Pressure Ratio Research Articles

Thermal physiological characteristics of the Xizang people in asymmetrical dressing exposures on the plateau

The Xizang people, living in the “Third Pole of the World,” have long-formed asymmetrical dressing habits that pose unique challenges to their physiological mechanisms. This study examined the physiological parameters of the Xizang people under symmetrical and various asymmetrical dressing angles to analyze the influence of these dressing styles on their thermal responses. Partial correlation analysis was used to further clarify the physiological thermal assessment indicator of the Xizang people. The results showed that, compared to symmetrical dressing, the Xizang people exhibited higher blood perfusion index and core temperature under asymmetrical dressing. In cold environments, those with symmetrical dressing had higher mean arterial pressure, heart rate, and relative activity ratio of sympathetic to parasympathetic nervous system, indicating dominant sympathetic nerve activity. At an ambient temperature of 15 °C, the Xizang people demonstrated a mean skin temperature difference of 2.6 °C and a right wrist temperature difference of 4.5 °C between symmetrical and the asymmetrical dressing angle with 50° Skin temperature was identified as the physiological thermal assessment indicator for the Xizang people considering asymmetrical dressing styles. This study provided a physiological foundation for the accurate design of plateau built environments suitable for the Xizang people.

Performance improvement of a centrifugal compressor for cogeneration

This work presents the performance improvement of a centrifugal compressor designed for cogeneration applications. The study involves modifications to geometric parameters, including impeller and diffuser configurations, to enhance pressure ratio, temperature ratio, and overall efficiency using computational fluid dynamics to verify the improvement of those parameters. The study has examined the compressor’s behaviour under surge, design, and choke conditions, showcasing improved homogeneity, reduced low-velocity zones, and an extended operating range. The compressor maps are presented to graphically observe the impact of each proposed modification, facilitating the analysis of each of these and evaluating the performance under various operating conditions. The final compressor configuration exhibits notable improvements in key performance metrics, with pressure ratio, temperature ratio, and efficiency showing increases of 1.753%, 1.640%, and 1.760%, respectively.

Comprehensive Experimental Assessment Of Unsteady Pressure And Heat Flux In A Small-Core Turbine Over-Tip Shroud

Abstract For novel high-speed small core turbines, with tip clearance below 0.5mm, even small blade-to-blade tip clearance variation is significant. The assessment of these complex flows is pertinent to the design of the next generation of small-core turbines. This manuscript provides a thorough experimental analysis of the shroud?s unsteady heat flux and static pressure in a small-core squealer-tip blade turbine. Atomic Layer Thermopile sensors and fast response pressure transducers were used to perform high-frequency acquisition at 2MHz around the 51% axial blade chord on the shroud. Measurements were taken at engine-representative conditions at several operational conditions and tip clearances. The signals were phase-locked averaged over the revolution period and synchronized to identify individual blade and row signatures. The linear relationship between the rotational tip Reynolds and the static pressure ratio across the blade tip reveals the transition point to reverse over-tip flows. Total heat flux is decomposed into different steady and unsteady heat flux contributions. It is demonstrated that the adiabatic wall temperature governs the unsteady heat flux and contributes to one third of the total surface heat flux. A linear trend was observed between the unsteady heat flux and the tip clearance measured at the pressure and suction side rims. Similar trends were observed between the local heat flux and the pressure ratio across the tip. A comparison with CFD predictions highlights some limitations on resolving the detached and secondary flows, evidencing the necessity of complementary experimental data.

Multi-Objective Optimization of a Small-Scale ORC-VCC System Using Low-GWP Refrigerants

The increasing global demand for energy-efficient cooling systems, combined with the need to reduce greenhouse gas emissions, has led to growing interest in using low-GWP (global warming potential) refrigerants. This study conducts a multi-objective optimization of a small-scale organic Rankine cycle–vapor compression cycle (ORC-VCC) system, utilizing refrigerants R1233zd, R1244yd, and R1336mzz, both individually and in combination within ORC and VCC systems. The optimization was performed for nine distinct cases, with the goals of maximizing the coefficient of performance (COP), maximizing cooling power, and minimizing the pressure ratio in the compressor to enhance efficiency, cooling capacity, and mechanical reliability. The optimization employed the Non-dominated Sorting Genetic Algorithm III (NSGA-III), a robust multi-objective optimization technique that is well-suited for exploring complex, non-linear solution spaces. This approach effectively navigated trade-offs between competing objectives and identified optimal system configurations. Using this multi-objective approach, the system achieved a COP of 0.57, a pressure ratio around 3, and a cooling capacity exceeding 33 kW under the specified boundary conditions, leading to improved mechanical reliability, system simplicity, and longevity. Additionally, the system was optimized for operation with a cooling water temperature of 25 °C, reflecting realistic conditions for contemporary cooling applications.

Research on aerodynamic performance of centrifugal compressors for hydrogen-mixed natural gas.

