Control of the injection velocity of embolic agents in embolization treatment.

BACKGROUND: Embolization is a common treatment method for tumor-targeting, anti-organ hyper-function, and hemostasis. However, the injection of embolic agents largely depends on the experiences of doctors, and doctors need to work in an X-ray environment that hurts their health. Even for a well-trained doctor, complications such as ectopic embolism caused by excessive embolic agents are always inevitable. RESULTS: This paper established a flow control curve model for embolic injection based on local arterial pressure. The end-vessel network was simplified as a porous media. The hemodynamic changes at different injection velocities and embolization degrees were simulated and analyzed. Sponge, a typical porous medium, was used to simulate the blocking and accumulation of embolic agents by capillary networks in the in vitro experimental platform. CONCLUSIONS: The simulation and experimental results show that the local arterial pressure is closely related to the critical injection velocity of the embolic agent reflux at a certain degree of embolization. The feasibility of this method for an automatic embolic injection system is discussed. It is concluded that the model of the flow control curve of embolic injection can effectively reduce the risk of ectopic embolism and shorten the time of embolic injection. The clinical application of this model is of great value in reducing radiation exposure and improving the success rate of interventional embolization.

The Role of Multiple Re-Entry Tears in Type B Aortic Dissection Progression: A Longitudinal Study Using a Controlled Swine Model.

PURPOSE: False lumen (FL) expansion often occurs in type B aortic dissection (TBAD) and has been associated with the presence of re-entry tears. This longitudinal study aims to elucidate the role of re-entry tears in the progression of TBAD using a controlled swine model, by assessing aortic hemodynamics through combined imaging and computational modeling. MATERIALS AND METHODS: A TBAD swine model with a primary entry tear at 7 cm distal to the left subclavian artery was created in a previous study. In the current study, reintervention was carried out in this swine model to induce 2 additional re-entry tears of approximately 5 mm in diameter. Computed tomography (CT) and 4-dimensional (4D) flow magnetic resonance imaging (MRI) scans were taken at multiple follow-ups before and after reintervention. Changes in aortic volume were measured on CT scans, and hemodynamic parameters were evaluated based on dynamic data acquired with 4D-flow MRI and computational fluid dynamics simulations incorporating all available in vivo data. RESULTS: Morphological analysis showed FL growth of 20% following the initial TBAD-growth stabilized after the creation of additional tears and eventually FL volume reduced by 6%. Increasing the number of re-entry tears from 1 to 2 caused flow redistribution, with the percentage of true lumen (TL) flow increasing from 56% to 78%; altered local velocities; reduced wall shear stress surrounding the tears; and led to a reduction in FL pressure and pressure difference between the 2 lumina. CONCLUSION: This study combined extensive in vivo imaging data with sophisticated computational methods to show that additional re-entry tears can alter dissection hemodynamics through redistribution of flow between the TL and FL. This helps to reduce FL pressure, which could potentially stabilize aortic growth and lead to reversal of FL expansion. This work provides a starting point for further study into the use of fenestration in controlling undesirable FL expansion. CLINICAL IMPACT: Aortic growth and false lumen (FL) patency are associated with the presence of re-entry tears in type B aortic dissection (TBAD) patients. Guidelines on how to treat re-entry tears are lacking, especially with regards to the control and prevention of FL expansion. Through a combined imagining and computational hemodynamics study of a controlled swine model, we found that increasing the number of re-entry tears reduced FL pressure and cross lumen pressure difference, potentially stabilising aortic growth and leading to FL reduction. Our findings provide a starting point for further study into the use of fenestration in controlling undesirable FL expansion.

[Research on injection flow velocity planning method for embolic agent injection system].

Interventional embolization therapy is widely used for procedures such as targeted tumour therapy, anti-organ hyperactivity and haemostasis. During embolic agent injection, doctors need to work under X-ray irradiation environment. Moreover, embolic agent injection is largely dependent on doctors' experience and feelings, and over-injection of embolic agent can lead to reflux, causing ectopic embolism and serious complications. As an effective way to reduce radiation exposure and improve the success rate of interventional embolization therapy, embolic agent injection robot is highly anticipated, but how to decide the injection flow velocity of embolic agent is a problem that remains to be solved. On the basis of fluid dynamics simulation and experiment, we established an arterial pressure-injection flow velocity boundary curve model that can avoid reflux, which provides a design basis for the control of embolic agent injection system. An in vitro experimental platform for injection system was built and validation experiments were conducted. The results showed that the embolic agent injection flow speed curve designed under the guidance of the critical flow speed curve model of reflux could effectively avoid the embolic agent reflux and shorten the embolic agent injection time. Exceeding the flow speed limit of the model would lead to the risk of embolization of normal blood vessels. This paper confirms the validity of designing the embolic agent injection flow speed based on the critical flow speed curve model of reflux, which can achieve rapid injection of embolic agent while avoiding reflux, and provide a basis for the design of the embolic agent injection robot.

