Main Vessel Research Articles

Versatility of the perforator radial artery flap in the reconstruction of the upper limbs and comparison of the outcomes with the “classic” radial flap, a retrospective study

IntroductionRadial forearm flap, first described in the early eighties in China, is a well-known and handy flap to cover soft tissue defects of the distal upper limb. It has, though, some inconveniences, such as the sacrifice of the radial artery and non-neglectable esthetic sequelae in the donor site. In the following years, a similar flap based on the perforators of the radial artery has been described as achieving similar results, allowing to spare a main vessel. The authors reviewed retrospectively the patients that underwent surgery with one of those two flaps in their center to compare outcomes. Materials and methodsPatients operated between January 2016 and January 2022 have been reviewed. Ten had a classic radial artery flap, and ten had a radial artery perforator flap. Twelve weeks after surgery, Vancouver Scar Scale was used to assess the results at the donor site and over the flap. Reintervention and failure rate within one year and patient satisfaction -using a visual analog scale ranging from 0 to ten-at 12 months were also assessed. ResultsAll classic radial artery flap group patients had “successful” surgery, and none needed secondary surgery. On the other side, three patients required a second surgery in the perforator flap group, and nine out of ten ended up with “successful” flaps. Mean Vancouver Scar Scale results regarding the flap are comparable, whereas those at the donor site are significantly better in the patients with the perforator flap. Patients’ satisfaction results are similar in both groups. ConclusionThe radial artery perforator flap is an important flap to be held in mind by all surgeons approaching reconstruction of the elbow, the forearm, and the hand, and should be preferred, when possible, to the classic radial forearm flap.

“Main Vessel-Oriented” Treatment Strategy Versus “Open Side Branch” Treatment Strategy in Acute Coronary Syndrome Patients With Culprit Bifurcation Lesions

Percutaneous coronary intervention of bifurcation lesions is associated with an increased risk of complications in patients with acute coronary syndrome (ACS). The study aimed to evaluate the in-hospital outcomes of patients with ACS with culprit bifurcation lesions who were treated with either a "main vessel-oriented" (MVO) treatment strategy or an "open side branch" (OSB) treatment strategy. This retrospective study included 575 consecutive patients with ACS. "MVO" and "OSB" treatment strategies were defined as primary/urgent percutaneous coronary intervention procedures performed by either totally ignoring the side branch (SB) or trying to maintain both main vessel and SB open with thrombolysis in myocardial infarction 3 flow. Procedural success and major cardiac/cerebrovascular events during hospitalization were noted. MVO and OSB treatment strategies were performed on 384 and 191 patients, respectively. The procedural success rate was significantly higher in the OSB treatment strategy whereas major cardiac/cerebrovascular events rates were similar except for the contrast-induced nephropathy rate being slightly higher in OSB treatment strategy. Subgroup analysis revealed a significantly higher procedural success rate in OSB treatment strategy if the SB was located within the bifurcation core, especially in those where the diameter of SB was ≥2mm. In conclusion, our results suggest a better procedural result with SB protection attempts in patients with ACS with a culprit bifurcation lesion if the SB is originating within the bifurcation core and its diameter is ≥2mm. MVO treatment strategy may be preferred in most cases with minor SBs located distant to the bifurcation core because of the similar procedural success.

Influence of seismic isolation on the earthquake response of internal components in a fast reactor

