Pulse Wave Research Articles

DNN-BP: a novel framework for cuffless blood pressure measurement from optimal PPG features using deep learning model.

Continuous blood pressure (BP) provides essential information for monitoring one's health condition. However, BP is currently monitored using uncomfortable cuff-based devices, which does not support continuous BP monitoring. This paper aims to introduce a blood pressure monitoring algorithm based on only photoplethysmography (PPG) signals using the deep neural network (DNN). The PPG signals are obtained from 125 unique subjects with 218 records and filtered using signal processing algorithms to reduce the effects of noise, such as baseline wandering, and motion artifacts. The proposed algorithm is based on pulse wave analysis of PPG signals, extracted various domain features from PPG signals, and mapped them to BP values. Four feature selection methods are applied and yielded four feature subsets. Therefore, an ensemble feature selection technique is proposed to obtain the optimal feature set based on major voting scores from four feature subsets. DNN models, along with the ensemble feature selection technique, outperformed in estimating the systolic blood pressure (SBP) and diastolic blood pressure (DBP) compared to previously reported approaches that rely only on the PPG signal. The coefficient of determination ( ) and mean absolute error (MAE) of the proposed algorithm are 0.962 and 2.480 mmHg, respectively, for SBP and 0.955 and 1.499 mmHg, respectively, for DBP. The proposed approach meets the Advancement of Medical Instrumentation standard for SBP and DBP estimations. Additionally, according to the British Hypertension Society standard, the results attained Grade A for both SBP and DBP estimations. It concludes that BP can be estimated more accurately using the optimal feature set and DNN models. The proposed algorithm has the potential ability to facilitate mobile healthcare devices to monitor continuous BP.

The role of non-invasive oscillometric method to detect aortic stiffness in patients with subclinical hypothyroidism

Introduction Subclinical hypothyroidism (SCH) is a biochemical condition that is diagnosed when peripheral free thyroid hormone levels are within normal reference laboratory range but serum thyroid-stimulating hormone (TSH) levels are mildly elevated. The aim of this study was to investigate the relationship between SCH and arterial stiffness using two different non-invasive methods, including echocardiography and oscillometric arteriography. Material and Methods The study included 33 newly diagnosed SCH patients and 34 age- and gender-matched healthy controls. Systolic and diastolic diameters and elastic parameters of the aorta were calculated by 2D Transthoracic echocardiography (TTE). Central blood pressure and aortic stiffness values of patient groups were measured noninvasively from the brachial artery using Mobil-O-Graph arteriography. Pulse wave velocity (PWV) and augmentation index (AIx) were used as arterial stiffness indicators. Results There was no significant difference between SCH and control groups with regard to age, gender, and body mass index (BMI). Aortic strain and aortic distensibility, were significantly lower in the SCH group than in the control group (p < 0.001). PWV and AIx which measured by Mobil-O-Graph arteriography were found to be significantly higher in the subclinical hypothyroid group compared to the control group (p < 0.05). Conclusion Aortic stiffness assessed by TTE and Mobil-O-Graph arteriography deteriorated in patients with SCH after excluding other cardiovascular risk factors. The assessment of aortic stiffness by the oscillometric method was easy and useful for widespread clinical use.

