Pressure Ratio Research Articles

Substantial Increase in Sub–Daily Precipitation Extremes of Flooding Season Over China

AbstractUnderstanding sub‐daily precipitation extremes (SPEs) can provide scientific insights for taking effective measures to mitigate climate risks. Leveraging gauge observations at hourly precipitation in 2,312 meteorological stations and extreme sub‐daily precipitation indices (ESPIs), we investigate the changes of SPEs in flooding season of 1971–2022 in China. On country scale, the occurrences and intensity of SPEs have significantly increased and even accelerated since the 21st century, suggesting increases in 2010s by 15%–38% compared with that in 1970s. The SPE risks for 20‐year and 50‐year return‐period increased by 2–4 and 8–20 times in 2001–2022 compared with that in 1971–2000, respectively. Over 80% stations are found to have positive trends in all ESPIs. On regional scale, seven sub‐regions experienced significant increases in ESPIs with larger magnitudes in the East China. The enlarged 500‐hPa geopotential height, 700‐hPa pseudoequivalent potential temperature, 700‐hPa specific humidity, saturated vapor pressure and urbanization ratio may be bonded to more SPEs.

The Protective Role of the Ratio of Arterial Partial Pressure of Oxygen and Fraction of Inspired Oxygen after Re-Supination in the Survival of Patients with Severe COVID-19 Pneumonia

The Protective Role of the Ratio of Arterial Partial Pressure of Oxygen and Fraction of Inspired Oxygen after Re-Supination in the Survival of Patients with Severe COVID-19 Pneumonia

Assessing the Role of Blood Gas Analysis in COVID-19 Patients for Early Warning and Clinical Guidance.

To assess the role of blood gas analysis as an auxiliary tool for detecting and predicting the progression of COVID-19 in patients. A consecutive cohort study was conducted of 106 patients diagnosed with the novel coronavirus. Patients were divided into two groups based on age and the course of the disease (mild to moderate and severe). Blood gas analysis parameters were measured for all participants and results were compared between groups. This study was conducted in the Department of Laboratory Medicine, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China. Arterial/alveolar oxygen partial pressure ratio, reduced hemoglobin fraction, sodium ion, lactic acid, oxygen saturation, oxygen partial pressure, and oxyhemoglobin fraction. Findings indicated statistically significant differences between the two groups in the measured parameters. Blood gas analysis has the potential to more accurately assess the progression of COVID-19 in elderly patients, specifically related to respiratory and acid-base balance issues. This study underscores the importance for bedside nurses to pay close attention to acid-base balance, lung ventilation/ventilation function, and hypoxia status in elderly critically ill patients with COVID-19, in order to more effectively diagnose and predict the progression of the disease.

Diagnostic Performance of Quantitative Flow Ratio for the Assessment of Non-Culprit Lesions in Myocardial Infarction (QFR-OUTSMART): Systematic Review and Meta-Analysis.

Quantitative flow ratio (QFR) analysis is a simple and non-invasive coronary physiological assessment method with evidence for evaluating stable coronary artery disease with correlation to fractional flow reserve (FFR). However, there is no evidence to recommend its use in non-culprit lesions (NCLs) in myocardial infarction (MI). We performed a systematic review and meta-analysis using the PRISMA and PROSPERO statements. The study's primary objective was to assess the diagnostic accuracy of QFR in identifying functionally significant NCLs after MI based on invasive FFR and non-hyperemic pressure ratios as references. We obtained values of the area under the curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). We performed a leave-one-out sensitivity analysis for each study's impact on the overall effect. We included eight studies, with 713 patients and 920 vessels evaluated with QFR. The overall AUC was 0.941 (I2 = 0.559, p < 0.002), with a sensitivity of 87.3%, a specificity of 89.4%, a PPV of 86.6%, and an NPV of 90.1%. Compared to FFR, we found an AUC of 0.957 (I2 = 0.331, p < 0.194), a sensitivity of 89.6%, a specificity of 89.8%, a PPV of 88.3%, and an NPV of 91%. The sensitivity analysis showed a similar diagnostic performance in both studies. QFR is effective in analyzing NCLs with a significant diagnostic yield compared to FFR, with an excellent AUC in MI patients. Performing prospective multicenter studies to characterize this population and reproduce our results is essential.

