Flow Ratio Research Articles

Clinical value of single projection angiography-derived FFR in non-infarct related artery

Abstract Background Murray law-based quantitative flow ratio (μFR) is an emerging technique which requires only one projection of coronary angiography with similar accuracy with quantitative flow ratio (QFR). However, it has not been validated for evaluation of non-infarct related artery (non-IRA) in acute myocardial infarction (AMI) setting. Therefore, our study aimed to evaluate the diagnostic accuracy of μFR and the safety of deferring non-IRA lesion with μFR>0.80 in the setting of AMI. Methods μFR and QFR were analyzed for non-IRA lesions of AMI patients enrolled in the FRAME-AMI trial, consisting of fractional flow ratio (FFR)-guided PCI and angiography-guided PCI groups. Diagnostic accuracy of μFR was compared to QFR and FFR. Patients were classified by non-IRA μFR values 0.80 as a cutoff value. The primary outcome was vessel-oriented composite outcomes (VOCO), a composite of cardiac death, non-IRA-related MI, and non-IRA-related repeat revascularization. Results 443 patients (552 lesions) were eligible for μFR and QFR analysis. μFR showed acceptable correlation with FFR (R=0.777, P<0.001), comparable C-index with QFR to predict FFR≤0.80 (μFR vs. QFR: 0.926 vs. 0.961, P=0.070), and shorter total analysis time (mean 32.7sec vs. 186.9sec, P<0.001). Non-IRA with μFR>0.80 and deferred PCI had significantly lower risk of VOCO than non-IRA with performed PCI (3.4% vs. 10.5%; HR, 0.37; 95% CI, 0.14-0.99; P=0.048). Conclusion In multivessel AMI patients, μFR of non-IRA showed acceptable diagnostic accuracy comparable to that of QFR to predict FFR≤0.80. Deferred non-IRA with μFR>0.80 showed lower risk of VOCO than revascularized non-IRA.

Spermidine attenuates left ventricular dysfunction in estrogen deprived aging rats through mitigating lipid peroxidation and mitochondrial dysfunction

Abstract Background Aging women with postmenopause are particularly susceptible to cardiovascular diseases (CVDs), which are associated with the elevation of oxidative stress and mitochondrial dysfunction. Although hormone replacement therapy (HRT) has been reported to provide cardiometabolic protection, long-term HRT could be linked to CVD consequences. A novel organic therapy with spermidine has shown promise as cardioprotection in several CVDs. However, the effects of spermidine on left ventricular (LV) function, mitochondrial function and oxidative stress in estrogen-deprived aging rats have not been investigated. Purpose To evaluate the effects of spermidine on LV function, mitochondrial function and oxidative stress in estrogen-deprived and D-galactose-induced aging rats Methods Twenty female Wistar rats were randomly assigned to the sham and the ovariectomy (OVX) along with D-galactose (150 mg/kg/day, s.c.) administration throughout the experiment for 12 weeks. OVX with D-galactose-treated rats were divided into three interventional groups: vehicle (ODV), spermidine (20 mg/kg/day, p.o., ODS), and estradiol (50 ug/kg/day, s.c., ODE) (n=5/group) for 8 weeks. The sham group received a vehicle (SVV, n=5). At the end, all rats underwent echocardiography, followed by euthanasia. The hearts were removed for measuring mitochondrial reactive oxygen species (ROS), mitochondrial membrane potential (MMP) changes (ΔΨm), and malondialdehyde (MDA) levels. Results Rats with OVX-induced estrogen deprivation with D-galactose-induced aging had LV impairments indicated by decreased LV ejection fraction, reduced ratio of peak velocity blood flow from left ventricular relaxation in early diastole (E) to peak velocity flow by atrial contraction (A), and increased sympathovagal imbalance (elevated low/high frequency (LF/HF) ratio) (Fig. 1A-C). These estrogen-deprived aging rats also had an increase in cardiac tissue MDA levels, mitochondrial ROS production, and MMP depolarization (Fig. 1D-F). Both spermidine and estrogen similarly demonstrated a significant reduction in all of those detrimental effects, leading to improved LV function (Fig. 1A-F). Conclusion Spermidine exerted cardioprotection comparable to estrogen supplement through mitigating oxidative stress and mitochondrial impairments in cardiac tissue, resulting in improved LV dysfunction and cardiac autonomic balance due to estrogen deprived aging conditions in rats. These findings suggest that spermidine administration could be a promising strategy for cardioprotection in postmenopausal women with aging.