Effects of pulse shape on pitch sensitivity of cochlear implant users

Contemporary cochlear implants (CIs) use cathodic-leading symmetric biphasic (C-BP) pulses for electrical stimulation. It remains unclear whether asymmetric pulses emphasizing the anodic or cathodic phase may improve spectral and temporal coding with CIs. This study tested place- and temporal-pitch sensitivity with C-BP, anodic-centered triphasic (A-TP), and cathodic-centered triphasic (C-TP) pulse trains on apical, middle, and basal electrodes in 10 implanted ears. Virtual channel ranking (VCR) thresholds (for place-pitch sensitivity) were measured at both a low and a high pulse rate of 99 (Experiment 1) and 1000 (Experiment 2) pulses per second (pps), and amplitude modulation frequency ranking (AMFR) thresholds (for temporal-pitch sensitivity) were measured at a 1000-pps pulse rate in Experiment 3. All stimuli were presented in monopolar mode. Results of all experiments showed that detection thresholds, most comfortable levels (MCLs), VCR thresholds, and AMFR thresholds were higher on more basal electrodes. C-BP pulses had longer active phase duration and thus lower detection thresholds and MCLs than A-TP and C-TP pulses. Compared to C-TP pulses, A-TP pulses had lower detection thresholds at the 99-pps but not the 1000-pps pulse rate, and had lower MCLs at both pulse rates. A-TP pulses led to lower VCR thresholds than C-BP pulses, and in turn than C-TP pulses, at the 1000-pps pulse rate. However, pulse shape did not affect VCR thresholds at the 99-pps pulse rate (possibly due to the fixed temporal pitch) or AMFR thresholds at the 1000-pps pulse rate (where the overall high performance may have reduced the changes with different pulse shapes). Notably, stronger polarity effect on VCR thresholds (or more improvement in VCR with A-TP than with C-TP pulses) at the 1000-pps pulse rate was associated with stronger polarity effect on detection thresholds at the 99-pps pulse rate (consistent with more degeneration of auditory nerve peripheral processes). The results suggest that A-TP pulses may improve place-pitch sensitivity or spectral coding for CI users, especially in situations with peripheral process degeneration.

Reference values of carotid intima-media thickness and arterial stiffness in Chinese adults based on ultrasound radio frequency signal: A nationwide, multicenter study.

Carotid intima-media thickness (IMT) and diameter, stiffness, and wave reflections, are independent and important clinical biomarkers and risk predictors for cardiovascular diseases. The purpose of the present study was to establish nationwide reference values of carotid properties for healthy Chinese adults and to explore potential clinical determinants. A total of 3053 healthy Han Chinese adults (1922 women) aged 18-79years were enrolled at 28 collaborating tertiary centers throughout China between April 2021 and July 2022. The real-time tracking of common carotid artery walls was achieved by the radio frequency (RF) ultrasound system. The IMT, diameter, compliance coefficient, β stiffness, local pulse wave velocity (PWV), local systolic blood pressure, augmented pressure (AP), and augmentation index (AIx) were then automatically measured and reported. Data were stratified by age groups and sex. The relationships between age and carotid property parameters were analyzed by Jonckheere-Terpstra test and simple linear regressions. The major clinical determinants of carotid properties were identified by Pearson's correlation, multiple linear regression, and analyses of covariance. All the parameters of carotid properties demonstrated significantly age-related trajectories. Women showed thinner IMT, smaller carotid diameter, larger AP, and AIx than men. The β stiffness and PWV were significantly higher in men than women before forties, but the differences reversed after that. The increase rate of carotid IMT (5.5μm/year in women and 5.8μm/year in men) and diameter (0.03mm/year in both men and women) were similar between men and women. For the stiffness and wave reflections, women showed significantly larger age-related variations than men as demonstrated by steeper regression slopes (all P for age by sex interaction <0.05). The blood pressures, body mass index (BMI), and triglyceride levels were identified as major clinical determinants of carotid properties with adjustment of age and sex. The age- and sex-specific reference values of carotid properties measured by RF ultrasound for healthy Chinese adults were established. The blood pressures, BMI, and triglyceride levels should be considered for clinical application of corresponding reference values.

Serum osteopontin level is independently associated with arterial stiffness in patients on hemodialysis