Hemodynamic assessment of intracranial atherosclerotic stenosis: comparison between invasive non-hyperemic pressure ratio and angiography-derived quantitative flow ratio

ObjectivesTo evaluate the diagnostic accuracy of the quantitative flow ratio (QFR) for hemodynamic exploration of intracranial atherosclerotic stenosis, using the invasive cerebrovascular pressure ratio (CVPR) and resting full-cycle ratio (RFR) as reference standards.Materials and methodsPatients with symptomatic unifocal intracranial atherosclerotic stenosis were included. The CVPR was defined as the ratio of the proximal and distal pressures. All patients underwent angioplasty under general anesthesia. The QFR was calculated based on digital subtraction angiography. Using the CVPR as a reference, we compared its correlation with the QFR across different degrees and locations of stenosis.ResultsThe CVPR and QFR were measured in 34 vessels of 32 patients. The QFR demonstrated a high correlation and excellent agreement(r = 0.8227, p &amp;lt; 0.001) with the CVPR in distal stenosis before intervention. In the subgroup with diameter stenosis &amp;gt;80%, the QFR showed a high correlation (r = 0.8812, p &amp;lt; 0.001) with the CVPR. In the anterior circulation subgroup, the QFR showed an excellent correlation (r = 0.9066, p &amp;lt; 0.001) with the CVPR. In the posterior circulation subgroup, the QFR showed a high correlation with the CVPR (r = 0.7706, p &amp;lt; 0.001). Diameter stenosis rates showed a moderate negative correlation with the CVPR.ConclusionThere was a strong correlation between the QFR and wire-based CVPR, especially for anterior circulation lesions before intervention. The QFR may serve as a predictive factor for evaluating hemodynamic changes in intracranial atherosclerotic stenosis.

Investigation of burnout effect in turbine blade tip leakage at transonic conditions – a numerical study

Abstract In the aviation industry, turbine blade tip leakage significantly impacts the economy due to aerodynamic losses in the turbine. The tip leakage flow increases when the tip surface is exposed to high heat loads from the burnout effect, contributing to nearly 30% of the total loss in the turbine stage. This study numerically investigates two-dimensional flat tip and burnt-out tip models under different flow accelerations at transonic conditions. Variations in the discharge coefficient are examined for different pressure ratios across the tip gap. Flow and shockwave patterns for various blade tip geometries are obtained and analyzed. The burnt-out tip notably increases tip leakage, and a significant decrease in turbine efficiency is observed beyond a critical burnout limit. The quantified losses at different stages of blade tip burnout are used to predict the effective operational life of the blade. A correlation is developed to relate the non-dimensional tip-leakage flow parameters to the normalized blade-tip geometry.

BN SO19 - Evaluating Wrap Pressure Augmentation Ratio and Physiological Transit Time for Post-Fundoplication Dysphagia