Natural gas-doped hydrogen transportation has been widely used in industrial engineering. The change of the physical parameters of the conveying medium affects the working performance of the centrifugal compressor. This study aims to explore the aerodynamic performance of centrifugal compressors for hydrogen mixed natural gas, including the effects of hydrogen blending ratio (HBR) and inlet temperature on the pressure ratio and isentropic efficiency of compressors. The numerical simulation method is used and the results are compared with the experimental results to determine the reliability of the numerical simulation method. The results show that the pressure ratio decreases with the increase of HBR where the inlet temperature and rotation speed are constant. The pressure ratio and efficiency of the compressor are the highest when the conveying medium is pure natural gas (HBR = 0). The maximum pressure ratio reduction is 4.8% when the HBR is 5% and the inlet temperature is increased by 20 K. In summary, when the conveying medium of the compressor changes from pure natural gas to hydrogen-mixed natural gas, the working range and efficiency of the compressor will be reduced. Therefore, it is necessary to increase the rotation speed of the compressor or redesign the centrifugal compressor for hydrogen-mixed natural gas in order to achieve a constant flow rate at the outlet of the compressor.

Comparing predictive accuracy: systolic blood pressure to left ventricular end-diastolic pressure ratio versus TIMI score for short-term mortality after primary percutaneous coronary intervention

Abstract Objective Aim of this study was to evaluate the predictive performance of systolic blood pressure (SBP) to left ventricular end-diastolic pressure (LVEDP) ratio for the prediction of in-hospital and short-term mortality in a contemporary cohort of patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) at a tertiary care cardiac center. Methods This study included a consecutive series of patients diagnosed with STEMI who underwent primary PCI. The SBP/LVEDP ratio and TIMI (Thrombolysis in Myocardial Infarction) score were calculated, and their ability to predict in-hospital and short-term mortality was evaluated by analyzing the area under the curve (AUC) on the receiver operating characteristics (ROC) curve. Results This study involved 977 patients, with 780 (79.8%) being male and a mean age of 55.6±11.5 years. Among them, 191 (19.5%) had an SBP/LVEDP ≤5.4. The in-hospital mortality rate was 4.3% (42), and the short-term all-cause mortality rate after a mean follow-up of 5.9±2.4 months was 15% (140). Patients with SBP/LVEDP ≤5.4 had higher in-hospital mortality rates (14.1% vs. 1.9%; p<0.001) and short-term mortality rates (35.1% vs. 9.8%; p<0.001) compared to those with SBP/LVEDP >5.4. The AUCs of SBP/LVEDP and TIMI for predicting in-hospital mortality were 0.766 [0.681-0.851] and 0.787 [0.713-0.861], respectively. For short-term mortality, the AUCs of SBP/LVEDP and TIMI were 0.731 [0.682-0.780] and 0.736 [0.690-0.782], respectively. Conclusion In conclusion, SBP/LVEDP showed sufficiently high predictive power comparable to the TIMI risk score. SBP/LVEDP is a readily available ratio that can rapidly provide valuable prognostic information during primary PCI.operating characteristics curveComparative distribution

Prognostic impact of the tricuspid annular plane systolic excursion/pulmonary arterial systolic pressure ratio in acute pulmonary embolism

Abstract Background Currently available risk stratification models for acute pulmonary embolism (PE) include hemodynamic status, cardiac biomarkers, right ventricle (RV) dysfunction on imaging, and clinical scores. Focusing on length-tension relationship of the ventricle might have a superior predictive capability over RV dysfunction in terms of mortality and classification of patients with acute PE. In this study, our hypothesis suggests that tricuspid annular plane systolic excursion (TAPSE)/systolic pulmonary artery pressure (sPAP) ratio has superior predictive capability for in-hospital mortality in patients with acute PE compared to TAPSE or sPAP as distinct measures. Methods This single-center study comprised retrospectively evaluated 703 patients referred to our tertiary cardiovascular center with acute PE. We divided patients into quartiles by TAPSE/sPAP ratio. Different models were developed to quantify the predictive relationship between in-hospital death and echocardiographic measurements. A base model was created with variables including risk status and RV/LV ratio >1. Then, to evaluate the predictive contribution of each measurement; TAPSE/sPAP, TAPSE, and sPAP were sequentially added to the base model. After that, the performance of each model was evaluated. Results Predictive and discriminative power was the highest in model containing TAPSE/sPAP. There was still a significant inverse association between TAPSE/sPAP and risk of in-hospital death even after adjusting by risk status and RV/LV ratio >1. ROC curve analysis for TAPSE/sPAP revealed the best cut-off value as 0.34. Conclusion The outcomes of our study reveals that the ratio of TAPSE/sPAP serves as a more potent predictor of mortality than either of the two measurements taken separately. The interpretation and utilization of the TAPSE/sPAP cut-off value in acute PE can assist in identifying patients at risk of deterioration and guide the consideration of more intensive treatment options across all risk groups.

