Conical Necks Research Articles

Conical Aortic Neck as a Predictor of Outcome after Endovascular Aneurysm Exclusion: Midterm Results

Conical neck may affect endovascular aneurysm repair (EVAR) outcomes. The aim of this study was to present EVAR neck adverse events [endoleak type Ia (ET Ia) and graft migration], in patients with conical neck morphology compared to patients with non-conical necks. An additional analysis of the factors that may affect neck adverse events in patients with conical necks, during the first postoperative year, was executed. A retrospective analysis of prospective data was conducted, including patients that underwent elective EVAR, between 2017 and 2019. All patients completed the clinical and imaging follow-up of the initial 12months. Regarding imaging, all cases underwent computed tomography angiography (CTA), preoperatively, at the 1st and 12th month of follow-up. Preoperative and postoperative aneurysm anatomic characteristics (supra-renal and infra-renal aortic diameters, aneurysm diameter, neck angle, thrombus, and calcification) were recorded. Proximal neck was defined as the infrarenal aortic segment, with a diameter less than 30mm. Conical neck was any neck with a diameter increase ≥2mm per cm of length (from outer-to-outer aortic wall). The proximal 15mm of the neck length were considered the zone of endograft sealing. Migration was any ≥10mm caudal movement of the endograft, relative to its position detected at the CTA of the first month. Neck adverse events were defined as the composite event of ET Ia and migration. The cohort included 150 patients; 66 (44%) presented conical neck morphology. No significant difference was detected regarding the preoperative anatomic characteristics between the conical and non-conical groups. Only distal (15mm) neck diameter was wider in the conical group (P<0.001). Supra-renal active fixation was used in 63.3% of the total cohort; 59.5% in patients with non-conical necks and 68.2% in patients with conical morphology (P=0.275). Graft oversizing was 18.2% and 18.7% in the non-conical and conical group, respectively (P=0.248). Oversizing >20% was equal between groups [37.8% vs. 33.3%% (P=0.608) while oversizing ≥30% was more common among patients with conical necks (3.5% vs. 10.6%, P<0.001, 3.2 odds ratio, 95% confidence interval: 0.79, 12.91). Regarding ET Ia and migration, no difference was recorded between the groups. In a subanalysis among patients with conical necks, a lower graft migration rate was detected among patients with higher oversizing rate (P=0.037). EVAR may offer similarly good midterm outcomes in patients with conical and non-conical neck anatomy. An oversizing to the higher suggested rate may be preventive of graft migration during the first postoperative year in necks with conical morphology. Aggressive oversizing (>20%) do not offer any benefit regarding the prevention of adverse events among patients with conical necks.

Long-Term Outcomes of Open and Endovascular Abdominal Aortic Repair in Younger Patients

Aim of this study is to evaluate long-term results in abdominal aortic aneurysm (AAA) surgery by either open aortic repair (OAR) or endovascular aortic repair (EVAR) in patients under 70years of age. A retrospective analysis of a prospectively collected database of patients with age under 70years old undergoing elective infrarenal AAA surgery between 2010 and 2018 was performed. The study population was divided into 2 groups: OAR and EVAR. Primary end points were overall survival and aneurysm-related death, while secondary outcomes were need for reintervention and development of minor and major complications. One hundred ninety-one patients younger than 70years old treated with elective AAA surgery were enrolled: 157 OAR (98% males, mean age 65±4years) and 34 EVAR (94% males, mean age 66±4years). Hospital stay, 30-day mortality, and need for reintervention were similar; OAR population presented higher incidence of postoperative major complications (18% vs. 2.9%; P = 0.01) while minor complications were 32% in the OAR versus 21% in the EVAR group (P = 0.08). Median follow-up was 69months for OAR (interquartile range [IQR] 53months) vs. 79months (IQR 51months) for EVAR (P = 0.9): long-term AAA-related reinterventions were more frequent after EVAR (1.9% OAR vs. 17% EVAR; P = 0.01) while AAA-related long-term mortality was similar in both subgroups (1.3% OAR and 3% EVAR; P = 0.8). At univariate analysis higher risk of reintervention was reported for conical necks in the EVAR group (P = 0.03) and for the concomitant presence of iliac aneurysms in both groups (P = 0.01). According to our data, EVAR in young patients is presenting an excessive rate of reintervention compared to OAR. The presence of conical neck is an independent predictor of EVAR failure and late reintervention, while it does not play a significant role in the OAR group. Open surgery should be considered the first option in younger patients with a long-life expectancy.