Endovascular Outcomes in Aortic Arch Repair with Double and Triple Parallel Stent Grafts.

PURPOSE: To report early and midterm outcomes of treating thoracic aortic aneurysm (TAA) and aortic dissection (AD) involving zone 1 and zone 0 with multiple parallel stent grafts (PSGs). MATERIALS AND METHODS: From February 2011 to August 2018, 31 of 1,806 patients (1.7%) who underwent thoracic endovascular aortic repair (TEVAR) with double PSGs (DPSGs) (n = 20) or triple PSGs (TPSGs) (n = 11) were retrospectively reviewed. Procedures were performed in high-risk patients who had TAA or AD involving zone 1 or zone 0. RESULTS: Fifteen patients (48.4%) who presented with symptomatic or impending rupture underwent urgent or emergent TEVAR with DPSGs or TPSGs. Nineteen patients (61.3%) were treated for zone 0 disease. Technical and clinical success rates were 70.0% for DPSG cohort and 45.5% for TPSG cohort. Intraoperative type Ia endoleak was observed in 30% of DPSG cohort and 45.5% of TPSG cohort. One patient in the DPSG cohort died of aortic sinus rupture intraoperatively. Minor stroke during the 30-day postoperative period was more frequent in the TPSG cohort (P = .042). Mean duration of follow-up was 28.9 months ± 17.7. The TPSG cohort had a higher incidence of major adverse events (72.7% vs 25.0%, P = .021). The most common adverse events were endoleaks (12.9%), endograft migration (9.7%), PSG stenosis or occlusion (6.5%), retrograde dissection (6.5%), and stroke (3.2%). Endograft migrations were more common in TPSG cohort (27.3%, P = .037). Overall mortality rate was 16.1% (5/31) perioperatively and during follow-up. There were no statistical differences in overall survival and reintervention-free survival. CONCLUSIONS: In the context of TEVAR with multiple PSGs for aortic arch repair, TPSGs may have a high risk of major complications.

Intravascular Ultrasound-Assisted Endovascular Treatment of Mesenteric Malperfusion in a Multichannel Aortic Dissection With Full True Lumen Collapse.

PURPOSE: To describe endovascular treatment of mesenteric malperfusion in a multichannel aortic dissection (MCAD) with full true lumen (TL) collapse following thoracic endovascular aortic repair (TEVAR). CASE REPORT: A 54-year-old man presented with chronic mesenteric ischemia and a previous TEVAR for MCAD complicated by superior mesenteric artery (SMA) malperfusion. Computed tomography angiography (CTA) demonstrated a 3-channel aortic dissection with a "false-true-false" configuration. The SMA was malperfused through the collapsed TL. CTA also showed a secondary entry tear, measuring 18 mm in diameter, at the end of the previous endograft. Direct open surgery or endovascular revascularization of the SMA was not feasible. A plan was devised to improve SMA perfusion by increasing the TL inflow. With the assistance of intravascular ultrasound (IVUS), an endograft was placed through one false lumen in the abdominal aorta and through the TL in the descending thoracic aorta to seal the secondary entry tear. Symptoms of mesenteric ischemia resolved 2 days after the procedure. At 1 year, he is asymptomatic, has gained weight, and has improved SMA perfusion and remodeling of the 3-channel dissection on CTA. CONCLUSION: IVUS imaging can help evaluate the complex hemodynamics of MCAD. Patient-specific endovascular treatment of MCAD with mesenteric malperfusion seems to be a feasible bailout alternative treatment for urgent, complex cases without reconstruction options.

Dissection Level Within Aortic Wall Layers is Associated with Propagation of Type B Aortic Dissection: A Swine Model Study.