ABSTRACT Objectives: Carotid–femoral pulse wave velocity (cfPWV) is an approach primarily adopted to define arterial stiffness (AS), which is one of the major contributors to unfavorable cardiovascular outcomes. Osteopontin (OPN), in addition to regulation of bone homeostasis, is an inflammatory mediator of atherosclerosis. We performed a research which estimated the correlation between blood OPN levels and AS in participants on maintenance hemodialysis (MHD). Materials and Methods: One hundred and twenty-six patients who received long-term MHD were included in the cross-sectional study. cfPWV values were calculated based on the carotid and femoral pulsation waveforms. Patients with cfPWV &gt;10 m/s were categorized into the AS group. We utilized a commercially available enzyme-linked immunosorbent assay to check serum concentrations of OPN. Results: Study patients belonging to AS were found to be older, had significantly higher prevalence of underlying diabetes mellitus (DM) and hypertension, had higher systolic blood pressure, and had higher serum total calcium and OPN levels. After adjusting for these variables, multivariate logistic regression analysis disclosed that OPN levels, older age, DM, and total serum calcium levels were independently correlated with AS in patients on MHD. Multivariate analysis based on forward stepwise linear regression also showed that the logarithmically transformed OPN level was an independent correlate of cfPWV in these participants. Conclusion: Serum OPN concentrations had a positive correlation with cfPWV and were therefore related to AS in patients on MHD.

Cerebral Small Vessel Disease in Children and Adolescents with Type 1 Diabetes Presenting with Diabetic Ketoacidosis during COVID-19 Era

Abstract Aim Cerebrovascular insult (CVI) is a known and significant morbidity of diabetic ketoacidosis (DKA); yet, its prevalence is underestimated. Untreated cerebral hypoperfusion in DKA may lead to cerebral injury, arterial ischemic stroke, cerebral venous thrombosis, and hemorrhagic stroke. This study assesses the cerebral perfusion status among children and adolescents with DKA during and after the resolution of DKA. Methodology Forty children and adolescents with type 1 diabetes mellitus (T1DM) presenting with DKA were assessed for severity of DKA, diabetes-duration, insulin therapy, Rappaport coma/ Near coma scale, Rancho los amigos levels of cognitive functioning scale, glycated-hemoglobin (HbA1c), D-dimer, INR and brain magnetic resonance imaging (MRI) during DKA and repeated neuro cognitive scoring, laboratory and MRI after resolution of the DKA. Results The mean age of the children and adolescents with T1DM presenting with DKA was 11.40 ± 2.82 years; their median diabetes-duration was 3 year; their mean HbA1c was 13.54 ± 2%. There was significant increase in platelet (P = 0.005), D-dimer (P &amp;lt; 0.001), Creatinine (P &amp;lt; 0.001) and Pulse wave velocity (P = 0.004) during attack of DKA while there was significance decrease in Apparent diffusion coefficient (P &amp;lt; 0.001). There was 30% of children and adolescents with T1DM had ischemic MRI changes during DKA. In children and adolescent with ischemic changes there was significant increase in severity of DKA (P = 0.003), HbA1c (P = 0.016), INR (P = 0.002), D-dimer (P &amp;lt; 0.001), Creatinine (P = 0.003). Conclusion Significant cerebral hypoperfusion occur during the DKA which is correlated with the DKA severity and D-dimer levels.

Should regression calibration or multiple imputation be used when calibrating different devices in a longitudinal study?

In longitudinal studies, the devices used to measure exposures can change from visit to visit. Calibration studies, wherein a subset of participants is measured using both devices at follow-up, may be used to assess between-device differences (i.e., errors). Then, statistical methods are needed to adjust for between-device differences and the missing measurement data that often appear in calibration studies. Regression calibration and multiple imputation are two possible methods. We compared both methods in linear regression with a simulation study, considering various real-world scenarios for a longitudinal study of pulse wave velocity. Regression calibration and multiple imputation were both essentially unbiased, but correctly estimating the standard errors posed challenges. Multiple imputation with predicted mean matching produced close agreement with the empirical standard error. Fully stochastic multiple imputation underestimated the standard error by up to 50%, and regression calibration with bootstrapped standard errors performed slightly better than fully stochastic multiple imputation. Regression calibration was slightly more efficient than either multiple imputation method. The results suggest use of multiple imputation with predictive mean matching over fully stochastic imputation or regression calibration in longitudinal studies where a new device at follow-up might be error-prone compared to the device used at baseline.

Calibration and characterization of optical and x-ray streak cameras using a Ti:Sapphire laser system.