Right ventricular myocardial work: a step forward for the assessment of right ventricular to pulmonary artery coupling

Abstract Background Right ventricular myocardial work (RVMW) is a novel method for non-invasive assessment of right ventricular (RV) function. By integrating RV global longitudinal strain as systolic function parameter, pulmonary systolic and diastolic pressures as afterload indices, and pulmonary and tricuspid valves timings, RVMW could provide a more comprehensive evaluation of RV function. Purpose The aim of this study was to assess patterns of RVMW indices in patients with preserved and impaired RV to pulmonary artery (PA) coupling (RVAC), as assessed by RV free wall longitudinal strain/pulmonary artery systolic pressure (RVFWLS/PASP) ratio. Methods We studied by echocardiography 158 consecutive patients with stable HF and left ventricular (LV) systolic dysfunction (LV ejection fraction < 50%). RVAC was assessed by RVFWLS/PASP and patients were grouped according to the median value. Four parameters of RVMW were obtained: RV global work index (RVGWI), RV global constructive work (RVGCW), RV global wasted work (RVGWW) and RV global work efficiency (RVGWE). Results According to RVFWLS/PASP ratio, patients were divided into two groups: A) preserved RVAC (RVFWLS/PASP ratio ≥ 0.51; N=84) and B) impaired RVAC (RVFWLS/PASP ratio < 0.51; N= 74). Both RVGWI (371±156 vs 384±207 mmHg%, P=NS) and RVGCW (449±171 vs 516±249 mmHg%, P=NS) did not significantly differ between the two groups (figure 1). However, group B (impaired RVAC) showed significantly greater RV wasted work (94±69 vs 44±30 mmHg%, P=0.0001) and significantly lower RV work efficiency (80±13 vs 88±8 %, P=0.0001) compared to group A (preserved RVAC, figure 2). Conclusions RVMW provided new insight in the RV function assessment, highlighting lower efficiency due to higher wasted work in RV to PA uncoupled patients.Figure 1Figure 2

Diastolic shock index: a novel prognostic parameter unveiling insights into vasodilatory cardiogenic shock

Abstract Introduction Systemic vasodilation is an increasingly acknowledged feature in cardiogenic shock (CS), defining a subset of patients with low systemic vascular resistances and higher vasopressor requirements. While a diastolic shock index (DSI) above 2.0 predicts vasoplegia and mortality in septic shock, its cut-off and prognostic significance in CS remain unclear. Our study aimed to characterize vasoplegia in CS using the DSI and assess its impact on prognosis. Methods Single-center retrospective cohort study on Cardiac Intensive Care Unit (CICU) admissions for CS from January 2017 to October 2023. Data included patient variables, CS features, vasoactive drugs, mechanical circulatory support, and 30-day mortality. DSI (heart rate (HR) to invasive diastolic blood pressure (DBP) ratio) impact on 30-day all-cause mortality was assessed with univariate Cox regression. Optimal DSI cut-off for adverse outcomes was determined through ROC curve analysis, and survival based on this cut-off was analyzed using Kaplan-Meier curves. Results 185 patients (mean age 59 ± 12 years, 63% male) were included. Acute myocardial infarction-related CS (47%) and heart failure-related CS (29%) were predominant. According to SCAI classification, 86% were class C, 22% class D, and 4% class E, with 26% experiencing previous cardiac arrest. Median Vasoactive-Inotropic Score (VIS) was 48 (IQR 21-85), and 25% used mechanical circulatory support. At admission, median HR was 105 bpm (IQR 90-125), DBP was 60 mmHg (IQR 55-65), and DSI was 1.71 (IQR 1.31-2.18). Thirty-day all-cause mortality was 36% (n=67), with median time to death of 4 days (IQR 1-10). DSI at 30 days predicted mortality (OR 1.42, 95%CI 1.06-1.91, p=0.020). DSI showed fair discriminative power for 30-day mortality (C-Statistic 0.60, 95% CI 0.51-0.68, p=0.031) with a cut-off of 2.2. Patients with DSI >2.2 exhibited heightened likelihood of prior cardiac arrest (38% vs. 20%, p=0.032), and higher serum lactate (5.5 vs. 3.9 mmol/L, p=0.008), and serum creatinine (2.64 vs. 1.88 mg/dL, p=0.003) at admission. Despite higher VIS at 48 hours (120±136 vs. 65±93.9, p=0.04), MCS need did not significantly differ. This group had superior 30-day mortality risk (log-rank p=0.011). Conclusion In our cohort, the admission Diastolic Shock Index (DSI) emerged as a promising identifier for CS vasoplegic patients and was a predictor of a higher risk for mortality. A DSI above 2.2 identified a subset of patients with previous cardiac arrest and higher lactate levels, enlightening possible risk factors associated with vasoplegia. Further studies are warranted to establish the robustness of this novel prognostic parameter in CS patients and its therapeutic implications.