Novel CMR-assessed right ventricular-pulmonary artery coupling index independently associates with exercise capacity and clinical risk in pulmonary arterial hypertension

Abstract Background We defined a novel noninvasive right ventricle (RV)–pulmonary artery (PA) coupling index as the ratio of cardiovascular magnetic resonance (CMR)-assessed RV direct flow (RVDF) and PA pulse wave velocity (PWV), and investigated its associations with exercise capacity and clinical risk in pulmonary arterial hypertension (PAH). Method 43 PAH patients (mean age 46±12 years, M:F 7:36) and 60 healthy volunteers (mean age 46±13 years, M:F 11:48) underwent CMR and cardiopulmonary exercise test (CPET) within one week. From cine CMR, RV ejection fraction (EF) and RV end-diastolic volume (RVEDV) were calculated using volumetric analysis; and tricuspid annular plane systolic excursion (TAPSE), feature tracking. PAPWV was the ratio of early systolic DPA flow and DPA area measured from instantaneous phase and magnitude through plane 2D flow CMR images across the pulmonary trunk, respectively. RVDF was the 4D flow CMR-assessed blood volume entering and exiting the RV in one cardiac cycle, indexed to RVEDV. RV-PA coupling was RVDF/PAPWV. Based on CPET-assessed peak oxygen consumption (PVO2), all 103 participants were stratified into two groups: PVO2>15 ml/kg/min; and PVO2≤15 ml/kg/min. Based on the REVEAL (Registry to Evaluate Early and Long-term PAH Disease Management) 2.0 score, the 43 PAH patients were stratified into low risk (score ≤6) and intermediate to high risk (score >6) groups. Results RVDF/PAPWV was significantly lower in PAH vs. controls (7.9 vs. 20.4 %/(m/s), P<0.001); and in PAH patients with intermediate to high risk vs. low risk (4.6 vs. 9.4 %/(m/s), P=0.001). On multivariable analyses, RVDF/PAPWV was an independent predictor of PVO2≤15 ml/kg/min (=0.302, P=0.001) among all participants, and of REVEAL 2.0 score >6 (=0.621, P=0.009) among PAH patients. Compared to RVEF and TAPSE, RVDF/PAPWV had numerically higher discrimination (p values non-significant based on Delong test) for PVO2≤15 ml/kg/min (AUC=0.914 vs. 0.872, 0.843); and among PAH patients, REVEAL 2.0 score >6 (AUC=0.851 vs. 0.723 and 0.728) (Figure). Conclusion CMR-derived noninvasive RVDF/PAPWV independently associates with exercise capacity and PAH clinical risk, supporting its utility as an imaging marker of disease progression and therapeutic response.

Association between stent implantation results and target vessel failure after IVUS-Guided PCI: A FLAVOUR substudy

Abstract Background Despite substantial advancements in coronary stent systems and implantation techniques, target vessel failure (TVF) remains a clinical issue to be addressed. Purpose We used deep learning algorithms for automatic stent analysis of intravascular ultrasound (IVUS) data to identify stent implantation characteristics associated with TVF. Methods In patients from the IVUS-guided group of the FLAVOUR trial who had undergone successful stenting, validated deep learning algorithms were applied to IVUS images to delineate plaque and stent strut for the quantification of stent expansion, apposition, and residual plaque burden. Stent overexpansion was defined as stent area exceeding 120% of the hypothetical healthy lumen area. Murray law-based quantitative flow ratio (μQFR) was also assessed from angiographic images. The primary endpoint was TVF at 2 years, defined as a composite of cardiac death, target vessel-related myocardial infarction, and ischemia-driven target vessel revascularization. Results A total of 459 vessels in 441 patients were included, with TVF events occurred in 15 vessels (3.3%) during the 2-year follow-up. Stent analysis was performed in 687,379 stent struts from 70,369 IVUS image frames of the interrogated vessels with the assistance of specific deep learning algorithms. On vessel-level multivariate analysis adjusting for procedural covariates, stent overexpansion length >5 mm (hazard ratio, 4.57; 95% confidence interval [CI], 1.31 to 15.92; P=0.017), residual plaque burden at proximal stent edge >50% (hazard ratio, 3.34; 95% CI, 1.19 to 9.33; P=0.022), and post-PCI μQFR <0.90 (hazard ratio, 5.09; 95% CI, 1.62 to 15.97; P=0.005) were more likely to be present in vessels with TVF events than in those without. Conclusions Besides the established indexes of post-procedural residual plaque burden and low μQFR, deep learning-powered IVUS stent overexpansion was significantly associated with increased risk of TVF.Suboptimal stenting results and TVF

Comparative analysis of post-PCI fractional flow reserve and quantitative flow ratio in predicting long-term Target Vessel Failure and hard endpoints