Nuclear energy is being considered as a frontrunner towards achieving the zero carbon goal. A sustainable use of nuclear energy is possible when a reactor design is deployed across regions with varying seismic hazard. Seismic isolation technology has been proven to reduce earthquake loads in the structures, and is being seen as a key towards the standardized reactor designs. This paper investigates the influence of seismic isolation on the response of a generic fast reactor (GFR) similar to the prototype fast breeder reactor (PFBR) currently under commissioning at Kalpakkam, India. This reactor comprises a head-supported main vessel that houses other reactor components (e.g., core, inner vessel). The major vessels of the reactor are partially filled with liquid sodium. In order to understand the influence of seismic isolation, simplified lumped mass stick models (LMSMs) for the GFR components were developed. These models were based on static analysis results obtained using corresponding finite element (FE) models. The component models were assembled to generate the LMSM and FE model for the GFR. The LMSM was verified through the comparison of dynamic properties obtained using the FE model, and through the comparison of response-history analysis results. These models considered fluid masses lumped at respective shells, thereby ignoring the fluid–structure interaction (FSI) effects. A representative system was analyzed with and without considering FSI effects. These effects did not influence acceleration response significantly. Fixed-base (FB) and isolated base (IB) configurations of the LMSM for the GFR were subjected to a series of response-history analyses. Seismic isolation led to a substantial reduction (e.g., up to 10 times) in the median floor accelerations, particularly for lower sliding friction and longer sliding period. The floor spectral ordinates for the IB configuration of GFR subjected to 1.00 g shaking were less than that for the FB configuration of GFR subjected to 0.25 g shaking at most periods, suggesting that the PFBR can be deployed at locations with seismic hazard much greater than that at Kalpakkam if suitable isolation systems are used.

Outcome of percutaneous coronary intervention using ultrathin-strut biodegradable polymer sirolimus-eluting versus thin-strut durable polymer zotarolimus-eluting stents in patients with comorbid peripheral arterial disease: a post-hoc analysis from two randomized trials.

In patients with peripheral arterial disease (PADs), who underwent percutaneous coronary intervention (PCI), little is known about the potential impact of using different new-generation drug-eluting stents (DES) on outcome. In PCI all-comers, the results of most between-stent comparisons-stratified by strut thickness-suggested some advantage of coronary stents with ultrathin-struts. The current post-hoc analysis aimed to assess outcomes of PCI with ultrathin-strut biodegradable polymer sirolimus-eluting stents (BP-SES) vs. thin-strut durable polymer zotarolimus-eluting stents (DP-ZES) in patients with PADs. We pooled 3-year patient-level data from two large-scale randomized all-comer trials to compare Orsiro ultrathin-strut BP-SES vs. Resolute-type thin-strut DP-ZES in trial participants with concomitant PADs. BIO-RESORT (December 2012 to August 2015) and BIONYX (October 2015 to December 2016) included all-comer patients who were aged 18 years or older, capable of providing informed consent, and required a PCI. The trials had web-based randomization, with block sizes of 4 and 8, performed in a 1:1:1 or 1:1 fashion. Assessors, research staff, and patients were blinded to the type of stent used. We assessed the composite main clinical endpoint target vessel failure [TVF: cardiac death, target vessel related myocardial infarction (MI), or clinically indicated target vessel revascularization (TVR)], its components, and stent thrombosis. Of 4,830 trial participants, 360 had PADs: 177 (49.2%) were treated with BP-SES and 183 (50.8%) with DP-ZES. Baseline characteristics were similar. For BP-SES, the 3-year TVF rate was 11.0% and for DP-ZES 17.9% [hazard ratio (HR): 0.59, 95% CI: 0.33-1.04; P=0.07]. For BP-SES, the TVR rate was lower than for DP-ZES (4.1% vs. 11.0%; HR: 0.36, 95% CI: 0.15-0.86; P=0.016), but this did not translate into between-group differences in cardiac death or MI. In small vessels (<2.75 mm), the TVR rate was also lower in BP-SES (5.6% vs. 13.9%; HR: 0.32, 95% CI: 0.11-0.91; P=0.024). Definite-or-probable stent thrombosis rates were 1.2% and 2.3% (P=0.43). In PCI patients with PADs, the 3-year TVF incidence was numerically lower in the ultrathin-strut BP-SES vs. the thin-strut DP-ZES group. Furthermore, TVR risk was significantly lower in ultrathin-strut BP-SES, mainly driven by a lower TVR rate in small vessels. BIO-RESORT trial: clinicaltrials.gov (NCT01674803); BIONYX trial: clinicaltrials.gov (NCT02508714).