Abstract Background Post-fundoplication dysphagia affects many patients that can often lead to significant weight loss and reduced quality of life, and prompt some to seek surgical reversal. Current diagnostic methods may not fully explain the dysphagia which may necessitate repeat oesophageal physiology testing. This study retrospectively evaluates two novel markers, Wrap Pressure Augmentation Ratio (WPAR) and Physiological Transit Time (PTT), to better understand and manage the post-fundoplication dysphagia. Method The study retrospectively reviewed 54 post-Nissen’s fundoplication patients from January 2020 to May 2024. WPAR was calculated as the ratio of the augmented wrap basal pressure to the median integrated relaxation pressure found during high-resolution manometry following the Chicago Classification guideline [1]. PTT was measured from controlled measurements of antegrade bolus movement [2] during multichannel impedance-pH studies [3]. Patients completed HODQ forms to assess dysphagia [4]. Optimal WPAR and PTT thresholds were determined using Youden’s J index from receiver operating characteristic curves. This study was ethically approved (REC 18/NW/0120, IRAS 333800). Results Out of 54 cases (female=28:26, mean age 50.6), 75.9% reported clinical dysphagia post-fundoplication. Significant correlations were found with WPAR (&amp;lt;1.49, p=0.017) and PTT (&amp;gt;0.83 minutes, p=0.028)(see Table 1). These findings suggest WPAR and PTT as effective markers for post-fundoplication dysphagia. The analysis revealed a moderate correlation between WPAR and PTT (r =-0.45, p&amp;lt;0.05), suggesting that lower WPAR values tend to be associated with longer PTT. SensitivityPositive Predictive Valueχ2p-valueWPAR &amp;lt;1.490.610.895.680.017PTT &amp;gt;0.83 minutes0.780.844.820.028 Table 1 showing predictive DR and PTT values for clinical dysphasia post fundoplication. Conclusion This pilot study identifies PAR and PTT as promising physiological markers for diagnosing post-fundoplication dysphagia. The moderate correlation between PAR and PTT suggests a potential link, indicating that lower pressure augmentation might be associated with slower oesophageal transit times. These markers could enhance management strategies for affected patients. However, the study's small sample size and lack of a control group limit generalizability. Larger, controlled studies are necessary to validate these findings and further explore the relationship between PAR and PTT.

Coupled Aeropropulsive Design Optimization of an Over-wing Nacelle Configuration

The over-wing nacelle (OWN) configuration has the potential to improve on the conventional under-wing nacelle (UWN) configuration by enabling higher bypass ratios and increasing noise shielding. To explore this potential, we perform coupled aeropropulsive design optimization to study the coupled analysis and the design tradeoffs between aerodynamics and propulsion. We find that the variations in wing shape are not significant when the OWN configuration is optimized for different fan pressure ratios. Optimizing the OWN configuration using the proposed approach results in 3% less shaft power than optimizing the wing and propulsor separately. The OWN has marginally superior performance over the UWN for the same lower fan pressure ratio. However, this low fan pressure ratio may be unattainable for the UWN configuration because of ground clearance constraints, whereas the OWN configuration is not subject to such constraints. We study the optimal OWN placement and show that placing it aft of the trailing edge and away from the wing root results in lower required shaft power. In this study, we perform single-point optimizations to understand the fundamentals of the OWN configuration in terms of aerodynamics and propulsion. However, multiple operating conditions, structural integrity, and inclusion of the pylon geometry should be considered to assess the net benefit of the OWN configuration. Nevertheless, these advancements in aeropropulsive optimization are critical to OWN configuration design and more sustainable aircraft.

Numerical Investigation of Unsteady Flow Characteristics of Planar Plug Nozzle in Over-Expanded Conditions

Abstract Plug nozzles are frequently regarded as a strong contender for futuristic single-stage-to-orbit space missions due to their inherent altitude-compensating properties. Optimizing the design of these nozzles to achieve peak performance during the initial ascent phase is of preeminent importance. The current research aims to deepen our comprehension of the unsteady behavior of plug nozzles during this ascent phase, commonly referred to as the overexpanded flow regime. It utilizes a full-spike plug nozzle and employs a finite volume-based solver within the OpenFOAM framework to investigate flow features across Nozzle Pressure Ratios (NPRs) ranging from 3 to 8. Additionally, the Ffowcs Williams Hawkings (FW-H) analogy is employed to assess the influence of acoustics in the nozzle's flow field at different NPRs.Spectral analysis and flow visualizations are employed to study the frequency content and the respective flow features of the system. It is observed that the flow exhibits separation beyond NPR 4 and is highly unsteady at NPR 6, which is inferred from the prominence of the recirculation bubble. However, beyond NPR 6, the flow tends to reattach the plug surface, dampening the disturbance.