Predictors of Right vEntricular Failure aftER LVAD implantation: PREFER LVAD study

Abstract Introduction The use of left ventricular assist devices (LVAD) is increasing both as bridge-to-transplantation or destination therapy, considering the lack of heart donors for transplantation in advanced heart failure (AHF) population. Right ventricular post-implantation failure, major bleedings and infective events remain the principal adverse events in LVAD carriers, thus an accurate selection of candidates is needed. Purpose To identify between clinical, laboratory, standard and advanced (Speckle Tracking, STE) echocardiography, and right heart catheterization (RHC) indices, the best predictors of outcome after LVAD implantation. Materials and Methods We screened in our third-level center 30 patients with AHF, followed up from May 2013 to February 2022, for the assessment of LVAD implantation suitability. They all underwent a complete cardiological history collection, electrocardiography, standard and STE left ventricular (LV) and left atrial (LA) size and function assessment. Regarding the right ventricle, SIENA score parameters, including RV sphericity index, RV free wall longitudinal strain (LS), right ventricular fractional area change (RVFAC), and 3D ejection fraction were used for exclude RV disfunction. RHC was performed on the same day of echocardiography. Follow-up was conducted at 1, 3, 6, 9 and 12 months repeating all the assessments, for the occurrence of RV failure, all-causes mortality, hemorrhagic events and re-hospitalization for heart failure. With a univariate and multivariate statistical analysis, we went to test among all the parameters the possible predictors of outcome. Results The final population consists of 29 patients (93% male, mean age of 63±11 years), in NYHA class III or IV and a severe reduction of left ventricular (LV) ejection fraction (EF), in whom arterial hypertension and smoking, present or previous, were present in 58% and 65% of cases, respectively. The population was divided into two groups according to the occurrence of at least one cardiovascular event. 11 major events were recorded: including 4 hemorrhagic events, 3 all-causes mortality and 4 hospital admission for HF. No RV failure occurred in the first 12 months of follow-up. No differences were identified between the two groups in terms of echocardiographic indices and RV function, including RVFAC or RV-FWLS. At univariate analysis (see Table 1), the only parameter able to predict major CV events was central venous pressure (CVP)/pulmonary capillary wedge pressure (PCWP) ratio, obtained by RHC, an index of balance between right and left heart filling pressure. Conclusions A careful application of SIENA score indices before LVAD implantation can significantly reduce the incidence of post-operative RV failure, as in our small population. Our results also confirmed the paramount role of RHC in the diagnostic work up of AHF.

Prognostic significance of right ventricle to pulmonary artery coupling acute improvement after mitral transcatheter edge-to-edge repair

Abstract Background Transcatheter Edge-to-Edge Repair (TEER) of mitral valve is a valid treatment option for severe mitral regurgitation. The right ventricle is acutely affected by early hemodynamic changes following the correction of significant mitral regurgitation. Echocardiographic parameters of the right chambers could have a prognostic impact even in a periprocedural setting. In particular, right ventricle to pulmonary artery coupling improvement may be of pivotal importance, as this parameter is a validated marker of right ventricle function. Purpose To evaluate the prognostic impact of early improvement of right ventricle to pulmonary artery coupling assessed by means of the Tricuspid Annular Plane Systolic Excursion/Pulmonary Artery Systolic Pressure (TAPSE/PASP) ratio after TEER. Methods This retrospective single centre study included patients treated with TEER in our hospital from 2015 to 2023. Transthoracic echocardiography was performed before and shortly after device positioning. Acute effects of TEER on echocardiographic parameters were assessed by paired samples t-test. Diagnostic accuracy of the percent variation in the TAPSE/PASP ratio was assessed by means of receiver-operating characteristics analysis. Prognosis was evaluated by Kaplan-Meier analysis. Results The study included 95 patients (age 78 ± 10 years; 63% men; BMI 25 ± 5 kg/m2) with severe or moderate-to-severe mitral regurgitation. Mean baseline Left Ventricle (LV) ejection fraction was 45 ± 16%, LV end-diastolic volume was 157 ± 62 ml and effective regurgitant orifice area was 41 ± 25 mm2. Post-procedural echocardiographic assessment showed early improvement of LV end-diastolic diameter (p < 0.001), LV end-diastolic volume (p = 0.025), LV stroke volume (p < 0.001), LV global longitudinal strain (p < 0.001), right ventricle free wall longitudinal strain (p < 0.001) and PASP (p = 0.002). Percent improvement of TAPSE/PASP ratio showed a sufficient diagnostic accuracy in predicting a composite outcome of hospitalisation for heart failure and all cause mortality at 1 year (area under the curve 0.66, p = 0.047), with an optimal cut-off of 5.5%. An improvement of the TAPSE/PASP ratio over this threshold was associated with a reduction in the composite outcome (hazard ratio 0.38, p = 0.045). Conclusion TEER improves both left and right ventricular dynamics, which can be detected with echocardiography. In particular, an acute improvement of the TAPSE/PASP ratio is associated with an improvement in short-term prognosis. A comprehensive assessment of right ventricular function, including TAPSE/PASP ratio, should be routinely performed before and after TEER.