Abstract Background The role of functional assessment after angiographically acceptable post-PCI result is debatable. Purpose We sought to investigate the correlation between Fractional Flow Reserve measured directly after drug eluting stent (DES) implantation (post-PCI FFR) and post-PCI Quantitative Flow Ratio (post-PCI QFR), clarify their relationship with clinical parameters, and long-term target vessel failure (TVF: cardiac death (CD), non-fatal target vessel myocardial infarction (MI) and target vessel revascularisation (TVR)), and a composite of CD and MI (CD/MI). Method Coronary arteries that underwent post-PCI FFR measurement at our centre between 2012 and January 2021 were consecutively included in this registry. Post-PCI QFR was calculated blinded to the post-PCI FFR value. We analysed the influence of LAD vs. (non-LAD) location, gender, age, hypertension, diabetes mellitus, hyperlipidemia, indication (acute (ACS) vs. chronic coronary syndrome), stent diameter, in-stent restenosis (ISR) vs. de novo lesion category, estimated glomerular filtration rate, proximal vs. distal lesions, severe aortic stenosis, atrial fibrillation during the procedure (AF), and prior myocardial infarction in the supply area (prior MI) on post-PCI FFR and QFR. Optimal cut-off was determined by ROC curves. Results A total of 400 coronary arteries were analysed. LAD location (p<0.001), male gender (p=0.0029) and smaller stent diameter (p=0.0073) proved to be predictors of a lower post-PCI FFR. LAD location (p=0.001), ISR (p=0.02), distal location (p=0.0019), AF (p=0.042) and prior MI (p=0.029) were predictors of a lower post-PCI QFR. There was a systematic bias in post-PCI QFR compared to post-PCI FFR (bias 0.0614, 95% CI, 0.053 - 0.069). During a median follow-up of 45 months, 31 CD, 20 MI and 35 TVR occurred. Follow-up was complete in 100%. There was a significant inverse correlation between post-PCI FFR and TVF (p<0.001) as well as between post-PCI QFR and TVF (p=0.045). In-stent restenosis (p=0.014) and prior MI (p=0.002) were also predictors of higher TVF rate. The predictors of CD/MI were lower post-PCI FFR (p<0.001), smaller stent diameter (p=0.03), higher age (p=0.031) and ACS indication (p=0.048), whereas post-PCI QFR was not. The best post-PCI FFR cut-off to predict TVF was 0.87 (p<0.0001). There was no single optimal post-PCI QFR cut-off to predict TVF. Conclusion Post-PCI QFR shows a systematic bias compared to post-PCI FFR. Post-PCI FFR is a significant predictor of TVF as well as CD/MI, whereas post-PCI QFR predicts TVF. No significant correlation between post-PCI QFR and CD/MI could be demonstrated. Our findings underscore the importance of considering multiple clinical parameters in predicting long-term outcomes. The best post-PCI FFR cut-off to predict TVF was 0.87. However, there was no single, universally applicable post-PCI QFR threshold to predict TVF.

Prognostic role of post-percutaneous coronary intervention quantitative flow ratio

Abstract Background/Introduction Accumulated evidence supports the prognostic value of post–percutaneous coronary intervention (PCI) physiological measurement. Quantitative Flow Ratio (QFR) is a well-studied angiography-based method for functional assessment. Purpose To investigate the possible prognostic implications of post-PCI QFR in patients undergoing revascularization. Methods We performed offline QFR analysis in all-comers undergoing PCI in a single center. A cut-off value of 0.8 was used to classify patients in high post-PCI QFR group (>0.8) and low post-PCI QFR group (≤0.8). Patients with at least one vessel with post-PCI QFR ≤0.8 were classified in the low post-PCI QFR group. Primary endpoint was the composite outcome of death, myocardial infraction, ischemia-driven revascularization, and heart failure-related hospitalization. Results We included 297 patients in the study. Mean age was 64 (±11) years and 81% of patients were male. Number of patients presented with chronic coronary syndrome was comparable to that of patients presented with acute coronary syndrome (52.9 vs 47.1 %, respectively). Patients in the low post-PCI QFR group had more often diabetes mellitus, lower left ventricular ejection fraction (LVEF) and higher SYNTAX score compared to patients in the high post-PCI QFR group. Median follow-up period was 29 (26-34) months. After adjusting for covariates, low post-PCI QFR was independently associated with higher rate of the composite outcome (HR: 2.22 95% CI 1.01-4.88, p=0.047). Conclusions In our study, patients with lower post-PCI value were independently associated with higher risk of cardiovascular adverse events.