Abstract 4121793: A Pressure-Volume Loops Approach Predicts Outcomes After Double Switch Operation For Congenitally Corrected Transposition Of The Great Arteries with Intact Ventricular Septum

Background: Double switch operation (DSO) for congenitally corrected transposition of the great arteries with intact ventricular septum (ccTGA) has a high rate of post-DSO LV dysfunction. Hypothesis: LV pressure-volume area (PVA), a surrogate of myocardial O 2 consumption, is a superior marker of LV preparedness and is associated with adverse outcomes after DSO. Aims: 1. Derive a mathematical relationship to estimate LV PVA (ePVA) from catheterization (pressure) and imaging (volumetric) data, using directly measured PVA (mPVA) as reference 2. Assess if lower ratio of LV ePVA to RV ePVA (as an internal control) is associated with adverse outcome after DSO. Methods: Aim 1: Using conductance catheter derived invasive subpulmonary LV PV loops, mPVA was recorded as the sum of stroke work (SW) and potential energy (PE). A mathematical relationship was established with standard catheterization/imaging data to estimate ePVA. Aim 2: In a retrospective cohort, LV:RV ePVA ratio was calculated as above, and along with standard clinical metrics, assessed for relationship with a composite outcome of ≥ moderate LV dysfunction, transplant, or death post-DSO. Results: Aim 1: In 20 PV loop studies in 18 pre-DSO patients, there was a strong linear correlation between measured and estimated SW and PE (R 2 &gt; 0.9 and p&lt;0.0001 for both). ePVA yielded high agreement and low bias compared to mPVA (mean bias 0.5±11%). Aim 2: Composite outcome occurred in 6/42 DSO patients (14%). LV:RV ePVA ratio (0.57 [0.49, 0.61] vs 0.90 [0.73, 1.1], p&lt;0.001) and LV:RV pressure ratio (0.80 [0.77, 0.87] vs 1.13 [1.01, 1.23], p&lt;0.001) were lower in those with adverse outcome. There were no differences in other pre-operative parameters. On time to event analysis, lower LV:RV ePVA ratio was the strongest determinant (HR 39, 95% CI 15-100; C Index 0.94), while lower LV:RV pressure ratio was the only other predictor (HR 24, 95% CI 13-42; C Index 0.88). In 8 patients with borderline pressure ratios of 0.77-0.88, ePVA ratio was an excellent discriminator - 3 patients with ePVA ratio of ≥0.67 had good outcomes, whereas 5 patients with ePVA ratio &lt;0.67 had adverse outcomes. Conclusion: LV:RV ePVA ratio &gt;0.67 is a strong and novel predictor of LV preparedness for DSO in patients with ccTGA.

Abstract 4132909: Hemodynamic Indices of Right Ventricular Function Differentially Predict Adverse Clinical Outcomes in Heart Failure with Preserved vs Reduced Ejection Fraction

Background: While the critical role of right ventricular dysfunction (RVD) in heart failure (HF) is increasingly recognized, the prevalence and prognostic impact of RVD across HF subtypes is poorly understood. Research Questions/Aims: We aimed to characterize differences in hemodynamic indices of RV function among patients with HF with preserved vs reduced ejection fraction (HFpEF, EF≥50% vs HFrEF, EF&lt;50%) and to examine associations of RVD with longitudinal clinical outcomes by HF subtype. Methods: We identified patients with prevalent HF undergoing clinically indicated right heart catheterization at Massachusetts General Hospital (2005-2016). We examined three RV hemodynamic indices: right atrial to wedge pressure ratio (RA/PCWP), RV stroke work index (RVSWI), and pulmonary artery pulsatility index (PAPi). We used multivariable linear regression to assess differences in RV indices in HFpEF vs HFrEF. We then used Cox models to examine the association of each index with HF hospitalizations (HFH), major adverse cardiac events (MACE), and death, stratified by HF subtype. Models were adjusted for age, sex, BMI, hypertension, diabetes, lung disease, sleep apnea, and prior MI. Results: Of 2,062 patients (age 66 years, 33% women), 1,242 (60%) had HFrEF and 820 (40%) had HFpEF. RVD (RVSWI &lt;450 mm Hg*ml/m 2 ) was present in 27% of HFrEF vs 21% of HFpEF patients. Those with HFpEF had higher RA/PCWP (β 0.12, SE 0.05, p=0.012) and RVSWI (β 0.22, SE 0.05, p&lt;0.001) relative to HFrEF. Over 4.1 median years follow-up, 915 HFH, 1,066 MACE, and 1,116 death events occurred. Among those with HFrEF, lower PAPi was associated with greater risk of HFH (HR 0.84 (0.77, 0.92); p&lt;0.001) and MACE (HR 0.88 (0.81, 0.96); p=0.003), and higher RVSWI was associated with greater risk of death (HR 1.17, (1.07, 1.27); p&lt;0.001, Figure ). In contrast, in those with HFpEF, only higher RA/PCWP was associated with greater risk of death (HR 1.11 (1.00, 1.23); p=0.042). Conclusion: RVD occurs frequently in both HFrEF and HFpEF, and hemodynamic measures of RV function are associated with greater risk of MACE, death, and HFH. Importantly, the prognostic value of RV indices varied by HF subtype, highlighting key differences in the role of RVD in HFrEF vs HFpEF.