Analysis of the effects of stent-induced deformation on the hemodynamics of MCA aneurysms

The use of a stent to coil an aneurysm can alter the position of the main blood vessel and affect blood flow within the sac. This study thoroughly examines the impact of stent-induced changes on the risk of MCA aneurysm rupture. The research aims to assess the effects of coiling and vessel deformation on blood flow dynamics by comparing the OSI, WSS, and blood structure of two distinct MCA aneurysms to identify high-risk areas for hemorrhage. Computational fluid dynamics is used to model blood flow. The results indicate that aneurysm deformation does not always decrease the risk of rupture, and coiling is more effective in occluding blood flow than aneurysm deformation.

Protected Loss-of-Flow Accident in a HLM Pool Facility: Long-Term Cooling Experiment

Since the 2000s, the development of Generation-IV fast reactors cooled by heavy liquid metals (HLMs) has been pursued by several research activities and projects, many of which are co-funded by the European Commission. One of the key points of HLMs regards their good neutronic and thermophysical properties, allowing for the of design cores with a high pitch-to-diameter ratio. In terms of passive safety, with a properly designed configuration, it is possible to increase the system capability to remove the decay power in a natural circulation regime, reducing active safety systems involvement. Such a safety-related aspect has been experimentally investigated at the ENEA Brasimone Research Center within the European Union co-funded Euratom H2020 SESAME project. An experimental campaign reproducing protected loss-of-flow accident (PLOFA) scenarios has been executed on CIRCE, a lead-bismuth eutectic-cooled pool-type facility reproducing in relevant scale the main components of HLM-cooled fast reactors. A test section named HERO has been installed in the CIRCE main vessel, hosting a double-wall bayonet tube steam generator scaled 1:1 in length with respect to the one envisioned for the ALFRED reactor. The tests reproduce the loss of primary coolant flow, while the power supplied by the heating source decreases according to a characteristic decay heat curve. The feedwater in the secondary system is regulated to operate the main steam generator as a decay heat removal (DHR) system. This paper presents the PLOFA transient reproducing the worst case, where the steam generator feedwater is suddenly stopped, simulating the full loss of the heat sink (no DHR). The main phenomena occurring during the transition from forced to natural circulation are presented and discussed. The experiment shows that, despite the loss of the forced circulation regime in the primary loop and the full loss of the heat sink, the entire system is still capable of operating safely, assuring an effective long-term cooling, as long as the thermal heat losses from the main vessel balance the decay power supplied by the heating source.

Experimental investigation on the heat transfer characteristics of argon space containing sodium vapor

A large quantity of argon is typically provided at the top of the main vessel of a sodium-cooled fast reactor (SFR) to serve as covering gas. The sodium coolant in an SFR evaporates and mixes with the argon covering gas during reactor operation. This mixed gas has a critical influence on the heat transfer at the top of the main vessel, particularly the temperature of the roof slab. The temperature distribution in the roof slab significantly affects reactor safety as it serves as the pressure boundary of the main vessel. Research on the behavior of sodium vapor has typically employed numerical simulations, and any experimental verifications have generally used simplified experimental models. To study the heat transfer characteristics of sodium vapor and eliminate the influence of simplifications on the results, the Heat transfer Experimental Facility for Argon space at the top of the main vessel (HEFA) was established based on a scaled-down top of the main vessel. The HEFA was employed to analyze influence of sodium vapor on the heat transfer characteristics of the reactor space by evaluating the effects of various heating temperatures with and without liquid sodium on the temperature distributions in the argon and roof slab. Furthermore, the emissivity of the liquid sodium surface was measured. The results show that the radiative absorption effect of sodium vapor primarily occurs near the liquid sodium surface. When the heating temperature was less than 400 °C, the presence of sodium vapor increased the temperature of the main vessel. When the heating temperature was 540 °C, the radiative absorption effect of the sodium vapor was enhanced, reducing the roof slab temperature. The observed phenomena can be considered to ensure reactor safety during the design of SFRs.