Optical and x-ray streak cameras are used to study transient phenomena, particularly in the high-energy density physics regime. The Orion laser facility employs many different types of streak cameras, which are used to collect data on laser-plasma interactions as well as to verify the temporal profile and timing between the multiple Orion beamlines. Streak cameras are complex devices with very precise timing associated with them, which can often malfunction, resulting in the loss of shot data. Since Orion is a kJ-class Nd:glass laser system, it is not optimal to try and fault-find using Orion shots since this is both time consuming and prohibitively expensive. To enable the facile set-up, fault-finding, timing-in, and in-house calibration of Orion optical and x-ray diagnostics, a single laboratory system has been commissioned to provide an adjustable stimulus to streak cameras and other Orion short pulse diagnostics (such as pulse dilation photomultiplier tubes). The system comprises a Ti:Sapphire laser system capable of generating 400nm or 266nm laser pulses of duration less than 0.1ps; an optical system to deliver single pulses, pulse pairs, or a train of pulses; and timing electronics to synchronize the streak cameras with the laser and to record output data. The system can operate at Hertz repetition rates rather than the sub-mHz rate of the Orion laser. We present the commissioned system and results from initial testing of both optical and x-ray streak cameras used on Orion laser-plasma experiments.

Prediction of hypertension risk based on multiple feature fusion

ObjectiveIn the application of machine learning to the prediction of hypertension, many factors have seriously affected the classification accuracy and generalization performance. We propose a pulse wave classification model based on multi-feature fusion for accuracy prediction of hypertension. Methods and MaterialsWe propose an ensemble under-sampling model with dynamic weights to decrease the influence of class imbalance on classification, further to automatically classify of hypertension on inquiry diagnosis. We also build a deep learning model based on hybrid attention mechanism, which transforms pulse waves to feature maps for extraction of in-depth features, so as to automatically classify hypertension on pulse diagnosis. We build the multi-feature fusion model based on dynamic Dempster/Shafer (DS) theory combining inquiry diagnosis and pulse diagnosis to enhance fault tolerance of prediction for multiple classifiers. In addition, this study calculates feature importance ranking of scale features on inquiry diagnosis and temporal and frequency-domain features on pulse diagnosis. ResultsThe accuracy, sensitivity, specificity, F1-score and G-mean after 5-fold cross-validation were 94.08%, 93.43%, 96.86%, 93.45% and 95.12%, respectively, based on the hypertensive samples of 409 cases from Longhua Hospital affiliated to Shanghai University of Traditional Chinese Medicine and Hospital of Integrated Traditional Chinese and Western Medicine. We find the key factors influencing hypertensive classification accuracy, so as to assist in the prevention and clinical diagnosis of hypertension. ConclusionCompared with the state-of-the-art models, the multi-feature fusion model effectively utilizes the patients’ correlated multimodal features, and has higher classification accuracy and generalization performance.

Mechanochemical patterning and wave propagation in multicellular tubes

Multicellular tubes are fundamental tissues for transporting and distributing liquids and gases in living organisms. Although the molecular, cellular and mechanical aspects in tube formation have been addressed experimentally, how these factors are coupled to control tube patterning and dynamics at the tissue level remains incompletely understood. Here, we propose a three-dimensional (3D) vertex model that incorporates a mechanochemical feedback loop correlating cell deformation and actomyosin signaling pathway to probe the morphodynamics of multicellular tubes. We show that diverse patterns, including ring, helix, double helix, and labyrinth, are generated in tubes through pitchfork bifurcation, where spatial fluctuations of both biochemical signaling and 3D cell deformation are remarkably involved. The mechanochemical feedback loop enables cell oscillations via Hopf bifurcation, which induces the mechanical and chemical patterns to propagate successively as either travelling or pulse waves while their spatial configurations are maintained, strikingly distinct from the classical Turing instability. Our simulations, together with stability analysis of a minimal model, uncover the essential role of mechanochemical principles in sculpting biological tubes.