Comparison of different non-invasive estimates of right ventriculo-arterial coupling as outcome predictors in dilated cardiomyopathy

Abstract Right ventriculo-arterial coupling (RVAC) has emerged as an outcome predictor in pulmonary hypertension, but its role in left-sided HF remains to be clarified. Different non-invasive estimates for RVAC have been proposed, but a direct comparison of their prognostic ability is lacking. We sought to evaluate RVAC non-invasively using five different methods in a cohort of patients with dilated cardiomyopathy (DCM) and to assess their prognostic role. We enrolled 121 consecutive patients with non-ischemic DCM in sinus rhythm, who underwent comprehensive echocardiography, including speckle-tracking and 3D analysis. They were prospectively followed for 19±11 months for a composite endpoint of death, nonfatal cardiac arrest and hospitalization. RVAC was measured using five non-invasive estimates: (1) as the tricuspid annular plane systolic excursion (TAPSE)/pulmonary artery systolic pressure (PASP) ratio; (2) as the right ventricular (RV) global longitudinal strain (RV-GLS)/PASP ratio; (3) as the longitudinal strain of the RV free wall (LS-RVFW)/PASP ratio; (4) as the 3D RV ejection fraction (RVEF)/PASP ratio; and (5) as the 3D RV stroke volume (SV)/3D RV end-systolic volume (ESV) ratio. Mean age in the study cohort was 59±14 years and the majority (74%) were men. 55 patients (46%) reached the endpoint: there were 27 deaths, 5 nonfatal cardiac arrests and 23 readmissions for heart failure. Patients with adverse outcome had lower TAPSE/PASP (0.42±0.23 vs. 0.62±0.33, p<0.001), lower RVEF/PASP (0.96±0.49 vs. 1.47±0.67, p<0.001), lower RV SV/ESV (0.57±0.20 vs. 0.93±0.29, p<0.001) and higher RV-GLS/PASP (-0.25±0.20 vs. -0.38±0.23, p=0.002) and LS-RVFW/PASP (-0.28±0.30 vs. -0.51±0.33, p<0.001), reflecting greater ventriculo-vascular decoupling. In univariate Cox regression, all three RVAC indices were outcome predictors: HR=0.09 [95% CI, 0.02-0.37], p=0.001 for TAPSE/PASP, HR=13.67 [95% CI, 2.77-67.48], p=0.001 for RV-GLS/PASP, HR=8.72 [95% CI, 3.24-23.45], p<0.001 for LS-RVFW/PASP, HR=0.27 [95% CI, 0.14-0.50], p<0.001 for RVEF/PASP, HR=0.004 [95% CI, 0.001-0.019], p<0.001 for RV SV/ESV. In ROC analysis, the SV/ESV ratio had the highest AUC (AUC=0.88, p<0.001), a value lower than 0.74 having 86% sensitivity and 77% specificity for event prediction. After adjustment for age, NYHA class, left ventricular ejection fraction, and maximal left atrial volume, all coupling indices remained independent predictors of outcome: HR=1.90 [95% CI, 1.01-3.57], p=0.047 for TAPSE/PASP, HR=2.15 [95% CI, 1.17-3.96], p=0.01 for RV-GLS/PASP, HR=2.48 [95% CI, 1.34-4.60], p=0.004 for LS-RVFW/PASP, HR=3.19 [95% CI, 1.19-8.52], p=0.02 for RVEF/PASP, HR=7.50 [95% CI, 3.47-16.22], p<0.001 for RV SV/ESV. In DCM, RVAC is significantly more impaired in patients with major adverse events. Non-invasive RVAC was an independent predictor of adverse outcome irrespective of the formula used for estimation, but 3D RV SV/ESV ratio had the greatest prognostic power.

Right ventricular remodelling and long-term survival after pulmonary endarterectomy versus balloon pulmonary angioplasty in chronic thromboembolic pulmonary hypertension.

Pulmonary endarterectomy (PEA) is the treatment of choice for chronic thromboembolic pulmonary hypertension (CTEPH), while balloon pulmonary angioplasty (BPA) is an alternative for inoperable patients. We aimed to compare right ventricular (RV) remodelling and late survival after PEA and BPA. In this prospective observational cohort study, we performed echocardiography at baseline and follow-up in patients with CTEPH treated with PEA (n=54) or BPA (n=44) between 2011 and 2022. Follow-up echocardiography was performed at 5 months (IQR 4-7) after PEA and 3 months (IQR 2-4) after the last BPA. Both groups showed significant improvements in left ventricular end-systolic eccentricity index, RV basal diameter and RV fractional area change (RV FAC). Tricuspid regurgitation pressure decreased by 26±18 mm Hg after PEA and 13±21 mm Hg after BPA (p=0.02 for between-group difference). Tricuspid annular systolic excursion (TAPSE) decreased by 4±5 mm after PEA but increased by 1±4 mm after BPA (p<0.001). The TAPSE/systolic pulmonary artery pressure ratio improved similarly in both groups. Five-year survival was 96% (95% CI 86% to 99%) for PEA and 79% (95% CI 61% to 89%) for BPA (p=0.25). Change in RV FAC was an independent predictor of survival (HR 0.9, 95% CI 0.82 to 0.99, p=0.03). Both PEA and BPA led to significant RV reverse remodelling, with no clear evidence of a difference in survival rates. Improvement in RV function, particularly RV FAC, was associated with better outcomes, highlighting the importance of RV recovery in CTEPH treatment.