Robust vessel segmentation in laser speckle contrast images based on semi-weakly supervised learning

Objective. The goal of this study is to develop a robust semi-weakly supervised learning strategy for vessel segmentation in laser speckle contrast imaging (LSCI), addressing the challenges associated with the low signal-to-noise ratio, small vessel size, and irregular vascular aberration in diseased regions, while improving the performance and robustness of the segmentation method. Approach. For the training dataset, the healthy vascular images denoted as normal-vessel samples were manually labeled, while the diseased LSCI images involving tumor or embolism were denoted as abnormal-vessel samples and annotated as pseudo labels by the traditional semantic segmentation methods. In the training phase, the pseudo labels were constantly updated to improve the segmentation accuracy based on DeepLabv3+. Objective evaluation was conducted on the normal-vessel test set, while subjective evaluation was performed on the abnormal-vessel test set. Main results. The proposed method achieved an IOU of 0.8671, a Dice of 0.9288, and a mean relative percentage difference (mRPD) with supervised learning of 0.5% in the objective evaluation. In the subjective evaluation, our method significantly outperformed other methods in main vessel segmentation, tiny vessel segmentation, and blood vessel connection. Additionally, our method exhibited robustness when abnormal-vessel style noise was added to normal-vessel samples using a style translation network. Significance. The proposed semi-weakly supervised learning strategy demonstrates high efficiency and excellent robustness for vascular segmentation in LSCI, providing a potential tool for assessing the morphological and structural features of vessels in clinical applications.

STEMI patients receiving percutaneous coronary intervention for a culprit lesion with coronary artery bifurcation-efficacy and safety of the jailed semi-inflated balloon.

We aimed to evaluate the efficacy and safety of the 'jailed semi-inflated balloon technique' (JSIBT) for side branch (SB) protection in STEMI patients with a culprit lesion involving a coronary artery bifurcation while undergoing emergent percutaneous coronary intervention (PCI). We treated between Jan, 2011 and Jun, 2020, a total of 264 STEMI patients with a culprit lesion that involved a coronary artery bifurcation using primary PCI. In 30 patients, SB was protected by JSIBT (the JSIBT group). In 234 patients, SB was either protected or not protected by a placed wire (the non-JSIBT group). In both groups, after PCI procedure, TIMI flows of main vessel (MV) and SB were increased significantly compared with their measurements before the procedure. TIMI flows of post-procedural MV were similar between the two groups. In the JSIBT group, TIMI flows of SB both peri-procedure and post-procedure measurements were significantly greater than the non-JSIBT group. Despite a higher incidence of SB dissection in the JSIBT group, no inter-group difference was found in their total SB complications (like SB dissection, SB occlusion, wire entrapment or balloon rupture/entrapment). While JSIBT was an independent predictor for the SB TIMI 3 flow measured at the end of primary PCI, it was not an independent predictor for SB complications. The use of JSIBT as a method of SB protection during primary PCI not only provided better SB protection, but it also had a similar rate of SB complications compared with those with or without prior application of SB wire. This technique may be an effective method of protecting SB for STEMI patients involving coronary artery bifurcation and underwent emergent PCI.

Margination of platelet-sized particles in red blood cell suspensions flowing through a Y-shaped confluence microchannel

In blood flow through microvessels, platelets are known to be distributed in high concentrations near the vessel wall, termed ‘margination’ or ‘near-wall excess’. At the confluence of two vessels, this preferential distribution of platelets is thought to be compromised and reconstituted in the downstream main vessel. The present study aimed to investigate the distance of this margination reconstruction from the confluence by in vitro experiments using platelet-sized fluorescent particles as a platelet surrogate and a Y-shaped confluence microchannel with rectangular cross sections. Fluorescence microscopy was performed using a confocal laser scanning microscope system to measure the distribution of particles in the red blood cell suspension flow. Immediately after confluence, particles were highly concentrated along a narrow band in the middle of the channel width, where particles located near the inner wall of the daughter channels flowed in. This dense band of particles faded downstream and disappeared less than 5 mm from the confluence. This margination distance is comparable to or smaller than the margination development distance in straight channels, but much smaller than that after bifurcation.

