aortic stiffness in patients with acute coronary syndromes

Abstract Background Patients admitted with an acute coronary syndrome (ACS) often have unknown cardiovascular risk factors, such as impaired glucose tolerance (IGT) or diabetes mellitus (DM). Detecting these conditions is crucial to intensify appropriate therapies. Increased aortic stiffness, assessed by aortic pulse wave velocity (PWV), is associated with higher mortality in patients at high cardiovascular risk. Purpose Estimating the prevalence of IGT and DM and their relationship with increased aortic stiffness in patients admitted with an ACS. Methods Seventy-five consecutive patients admitted for ACS (21% women, mean age 63.6±11.1 ys), with fasting plasma glucose (PG) and glycated hemoglobin (HbA1c) not diagnostic for diabetes mellitus, underwent a fully standardized oral glucose tolerance test. All patients were also evaluated with the Arteriograph device, which applies a brachial cuff-based oscillometric method for the estimation of aortic PWV and arterial pulse waveform features. The automated vascular studies and OGTTs were performed after patient stabilization, at least 96 hours after admission. Results Forty-one patients (55% of the total study population) showed an abnormal OGTT response: 14 patients had a 2-h PG-OGTT ≥ 200 mg/dL, uncovering a diagnosis of DM, and 27 patients had a 2-h PG-OGTT ≥ 140 mg/dL, uncovering a diagnosis of IGT. Patients with DM showed no differences in terms of age, cardiovascular risk factors, Framingham risk score, C-reactive protein values, whereas a significant difference was observed in the number of diseased coronary vessels (2.2±0.8 vs 1.6±0.9, p=0.016) and PWV values (10.0±1.3 vs 8.8±1.6 m/s, p=0.028). Similarly, when considering all patients with an abnormal OGTT, a significant difference was observed in PWV values compared to patients with a normal OGTT (9.5±1.5 vs 8.4±1.7 m/s, p=0.032), as well as in estimated glomerular filtration rate (78±18 vs 83±23 mL/min/1.73mq, p=0.05), and peak troponin values (3698±2905 vs 2124±2561 ng/ml, p=0.02). At follow-up (mean time 51.7 months), no patients had died, but 5 patients had a new major cardiovascular event. Aortic pulse wave velocity values were different between patients with and without events (10.6±2.3 vs 8.6±1.4 m/s, p=0.024), and PWV was a significant predictor of events at univariate regression analysis (hazard ratio 1.93; 95 confidence intervals 1.01-3.69, p=0.047). Conclusions An unknown diagnosis of DM and/or IGT is very frequent in patients with ACS. Undiagnosed dysglycemic conditions are linked to a higher prevalence of coronary multivessel disease and increased aortic stiffness, which is also predictive of future cardiovascular events. A systematic screening with OGTT may help identifying patients at even higher cardiovascular risk, and tailoring secondary prevention strategies through personalized aggressive therapeutic interventions.

Optimal blood pressure values to reduce arterial stiffness, an analysis from UK Biobank