Abstract 4138793: Impact of diabetes mellitus on the severity and long-term outcomes of chronic thromboembolic pulmonary hypertension: a retrospective cohort study

Background: Previous studies have indicated that diabetes mellitus (DM) is linked to the severity and mortality of both pulmonary thromboembolism and pulmonary arterial hypertension. But the relationships between diabetes and chronic thromboembolic pulmonary hypertension (CTEPH) have not been discussed. This study aims to investigate the relationships of DM with disease severity and clinical worsening events in patients with CTEPH. Methods: We analysed data of patients with CTEPH from the National Center for Cardiovascular Diseases in China between January 1, 2013 and August 31, 2023. A 2-group propensity score matching was conducted to adjust for differences between CTEPH patients with and without DM, employing a 1:1 pairing algorithm. The association between DM and long-term adverse outcomes was appraised utilizing multivariable Cox regression models. Subgroup analyses, predicated on age, sex, World Health Organization functional class (WHO-FC) and body mass index, were carried out to evaluated interaction effects. Results: In total, 489 consecutive CTEPH patients were included in the study, with 25.97% diagnosed with DM. Subsequent matched analysis comprised 127 patients with DM and 127 without DM. CTEPH patients with DM exhibited inferior WHO-FC as well as cardiac index, elevated N-terminal pro–brain natriuretic peptide levels, pericardial effusion, tricuspid annular plane systolic excursion / systolic pulmonary arterial pressure ratio and pulmonary vascular resistance. After adjusting for confounding factors, DM remained independently associated with adverse outcomes in patients with CTEPH. In addition, further subgroup analyses disclosed a more robust association in patients without overweight or obesity. Conclusions: DM correlates with heightened severity of CTEPH and serves as an autonomous predictor of long-term prognosis in CTEPH. Moreover, this correlation is more pronounced in individuals devoid of overweight or obesity.

Abstract 4132249: Preoperative identification of respiratory viral genomes in the trachea but not in the nasopharynx is a risk factor for postoperative pulmonary hypertension in patients with congenital cardiac communications