BLOOD SUPPLING THE TESTICLES IN FERTILE PERIOD OF HUMAN’S LIFE

In work, the sources of blood supply to the testicle on the way to its moving from the abdominal cavity to the scrotum during the fertile period of a person were investigated. A comparative anatomical assessment of the blood supply to the testicles of some mammals in different periods of their sexual development is also provided. The functional disorders in the human endocrine system at the stages of puberty after the determination of blood hormones were described. On the basis of morphological studies carried out on fetus, variants of the departure of the testicular artery and percentage variants of branching of this artery on the trunk were established. As a result of the study, the largest increase in the diameter of the testicular artery up to 0.7 mm was determined from the 5th to the 7th month of the fertile period of a human’s life, as the variability of the angle of departure of the testicular arteria from the main vessel. Options for branching the testicular artery into distributive and mixed groups are also proposed. The detailed morphological study of the intra-organ bed of the testicle, as a tubular organ, as well as the vessels that blood to the organs surrounding the testicles: epididymes, vas deferens, provides results of the work. In the work, the effect of ligation vessels of the testicle, epididimes and vas deferens on the structure and function of the organs that provide blood supply, the author also investigated. In the course of the experiment, it was proven that cutting the testicular arteries in not sexually immature animals lends to greater destruction of the seminiferous tubules than their ligation in sexually mature animals. As a result of the experiment, the author proposed practical recommendations for operations on the testicles. In particular, to determine of the sectional level of the main feeding vessel responsibility to variants and groups of branching testicular arteries.

Evaluation of facial artery course variations, diameters, and depth by Doppler ultrasonography

The facial artery (FA) is the main blood vessel supplying blood to the face. It is essential to understand the anatomy of FA around the nasolabial fold (NLF). This study aimed to provide the detailed anatomy and relative positioning of FA to help avoid unexpected complications in plastic surgery. FA was observed from the inferior border of the mandible to the end of its terminal branch in 66 hemifaces of 33 patients with Doppler ultrasonography. The evaluation parameters were: (1) location, (2) diameter, (3) FA-skin depth, (4) relationship between the NLF and FA, (5) distance between the FA and significant surgical landmarks, and (6) the running layer. The FA course is classified based on the terminal branch. The most common FA course was Type 1, which had an angular branch as the final branch (59.1%). The most common FA-NLF relationship was that the FA was situated inferior to the NLF (50.0%). The mean FA diameter was 1.56±0.36mm at the mandibular origin, 1.40±0.37mm at the cheilion, and 1.32±0.34mm at the nasal ala. The FA diameter on the right hemiface was thicker than that on the left hemiface (p<0.05). The FA mainly terminates in the angular branch, running in the medial NLF and in dermis and subcutaneous tissue, with a blood supply advantage in the right hemisphere. We suppose that a deep injection into periosteum around the NLF may be safer than an injection into the superficial musculoaponeurotic system (SMAS) layer.

C54 ACUTE AND LONG TERM PERFORMANCE OF MAGMARIS BIORESORBABLE SCAFFOLD IMPLANTATION IN SPONTANEOUS CORONARY ARTERY DISSECTION (SCAD): THE EXPERIENCE OF THE COORDINATOR CENTER OF THE INTERNATIONAL MULTICENTER REGISTRY DISCO

Abstract Background Spontaneous Coronary Artery Dissection (SCAD) is a challenging clinical scenario and represents an increasingly studied cause of acute coronary syndrome (ACS). An interventional strategy in these cases remains controversial since it may require an extensive permanent metallic stenting of vessel to seal the dissection with a non negligible rate of complications. Moreover, SCAD patients are usually young women with non–calcified disease where Bioresorbable Scaffolds (BrS) may be an intriguing option. Methods DISCO IT/SPA is a International observational registry which retrospectively enrolled patients admitted with a diagnosis of SCAD across 26 Italian and Spanish centers. Baseline, procedural characteristics, in–hospital management and outcomes of 369 SCAD patients were collected, of these 12 patients were treated with PCI with BrS MAGMARIS at the coordinator center of Rivoli and Orbassano. Major cardiovascular events (MACEs) were defined as the composite of cardiovascular death, non–fatal Myocardial infarction (MIs) and any PCI performed. Results In our cohort of SCAD patients treated with BrS there was a slight prevalence of women (n=7, 58,3%) with an average age of 50,9±7,4 years. NSTE–ACS was the most common clinical presentation (83,3%), followed by STEMI (16,7%). In 7 patients the first treatment choice for SCAD was PCI with BrS deployment, in 5 patients BrS were deployed during hospitalization for unplanned PCIs (four of them) and after one month for a MI due to SCAD recurrence in the last patient. Multivessel disease was present only in one case and LAD–DG was the main vessel affected (n=10, 83,3%). SCAD type 2A was the most frequent (41,7%). Intravascular imaging was performed in 10 cases (83,3%) and procedural success was achieved in all cases. Angiographic follow–up was obtained in 9 patients (75%), through coronary angiogram (n=8) or CT scan (n=1), at a mean length of 5,2±5,6 months. In–hospital MACE were 5 (23,8%) but none of them occurred after BrS deployment. The only MACE reported after BrS deployment was an unplanned PCI for SCAD progression. Conclusions In SCAD bioresorbable scaffolds represent an excellent option to preserve the natural physiology of the coronary vessels. Notably, in our cohort we reported a very high procedural success rate in PCI assisted in large part by intracoronary imaging. Further studies with larger numerosity are needed to demonstrate the advantages of this type of scaffold in these patients.