Abstract Introduction Increased arterial stiffness is a powerful independent risk factor for adverse cardiovascular events. While pulse wave velocity has been used extensively as a biomarker of vascular health reflecting functional and structural arterial changes, its use in clinical practice was limited. The Arterial Stiffness Index (ASI) simplifies the assessment of arterial stiffness using a pulse waveform obtained at the finger with an infrared sensor with BP measured using an automated device. Age and raised blood pressure (BP) are major contributors to increased arterial stiffness, but time trajectories of ASI in the general population and optimal BP values to reduce arterial stiffening are scarcely known. Purpose To establish temporal changes of ASI and identify BP values associated with longer-term improvement of arterial stiffness. Methods The study analysed data from UK Biobank (baseline n=154,684, median age 54, interquartile range (IQR) [40-72] years; 52% female; 91% white, 28% hypertension). ASI was measured using PulseTrace PCA2 device (CareFusion, USA) at baseline with measurements repeated in 4617 individuals after a median follow up of 3.0, IQR [2.8-3.3] years. BP was measured during the same time points. Multivariable (adjusted for age, sex, diabetes, and use of BP-lowering drugs) linear regression was used to determine the association of BP with baseline and the association of BP and ASI changes during follow up. ROC analysis was used to determine BP values associated with improvement (reduction) of ASI during follow up. Continuous data are presented as median [IQR] and compared using Wilcoxon test. R software packages were used for analyses. Results At baseline, ASI (m/sec) was higher in those with systolic BP (SBP) >140 mmHg (9.60 [7.15-11.85] vs. 8.67 [6.77-10.70] for SBP ≤140 mmHg, p<0.001) and in those with diastolic BP (DBP) >90 mmHg (9.90 [7.48-12.16] vs 8.81 [6.78-10.90] for DBP ≤90 mmHg, p<0.001). Both SBP and DBP were independently associated with ASI at baseline (B±SE 0.08±0.02 and 0.79±0,29m, respectively; p<0.001 for both). During follow up, the population level SBP remained unchanged (change 0 [-8 - 8] mmHg), with some reduction in DBP (-1.0 [-6.0 - 3.5]) mmHg. SBP reduced in 2234 (48%) and DBP in 2517 (55%). ASI increased by 0.56 [-1.46 - 2.78] m/s, with ASI reduction observed in 1935 (42%). An increase in DBP but not in SBP was independently associated with an increase in ASI (B±SE DBP 0.04±0.01, p<0.001; SBP 0.007±0.006, p=0.22; DBP 0.04±0.007, p<0.001). The baseline BP was predictive of the magnitude of changes in ASI: SBP 132 mmHg (AUC 0.53, p=0.001) and DBP 83 mmHg (AUC 0.54, p<0.001). Conclusions Increased arterial stiffness is associated with higher BP, particularly with higher DBP. Raised ASI is reversible, providing BP is adequately controlled with optimal BP being <132/83 mmHg.

Understanding perioperative risk determinants in carotid endarterectomy: the impact of compromised circle of Willis morphology on inter-hemispheric blood flow indices based on intraoperative internal carotid artery stump pulse pressure and backflow patterns.

Carotid artery stenosis (CAS) often requires surgical intervention through carotid endarterectomy (CEA) to prevent stroke. Accurate cerebrovascular risk assessments are crucial in CEA, as poor collateral circulation can lead to insufficient interhemispheric blood flow compensation, resulting in ischemic complications. Therefore, understanding perioperative risk determinants is vital. This study aims to determine the impact of compromised circle of Willis (CoW) morphology on inter-hemispheric blood flow, focusing on indices based on intraoperative internal carotid artery stump pulse pressure and backflow patterns. In 80 CAS patients who underwent CEA, preoperative CT angiography for CoW was conducted. Patients were categorized into five subgroups based on their CoW anatomy and three additional groups based on intraoperative internal carotid artery (ICA) stump backflow patterns evaluated by the surgeon. Continuous blood pressure signals, including systolic, diastolic, mean, and pulse pressure values, were recorded during the procedure. The relationship between CoW anatomical variants and the systolic and diastolic segments of the averaged pressure waveforms, particularly diastolic pressure decay, was analyzed. The correlation between CoW anatomy and stump backflow intensity was also examined. Significant variability in ICA stump backflow and pressure values was evident across CoW variants. Patients with compromised CoW morphology exhibited weaker backflow patterns and lower ICA stump pulse pressure values, consistent with impaired interhemispheric blood flow. Notably, ICA stump diastolic pressure decay was consistent across most CoW variant groups, indicating developed collateral circulation in cases with CoW anomalies. Thus, impaired CoW integrity is associated with compromised interhemispheric blood flow indices based on intraoperative ICA stump pulse pressure and backflow patterns during CEA. Integrating intraoperative pulse waveform analysis with preoperative CT angiography provides a more detailed assessment of cerebrovascular risk, guiding the selective use of shunts. This combined approach may improve surgical outcomes and patient safety by identifying patients at increased risk of perioperative neurological events due to CoW anomalies.

Spaceborne particle identification platform and its application based on convolutional neural network

The identification of particle types in space radiation particle detection is a problem of great concern in scientific research and engineering applications. At present, the particle types are mainly identified by the difference in energy deposition of particles in the sensor, the difference in waveform in the sensor, the flight time and energy of particles, and the difference in the deflection path of particles in the electric field, such as traditional telescope detectors, particle pulse waveform analysis, flight time TOF system and electrostatic analyzer. However, the current on-orbit particle identification logic is relatively simple and the identification accuracy is limited. Convolutional neural networks have powerful target classification capabilities and are good at capturing and extracting target feature details, which can improve the accuracy of particle energy measurement and identification. Based on the environment commonly used in space environment detection payloads, this paper proposes a method for building an on-orbit convolutional neural network particle identification platform to achieve particle type identification. The platform first constructs a multi-dimensional input data set, completes the model training and weight derivation with the help of the software platform, and completes the waveform inference and data set expansion through the hardware platform. The established identification platform is used to train and test the neutron and gamma waveform data obtained in actual tests, and the accuracy of the identification of the software and hardware platforms is analyzed, completing the verification of the platform. The establishment and application of this platform provides a new idea and method for particle measurement and identification in future space environment detection, and has strong engineering practice significance.