Diagnostic accuracy of automatic quantitative flow ratio for hemodynamic assessment of coronary artery stenosis: prospective observational study

Abstract Background Quantitative flow ratio (QFR) is a method for evaluating fractional flow reserve (FFR) without the use of an invasive coronary pressure wire or pharmacological hyperemic agent. Automatic QFR (auto QFR) is a recently developed, simpler method of calculating QFR that uses a patient-specific TIMI (Thrombolysis in Myocardial Infarction) frame count, but with automatically specified start and end frames. Although the previous studies demonstrated that contrast QFR is more accurate than fixed QFR, there is no evidence for auto QFR. Purpose The aim of this study was to evaluate the diagnostic performance of auto QFR, fixed QFR, and contrast QFR for the diagnosis of hemodynamically significant coronary stenosis defined by FFR ≤0.80. Methods This prospective, multicentre trial enrolled patients suspected with coronary artery disease undergoing diagnostic coronary angiography with an indication for to perform invasive FFR. QFR was calculated at a blinded core laboratory. The primary endpoint was the diagnostic accuracy of auto QFR, fixed QFR, and contrast QFR to determine hemodynamically significant coronary stenosis using invasive FFR (≤0.80) as a reference standard. Results A total of 325 vessels from 274 patients were analysed. Mean FFR was 0.82±0.09, mean auto QFR was 0.80±0.12, and mean contrast QFR was 0.82±0.11, respectively. The overall diagnostic accuracy for identifying an FFR of ≤0.80 was highest by contrast QFR (81.5%), followed by fixed QFR (79.1%), and auto QFR (77.5%). The AUC was higher for contrast QFR (AUC 0.885; 95% CI: 0.845-0.925) than fixed QFR (AUC 0.856; 95% CI: 0.812-0.900) or auto QFR (AUC 0.854; 95% CI: 0.806-0.901), but did not differ significantly between fixed QFR and auto QFR (Figure). Conclusions There was no significant difference in AUC between fixed and auto QFR, but the accuracy of contrast QFR was significantly higher compared to both QFRs. Auto QFR has the advantage of faster computation time while using patient-specific coronary flow, but accuracy still needs to be improved.

Impact of preoperative quantitative flow ratio on long term coronary artery bypass grafts patency

Abstract Background Preoperative fractional flow reserve (FFR) in the native coronaries is a known predictor of long-term graft patency after coronary artery bypass graft (CABG) surgery. Quantitative flow ratio (QFR) is an angiogram-based functional assessment tool of coronary stenoses. Its predictive value of graft patency is unknown. Purpose To investigate the impact of preoperative QFR value on long-term graft patency after CABG. Methods In this retrospective multicentric study we included consecutive patients treated with CABG between 2011 and 2022, with available coronary angiogram before and at any timepoint after CABG. Three-vessel QFR analysis of the preoperative angiography has been performed. Follow-up angiography was checked for graft patency. Only vessels entered the analysis for which baseline QFR was appropriate and which has been bypassed. Results 400 patients were included with mean age of 67±8 years. They received on average 2.0±0.9 bypasses. 788 coronaries and bypasses were analyzed, among the latter 455 were arterial and 333 were veins. 37% were placed on LAD, 26% on RCA and 26% on the LCx. Stenosis severity at baseline was 73±22% with a QFR value of 0.68±0.30. Follow-up angiographies were performed at 34±29 months. Overall graft patency was 83%, with higher occlusion rate for venous than arterial conduits (27% vs 9%, respectively; HR 3.9 [2.60-5.88]). Occlusion rate was lower for grafts implanted on QFR significant native vessels versus those, placed on non-significant ones (13% vs 30%, respectively; HR 2.86 [1.93-4.26]). Benefit was maintained for both, arterial (5% vs 22%, respectively; HR 5.23 [2.78-10.38]), as well as for venous conduits (24% vs 39%; HR 2.09 [1.21-3.50]). Conclusion QFR significantly predicts graft patency irrespective of whether the graft is arterial or venous. However, patency of venous grafts is poor, even if implanted on functionally significant native stenotic coronaries.Graft patency

Comparison of fully angiography-derived versus a hybrid of angiography and pressure-wire-derived approach to assess coronary microvascular resistance: the OxAMI-Hybrid study

Abstract Background Despite growing evidence of its clinical implications, assessment of coronary microvascular dysfunction (CMD) remains limited in routine clinical practice. Hence, there is an increasing interest in angiography-derived indices to encourage assessment of CMD in the cardiac catheterisation laboratory. We investigate here a novel approach, IMRhybrid, using a combination of pressure-wire-based assessment of distal coronary pressure (Pd) and an angiography-derived surrogate of coronary flow. Methods Patients were enrolled to the OxAMI-Hybrid study. The accuracy of IMRhybrid was assessed in diagnosing CMD using fully pressure wire and bolus thermodilution Index of Microcirculatory Resistance (IMR) as a reference. The accuracy of IMRhybrid was then compared against a fully angiography-derived index of microvascular resistance (IMRangio). Based on previous work, angiography-derived IMR, IMRangio, was calculated as IMRangio = Quantitative Flow Ratio (QFR) ado x Pahyperaemia x TIMI Frame Count (TFC) hyperaemia / Frame Rate. Conversely, IMRhybrid was expressed as IMRhybrid = Pdhyperaemia x TFChyperaemia / Frame Rate, where frame rate was fixed at 15 frame per second for both indices. In both cases, TFC/frame rate represented angiography-derived mean transit time, mTt in hyperaemia. Results 60 patients were enrolled prospectively, of which 28 with acute coronary syndrome and 32 with stable coronary artery disease. A total of 66 vessel analyses were performed. Both IMRhybrid and IMRangio correlated with IMR (rho=0.51, p <0.001 and rho=0.51, p <0.001 respectively) and showed good and comparable overall diagnostic accuracy in predicting IMR ≥ 25 (83.3% and 75.4% respectively) with a receiver operator curve (ROC) analyses showing an AUC of 0.82 and 0.81 respectively (p for comparison= 0.97). Conclusion Both approaches, IMRhybrid and IMRangio provide viable and comparable methods of assessing CMD which correlate with bolus thermodilution-based IMR, retaining good diagnostic accuracy. IMRhybrid is a simple alternative to conventional bolus thermodilution-based IMR, offering the advantage of being suitable with any pressure wire system.A: IMR, B: QFR, C: TFCA+C: IMRhybrid, B+D: IMRangio