OBJECTIVE: Haemodynamic and geometric factors play pivotal roles in the propagation of acute type B aortic dissection (TBAD). The aim of this study was to evaluate the association between dissection level within all aortic layers and the propagation of acute TBAD in porcine aorta. METHODS: In twelve pigs, two models of TBAD were created. In model A (n = 6), the aortic wall tear was superficial and close to the intima (thin intimal flap), whereas in model B (n = 6) it was deep and close to the adventitia (thick intimal flap). Dissection propagation was evaluated using angiography or computed tomography scans, and the haemodynamic measurements were acquired using Doppler wires. Most pigs were followed up at 1, 3, 6, 12, 18, and up to 24 months; four animals were euthanised at three and six months, respectively (two from each group). RESULTS: Both models were successfully created. No statistical difference was observed for the median antegrade propagation distance intra-operatively between the two models (p = .092). At 24 months, the longitudinal propagation distance was significantly greater in model B than in model A (p = .016). No statistical difference in retrograde propagation was noted (p = .691). Over time, aortic wall dissection progressed most notably over the first three months in model A, whereas it continued over the first 12 months in model B. Flow velocity was significantly greater in the true lumen than in false lumen at the level of the primary tear (p = .001) and in the middle of the dissection (p = .004). The histopathological images at three and six months demonstrated the fibres were stretched linearly at the outside wall of false lumen in both models, while the depth of intimal tears developed to be superficial and similar at the distal dissection. CONCLUSION: In this swine model of TBAD, a deeper intimal tear resulted in greater dissection propagation.

High Wall Stress May Predict the Formation of Stent-Graft-Induced New Entries After Thoracic Endovascular Aortic Repair.

PURPOSE: To explore the potential role of morphological factors and wall stress in the formation of stent-graft-induced new entries (SINE) based on computed tomography (CT) images after thoracic endovascular aortic repair (TEVAR). CASE REPORT: Two female patients aged 59 years (patient 1) and 44 years (patient 2) underwent TEVAR for type B dissection in the chronic (patient 1) or subacute (patient 2) phase. CT scans at 3-month follow-up showed varying degrees of false lumen thrombosis in both patients. At 14-month follow-up, a SINE was observed in patient 1 while the dissected aorta in the other patient remained stable. Morphological and finite element analyses were performed based on the first follow-up CT images. The computational results showed that the SINE patient had higher stent-graft tortuosity than the non-SINE patient and much higher wall stress in the region close to the distal SINE. CONCLUSION: This case study suggests that high stent-graft tortuosity can lead to high wall stress, which is potentially linked to the formation of SINE. Further large population-based studies are needed to confirm this preliminary finding.

Outcomes of thoracic endovascular repair for type B aortic dissection with multichanneled morphology.

OBJECTIVE: Clinical outcomes after thoracic endovascular aortic repair (TEVAR) for patients with multichanneled aortic dissection (MCAD) are poorly understood but seem substantially different from those for patients with double-channeled aortic dissection (AD). This study compared the anatomic and clinical factors for patients with MCAD who underwent TEVAR with or without full true lumen (TL) collapse. METHODS: From January 2012 to March 2016, 54 of 644 consecutive type B AD patients (8.4%) who presented with MCAD were reviewed. Patients were classified as MCAD with full TL collapse and without full TL collapse according to computed tomography angiography findings. We analyzed potential variables including clinical characteristics, anatomic morphologic features, and procedural details. Multivariable analysis was performed to determine independent predictors of AD-related deaths. RESULTS: A total of four patients (7.4%) died preoperatively of aortic rupture, all of whom experienced full TL collapse. MCAD patients with full TL collapse showed significantly higher 30-day major adverse events than those without full TL collapse (36.8% vs 9.7%; P = .030). The mean follow-up duration was 25.6 ± 13.2 months (range, 3-53 months). The overall mortality for all MCAD patients was 16.7%, whereas the follow-up major adverse events rate was 40.0% after TEVAR. Significant differences were present between patients with full TL collapse and patients without full TL collapse in survival at 3 years (55.4% vs 94.7%; P = .002). Maximum diameter of affected aorta (hazard ratio, 1.176; 95% confidence interval, 1.015-1.362; P = .031) was identified as the only predictor of AD-related deaths. CONCLUSIONS: MCAD was identified in a small but not insignificant number of our patients presenting with type B AD. Urgent or elective TEVAR was indicated in all our patients with MCAD. In patients with MCAD, full TL collapse was associated with worse outcomes, and this finding may indicate the need for more urgent or emergent repair.