Introduction: Pulmonary vascular remodeling is a key determinant of outcomes in patients undergoing surgery for congenital cardiac communications (CCCs). Respiratory epithelial cells infected by viruses express cytokines and growth factors with potential impact on airway and vascular remodeling. Hypothesis: Preoperative exposure to respiratory viruses renders CCC patients susceptible to postoperative pulmonary hypertension. Aims: To investigate if asymptomatic patients carrying respiratory viral genomes (RVGs) in the airways are at risk for pulmonary hypertension following cardiac surgery. To analyze the role of postoperative inflammatory reaction. Methods: The study comprised patients with unrestrictive CCCs undergoing surgery under cardiopulmonary bypass (CPB). In the absence of any signs of recent infection, RVGs were searched for in nasopharyngeal aspirates 2-3 days before surgery, and in tracheal aspirates collected in the operating room (RT-PCR, panel for 19 viruses). Serum levels of 36 inflammatory proteins were measured by chemiluminescence preoperatively and 4 hours post CPB. Pulmonary/systemic mean arterial pressure ratio (PAP/SAP) computed during the first 12 hours postoperatively (invasive assessment) was defined as the study outcome. A cutoff level was set at 0.40. Results: Sixty patients were enrolled (age 11 [7-16] months, median with interquartile range). Preoperative PAP/SAP was 0.78 (0.63-0.88). RVGs were present in nasopharyngeal and tracheal aspirates in 64% and 38% of patients, respectively. The presence of RVGs in tracheal aspirates was associated with an upward shift of postoperative PAP/SAP curve (p=0.006). The same was not observed for positive tests in nasopharyngeal aspirates (p=0.343). Of all factors analyzed as possible predictors of postoperative PAP/SAP &gt;0.40, only preoperative peripheral oxygen saturation and the presence of RVGs in the trachea were selected at multivariate analysis (respective OR with 95% CI, 0.40 [0.23-0.72] and 4.42 [1.17-16.78]. Heightened post-CPB levels of interleukin-1 receptor antagonist and chemokines MIF and MCP-1 were found to increase the risk of having a PAP/SAP &gt;0.40 in RVG carriers (respective OR with 95% CI, 2.04 [1.09-3.81], 2.34 [1.15-4.74] and 2.18 [1.07-4.43]. Conclusion: The observed relation of postoperative hemodynamics to respiratory viruses and post-CPB inflammatory reaction may have pathophysiological and therapeutic implications in pulmonary hypertension associated with congenital heart disease.

Air Excess Coefficient and Irreversibility Value Analysis of Gas Turbines

Gas turbines used in natural gas cycle power plants have been researched in terms of energy efficiency. Gas turbines used in power generation plants have a very complex structure because they contain many components. In order to determine the thermodynamic performance of this system, the efficiency of each component and the increase in entropy of each component were calculated using exergy analysis. Irreversibility was chosen as the main parameter and used for thermodynamic optimization of production. The system consists of many components. An increase in the irreversibility of a single component causes an increase in the irreversibility of other components. The effect of gas turbine pressure ratio and excess air percentage on fuel consumption, fuel exergy, combustion chamber exergy change and irreversibility change was investigated. It was observed that the increase in compressor pressure ratio increased irreversibility. Maximum irreversibility was observed in the combustion chamber. Irreversibility was compared with the excess air used in the combustion chamber. The air excess coefficient was examined as percentages of 100%, 200%, and 300%, respectively. The compression pressure ratio was examined for air excess coefficient percentage values from 3 to 40.

Shape Optimization of a Diffusive High-Pressure Turbine Vane Using Machine Learning Tools

Machine learning tools represent a key methodology for the shape optimization of complex geometries in the turbomachinery field. One of the current challenges is to redesign High-Pressure Turbine (HPT) stages to couple them with innovative combustion technologies. In fact, recent developments in the gas turbine field have led to the introduction of pioneering solutions such as Rotating Detonation Combustors (RDCs) aimed at improving the overall efficiency of the thermodynamic cycle at low overall pressure ratios. In this study, a HPT vane equipped with diffusive endwalls is optimized to allow for ingesting a high-subsonic flow (Ma=0.6) delivered by a RDC. The main purpose of this paper is to investigate the prediction ability of machine learning tools in case of multiple input parameters and different objective functions. Moreover, the model predictions are used to identify the optimal solutions in terms of vane efficiency and operating conditions. A new solution that combines optimal vane efficiency with target values for both the exit flow angle and the inlet Mach number is also presented. The impact of the newly designed geometrical features on the development of secondary flows is analyzed through numerical simulations. The optimized geometry achieved strong mitigation of the intensity of the secondary flows induced by the main flow separation from the diffusive endwalls. As a consequence, the overall vane aerodynamic efficiency increased with respect to the baseline design.