An observational study assessing the use of Sirolimus-eluting balloons for side-branch treatment in the provisional stenting of coronary bifurcations

BackgroundDrug eluting balloons (DEB) are a feasible method of rapid delivery of drug to a coronary vessel wall. Their efficacy has been established for the treatment of in-stent restenosis and small vessel disease but there is limited data for their use in bifurcation lesions. ObjectiveThe aim of this study was to assess the effectiveness of provisional upfront side-branch DEB use in bifurcation lesions compared to a simple balloon (POBA) or upfront 2 stent bifurcation strategy. MethodsWe conducted an observational study of 625 patients undergoing PCI to bifurcation lesions. All the patients had a DES deployed in the main vessel (MV). Decision on revascularization option for the side branch (SB) was made by the operator. The primary endpoint was target vessel failure. Secondary endpoints were target vessel myocardial infarction and all-cause mortality. Results311 patients had upfront DEB to the SB whilst the remaining were treated with either DES (188) or POBA (126). Baseline characteristics were similar aside from history of previous MI, which were higher in patients treated with DES or POBA, p = 0.009 whereas patients with previous CABG were likely to undergo DEB treatment (p = 0.004). TVF was more likely to occur in the POBA group (7.5 %) compared to the DEB (3.3 %) and DES (3.3 %) groups (p = 0.0019). There was no significant difference in TV-MI (p = 0.62) or death (p = 0.98) between the groups. ConclusionThis study suggests that provisional bifurcation stenting with upfront Sirolimus DEB use in the SB is an effective treatment for non-LMS bifurcation PCI.

Diagnostic performance of angiography-derived fractional flow reserve analysis based on bifurcation fractal law for assessing hemodynamic significance of coronary stenosis.

Blood flow into the side branch affects the calculation of coronary angiography-derived fractional flow reserve (FFR), called Angio-FFR. Neglecting or improperly compensating for the side branch flow may decrease the diagnostic accuracy of Angio-FFR. This study aims to evaluate the diagnostic accuracy of a novel Angio-FFR analysis that considers the side branch flow based on the bifurcation fractal law. A one-dimensional reduced-order model based on the vessel segment was used to perform Angio-FFR analysis. The main epicardial coronary artery was divided into several segments according to the bifurcation nodes. Side branch flow was quantified using the bifurcation fractal law to correct the blood flow in each vessel segment. In order to verify the diagnostic performance of our Angio-FFR analysis, two other computational methods were taken as control groups: (i) FFR_s: FFR calculated by delineating the coronary artery tree to consider side branch flow, (ii) FFR_n: FFR calculated by just delineating the main epicardial coronary artery and neglecting the side branch flow. The analysis of 159 vessels from 119 patients showed that our Anio-FFR calculation method had comparable diagnostic accuracy to FFR_s and provided significantly higher diagnostic accuracy than that of FFR_n. In addition, using invasive FFR as a reference, the Pearson correlation coefficients of Angio-FFR and FFRs were 0.92 and 0.91, respectively, while that of FFR_n was only 0.85. Our Angio-FFR analysis has demonstrated good diagnostic performance in assessing the hemodynamic significance of coronary stenosis by using the bifurcation fractal law to compensate for side branch flow. Bifurcation fractal law can be used to compensate for side branch flow during the Angio-FFR calculation of the main epicardial vessel. Compensating for side branch flow can improve the ability of Angio-FFR to diagnose stenosis functional severity. • The bifurcation fractal law could accurately estimate the blood flow from the proximal main vessel into the main branch, thus compensating for the side branch flow. • Angiography-derived FFR based on the bifurcation fractal law is feasible to evaluate the target diseased coronary artery without delineating the side branch.