Application of color-coded quantitative digital subtraction angiography in predicting the outcomes of immediate type I and type III endoleaks.

OBJECTIVE: Immediate type I and type III endoleaks after endovascular aneurysm repair (EVAR) could be persistent or temporary. Reintervention is necessary for persistent ones. Color-coded quantitative digital subtraction angiography (CQDSA) could provide a quantitative evaluation of the endoleak hemodynamics. We aimed to use CQDSA to quantify immediate type I and type III endoleaks after EVAR and to find a practical way to predict their outcomes. METHODS: Between January 2012 and December 2014, 485 consecutive patients with abdominal aortic aneurysms underwent EVAR at our institution. Thirty-five patients (31 men, four women) with slight immediate type I and type III endoleaks after EVAR were recruited in the prospective observational nested case-control study. After at least 6 months of follow-up, these patients were divided into two groups based on endoleak-related adverse events. Their final intraprocedure DSA images were collected and converted into a single polychromatic image for CQDSA measurements. The parameter time to peak (TTP) of the selected regions of interest in the endoleak area and a reference area at the same latitude within the stent graft were derived from the time-intensity curve. A receiver operating characteristic curve was generated to test the ability of TTP to predict endoleak-related adverse events and to identify the optimal cutoff value. RESULTS: Finally, two groups were identified: 12 patients with endoleak-related adverse events and 23 patients without endoleak-related adverse events. Median follow-up time for all patients was 24.0 months. Age, gender, and comorbidity were similar in these two groups. TTP was significantly lower in patients with endoleak-related adverse events (P = .002). The risk of endoleak-related adverse events was significantly higher in patients with mixed-type endoleak than in those with simple-type endoleak (P = .003). According to the receiver operating characteristic curves, TTP ≤5 seconds reached the maximal sum of sensitivity and specificity (sensitivity, 91.67%; specificity, 69.57%). Logistic regression analysis confirmed that TTP ≤5 seconds (P = .016) and mixed-type endoleak (P = .044) were associated with higher risk of endoleak-related adverse events. CONCLUSIONS: CQDSA could help predict the outcomes of immediate type I or type III endoleaks after EVAR. TTP ≤5 seconds and mixed-type endoleak were two potential predictors of endoleak-related adverse events. This approach may offer an objective assessment of such immediate endoleaks and reference for immediate reintervention or conservative therapy.

Early and intermediate results of endovascular treatment of symptomatic and asymptomatic visceral artery aneurysms.

OBJECTIVE: The treatment outcomes of symptomatic visceral artery aneurysms (SVAAs) have been sparsely characterized, with no clear comparisons between different treatment modalities. The purpose of this study was to review the outcomes of SVAAs and asymptomatic visceral artery aneurysms (ASVAAs) after endovascular treatment (ET). METHODS: The records of all patients with visceral artery aneurysms (VAAs) at our center from March 2004 to December 2014 were retrospectively reviewed. Patient demographics, aneurysm characteristics, management, perioperative and long-term outcomes, and complications were recorded. RESULTS: A total of 155 patients' records were reviewed; 106 patients (113 VAAs) were repaired with ET, including 27 symptomatic and 79 asymptomatic patients. The remaining 49 patients were treated with open surgery repair or conservative therapy. There was no significant difference of the diameters between SVAA and ASVAA (36.9 ± 15.3 mm vs 33.6 ± 36.1 mm, respectively; P = .746), and pseudoaneurysms were more common in the SVAA patients (13.8% vs 2.4%; P = .037). The most common presentation was abdominal pain. In the SVAA group, 17.2% of patients presented with rupture. The immediate technical success rates of SVAA and ASVAA repairs were 96.3% and 97.5%, respectively. The 30-day mortality rate was 2.8% for all VAAs; however, this was significantly higher in the SVAA group (11.1%) than in the ASVAA group (0%; P = .015). The perioperative complication rate was not statistically different between the two groups (P = .553). The median duration of follow-up was 39.1 ± 29.2 months (range, 1-112 months). Overall mortality in all VAA patients was 6.6%, and the direct and indirect aneurysm-related mortality was 3.8%. There was a statistical difference in the overall survival rate between the SVAA and ASVAA groups at 3 years (85.2% vs 97.5%; P = .044). The reintervention rate was 3.8%, and this tended to be higher for SVAAs (11.1%) than for ASVAAs (1.3%; P = .050). CONCLUSIONS: ET for VAA is safe and effective; however, SVAA has a significantly higher 30-day mortality rate than ASVAA.