Relationships Among the EmPHasis-10 Questionnaire, the Simplified Four-Strata Risk Assessment Tool, and Echocardiographic Parameters in Patients with Precapillary Pulmonary Hypertension

Background/Objectives: Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are complex diseases that require precise diagnosis and management. The ESC risk score has been used in both conditions. We assessed the relationship between the EmPHasis-10 questionnaire (patient subjective evaluation) and objective assessment using endorsed tools (simplified four-strata risk assessment and right ventricular imaging by transthoracic echocardiography). Methods: The present study retrospectively extracted data from 40 adult patients (27 PAH and 13 CTEPH cases) diagnosed in a single center in Romania. The EmPHasis-10 questionnaire and the four-strata risk assessment (FSRA) tool were applied to each patient. Mean pulmonary artery pressure (mPAP), tricuspid annular plane systolic excursion (TAPSE), TAPSE/systolic pulmonary artery pressure (TAPSE/sPAP) ratio, and right ventricular outflow tract acceleration time (RVOT-AT) were assessed. Results: A significant correlation was observed between the EmPHasis-10 scores and the FSRA tool, the WHO functional class, and the 6 min walking distance. Emphasis-10 score did not correlate with any of the echocardiographic parameters. The FSRA tool showed a moderate positive correlation with mPAP (r = 0.42, p = 0.01) and a negative correlation with TAPSE (r = −0.46, p = 0.003); additionally, across the entire cohort, it was moderately negatively correlated with both RVOT-AT (r = −0.42, p = 0.01) and TAPSE/sPAP ratio (r = −0.43, p = 0.005). Conclusions: Our study evidenced the alignment between EmPHasis-10 scores and prognostic risk score, with poorer health-related quality of life corresponding to higher FSRA. The EmPHasis-10 questionnaire proves to be a valuable, easy-to-use instrument, offering meaningful insights into patients’ health-related quality of life, underscoring its utility in enhancing comprehensive patient assessment and management.

Comparison of Nitroglycerin-Induced Pressure Ratio Drop and Resting Full-Cycle Ratio in a Pressure Wire Study

Background/Objectives: The acute drop in distal coronary pressure (Pd)-to-aortic pressure (Pa) ratio after intracoronary nitroglycerin (NTG-Pd/Pa) administration is an acceptable estimate of fractional flow reserve (FFR). We aimed to compare the diagnostic performance of NTG-Pd/Pa with that of the resting full-cycle ratio (RFR) in predicting the binary results of FFR. Methods: This study included two prospective studies registered under the numbers NCT04700397 and NCT03693157. Altogether, 202 vessels were included. The optimal cutoff of NTG-Pd/Pa for predicting FFR ≤ 0.8 was identified and validated in another prospective registry. We used the McNemar’s test and the DeLong method to compare the diagnostic efficiency of NTG-Pd/Pa vs. RFR in predicting FFR ≤ 0.8 in a pooled cohort. Results: NTG-Pd/Pa was strongly correlated with FFR (r = 0.945, p &lt; 0.001). The NTG-Pd/Pa cutoff for predicting FFR ≤ 0.8 was 0.85 in both the derivation and validation cohorts. The area under the receiver-operating characteristic curve (AUC) and accuracy in predicting FFR ≤ 0.8 were higher for NTG-Pd/Pa than for RFR in the pooled cohort (AUC 0.97 vs. 0.91, p &lt; 0.001; accuracy 91% vs. 84%, p &lt; 0.001). The sensitivity and negative predictive values were also higher for NTG-Pd/Pa than for RFR (all p &lt; 0.05). The specificity and positive predictive value were numerically higher for NTG-Pd/Pa than for RFR (all p &gt; 0.05). Conclusions: The diagnostic performance of NTG-Pd/Pa may surpass that of the RFR in predicting the binary results of the FFR.