Flexible micro-strain graphene sensors enhanced by laser-induced cracks for health monitoring

In-situ fabrication of patterned laser-induced graphene (LIG) has unique advantages, holding broad application prospects in the preparation of flexible electronic devices. However, a facile strategy is still demanded to improve the sensitivity of LIG-based sensors in detecting micro-strains. Herein, we propose a flexible graphene strain sensor enhanced by laser-induced cracks, which is capable of detecting small deformations. When the scanning spacing was expanded from 100 μm to 140 μm, abundant micro-cracks formed between adjacent LIG stripes, providing more sensing units. The open and close of cracks lead to significant change of resistance, enhancing the sensitivity of LIG-based sensors. The average gauge factors of sensors were improved to 98 (0–2 % strain), increasing nearly 20 times. Furthermore, the sensor exhibits excellent cyclic stability, remaining stable throughout nearly 5000 successive stretch-release cycles. The strain sensors exhibit high performance response to subtle signals of the human body. High-quality seismocardiography (SCG), pulse wave and respiration curves were achieved by our sensors, providing a lot of useful information for screening chronic diseases. Overall, this research highlights an effective method for fabricating high performance flexible strain sensors for long-term health monitoring.

Effect of low-dose terazosin on arterial stiffness improvement: A pilot study.

Arterial stiffness, a prominent hallmark of ageing arteries, is a predictor of all-cause mortality. Strategies for promoting healthy vascular ageing are encouraged. Here we conducted a pilot study to evaluate the potential effects of low-dose Terazosin on arterial stiffness. We enrolled patients aged over 40 with elevated arterial stiffness, defined as a brachial-ankle pulse wave velocity (baPWV) ≥1400 cm/s, who were administered Terazosin (0.5 and 1.0 mg/day) from December 2020 to June 2023. Treatment responses were assessed every 3 months. Linear regression analysis was used to characterise the improvement. We matched cases who took Terazosin for 1 year with Terazosin-free controls using propensity score matching (PSM). Our findings demonstrate that Terazosin administration significantly affected arterial stiffness. (1) Arterial stiffness significantly improved (at least a 5% reduction in baPWV) in 50.0% of patients at 3 months, 48.6% at 6 months, 59.3% at 9 months, and 54.4% at 12 months, respectively. (2) Those with higher baseline baPWV and hypertension exhibited a significantly reduced risk of non-response. (3) Terazosin was associated with a reduction of baPWV at 1-year follow-up (linear regression: β = -165.16, p < 0.001). This pilot study offers valuable insights into the potential significance of Terazosin in improving arterial stiffness and paves the way for future randomised clinical trials in combating vascular ageing.

Semaglutide Concurrently Improves Vascular and Liver Indices in Patients With Type 2 Diabetes and Fatty Liver Disease.

The cardiovascular benefits of semaglutide are established; however, its effects on surrogate vascular markers and liver function are not known. To investigate the effects of semaglutide on vascular, endothelial, and liver function in patients with type 2 diabetes (T2DM) and nonalcoholic fatty liver disease (NAFLD). Overall, 75 consecutive subjects with T2DM and NAFLD were enrolled: 50 patients received semaglutide 1 mg (treatment group) and 25 patients received dipeptidyl peptidase 4 inhibitors (control group). All patients underwent a clinical, vascular, and hepatic examination with Fibroscan elastography at 4 and 12 months after inclusion in the study. Treatment with semaglutide resulted in a reduction of Controlled Attenuation Parameter (CAP) score, E fibrosis score, NAFLD fibrosis score, Fibrosis-4 (FIB-4) score and perfused boundary region (PBR) at 4 and at 12 months (P < .05), contrary to controls. Patients treated with semaglutide showed a greater decrease of central systolic blood pressure (SBP) (-6% vs -4%, P = .048 and -11% vs -9%, P = .039), augmentation index (AIx) (-59% vs -52%, P = .041 and -70% vs -57%, P = .022), and pulse wave velocity (PWV) (-6% vs -3.5%, P = .019 and -12% vs -10%, P = .036) at 4 and at 12 months, respectively. In all patients, ΔPWV and ΔPBR were correlated with a corresponding reduction of CAP, E fibrosis, NAFLD fibrosis, and FIB-4 scores. Twelve-month treatment with semaglutide simultaneously improves arterial stiffness, endothelial function, and liver steatosis and fibrosis in patients with T2DM and NAFLD.