Endovascular Versus Open Repair for Ruptured Abdominal Aortic Aneurysms in a Chinese Population.

BACKGROUND: The aim of this study was to compare the perioperative outcomes and midterm survival rate between open surgical repair (OSR) and endovascular aneurysm repair (EVAR) of ruptured abdominal aortic aneurysms (RAAAs) in a Chinese population. METHODS: A retrospective review was performed of the demographic characteristics and perioperative outcomes from 59 RAAA patients (mean 66.6 ± 13.3 years of age; 49 men) undergoing OSR or EVAR at our center between January 2003 and November 2014. The perioperative mortality and midterm survival were assessed and compared between the OSR and EVAR groups. RESULTS: Twenty-three patients underwent OSR, and 36 patients underwent EVAR. The overall 30-day mortality was 36.5% (47.8% OSR vs. 27.8% EVAR, P = 0.14). Total surgical time, estimated blood loss, and blood transfusion in the OSR group were significantly greater than those in the EVAR group (P < 0.001). Reintervention within 30 days and during the follow-up was more frequent in the EVAR group (36.1%) than in the OSR group (8.7%, P = 0.026). The mean follow-up was 38.2 ± 29.3 months (range 6-100). A Kaplan-Meier survival curve analysis showed no significant difference between the 2 groups (P = 0.079). The overall survival rate at 1 year was 52.5% (31/59). Univariate and multivariate logistic regression analyses demonstrated that free intraperitoneal rupture (odds ratio [OR] 0.143, 95% confidence interval [CI] 0.030-0.694, P = 0.016) and cardiovascular disease (OR 0.072, 95% CI 0.006-0.898, P = 0.041) were independent risk factors for the 30-day mortality. Only intraperitoneal rupture was associated with the higher midterm mortality (OR 4.852, 95% CI 1.046-22.499, P = 0.044). CONCLUSIONS: In an experienced vascular center in China, although the 30-day mortality and midterm survival of RAAAs were not significantly different between the EVAR and OSR groups, EVAR has superior perioperative advantages. Consequently, EVAR is recommended as the first-line treatment for anatomically suitable RAAA.

[Endovascular treatment of popliteal artery aneurysm in a clinical analysis of 9 cases].

OBJECTIVE: To evaluate the efficacy of endovascular repair of popliteal artery aneurysm (PAA) and to summarize the clinical experience and lessons. METHODS: A clinical data of 9 PAA cases (males 8, females 1, age range 55-84) undergoing endovascular repair from October 2006 to December 2014 at Zhongshan Hospital Fudan University were retrospectively analyzed. CT angiography was made in all of the 9 cases preoperatively, and 10 PAA were included in the analysis. Of the 9 cases, 6 cases were symptomatic. The mean diameter of PAA was 3.9 cm (range, 2.1-8.2). RESULTS: The technique successful rate of endovascular repair was 10/10. The preoperative complications were 2/10, including one case suffered hematoma in the arterial puncture site and 1 case with distal artery embolization. The mean follow-up was 33 months (range, 3-87). During the follow-up, 2 cases received the secondary intervention and drug thrombolysis because of the stent distal thrombosis. The stent-graft primary patency at 1 year was 78.8% (95% CI: 48%-91%). One case suffered stent fracture, and one case died of brainstem hemorrhage 15 months post endovascular repair of PAA. CONCLUSIONS: Endovascular treatment of PAA is safe and effective in perioperative and midterm follow-up. However, individual endovascular strategy and postoperative complications in the long-term follow-up should be payed more attention.

[Clinical analysis of hybrid treatment for extensive aortic disease].