Impact of piezoelectric driving waveform on performance characteristics of vibrating mesh atomizer (VMA)

Vibrating mesh atomizer (VMA) is a specific type of ultrasonic atomizer known for its low power consumption and production of uniformly fine droplets. While previous research has provided a basic understanding of VMA operation, it has primarily focused on driving the piezoelectric actuator with continuous and symmetrical waveforms, such as sine and square waveforms. This study aims to experimentally investigate the impact of different driving waveforms on the ultrasonic atomization process and the associated performance characteristics. Specifically, the effects of pulse waveforms (Gauss and Lorentz pulse) were analyzed with high rates of energy deposition and asymmetrical hybrid waveforms (trapezia and absolute sine), featuring distinct negative cycles, by comparing them with conventional symmetrical waveforms (sine and square). Pulse waveforms suppress the growing stage but provide a high flux of input energy, facilitating the detachment of liquid into fine droplets, resulting in uniformly distributed droplets with VMDs of 5.84 μm and 4.71 μm for Gauss and Lorentz waveforms, respectively. Conversely, shorter negative cycles in asymmetrical hybrid waveforms reduce liquid suction into the micronozzle, leading to higher energy flux during subsequent positive cycles that promote the growing stage, producing larger droplets with VMDs of 10.82 μm and 11.86 μm for trapezia and absolute (abs) sine waveforms, respectively. Additionally, high-speed imaging reveals irregular pulsating behaviors in the atomization process when using pulse waveforms, suggesting a reciprocating-pump-like operation mechanism in VMA atomization. These new insights contribute to an improved understanding of the atomization mechanism in VMAs.

Pulse component extraction and its application in simulation of pulse-like ground motions

A procedure for simulating new pulse-like ground motion based on natural pulse-like ground motion record is proposed. Firstly, an extraction method of pulse waveform based on Modified Ensemble Empirical Mode Decomposition is proposed, which reveals the relationship between half-wavelength width and pulse time-frequency information. Secondly, according to the response spectrum of the extracted non-pulse time-history, a triangular series is used to generate a stationary time-history, and then the extracted pulse component is added to the time-history, and the intensity envelope is adjusted to obtain the simulated pulse-like ground motion. Finally, the seismic response results of the Bouc-Wen-Baber-Noori model and the three-dimensional finite element model of the high-rise building are validated. It shows that the nonlinear effect of the simulated pulse-like ground motion by this method is close to that of the original natural pulse-like ground motion. The simulated pulse-like ground motion by this method can be used to analyze the inelastic response of various structures.

Self-repairing Al2O3−TiO2 coatings fabricated through plasma electrolytic oxidation with various cathodic pulse parameters

The influence of cathodic pulse parameters was evaluated on plasma electrolytic oxidation (PEO) coatings grown on 7075 aluminum alloy in a silicate-based electrolyte containing potassium titanyl oxalate (PTO) using pulsed bipolar waveforms with various cathodic duty cycles and cathodic current densities. The coatings were characterized by SEM, EDS, and XRD. EIS was applied to investigate the electrochemical properties. It was observed that the increase of cathodic duty cycle and cathodic current density from 20% and 6 A/dm2 to 40% and 12 A/dm2 enhances the growth rate of the inner layer from 0.22 to 0.75 µm/min. Adding PTO into the bath showed a fortifying effect on influence of the cathodic pulse and the mentioned change of cathodic pulse parameters, resulting in an increase of the inner layer growth rate from 0.25 to 1.10 µm/min. Based on EDS analysis, Si and Ti were incorporated dominantly in the upper parts of the coatings. XRD technique merely detected γ-Al2O3, and there were no detectable peaks related to Ti and Si compounds. However, the EIS results confirmed that the incorporation of Ti4+ into alumina changed the electronic properties of the coating. The coatings obtained from the bath containing PTO using the bipolar waveforms with a cathodic duty cycle of 40% and current density values higher than 6 A/dm2 showed highly appropriate electrochemical behavior during 240 d of immersion due to an efficient repairing mechanism. Regarding the effects of studied parameters on the coating properties, the roles of cathodic pulse parameters and PTO in the PEO process were highlighted.