Reproductive hormones and sex differences in relation to brachial-ankle pulse wave velocity in obese subjects: a retrospective case-control study.

Reproductive hormones may be a risk factor for cardiovascular disease (CVD), but their influence is often underestimated. And obesity can exacerbate the progression of CVD. Arterial stiffness (AS) is correlated with the risk of CVD. Brachial-ankle pulse wave velocity (BaPWV) has served as a practical tool for assessing AS with broad clinical applications. This study aimed to investigate the association between reproductive hormones and baPWV in obese male and female subjects. A retrospective case-control design was designed. Arterial stiffness (AS) was assessed using baPWV, with a baPWV≥1400 cm/s indicating increased AS. Between September 2018 and October 2022, 241 obese subjects with increased AS were recruited from Ningbo Yinzhou No.2 Hospital. The control group consisted of 241 obese subjects without increased AS. A 1:1 propensity score matching was performed to correct potential confounders by age and sex. We additionally performed a sex-based sub-analysis. Correlation analysis demonstrated that luteinizing hormone (LH) (r=0.214, P=0.001) and follicle-stimulating hormone (FSH) (r=0.328, P<0.001) were positively correlated with baPWV in obese male subjects. In the multivariate conditional logistic regression analysis, FSH (OR=1.407, 95%CI=1.040-1.902, P=0.027) rather than LH (OR=1.210, 95%CI=0.908-1.612, P=0.194) was independently and positively associated with increased AS in obese male subjects. However, there was no significant correlation between reproductive hormones and baPWV in women. Our study identified FSH as a potential risk factor for arteriosclerosis in obese male subjects. This provides a novel and intriguing perspective on the pathogenesis of cardiovascular disease in obese subjects.

Association of Aortic Stiffness and Pressure Pulsatility With Noninvasive Estimates of Hepatic Steatosis and Fibrosis: The Framingham Heart Study.

Arterial stiffening may contribute to the pathogenesis of metabolic dysfunction-associated steatotic liver disease. We aimed to assess relations of vascular hemodynamic measures with measures of hepatic steatosis and fibrosis in the community. Our sample was drawn from the Framingham Offspring, New Offspring Spouse, Third Generation, Omni-1, and Omni-2 cohorts (N=3875; mean age, 56 years; 54% women). We used vibration-controlled transient elastography to assess controlled attenuation parameter and liver stiffness measurements as measures of liver steatosis and liver fibrosis, respectively. We assessed noninvasive vascular hemodynamics using arterial tonometry. We assessed cross-sectional relations of vascular hemodynamic measures with continuous and dichotomous measures of hepatic steatosis and fibrosis using multivariable linear and logistic regression. In multivariable models adjusting for cardiometabolic risk factors, higher carotid-femoral pulse wave velocity (estimated β per SD, 0.05 [95% CI, 0.01-0.09]; P=0.003), but not forward pressure wave amplitude and central pulse pressure, was associated with more liver steatosis (higher controlled attenuation parameter). Additionally, higher carotid-femoral pulse wave velocity (β=0.11 [95% CI, 0.07-0.15]; P<0.001), forward pressure wave amplitude (β=0.05 [95% CI, 0.01-0.09]; P=0.01), and central pulse pressure (β=0.05 [95% CI, 0.01-0.09]; P=0.01) were associated with more hepatic fibrosis (higher liver stiffness measurement). Associations were more prominent among men and among participants with obesity, diabetes, and metabolic syndrome (interaction P values, <0.001-0.04). Higher carotid-femoral pulse wave velocity, but not forward pressure wave amplitude and central pulse pressure, was associated with higher odds of hepatic steatosis (odds ratio, 1.16 [95% CI, 1.02-1.31]; P=0.02) and fibrosis (odds ratio, 1.40 [95% CI, 1.19-1.64]; P<0.001). Elevated aortic stiffness and pressure pulsatility may contribute to hepatic steatosis and fibrosis.