Changes of angiography-derived coronary microcirculatory resistance before and after drug-coated balloon treatment

Abstract Background Drug coated balloon (DCB) is a treatment option for a lesion in a small coronary artery. The effect of DCB is proven in mechanistic and clinical outcomes, however, its influence on the microvascular function has not been elucidated. In addition, because there are differences in the types of drugs and coatings among different DCBs, their effects on microvascular function may vary. Angiography-derived microcirculatory resistance (AMR) is a novel angiographic parameter calculated from angiography-derived quantitative flow ratio and flow velocity estimation. AMR is reported to have a good correlation with the wire-based index of microvascular resistance. Purpose To investigate the AMR in coronary vessels treated with sirolimus or paclitaxel coated balloon. Methods This is a subanalysis of the TRANSFORM I (The TReAtmeNt of Small Coronary Vessels: MagicTouch Sirolimus Coated Balloon) trial. TRANSFORM I is a prospective, randomized, multi-center, open-label noninferiority trial conducted in Europe that enrolled 121 patients (126 vessels) with stabilized acute coronary syndrome or chronic coronary syndrome who had at least one de novo coronary artery lesion in a small coronary vessel. Patients were randomized 1:1 to treatment with the sirolimus coated balloon (SCB) or paclitaxel coated balloon (PCB). The SCB is coated with phospholipid encapsulated sirolimus nanocarrier, whereas the PCB is coated with crystalline paclitaxel. In this subanalysis, angiography at baseline and post-procedure were analyzed to calculate the AMR by an imaging core lab. Coronary microvascular dysfunction (CMD) was defined as AMR≧2.5 mmHg*s/cm. Results In the total of 126 vessels, 63 were included in each of the SCB and PCB group. Angiography both at baseline and post-procedure were analyzable for AMR in 59 vessels in SCB and in 59 vessels in PCB group. In SCB group, the median AMR increased significantly after procedure (baseline; 2.03 [1.58-2.42], post-procedure;2.21 [1.78-2.53], p=0.03). However, the proportion of vessels with CMD did not significantly change (baseline; 22.0% [13/59], post-procedure; 32.2% [18/59], p=0.19) (Figure). In the PCB group, the median AMR increased significantly after procedure (baseline; 2.22 [1.66-2.53], post-procedure;2.45 [1.93-2.96], p=0.003). Furthermore, the proportion of vessels with CMD significantly increased (baseline; 27.1% [16/59], post-procedure; 47.5% [28/59], p=0.046) (Figure). The AMR measurement was not significantly different between SCB and PCB at baseline (p=0.53), but it was significantly higher in PCB than in SCB at post-procedure (p=0.04). Conclusion After DCB treatment, AMR significantly increased in both arms. The proportion of the vessel with CMD after procedure did not significantly change in the SCB group but increased in the PCB group. The potential mechanism of increase in AMR after DCB treatment (e.g. embolization of small crystals) may warrant further investigation.Proportion of AMR≥2.5

Comparison of vessel-Fractional Flow Reserve (vFFR) and Quantitative Flow Ratio (QFR) using instantaneous wave-Free Ratio (iFR) or Resting Full-cycle Ratio (RFR) as reference