Cleanroom-free fabrication of flexible capacitive pressure sensors using paintable silver electrodes on stationery paper and random microstructured polydimethylsiloxane dielectric layer

Abstract In this work, we propose a facile, low-cost, and cleanroom-free approach for fabricating flexible capacitive pressure sensors based on paintable Ag electrodes on stationery paper substrates (Ag–paper electrodes) and a random microstructured polydimethylsiloxane (PDMS) dielectric layer transferred from emery paper. COMSOL Multiphysics simulations and experimental investigations suggest that the pressure sensor with random microstructured PDMS dielectric layer performs better than the sensor with ordered micropyramidal dielectric layer. The developed Ag–paper electrode and random microstructured PDMS dielectric layer-based pressure sensors are workable in a wide pressure range (up to 630 kPa) and exhibit a high sensitivity of 0.132 kPa−1 up to 1 kPa, low hysteresis (6.6%) with loading–unloading of ∼500 kPa pressure, high stability during a ∼5250 cyclic test, and the ability to sense a low pressure of ∼27 Pa. The developed sensor also successfully transduces arterial pulse wave forms when it is properly attached to the wrist. Using the proposed process, a flexible capacitive pressure sensor matrix of 4 × 4 array is also successfully developed for single- and multiple-point pressure mapping with minimal cross-talk. The proposed sensor process is simple and inexpensive to implement, and offers spatial pressure mapping for e-skin applications.

Association Between Arterial Pulse Waveform Analysis and Mortality in Patients With Septic Shock: A Retrospective Cohort Study Using Japanese Diagnosis Procedure Combination Data.

Purpose: Specialized pressure transducers for arterial pulse waveform analysis (S-APWA) devices are dedicated kits connected to an arterial pressure catheter that monitors hemodynamic parameters, such as cardiac output, pulse pressure variation, and stroke volume variation, less invasively. While the association between the use of S-APWA devices and clinical outcomes in perioperative patients has been previously evaluated, its assessment in patients with septic shock remains inadequate. Materials and Methods: This retrospective cohort study utilized a nationwide Diagnosis Procedure Combination database in Japan. Adult patients with septic shock admitted to the intensive care unit (ICU) with arterial pressure catheter placement on the admission day from August 2012 to February 2021 were included. Hospitalizations meeting the eligibility criteria were categorized into groups based on S-APWA device usage. The primary outcome, evaluated using Cox regression analysis, was 30-day all-cause mortality in the propensity score overlap-weighted population. Secondary outcomes included in-hospital mortality, ICU duration, and overall hospital stay. Results: Among 5130 eligible hospitalizations, 643 were in the S-APWA group and 4487 were in the conventional pressure transducer group. Cox regression analysis within the propensity score overlap-weighted population showed no significant difference in 30-day mortality (adjusted hazard ratio: 0.94; 95% confidence interval: 0.9-1.38; P = .58). Logistic regression analysis indicated no significant differences in the in-hospital mortality. While the S-APWA group had prolonged ICU stays, no significant difference in the overall hospital stay was observed according to linear regression analyses. Conclusions: Our study found no significant association between S-APWA use and 30-day mortality in patients with septic shock. These findings offer insights into optimizing monitoring systems in ICUs.