OBJECTIVE: To evaluate the effect of extensive aortic diseases (EAD) after hybrid repair with supra-arch branches or visceral arterial debranching and endovascular repair. METHODS: A total of 24 EAD patients (19 male and 5 female) underwent hybrid repair in Department of Vascular Surgery, Zhongshan Hospital, Fudan University between March 2005 and April 2015. The clinical data was analyzed retrospectively. The mean age was (49±12) years (from 29 to 69 years). The high-risk candidates for open surgery were enrolled in the study. The patients, including 14 cases with thoracic aortic aneurysms and 10 cases with aortic dissection, were treated by one or two stages. Post-operative follow-up with CT angiography was performed at 3, 6 and 12 months and then annually thereafter. RESULTS: A total of 74 branches, including 63 with visceral arteries and 11 with supra-arch arteries, were recanalized. Nine patients were treated in two-stage hybrid procedure and fifteen were repaired by one stage. The perioperative mortality was 12.5% (3/24), whereas the aneurysm-related mortality was 8.3% (2/24). The 30-day patency of the grafts was 95.9% (71/74). There was no endoleak, paralysis, and intestinal ischemia at 30 days post-hybrid procedures. Four cases (16.6%) suffered acute renal dysfunction. During the follow-up (3 to 123 months), there were two deaths and one endoleak (type Ia and III) which emerged at 4 months post-procedure. The 1-year and 3-year survival rates were 81.7% and 73.5%, respectively. CONCLUSIONS: Hybrid treatment is safe and effective for complex EAD patients in the midterm follow-up. It is especially suitable for the high-risk patients with comorbidities, re-intervention, or little tolerance to open surgery repair.

Patients carrying CYP2C19 loss of function alleles have a reduced response to clopidogrel therapy and a greater risk of in-stent restenosis after endovascular treatment of lower extremity peripheral arterial disease.

OBJECTIVE: This study evaluated the relationship between the cytochrome P450 (CYP) 2C19 genotype and the antiplatelet effect of clopidogrel therapy and investigated whether genotyping can predict the risk of ischemic events after endovascular treatment (ET) of lower extremity peripheral arterial disease. METHODS: From January 2011 to July 2012, 120 consecutive patients with arteriosclerosis obliterans (TransAtlantic Inter-Society Consensus for the Management of Peripheral Arterial Disease [TASC II] A-C) in the superficial femoral artery were included in a prospectively maintained database. Patients received 75 mg clopidogrel and 100 mg aspirin daily for at least 5 days before TaqMan (Life Technologies, Grand Island, NY) of CYP2C19 single-nucleotide polymorphisms and thromboelastography of the clopidogrel response. ET was subsequently performed, and follow-up evaluations, including duplex ultrasound imaging and ankle-brachial index assessment, were performed at 1, 3, 6, and 12 months after ET. During the follow-up, stent patency was assessed by ultrasound imaging, computed tomography angiography, or digital subtraction angiography. RESULTS: A total of 74 ET procedures were performed. Fifty of the enrolled patients (41.7%) completed the follow-up examinations and were included in the analysis. The mean duration of follow-up was 9.8 ± 2.1 months (range, 1-30 months). Carriers of at least one CYP2C19 loss-of-function (LOF) allele had a diminished pharmacodynamic response to clopidogrel (51.6 ± 20.1 vs. 39.8 ± 15.2 for patients without and with LOF alleles, respectively; P = .022). Carriers of one LOF allele had an increased incidence of ischemic events compared with patients without any LOF alleles (59.0% vs. 20.8%, respectively; P = .008). This trend was even more evident in patients with two LOF alleles compared with patients with no LOF alleles (100% vs. 20.8% ischemic events; P = .002). The cumulative primary patency rate at 12 months was 56.0%, with significant differences between groups (73.1% vs. 34.6% in patients without and with LOF alleles, respectively; P = .0.006). CYP2C19 LOF carrier status was associated with an increased rate of primary end points (P = .007). On the basis of their adenosine diphosphate-induced platelet aggregation, patients with high platelet reactivity had a significantly higher risk of ischemic events (P = .012). CYP2C19 genotypic classification (adjusted hazard ratio, 2.688; 95% confidence interval, 1.366-5.288; P = .004) and history of smoking (adjusted hazard ratio, 2.430; 95% confidence interval, 1.024-5.765; P = .044) were independent risk factors for ischemic events. CONCLUSIONS: CYP2C19 LOF alleles were associated with a diminished platelet response to clopidogrel treatment. Patients carrying CYP2C19 LOF alleles who are treated with clopidogrel may trend toward a poor prognosis after ET.

Advanced removal of phosphorus from urban sewage using chemical precipitation by Fe-Al composite coagulants.