Abstract Background Angiography-based functional assessment remains the state of the art to assess the hemodynamic relevance of intermediate coronary stenoses. In addition to fractional flow reserve (FFR), adenosin free indices like instantaneous wave-free ratio (iFR) or resting full-cycle ratio (RFR) are widely used for the invasive evaluation. Although these methods are widely accepted, they are underused in clinical routine due to costs, their invasive nature, longer procedural times, and lack of availability. Vessel-fractional flow reserve (vFFR) and quantitative flow ratio (QFR) are new software-based methods for the evaluation of coronary-physiology. The aim of this study is to compare vFFR and QFR with the established invasive methods iFR or RFR. Methods We prospectively analyzed 95 Patients in our QFR-Registry vFFR- and QFR-computation was performed three-times by two certified, blinded, and independent experts using the QAngio XA 3D 3.2- and CAAS-software, respectively. Results: 101 main epicardial coronary arteries (52 LAD; 19 LCx; 30 RCA) were analyzed using vFFR, QFR and iFR or RFR. vFFR showed a good correlation with adenosine-free indices in all 3 measurements (AUC 0.883 with r=0.672, p<0.001; AUC 0.841 with r=0.618 p<0.001; AUC 0.840 with r=0.592, p<0.001 respectively). The diagnostic accuracy between the three vFFR-measurements and iFR/RFR was 83%; 81% and 79% respectively. QFR-computations showed a similar correlation with iFR/RFR (AUC 0.899 with r=0.720, p<0.001; AUC 0.919 with r=0.649, p<0.001; AUC 0.930 with r=0.703, p<0.001 respectively) with a diagnostic accuracy 88%, 89% and 88% respectively. The intra- and inter-observer reliability for vFFR (intra: mean difference 0.002±0.0568; inter: 0.024±0.054) and QFR (intra: mean difference 0.018±0.071; inter: 0.016±0.075) analyzed in a Bland-Altman Blot showed a good correlation between virtual assessments and invasive measurements with iFR/RFR. Conclusion The data show a good diagnostic agreement between vFFR and QFR and adenosine free invasive assessments. vFFR and QFR appear reasonable alternative approaches for the evaluation of intermediate stenoses. These data provide the rational to prospectively test for a clinical noninferiority of the non-invasive flow measurements.Diagnostic performance of vFFR/cQFR

Association Between Derivatives of Reactive Oxygen Metabolites and Hemodynamics in Children with Left-to-Right Shunt Congenital Heart Disease

Existing reports on the association between oxidative stress and pulmonary hemodynamics in congenital heart disease (CHD) are limited, and the relationship remains inadequately understood. To address this, we evaluated the link between oxidative stress and hemodynamics in children with left-to-right shunt CHD. We analyzed the derivatives of reactive oxygen metabolites (d-ROMs) in a cohort of 60 children with left-to-right shunt CHD and compared them to 60 healthy, age- and sex-matched controls. In the CHD group, hemodynamics measured by cardiac catheterization were evaluated in relation to d-ROMs. We also assessed the diagnostic performance of the d-ROMs for a pulmonary-to-systemic blood flow ratio (Qp/Qs) of >1.5. We found that the blood d-ROM levels in the CHD group were significantly higher than those in the control group (p < 0.001). A significant positive correlation was observed between d-ROMs and Qp/Qs (p < 0.001), d-ROMs and the ratio of the right ventricular end-diastolic volume (p < 0.001), d-ROMs and the mean pulmonary arterial pressure (p < 0.001), and d-ROMs and the ratio of the left ventricular end-diastolic volume (p = 0.007). In the receiver operating characteristic curve analysis, the area under the curve for d-ROMs in predicting Qp/Qs > 1.5 was 0.806 (p < 0.001), which, although not statistically significant, was higher than that of the plasma N-terminal pro-brain natriuretic peptide (0.716). These findings indicate that d-ROM levels are closely associated with hemodynamics and the disease severity in patients with left-to-right shunt CHD and may serve as a valuable marker for determining the need for surgical intervention.

Prognostic Role of Functional SYNTAX Score Based on Quantitative Flow Ratio

Prognostic Role of Functional SYNTAX Score Based on Quantitative Flow Ratio

Self-sustained stable combustion of off-gas from Solid Oxide Fuel Cell in a cone-shaped porous burner with preheaters

A divergent porous medium burner with three embedded preheaters has been numerically studied in this paper. The burner can be used to recover heat from Solid Oxide Fuel Cell for burning extremely low calorific off-gas. The developed burner consists of a conical section filled with porous media in the upper part and three preheaters located downstream through which the fresh mixture recovers heat from exhaust gas. A coupled solution method is used to study the structure of the preheater, and the feasibility of the method is verified. The results show that the burner can use the heat recovered from the exhaust gas to burn mixtures without the need for any external heating. The burner is capable of dealing with extremely low calorific off-gas, it can stabilize the combustion of a mixture with a heating value of 0.908 MJ/kg. The results also show that the mass flow ratio has a great influence on the recovery efficiency. When the mass flow ratio is less than one, the recovery efficiency increases sharply with the increase of mass flow ratio. With the further increase of mass flow ratio, the recovery efficiency decreases. This study provides the guidance for the treatment of low-grade off-gas without additional energy consumption.