The 17th expert consensus document of the European Bifurcation Club - techniquesto preserve access to the side branch during stepwise provisional stenting.

Provisional stenting has become the default technique for the treatment of most coronary bifurcation lesions. However, the side branch (SB) can become compromised after main vessel (MV) stenting and restoring SB patency can be difficult in challenging anatomies. Angiographic and intracoronary imaging criteria can predict the risk of side branch closure and may encourage use of side branch protection strategies. These protective approaches provide strategies to avoid SB closure or overcome compromise following MV stenting, minimising periprocedural injury. In this article, we analyse the strategies of SB preservation discussed and developed during the most recent European Bifurcation Club (EBC) meetings.

B-16 | The RESOLUTE ONYX Bifurcation Study: 3-Year Outcomes in Patients With Coronary Bifurcation Lesions

Coronary bifurcation lesions are challenging to treat, with higher risk of procedural complications and adverse events than non-bifurcation lesions. In this study, we evaluated the 3-year clinical outcomes in patients with bifurcation lesions treated with the Resolute Onyx zotarolimus-eluting stent (ZES). Patients with a single bifurcation target lesion undergoing planned treatment using the provisional stenting technique were enrolled at 25 centers in the United States and Europe. Inclusion criteria included main branch reference vessel diameter (RVD) 2.25-5.0 mm, lesion length ≤35 mm, stenosis ≥50%, side branch ≥2.0 mm, and TIMI flow ≥2. The primary endpoint was target vessel failure (TVF) at 1-year. Follow-up was for 3 years. Between Apr 2017 to Dec 2019, 205 patients with 209 bifurcation lesions (of 267 total) were enrolled. Patients were 66.6 ± 10.7yrs, 21.5% female, 26.3% type II diabetic, 35.1% had previous PCI. Core lab analysis showed that 32.5% of lesions were true bifurcation lesions per Medina classification (1.1.1, 1.0.1, 0.1.1). Target vessel RVD was 2.65 ± 0.47 mm and lesion length was 17.03 ± 9.64 mm. 12.1% of patients had TVF through 3 years. There were no instances of stent thrombosis (Figure). Patients with coronary bifurcation lesions treated with the Resolute Onyx ZES had favorable long-term clinical outcomes at 3 years, with only 6% of target lesion revascularization and no cases of stent thrombosis. These results support the use of Resolute Onyx ZES to treat complex coronary bifurcation lesions using a planned provisional stenting technique, safely and effectively.

Design and Assessment of the New CIRCE-THETIS Facility for the Development of Heavy Liquid Metal Cooled Fast Reactors