Calculation and experimental analysis of heat transfer of assemblies of ribbed heat exchange elements

The results of thermal-hydraulic and strength tests of finned tube assemblies welded from KP 20 elements of four sizes are presented. The elements are representing by steel plate 0.4 mm in thickness, covered with a copper film 0.025 mm in thickness. One or two conical necks 17 mm long are extended in the plates. A set of placed in each other cones form a welded finned tube 23/20 mm with a toothed inner surface. As a result of the tests: high strength characteristics of these assemblies were demonstrated (internal pressure of burst under normal conditions is 40 MPa, resistance to sudden changes in temperature and freezing of water in “pipes”); a high average coefficient of thermal conductivity in the thickness of the ribs was confirmed at the level of 75 W/(m×K); the increase in the intensity of the heat transfer process is 2.15 times with the help of technological protrusions on the inner surface of the “pipe” to a turbulent single-phase flow in comparison with the calculated values for “smooth” pipes with a moderate increase in hydraulic resistance; the method of heat-hydraulic calculation of heat exchangers consisting of such “pipes” is proposed. The method is based on the ratios set out in the regulatory document “RD 24.035.05-89”. Thermal and hydraulic calculation of NPP heat exchanging equipment”, with amendments considering the high degree of finning of the tested “pipes” and the asymmetry of the edges of the ribs relative to the axis of the “pipes” bearing pressure, as well as the change in the value of the correction for the smallness of the tube bundle — we also identified areas of effective use of assemblies tested sizes of elements KP 20.

Predictors of Aneurysm Sac Shrinkage Utilizing a Global Registry

Aneurysm sac remodeling is a complex multifactorial process with unknown factors influencing sac regression after endovascular aortic aneurysm repair (EVAR). We sought to identify factors associated with this process by analyzing data obtained from patients treated with the GORE EXCLUDER endovascular aneurysm repair (EVAR) endoprosthesis from December 2010 to October 2016 enrolled in the Global Registry for Endovascular Aortic Treatment (GREAT). All patients enrolled in GREAT with three years CT angiography (CTA) follow-up in each of the three successive years after EVAR were included. The percentage of sac size reduction toward device diameter was calculated and used as a surrogate for sac regression with the formula used being: sac size reduction = ((AAA baseline diameter - AAA diameter at follow-up)/(AAA baseline diameter - device diameter))∗100. The cohort was divided into two groups in accordance with the percentage of aneurysm sac reduction at three years; one with the top quartile of patients and the other with the lowest three quartiles. Demographic and procedural variables were analyzed using univariate and regression modeling to determine factors predictive of sac regression. There were 3265 subjects enrolled with follow-up as of May 2018 of which 526 (16.2%) had three years of CTA surveillance. Overall aneurysm sac size decreased from a mean of 58.0mm (Std Dev: 10.4, range: 34.2, 100.0) to a mean of 49.3mm (Std Dev: 14.1, range: 0, 140) for a percentage reduction toward device diameter of a mean 28.2% (Std Dev: 39.0, range: -103.7, 183.9). On multivariate logistic regression model; two factors proved to be statistically significant contributors to a larger percentage reduction in aneurysm sac: a conical neck (odds ratio [OR]=1.64, P-value=0.023) and a larger proximal device diameter (OR=1.09, P-value=0.023). On the other hand, two factors were negative predictors of sac shrinkage, namely: old age (OR=0.96, P-value=0.002) and larger baseline aneurysm sac diameter (OR=0.98, P-value=0.028). Aneurysms with conical necks and larger proximal device neck diameters have an increased percentage change in sac size over time after EVAR. Older age and larger initial diameters of aneurysms were negatively associated with percentage change in sac size as well as sac regression. Further study is needed to determine the clinical utility of these observations and applicability across multiple endoprosthesis platforms.

Lipid exchange enhances geometric pinning in multicomponent membranes on patterned substrates.