Physics-Informed Graph Neural Networks to solve 1-D equations of blood flow

Background and Objective:Computational models of hemodynamics can contribute to optimizing surgical plans, and improve our understanding of cardiovascular diseases. Recently, machine learning methods have become essential to reduce the computational cost of these models. In this study, we propose a method that integrates 1-D blood flow equations with Physics-Informed Graph Neural Networks (PIGNNs) to estimate the propagation of blood flow velocity and lumen area pulse waves along arteries. Methods:Our methodology involves the creation of a graph based on arterial topology, where each 1-D line represents edges and nodes in the blood flow analysis. The innovation lies in decoding the mathematical data connecting the nodes, where each node has velocity and lumen area pulse waveform outputs. The training protocol for PIGNNs involves measurement data, specifically velocity waves measured from inlet and outlet vessels and diastolic lumen area measurements from each vessel. To optimize the learning process, our approach incorporates fundamental physical principles directly into the loss function. This comprehensive training strategy not only harnesses the power of machine learning but also ensures that PIGNNs respect fundamental laws governing fluid dynamics. Results:The accuracy was validated in silico with different arterial networks, where PIGNNs achieved a coefficient of determination (R2) consistently above 0.99, comparable to numerical methods like the discontinuous Galerkin scheme. Moreover, with in vivo data, the prediction reached R2 values greater than 0.80, demonstrating the method’s effectiveness in predicting flow and lumen dynamics using minimal data. Conclusions:This study showcased the ability to calculate lumen area and blood flow rate in blood vessels within a given topology by seamlessly integrating 1-D blood flow with PIGNNs, using only blood flow velocity measurements. Moreover, this study is the first to compare the PIGNNs method with other classic Physics-Informed Neural Network (PINNs) approaches for blood flow simulation. Our findings highlight the potential to use this cost-effective and proficient tool to estimate real-time arterial pulse waves.

Intracranial aneurysm stiffness assessment using 4D Flow MRI

BackgroundAlthough arterial stiffness is known as a biomarker for cardiovascular events and stroke, there is limited information in the literature regarding the stiffness of intracranial aneurysms. In this study, we aim to assess the stiffness of intracranial aneurysms using 4D Flow MRI. MethodsA total of 27 aneurysms in 25 patients with internal carotid artery aneurysms were included in this study. Using 4D Flow MRI, we measured the arterial pulse wave form during a cardiac cycle at planes proximal and distal to the target aneurysm. The damping of these waveforms through the aneurysm was defined as the aneurysm damping index (ADI) and compared to the contralateral side. We also investigated the clinical factors related to the ADI. ResultsADI assessment was successful in all cases. The average ADI was 1.18±0.28, which was significantly larger than 1.0 (P = 0.0027 [t-test]). The ADI on the aneurysm side was larger than on the contralateral side (1.19±0.30 vs 1.05±0.17, P = 0.029 [t-test]). On multivariate analysis, the use of beta-blockers (β=0.46, P = 0.015) and smoking history (β=-0.22, P = 0.024) showed a significant correlation with ADI. ConclusionWe have proposed a novel method to observe arterial pulse wave dumping through intracranial aneurysm using 4D Flow MRI. The damping can be quantitatively observed, and the ADI has correlations with clinical factors such as antihypertensive drugs and smoking. Further studies should focus more on evaluating aneurysm stiffness and its clinical applications.

Abstract P320: Novel Pulse Waveform Index Obtained by Ambulatory Blood Pressure Monitoring is Associated with Echocardiographic Ejection Fraction in Patients with Heart Failure

Introduction: Simple, non-invasive assessment of cardiac function is useful in the management of heart failure (HF). Hypothesis: We hypothesized that pulse waveform analysis from oscillometric cuff blood pressure (BP) measurement can estimate cardiac function. The aim of this study is to investigate the association of the pulse waveform index we developed from ambulatory BP monitoring, which represents cardiac systolic function in the ambulatory setting, with echocardiographic left ventricular ejection fraction (LVEF) in patients with HF. Methods: A cuff volumetric waveform was obtained from the diastolic phase of each BP measurement with a multisensor ABPM (TM-2441, A&D). The area of the ejection portion is the square forward pulse wave (Sf), which is related to the cardiac ejection. The amplitude (Am) of the waveform represents arterial and cuff compliance. Sf is divided by Am, i.e., Sf/Am, to eliminate the effect of arterial and cuff compliance, which represents left ventricular systolic function ( Figure) . Results: Patients with HF who were clinically stable in the inpatient or outpatient setting (n=195) underwent both measurements of the multisensor-ABPM and echocardiography. LVEF was determined by the modified Simpson’s method. Patient characteristics were as follows: mean age, 72.1±14.7 years; male, 57%; and atrial fibrillation (AF), 39%. Sf/Am was associated with LVEF (r=0.44, p<0.001) ( Figure ). This association was also significant in the multivariable linear regression model including age, sex, body mass index, use of HF medications, coronary artery disease, and AF (β=0.43, p<0.001). Conclusions: Sf/Am, which is obtained by ABPM, is associated with echocardiographic LVEF.