Arterial stiffness in subclinical atherosclerosis quantified with ultrafast pulse wave velocity measurements: a comparison with a healthy population using propensity score matching.

This study aimed to evaluate changes in ultrafast pulse wave velocity (ufPWV) in individuals with arterial stiffness and subclinical atherosclerosis (subAS), and to provide cutoff values. This retrospective study recruited 231 participants, including 67 patients with subAS. The pulse wave velocity was measured at the beginning and end of systole (PWV-BS and PWVES, respectively) using ultrafast ultrasonography to assess arterial stiffness. The right and left common carotid arteries were measured separately, and laboratory metabolic parameters were also collected. Participants were balanced between groups using propensity score matching (PSM) at a 1:1 ratio, adjusting for age, sex, and waist-to-hip ratio as potential confounders. Cutoff values of ufPWV for monitoring subAS were determined via receiver operating characteristic (ROC) curve analysis. PWV-ES, unlike PWV-BS, was higher in the subAS subgroup than in the subAS-free group after PSM (all P&lt;0.05). For each 1 m/s increase in left, right, and bilateral mean PWV-ES, the risk of subAS increased by 23% (95% confidence interval [CI], 1.04 to 1.46), 26% (95% CI, 1.07 to 1.52), and 38% (95% CI, 1.12 to 1.72), respectively. According to ROC analyses, predictive potential was found for left PWV-ES (cutoff value=7.910 m/s, P=0.002), right PWV-ES (cutoff value=6.615 m/s, P=0.003), and bilateral mean PWV-ES (cutoff value=7.415 m/s, P&lt;0.001), but not for PWV-BS (all P&gt;0.05). PWV-ES measured using ultrafast ultrasonography was significantly higher in individuals with subAS than in those without. Specific PWV-ES cutoff values showed potential for predicting an increased risk of subAS.

Identification of congenital aortic valve malformations in juvenile natriuretic peptide receptor 2-deficient mice using high-frequency ultrasound.

Mouse models of congenital aortic valve malformations are useful for studying disease pathobiology, but most models have incomplete penetrance [e.g., ∼2 to 77% prevalence of bicuspid aortic valves (BAVs) across multiple models]. For longitudinal studies of pathologies associated with BAVs and other congenital valve malformations, which manifest over months in mice, it is operationally inefficient, economically burdensome, and ethically challenging to enroll large numbers of mice in studies without first identifying those with valvular abnormalities. To address this need, we established and validated a novel in vivo high-frequency (30 MHz) ultrasound imaging protocol capable of detecting aortic valvular malformations in juvenile mice. Fifty natriuretic peptide receptor 2 heterozygous mice on a low-density lipoprotein receptor-deficient background (Npr2+/-;Ldlr-/-; 32 males and 18 females) were imaged at 4 and 8 wk of age. Fourteen percent of the Npr2+/-;Ldlr-/- mice exhibited features associated with aortic valve malformations, including 1) abnormal transaortic flow patterns on color Doppler (recirculation and regurgitation), 2) peak systolic flow velocities distal to the aortic valves reaching or surpassing ∼1,250 mm/s by pulsed-wave Doppler, and 3) putative fusion of cusps along commissures and abnormal movement elucidated by two-dimensional (2-D) imaging with ultrahigh temporal resolution. Valves with these features were confirmed by ex vivo gross anatomy and histological visualization to have thickened cusps, partial fusions, or Sievers type-0 bicuspid valves. This ultrasound imaging protocol will enable efficient, cost effective, and humane implementation of studies of congenital aortic valvular abnormalities and associated pathologies in a wide range of mouse models.NEW & NOTEWORTHY We developed a high-frequency ultrasound imaging protocol for diagnosing congenital aortic valve structural abnormalities in 4-wk-old mice. Our protocol defines specific criteria to distinguish mice with abnormal aortic valves from those with normal tricuspid valves using color Doppler, pulsed-wave Doppler, and two-dimensional (2-D) imaging with ultrahigh temporal resolution. This approach enables early identification of valvular abnormalities for efficient and ethical experimental design of longitudinal studies of congenital valve diseases and associated pathologies in mice.