Phosphorus (P) removal is a significant issue in wastewater treatment. This study applies Fe-Al composite coagulant to the advanced treatment of different P forms in biological effluent. For 90% total P removal, the dosage of FeCl3-AlCl3 composite coagulant reduces by 27.19% and 43.28% than FeCl3 and AlCl3 only, respectively. Changes in effluent P forms could explain the phenomenon of composite coagulant dosage reduction. The suspended P in the effluent of composite coagulant is easier removed by precipitation than single coagulant. In this study, the hydrolysis speciations of Fe3+, Fe2+, and Al3+ at a pH range are calculated by Visual MINTEQ. Changes in the morphology of metal hydroxides correlate with P removal at pH 4-9. Besides, analyses of scanning electron microscope (SEM), Fourier transformed infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) are performed on the coagulation precipitations. Fe2+ reacts directly with P to form flocs of Fe3(PO4)2, and Al2(SO4)3 assists in the sedimentation of the small-volume flocs. Al13 is a significant hydrolysis product of Al3+, and Fe and P would substitute for the peripheral AlVI of the Al13 structure to form stable Fe-O-Al covalent bonds.

A new method for scaling inlet flow waveform in hemodynamic analysis of aortic dissection.

Computational fluid dynamics (CFD) simulations have shown great potentials in cardiovascular disease diagnosis and postoperative assessment. Patient-specific and well-tuned boundary conditions are key to obtaining accurate and reliable hemodynamic results. However, CFD simulations are usually performed under non-patient-specific flow conditions due to the absence of in vivo flow and pressure measurements. This study proposes a new method to overcome this challenge by tuning inlet boundary conditions using data extracted from electrocardiogram (ECG). Five patient-specific geometric models of type B aortic dissection were reconstructed from computed tomography (CT) images. Other available data included stoke volume (SV), ECG, and 4D-flow magnetic resonance imaging (MRI). ECG waveforms were processed to extract patient-specific systole to diastole ratio (SDR). Inlet boundary conditions were defined based on a generic aortic flow waveform tuned using (1) SV only, and (2) with ECG and SV (ECG + SV). 4D-flow MRI derived inlet boundary conditions were also used in patient-specific simulations to provide the gold standard for comparison and validation. Simulations using inlet flow waveform tuned with ECG + SV not only successfully reproduced flow distributions in the descending aorta but also provided accurate prediction of time-averaged wall shear stress (TAWSS) in the primary entry tear (PET) and abdominal regions, as well as maximum pressure difference, ∆Pmax, from the aortic root to the distal false lumen. Compared with simulations with inlet waveform tuned with SV alone, using ECG + SV in the tuning method significantly reduced the error in false lumen ejection fraction at the PET (from 149.1% to 6.2%), reduced errors in TAWSS at the PET (from 54.1% to 5.7%) and in the abdominal region (from 61.3% to 11.1%), and improved ∆Pmax prediction (from 283.1% to 18.8%) However, neither of these inlet waveforms could be used for accurate prediction of TAWSS in the ascending aorta. This study demonstrates the importance of SDR in tailoring inlet flow waveforms for patient-specific hemodynamic simulations. A well-tuned flow waveform is essential for ensuring that the simulation results are patient-specific, thereby enhancing the confidence and fidelity of computational tools in future clinical applications.

Enhanced denitrification performance in iron-carbon wetlands through biomass addition: Impact on nitrate and ammonia transformation.

This study investigated the influence of biomass addition on the denitrification performance of iron-carbon wetlands. During long-time operation, the effluent NO3--N concentration of CW-BFe was observed to be the lowest, registering at 0.418 ± 0.167 mg/L, outperforming that of CW-Fe, which recorded 1.467 ± 0.467 mg/L. However, the effluent NH4+-N for CW-BFe increased to 1.465 ± 0.121 mg/L, surpassing CW-Fe's 0.889 ± 0.224 mg/L. Within a typical cycle, when establishing first-order reaction kinetics based on NO3--N concentrations, the introduction of biomass was found to amplify the kinetic constants across various stages in the iron-carbon wetland, ranging between 2.4 and 5.4 times that of CW-Fe. A metagenomic analysis indicated that biomass augments the reduction of NO3--N and NO2--N nitrogen and significantly bolsters the dissimilation nitrate reduction to ammonia pathway. Conversely, it impedes the reduction of N2O, leading to a heightened proportion of 2.715 % in CW-BFe's nitrogen mass balance, a stark contrast to CW-Fe's 0.379 %.