Within the roadmap for the technological development of Generation IV reactors, the HORIZON2020 European Union–funded Partitioning And Transmuter Research Initiative in a Collaborative Innovation Action (PATRICIA) project was launched to support innovative solutions for the development of the Multi-purpose hYbrid Research Reactor for High-tech Applications (MYRRHA) accelerator-driven system concept and lead fast reactor technologies in general. The ENEA contributes to the project by involving the experimental infrastructures of the Brasimone Research Center (Italy). In particular, a large-scale pool-type facility named CIRColazione Eutettico (CIRCE), using lead-bismuth eutectic as the primary coolant and pressurized water as the secondary fluid, is under refurbishment with the implementation of a novel test section (TS) named Thermal-hydraulic HElical Tubes Innovative System (THETIS) to be installed in the CIRCE main vessel. The new TS will include a vertical mechanical pump for primary coolant circulation and a new prototypical helical coil steam generator (HCSG). This steam generator concept turns out to be very promising for nuclear power plants since the helical geometry is very compact and it assures high power removed, taking up a minimum amount of space. Accordingly, with the aims of the project, the experimental tests in CIRCE-THETIS will focus on (1) investigating the thermal-hydraulic behavior of the system in steady-state operation (forced circulation regime) during operational and accidental transients (postulated scenarios) and in a natural circulation regime considering as heat sink the HCSG (acting as a decay heat removal system) and the reactor vessel auxiliary cooling system in stand-alone or coupled operation and (2) characterizing the performance of the HCSG. The present work presents the layout of the CIRCE-THETIS facility at the end of the final design phase, describing in detail the main components of the TS, along with the instrumentation installed. Focus will be given to the HCSG mock-up, for which pretest analyses using the system thermal-hydraulic code RELAP5/Mod3.3 and a computational fluid dynamics code have been carried out to support the design of the component and to evaluate its thermal-hydraulic performance under the operative conditions foreseen during the experiments.

Quantifying Stent Wall Shear Stress for Assessing Stent and Flow Diverter Performance for Treating Intracranial Aneurysms

AbstractAnalysis of flow diverting intracranial aneurysm repair devices has traditionally focused on reducing intrasaccular blood flow velocity and aneurysm wall shear stress (WSS) as the primary metrics for improved perceived device performance. However, the interpretation of this data has been debated, particularly with regard to the specific biological benefits of high or low aneurysm WSS. Therefore, this research proposes an additional parameter of WSS at the stent struts that could provide valuable insight regarding the device's potential to promote occlusion at the aneurysm neck by indicating locations of increased platelet activation and microparticle shedding. Fluid flow effects were evaluated for two flow diverters (Pipeline™ and FRED™) and three stents (Enterprise™, Atlas™, and LVIS™) using computational fluid dynamics (CFD) models developed from two patient-derived CTA datasets with aneurysms in the middle cerebral artery (MCA) and basilar artery (BA), respectively. The device WSS data provides an additional metric for evaluating the ability of the device to constrain the blood flow within the main vessel, as well as indicating potential locations of the initiation of aneurysm occlusion. It is hypothesized that high device WSS close to the aneurysm neck creates a higher likelihood of thrombus formation and aneurysm occlusion due to platelet activation and microparticle shedding, while high device WSS proximal or distal on the device would indicate a higher likelihood of undesirable daughter vessel occlusion. Conversely, low-to-moderate device WSS throughout the device length could be interpreted as a reduced likelihood of complete occlusion of the aneurysm over time, resulting in lesser device performance.

Experimental study on convectional heat transfer characteristics of argon space in the pool-type fast reactor vessel

A large amount of sodium is used as coolant in the pool-type fast reactor, and argon is used as covering gas in the top part of main vessel. At the top of the main vessel, an annular cavity is formed between the rotating plug and its support, where natural convection of argon is formed. This kind of structure makes the heat transfer complicated at the top of main vessel. Excessive temperature or large temperature gradient at the top of main vessel may occur. Therefore, it is necessary to carry out analysis of the temperature distribution at the top of the main vessel. Many researches based on CFD have been carried out on the analysis of the top domain, but few of them are verified by experiment. In addition, a few experiments have been performed using simplified facility, which is not so similar to the real geometry. Therefore, a scaled-down Heat-transfer Experimental Facility for Argon space at the top of main vessel (HEFA) is established, which is much similar to the real geometry. In HEFA, the annular gap is kept, in addition, a heated stainless bottom plate is used to simulate the liquid sodium surface. Two conditions were set up, one for vacuum, the other for argon. The temperature of the facility was measured in the two conditions. By comparing the results of two condition, the results show that convection of the argon increases the overall temperature of the roof slab and reduces its temperature gradient of roof slab. The circumferential temperature difference at annular gap around rotating plug was observed in the argon condition. It is judged that the circumferential temperature difference is caused by natural convection in the annular gap with one side rising and the other falling. This phenomenon must be paid much attention in the design of SFR.