Few-layer NbTe2 nanosheets-based saturable absorber for generating 176 fs pulse at 1 μm in ultrafast fiber laser

Ultrafast fiber lasers play an increasingly vital role in diverse fields of science and industry. In this study, a novel NbTe2 nanosheet-based saturable absorber (SA) was prepared by using liquid phase exfoliation and flame brush technology for the first time. Using a twin balance measurement system, the nonlinear optical absorption property was checked. It was found that the fabricated NbTe2 nanosheets-based SA has excellent saturable absorption properties with a large modulation depth of 5.3 %, a very high saturation intensity of 1.11 GW/cm2, and a low non-saturation loss of 63.6 %. After inserting the NbTe2 nanosheets-based SA into a ring-cavity ytterbium-doped fiber laser (YDFL), a stable soliton mode-locking state was achieved. A 176-fs ultrafast soliton pulse train was successfully generated at 1029.76 nm with the repetition rater of 3.097 MHz. Thanks to the unique and very high saturation intensity of NbTe2 nanosheets, the proposed YDFL system achieved a maximum peak power of 96.3 kW and a single pulse energy of 14.09 nJ under 370 mW pump power. These findings indicate that NbTe2 nanosheets have great potential for generating ultra-short optical pulses with higher peak power in mode-locked fiber lasers.

Electro-optic Q-switched Yb:YAG thin disk laser with widely continuously tunable pulse width at a stable output of over 80 W

We report an electro-optic Q-switched Yb:YAG thin disk laser with widely continuously tunable pulse width ranging from 16.4 to 432.2 ns. The tunability was achieved through a simple and convenient method by rotating both the Pockels cell and the quarter-wave plate at either identical or slightly different angles. Based on the 72-pass pump module and 224.4 W laser diode pumping source, a pulsed output of over 80 W was attained at a repetition rate of 100 kHz. The output power and output pulse train remained stable in the whole tuning range. The corresponding output power was 82.7 W and 84.4 W for the minimum and maximum pulse width, respectively. A model which was exceedingly more accurate than previous models describing the tunability of the pulse width were proposed and the simulation results of this model exhibited strong agreement with the experimental measurements.

The use of pulse transit time in diagnostics of sleep-disordered breathing in children

&lt;b&gt;&lt;br&gt;Introduction:&lt;/b&gt; Sleep is the physiological state of the body where proper morphology and duration are indispensable for human functions throughout both, physical and mental spheres. Disordered breathing during sleep impairs its morphology and results in major disorders in any age group. Adverse effects of Obstructive Sleep Apnea Syndrome in children and poor availability of centers offering children’s polysomnography call for a reliable and easily accessible screening method.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Aim:&lt;/b&gt; The aim of the study were to evaluate the usefulness of pulse transit time in the diagnostics of disordered sleep breathing in children and to attempt to employ the parameter in screening tests. Pulse transit time is a physiological parameter determining the time needed for the pulse wave to travel between two measurement points.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Material and methods:&lt;/b&gt; Enrolled in the retrospective study were 153 patients (100 boys and 53 girls) suspected of obstructive sleep apnea syndrome who underwent polysomnography at I. Mościcki ENT Hospital in Chorzów.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Results:&lt;/b&gt; Statistically significant relations between apnea/hypopnea index and pulse transit time were observed in both, individual age groups and all of the patients. Pulse transit time results proved a negative correlation with apnea/hypopnea index values commonly accepted as a parameter concluding the polysomnography procedures.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Conclusions:&lt;/b&gt; The results of the study indicate that pulse transit time measurements may find application in screening tests of sleep-disordered breathing in children.&lt;/br&gt;