Theoretical analysis of heat and mass transfer characteristics of a counter-flow packing tower with different heating modes

Mass extraction/injection and multi-stage system have been proven to be effective approaches to improve the performance of humidification and dehumidification (HDH) desalination system. However, these two optimization schemes cause that the flow ratios of water to air at different positions of humidifier or that of different humidifiers have great difference. A single heating mode is inapplicable to all flow ratios of water to air. Hence, it is necessary to reveal the relationship among mass flow ratio, heating mode and thermal efficiency of humidifier for the selection of appropriate heating mode. A theoretical model of packing tower (typical kind of humidifier) which agrees well with experimental results was established in this paper, and the average relative errors of outlet air temperature, humidity and thermal efficiency are 2.3 %, 4.9 % and 5.8 %, respectively. A comparison among the thermal efficiencies of a counter-flow packing tower with different heating modes (I: solution heated, II: air heated, III: solution-air heated) was conducted. It is found that there exist two values of mass flow ratio (FRI-II and FRII-III) at which the thermal efficiencies of air heated and solution-air heated are equal and that of solution heated and solution-air heated are equal, respectively. However, the thermal efficiency of solution heated is always higher than that of solution-air heated (FRI-III does not exist). It seems clear that there is a relationship between FR and thermal efficiency (η) as follows: FR < FRI-II, ηI > ηIII > ηII; FRI-II < FR < FRII-III, ηI > ηII > ηIII; FR > FRI-II, ηII > ηI > ηIII. Additionally, the effects of inlet parameters on the FRI-II and FRII-III are also evaluated. The results show that the maximum temperature, inlet solution concentration and ambient temperature have positive effects on FRI-II and FRII-III, but ambient relative humidity has negative effect. In the final part, the selection of the heating mode of a counter-flow packing tower is taken as example to introduce the application of FRI-II and FRII-III proposed in this paper.

Correlation and Agreement of Quantitative Flow Ratio With Fractional Flow Reserve in Saphenous Vein Grafts.

The applicability of quantitative flow ratio (QFR), a nonhyperemic, invasive coronary angiography-derived computation of fractional flow reserve (FFR), has not been studied in coronary artery bypass grafts. We sought to explore the correlation and diagnostic agreement between QFR and FFR in saphenous vein grafts (SVGs). A total of 129 prospectively included patients (mean age 73±8 years, 84% male) with prior coronary artery bypass grafting underwent invasive coronary angiography and pressure-derived functional assessment in 150 nonoccluded SVGs. QFR dedicated angiography images of the SVGs were acquired and used for offline QFR computation. The diagnostic performance of QFR was compared with 2-dimensional quantitative coronary angiography, using FFR as a reference. A threshold of ≤0.80 was used to define functional significance. QFR was successfully computed in 140 (93%) SVGs. We found a significant correlation between QFR and FFR (r=0.72, P<0.001). FFR indicated significant disease in 43 (31%) SVGs, whereas QFR analysis showed significant lesions in 53 (38%) bypass grafts. QFR exhibited a higher sensitivity and diagnostic accuracy compared with angiographic lesion assessment (84% versus 63%, P=0.030 and 83% versus 74%, P=0.036, respectively), whereas specificity did not differ (82% versus 79%, P=0.466). Lastly, QFR demonstrated a higher area under the receiver operating curve than quantitative coronary angiography (0.90 versus 0.82, P=0.008) for the detection of FFR-defined significant vein graft disease. This study shows the potential applicability of contemporary QFR computation in venous bypass grafts with a moderate correlation and good diagnostic accuracy compared with functional assessment using FFR.

Dynamic susceptibility contrast‑enhanced perfusion magnetic resonance imaging parameters for predicting MGMT promoter methylation and prognostic value in newly diagnosed patients with glioblastoma.

O6-methylguanine DNA methyltransferase (MGMT) promoter methylation is an important clinical biomarker of newly diagnosed glioblastoma. Previous radiological studies using dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) perfusion have aimed to predict MGMT methylation status non-invasively in gliomas with radiological characteristics. The possibility of predicting MGMT methylation status using DSC-MRI perfusion with a radiological approach remains controversial. The present study aimed to evaluate the usefulness of MRI perfusion parameters as non-invasive markers to predict MGMT methylation status and prognosis in newly diagnosed glioblastoma patients. Thus, 50 patients with histologically confirmed primary glioblastoma, IDH-wildtype who underwent tumor resection at Osaka University Hospital (Suita, Japan) between January 2017 and January 2023 were included in this study. The mean cerebral blood volume (CBV) ratio (rCBV) and cerebral blood flow (CBF) ratio (rCBF) for tumors with MGMT methylation (mean rCBV:2.09 and mean rCBF:3.08) were significantly higher compared with those for tumors without MGMT methylation (mean rCBV:1.33 and mean rCBF:1.85; P<0.05). While patients with MGMT methylation had longer progression-free survival (PFS) compared with those without MGMT methylation (P<0.05), there was no significant difference in OS with or without MGMT methylation (P=0.06). By contrast, there was no association between MRI perfusion parameters and OS or PFS in patients with glioblastoma. Furthermore, the association between CBV, CBF, MGMT promotor methylation status, OS, and PFS were explored. There was no significant prognostic difference between low vascularity tumors (rCBV <1.3 or rCBF <1.8) with or without MGMT methylation. On the other hand, high vascularity tumors (rCBF ≥1.8) with MGMT promotor methylation were associated to longer OS and PFS compared with those without. However, there was no association between MGMT methylation status and OS or PFS in patients with high rCBV (rCBV ≥1.3). The present study indicated that CBV and CBF could be used to predict the MGMT methylation status in glioblastomas. However, the prognostic value of tumor vascularity and MGMT methylation status may be limited.