Clinical, echocardiographic and haemodynamic predictors of morbidity and mortality in pulmonary hypertension: a nation-wide registry

Abstract Background and aims In this retrospective analysis of a nation-wide registry on pulmonary arterial hypertension (PAH), group IV and V, we aimed to evaluate the clinical, echocardiographic,haemodynamic and neurohumoral predictors of morbidity and mortality. Methods This study included 903 patients enrolled from 24 cardiology centers participating in the RegiStry on clInical outcoMe and sUrvival in pulmonaRy hypertension Groups (SIMURG II). ESC/ERS 2022 risk scoring model was used for risk predictions at baseline assessment. Composite endpoint (CEP) definitions were adopted from the SERAPHIN and GRIPHON trials. Results Age was 51.27 + 21.37 years, and 72 % of patients were female. Incident cases were noted in 65.9 % of overall group. Idiopathic PAH (IPAH), PAH-associated with congenital heart diseases (CHD-PAH), PAH-associated with connective tissue diseases (CTD-PAH), porto-PAH, Group IV and V pulmonary hypertension (PH) were documented in 33 %, 33.5 %, 12 %, 1.6 %, 20 % and 1.7 % of overall patients, respectively. Background mono and dual targeted combinations, and sequential dual or triple combinations were noted in 17 %, 57 % and 26 % of patients, respectively. Baseline low-, intermediate- and high-risk were noted in 1.2 %, 14.1 %, and 84.7 %, respectively. Median follow-up time was 867 (412-1667) days. Overall rates of mortality and CEP were 26 % and 39%, respectively. Prevalent versus incident cases were associated signifinatly lower mortality and CEP rates (p=0.028 and p=0.024, respectively). Mortality and CEP rates were 31 % and 44 % in IPAH, 20 % and 39 % in CHD-PAH, 31 % and 43 % in CTD-PAH, and 25 % and 30 % in group IV patients, respectively. CHD-PAH compared with other groups was associated with a higher Kaplan-Meier (K-M) survival and CEP-free survival (p&amp;lt; 0.0001 and p=0.00023, respectively). Survival was associated with prevalent versus incident status, baseline functional class (FC) and six-minute walk distance (6MWD) in all subgroups (p&amp;lt;0.0001 for all), NT-brain natriuretic peptide and right atrial area in IPAH,CHD-PAH and CTD-PAH, and mixed venous O2 saturation % in IPAH and CHD-PAH (p varying from &amp;lt;0.0001 to 0.027). But, TAPSE / systolic pulmonary artery pressure ratio, right atrial-pulmonary capillary wedge pressure difference, pulmonary vascular resistance and its ratio to systemic vascular resistance, cardiac index were not related with survival. Baseline high versus intermediate /low risk was associated with a lower overall survival and CEP-free survival ( p=0.03 and p=0.003, respectively). Male sex [hazard ratio(HR):1.73;1.2-2,51,p = 0.004], 6MWD (p&amp;lt;0.001), FC III/IV (HR: 2.52;1.47-4.32, p&amp;lt;0.001) and baseline low-risk (HR:0.37;0.21-0.65, p&amp;lt;0.001) were independent predictors of mortality. Conclusions Our nation-wide data revealed current insights regarding the clinical, echocardiographic,haemodynamic and neurohumoral predictors of morbidity and mortality in PAH and group IV PH.

The effect of transcatheter aortic valve implantation on fractional flow reserve and non-hyperemic pressure ratios

Abstract Background Coronary artery disease in patients undergoing transcatheter aortic valve implantation (TAVI) is a very frequent clinical issue. Complex coronary artery disease can negatively influence outcomes after TAVI, however, angiography-guided percutaneous coronary intervention (PCI) has not been shown to offer any prognostic benefit. Coronary pressure indices, to select which lesions need treatment, are promising but are currently underused in aortic stenosis (AS) patients due to many physiological pitfalls. Available studies are small and show conflicting results on the effect of transcatheter aortic valve implantation (TAVI) on these indices. Purpose The aims is to compare the effects of TAVI on fractional flow reserve (FFR) and Non-hyperemic pressure ratio’s (NHPRs). Both immediate and long-term effects were studied. Methods Lesion specific coronary pressure data was extracted from 6 studies resulting in 147 lesions for immediate change in FFR analysis and 105 for NHPR analysis. To investigate the long-term changes, 93 lesions for FFR analysis and 68 for NHPR analysis were found. Results Immediately after TAVI, FFR decreased significantly (-0.0130 ± 0.0406 standard deviation, p-value: 0.0002) while NHPR remained stable (0.0003 ± 0.0675, p-value: 0.9675). Long-term after TAVR, FFR decreased significantly (-0.0230 ± 0.0747, p-value:0.0038) while NHPR increased non-significantly (0.0166 ± 0.0699, p-value: 0.0543). This increase in NHPRs became significant when only borderline NHPR lesions were considered (0.0249 ± 0.0441, p-value: 0.0015). All other results were confirmed in borderline-only lesions. Conclusions TAVI caused small significant, but opposite, changes in FFR and NHPR. In AS, FFR might underestimate lesion significance while NHPRs might overestimate its significance. This is only clinically relevant in borderline lesions, clear positive or negative physiological assessments can be trusted.Figure 1Figure 2