Carbon dioxide hydrate formation in porous media under dynamic conditions

AbstractInjecting carbon dioxide (CO2) into subsea water zones where the in situ temperatures are below the hydrate‐forming temperature of CO2 has been recently proposed to lock CO2 inside the water zones in solid hydrate form. It is a common concern that CO2 may form hydrates during the injection period that will reduce well injectivity. CO2 injection into sandstone cores under simulated subsea temperatures of 2°C and 3°C was investigated in this study. Experimental result shows that, at 2°C temperature, flowing CO2 at Darcy velocity 0.033 cm/s begins to form hydrate in the sandstone core at about 3.06 MPa (450 psi), which is much higher than the minimum required pressure of 1.5 MPa (220 psi) for CO2 to form hydrate in static condition. The pressure ratio is 450/220 = 2.05. At 3°C temperature, flowing CO2 at Darcy velocity 0.045 cm/s begins to form hydrate in sandstone core at about 3.67 MPa (540 psi), which is much higher than the minimum required pressure of 1.87 MPa (275 psi) for CO2 to form hydrate in static conditions. The pressure ratio is 540/275 = 1.96. The reason why the required minimum pressure for CO2 to form hydrates in dynamic conditions is about double the required hydrate‐forming pressure in static conditions is not fully understood. It is speculated that the shear rate effect of flowing fluids should slow down the growth of hydrate crystals or break down hydrate films, resulting in delayed formation of bulk CO2 hydrates. More investigations in this area are needed in the future.

Mid-Term Results of Pulmonary Valve-Sparing Repair for Tetralogy of Fallot With Pulmonary Stenosis.

The transannular patch remains the most common procedure performed for patients with Tetralogy of Fallot (TOF) with pulmonary stenosis. Pulmonary regurgitation has a negative impact on early and late outcomes. To address this issue pulmonary valve-sparing repair (PVSR) has been developed. Our study goal is to evaluate the mid-term outcomes (five years) of PVSR at our institution. The data were collected retrospectively from June 2014 to June 2022. A total of 390 patients had total repair of TOF. Among these, PVSR was performed in 154 (39.4%) patients. The mid-term outcomes on the status of the pulmonary valve gradient, degree of pulmonary regurgitation, reintervention rate, and mid-term survival after PVSR were investigated. The median age at time of TOF repair was 12 (interquartile range [IQR]: 8-48) months and the median weight was 7.9 (IQR: 3.1-49.5) kg. The mean preoperative right ventricular outflow tract (RVOT) gradient was 77 ± 19.6 mm Hg. All patients had a pulmonary valve Z score of more than -2.5. The post-repair mean RV/LV pressure ratio was 0.49 ± 0.12. There was no surgical mortality. The median follow-up was 3 years (6 months to 8 years). The reintervention rate on the pulmonary valve was 4/154 (2.6%) at five years. The freedom from reintervention and from developing moderate pulmonary valve regurgitation at 5 years was 95% (151/154) and 77% (119/154), respectively. Pulmonary valve-sparing repair gives good mid-term outcomes in a specific group of patients with TOF. Reintervention rates are very low and the peak gradient across the pulmonary valve came down in the majority of patients during mid-term follow up. An RVOT gradient more than 40mm Hg at discharge predicts a high risk of need for reintervention. We continue to monitor our patients for the long term outcome.

Horizontal walls effect on the subsonic flow around airfoil by the image method

The aim of this work consists in developing a new numerical method and a calculation program making it possible to determine the effect of one and two horizontal walls on the distribution of the pressure ratio, and the aerodynamics coefficients of a subsonic flow around airfoils. The model is considered for the perfect gas. The calculation is presented by adding the effect of one and two walls on the discretization of the airfoils boundary to obtain a closed surface. The method is called by the image method. So for the case of the existence of one wall, we will see a single image of the main airfoil, and in the case of two walls, we will have an infinity of images. The equation system is obtained by considering the effect of all images using alternating digital series, whose convergence is ensured numerically. We therefore obtain a large system of equations, the resolution of which is done by the Khaletski method to obtain the velocities and pressure. The application is made for some practical interest’s airfoils. Since the airfoils boundary is given by tabulated values, the cubic spline interpolation is used to obtain an analytical equation of the upper and the lower surfaces. The comparison is made with the case of open air flow by extending the distance between the walls and the airfoil chord towards infinity.