Influence of Synthesis Parameters on Structure and Characteristics of the Graphene Grown Using PECVD on Sapphire Substrate.

The high surface area and transfer-less growth of graphene on dielectric materials is still a challenge in the production of novel sensing devices. We demonstrate a novel approach to graphene synthesis on a C-plane sapphire substrate, involving the microwave plasma-enhanced chemical vapor deposition (MW-PECVD) technique. The decomposition of methane, which is used as a precursor gas, is achieved without the need for remote plasma. Raman spectroscopy, atomic force microscopy and resistance characteristic measurements were performed to investigate the potential of graphene for use in sensing applications. We show that the thickness and quality of graphene film greatly depend on the CH4/H2 flow ratio, as well as on chamber pressure during the synthesis. By varying these parameters, the intensity ratio of Raman D and G bands of graphene varied between ~1 and ~4, while the 2D to G band intensity ratio was found to be 0.05-0.5. Boundary defects are the most prominent defect type in PECVD graphene, giving it a grainy texture. Despite this, the samples exhibited sheet resistance values as low as 1.87 kΩ/□. This reveals great potential for PECVD methods and could contribute toward efficient and straightforward graphene growth on various substrates.

Nomogram based on virtual hyperemic pullback pressure gradients for predicting the suboptimal post-PCI QFR outcome after stent implantation.

Growing evidence shows an association between higher post-PCI quantitative flow ratios (QFR) and improved clinical prognosis, however, no models are available to predict suboptimal QFRs (< 0.91) after angiographically successful PCI. This study aims to establish a prediction nomogram for this domain. This study included 450 vessels derived from 421 consecutive patients enrolled in the PIONEER IV trial, which were randomly assigned in a 1:1 ratio to a training (N = 225) and internal validation (N = 225) set, with external validation performed in 97 vessels from 95 consecutive patients enrolled in the ASET Japan trial. LASSO regression was used for optimal feature selection, and multivariate logistic regression was subsequently utilized to construct the nomogram. The performance of the nomograms was assessed and validated by area under the receiver operating characteristics curve (AUC), calibration curves, decision curve analysis, and clinical impact curves. The nomogram was constructed incorporating a novel metric, quantitative flow ratio derived pullback pressure gradient (QFR-PPG), alongside four conventional parameters: left anterior descending artery disease, pre-procedural QFR, reference vessel diameter, and percent diameter stenosis. AUCs of the nomogram were 0.866 (95%CI:0.818-0.914), 0.784 (95% CI:0.722-0.847), and 0.781 (95% CI:0.682-0.879) in the training, internal validation and external validation sets, respectively. Bias-corrected curves revealed a strong consistency between actual observations and prediction. The risk of a suboptimal post-PCI QFR in patients after angiographically successful PCI can be effectively predicted using a nomogram incorporating five variables available pre-PCI, with its performance and clinical predictive value confirming its utility in helping clinicians with decision-making and planning revascularization. Registered on clinicaltrial.gov (NCT04923191 and NCT05117866).

Mechanical and Tribological Properties of Laminated (NbTaMoW)Nx Films.

Laminated (NbTaMoW)Nx films were prepared via co-sputtering. The sputtering variables were a substrate holder rotation speed of 2 and 10 rpm and a nitrogen flow ratio (fN2 = N2/(Ar + N2)) of 0.1, 0.2, and 0.4. The (NbTaMoW)Nx films fabricated at 30 rpm displayed columnar structures. The phase structures of the laminated (NbTaMoW)Nx films varied from multiple body-centered cubic phases to a nanocrystalline and a face-centered cubic phase as the fN2 increased from 0.1 to 0.2 and 0.4. The mechanical and tribological properties of the laminated (NbTaMoW)Nx films were evaluated. The laminated (NbTaMoW)Nx films deposited at an fN2 of 0.4 had hardnesses of 25.2 and 26.1 GPa when prepared at 2 and 10 rpm, respectively, lower than the value of 29.9 GPa for the columnar (NbTaMoW)Nx film prepared at an fN2 of 0.4 and 30 rpm. In contrast, the wear resistances of the laminated (NbTaMoW)Nx films were superior to those of the columnar (NbTaMoW)Nx films.