Right ventricular to pulmonary artery coupling credicts poor outcomes after interatrial shunting in heart failure

Abstract Background Left atrial decompression is under investigation for heart failure (HF) with the potential to improve symptoms and potentially clinical outcomes. However, heterogeneous outcomes have been observed in randomized controlled studies. Purpose This study aimed to explore whether right ventricular (RV) -pulmonary artery (PA) coupling, as assessed from the tricuspid annular plane systolic excursion (TAPSE) /systolic PA pressure ratio, can be useful in predicting outcomes after implantation of the interatrial shunting device. Methods A total of 106 HF patients, n=62 with reduced ejection fraction (HFrEF), n=44 with preserved ejection fraction (HFpEF), were prospectively enrolled in the PRELIEVE registry with the Atrial Flow Regulator (AFR) implantation. Serious adverse events included cardiovascular mortality and HF worsening (W). Results Serious adverse events (SAEs) occurred in a total of 19 (18%) patients. There were no differences in baseline comorbidities, KCCQ scores, the 6-minute walking distance between patients with and without SAEs (Table). Patients with SAEs showed higher systolic pulmonary arterial pressure, NT-proBNP, serum creatinine and lower TAPSE/PASP ratio. Incidence of SAEs was higher in patients within the first TAPSE/PASP vs the third tertile (59% vs 12%, p=0.026), respectively. A TAPSE/PASP of &amp;lt;0.55 was identified to bear the most optimal sensitivity to predict the event (AUC=0.683, CI95% (0.533-0.833). Conclusion The reduced TAPSE/PASP ratio was associated with higher rates of serious adverse events in patients with heart failure undergoing controlled inter-atrial shunting. The hypothesis generating finding that reduced RV-PA coupling may identify potential clinical non-responders to left atrial decompression should be further prospectively validated.

Clinical implications of persistently increased blood urea nitrogen/serum creatinine ratio (PI-BUN/Cr) in severe COVID-19 patients

BackgroundPatients with COVID-19 may experience a persistent increase in the blood urea nitrogen over creatinine ratio (PI-BUN/Cr). Its elevation could reflect multiple underlying pathophysiological processes beyond prerenal injury but also warrants nuanced interpretation due to its complex interplay with various factors, underscoring the importance of investigating its effects on mortality and acute kidney injury in this population.MethodsWe analized a retrospective and longitudinal cohort of patients admitted to a single center in Mexico City for patients with severe COVID-19. Between March 5, 2020 and August 25, 2021, we included patients with confirmed positive diagnosis for SARS-CoV-2, age > 18 years, disease severity was defined by clinical data of respiratory distress syndrome and a ratio of partial oxygen pressure to inspired oxygen fraction < 300 mmHg on admission. We excluded patients with End Stage Kidney Disease. Data was obtained from electronic medical records. PI-BUN/Cr was defined as an increase in the BUN/Cr ratio > 30 in more than 60% of measurements in the hospital. The outcomes included: risk factors to mortality and AKI in-hospital.ResultsThe cohort included 3,007 patients with a median age of 54.6 ± 14.5 years. 35% of patients died; 44.6% developed PI-BUN/Cr ratio and 71.4% AKI. Mortality was associated with older age > 60 years [Hazard ratio (HR)] = 1.45, 95% CI: 1.28–1.65; p < 0.001); male (HR 1.25, 95% CI 1.09–1.44; p = 0.002) and AKI (HR 3.29, 95% CI 2.42–4.46; p < 0.001); PI-BUN/CR & Non-AKI (HR = 2.82, 95% CI: 1.61–4.93; p < 0.001); Non PI-BUN/CR & AKI (HR = 5.47, 95% CI: 3.54–8.44; p < 0.001); and PI-BUN/CR & AKI (HR = 4.26, 95% CI: 2.75–6.62, p < 0.001). Only hiperuricemia was a risk factor for AKI (HR = 1.71, 95% CI: 1.30–2.25, p < 0.001).ConclusionsWhile PI-BUN/Cr alone may not directly associate with mortality, its capacity to sub-phenotype patients according to their AKI status holds significant promise in offering valuable insights into patient prognosis and outcomes. Understanding the nuanced relationship between PI-BUN/Cr and AKI enhances our comprehension of renal function dynamics. It equips healthcare providers with a refined tool for risk stratification and personalized patient management strategies.

The Potential of Dehydrated Geniotrigona thoracica Stingless Bee Honey against Metabolic Syndrome in Rats Induced by a High-Carbohydrate, High-Fat Diet

Background/Objectives: Metabolic syndrome (MS) is diagnosed when at least three out of five key risk factors are present: obesity, high blood pressure, insulin resistance, high triglycerides (TG) and low high-density lipoprotein (HDL). MS is often associated with chronic low-grade inflammation. Recent studies have shown that raw stingless bee honey (SBH) can alleviate MS risk factors. However, the high moisture content in raw SBH predisposes it to fermentation, which can degrade its quality. Therefore, dehydrating SBH is necessary to prevent the fermentation process. This study aimed to compare the effects of dehydrated (DeGT) and raw (RGT) SBH from Geniotrigona thoracica species on high-carbohydrate, high-fat diet (HCHF)-induced MS in rats. Methods: Twenty-four male Wistar rats were divided into four groups: control (C), HCHF-induced MS without treatment (MS), HCHF-induced MS treated with DeGT (MS+DeGT) and HCHF-induced MS treated with RGT (MS+RGT). Group C received standard rat chow, while the other groups were fed with HCHF diet for 16 weeks. In the final eight weeks, two HCHF-induced groups received their respective SBH treatments. Results: Both DeGT and RGT treatments reduced energy intake, fat mass, high blood pressure, inflammatory (tumour necrosis factor-alpha (TNF-α)) and obesity (the leptin/adiponectin (L/A) ratio, corticosterone, 11 beta-hydroxysteroid dehydrogenase type-1 (11βHSD1)) markers, as well as prevented histomorphometry changes (prevented adipocyte hypertrophy, increased the Bowman’s space area and glomerular atrophy). Additionally, DeGT increased serum HDL levels, while RGT reduced serum TG, leptin and other inflammatory markers (interleukin-6 (IL-6) and interleukin-1 beta (IL-1β)), as well as hepatosteatosis. Conclusions: While DeGT demonstrates potential as a preventive agent for MS, RGT exhibited more pronounced anti-MS effects in this study.

Right ventricular-pulmonary artery coupling for prognostication in acute pulmonary embolism.

Acute pulmonary embolism (PE) increases pulmonary pressure and impair right ventricular (RV) function. Echocardiographic investigation can quantify this mismatch as the tricuspid annular plane systolic excursion (TAPSE) to pulmonary arterial systolic pressure (PASP) ratio. The aim of the study was to investigate the prognostic capabilities of TAPSE/PASP ratio in patients with acute PE. We utilized the RIETE registry to analyze consecutive hemodynamically stable PE patients. We used multivariable logistic regression analyses to assess the association between the TAPSE/PASP ratio and 30-day all-cause mortality across the strata of European Society of Cardiology (ESC) risk categories. We included 4,478 patients, of whom 1,326 (30%) had low-risk, 2,425 (54%) intermediate-low risk, and 727 (16%) intermediate-high risk PE. Thirty-day mortality rates were 0.7%, 2.3% and 3.4%, respectively. Mean TAPSE/PASP ratio was 0.65±0.29 in low-risk patients, 0.46±0.30 in intermediate-low risk, and 0.33±0.19 in intermediate-high risk patients. In multivariable analyses, there was an inverse association between TAPSE/PASP ratio and 30-day mortality (adjusted OR 1.32 [95%CI 1.14-1.52] per 0.1 decrease in TAPSE/PASP). TAPSE/PASP ratio below optimal cut-points was associated with increased mortality in low- (<0.40, aOR: 5.88; 95%CI:1.63-21.2), intermediate-low (<0.43, aOR: 2.96; 95%CI:1.54-5.71) and intermediate-high risk patients (<0.34, aOR: 4.37; 95%CI:1.27-15.0). TAPSE/PASP <0.44 showed net reclassification improvement of 18.2% (95%CI:0.61-35.8) vs. RV/LV ratio >1, and 27.7% (95%CI:10.2-45.1) vs. ESC risk strata. Decreased TAPSE/PASP ratio was associated with increased mortality. The ratio may aid in clinical decision-making, particularly for intermediate-risk patients for whom the discriminatory capability of the current risk stratification tools is limited.

Heat energy utilization of a double-flash geothermal source efficiently for heating/electricity supply through particle swarm optimization method

The principal aim of this article is to optimize the thermal and electrical efficiency of a geothermal combined heat and power system through metaheuristic particle swarm optimization (PSO) method. The objective of this research is to conduct a thorough analysis of the incorporation of metaheuristic PSO technique, with a specific emphasis on the potential advantages and obstacles associated with the utilization of metaheuristic approaches in improving the effectiveness of geothermal energy systems. The utilization of a double-flash geothermal system in conjunction with a transcritical carbon dioxide Rankine cycle is utilized for the co-generation of electricity and thermal energy. The research utilized a PSO method to enhance power generation, heating capacity, and overall system efficiency. The PSO algorithm was employed to determine the optimum operational parameters for a pressure level of 820 kPa and a pressure ratio of 1.59, leading to the maximization of power output to 2591.4 kW The PSO algorithm effectively identified the optimal operational parameters as a pressure of 820 kPa and a pressure ratio of 1.59, resulting in the achievement of a peak power output of 2591.4 kW. The methodology has determined that a pressure of 916.4 kPa and a pressure ratio of 1.5 represent the optimal parameters for achieving a maximum heating capacity of 12329.1 kW.