Experiments on supported lipid bilayers featuring liquid ordered/disordered domains have shown that the spatial arrangement of the lipid domains and their chemical composition are strongly affected by the curvature of the substrate. Furthermore, theoretical predictions suggest that both these effects are intimately related with the closed topology of the bilayer. In this work, we test this hypothesis by fabricating supported membranes consisting of colloidal particles of various shapes lying on a flat substrate. A single lipid bilayer coats both colloids and substrate, allowing local lipid exchange between them, thus rendering the system thermodynamically open, i.e. able to exchange heat and molecules with an external reservoir in the neighborhood of the colloid. By reconstructing the Gibbs phase diagram for this system, we demonstrate that the free-energy landscape is directly influenced by the geometry of the colloid. In addition, we find that local lipid exchange enhances the pinning of the liquid disordered phase in highly curved regions. This allows us to provide estimates of the bending moduli difference of the domains. Finally, by combining experimental and numerical data, we forecast the outcome of possible experiments on catenoidal and conical necks and show that these geometries could greatly improve the precision of the current estimates of the bending moduli.

Acoustic performance analysis of Helmholtz resonators with conical necks and its application

The acoustic properties of the Helmholtz resonators with conical necks, which have broad acoustic attenuation band performance in the low frequency range, are investigated in this study. In order to investigate its wide-band acoustic attenuation mechanism, three-dimensional finite element models for the Helmholtz resonators with different necks are built respectively. The acoustic performance prediction model based on the one-dimensional analytical approach with acoustic length corrections is built to calculate the transmission loss results more efficiently, and the formula for calculating the resonance frequency is also derived. Then, the prediction model and the formula are verified by finite element method and experiment, which show good agreements. As a result, the prediction model is applied to analyze the sound attenuation properties of the Helmholtz resonators with conical necks, and the results show that the acoustic attenuation bandwidth in the low frequency range is improved by increasing the taper angle of the neck. At last, the approaches for the Helmholtz resonators with conical necks are applied to design an actual middle silencer of a passenger car. The results show that the designed middle silencer performs much better than the original one, which can effectively eliminate the exhaust order noise to meet the standard of exhaust noise control. The test results fully reveal that the Helmholtz resonators with conical necks in the muffler can play a better role in eliminating exhaust order noise, and the approaches proposed in this article can effectively guide the design of Helmholtz resonators with conical necks.

Expanded Suitability of Ruptured Abdominal Aortic Aneurysms for Total Endovascular Repair Using the Endurant Endograft and Heli-FX EndoAnchors

Purpose: To assess if the suitability of endovascular aneurysm repair (EVAR) of ruptured abdominal aortic aneurysms (RAAAs) can be expanded by combining the Endurant stent-graft with the Heli-FX EndoAnchors. Materials and Methods: Contrast-enhanced computed tomography (CT) scans of 90 patients (mean age 73.2±9 years; 87 men) with RAAA admitted between January 2014 and January 2018 in 2 tertiary care centers were analyzed in a 3-dimensional workstation. Anatomical features of the aneurysms according to the instructions for use (IFU) for the Endurant endograft were evaluated and expansion of treatment with Heli-FX EndoAnchors was assessed. Results: Neck length <10 mm was present in 41 (45.6%) patients; 5 had neck diameters outside the IFU and 45 (50.0%) had conical necks. Thrombus and calcium were absent in 63 (70.0%) and 73 (81.1%), respectively. In the study cohort, 44 (48.9%) patients met all the neck criteria, although overall IFU compliance was found in only 35 (38.9%) patients due to iliac-related issues in 21 patients. The adjunctive use of EndoAnchors in the entire study group would enhance the therapeutic range to an additional 24 patients, 8 of whom would need an associated iliac procedure. This represents an expansion of the total EVAR approach from 48.9% to 75.6% of cases if some iliac issues are overcome and from 38.9% to 56.7% without correcting iliac deficiencies. Conclusion: The main reason of being unfit for endovascular treatment in this series was neck length <10 mm. Based on this analysis, nearly 40% of RAAA patients would have been candidates for EVAR based on the IFU neck criteria for the Endurant stent-graft. This suitability could be nearly doubled with the use of EndoAnchors and correction of unsuitable iliac anatomy. The use of EndoAnchors has the potential to offer a significant benefit in the endovascular treatment of RAAA patients.

Sexual morph of Phaeoacremonium aureum from Rhizophora mucronata collected in southern Thailand

Sexual morph of Phaeoacremonium aureum was collected from a mangrove in Krabi Province, southern Thailand. It was linked to P. aureum based on the analysis of sequence data. The sexual morph is characterized by ascomata with relatively long conical necks and suballantoid to oblong, slightly curved ascospores, with rounded ends and small guttules at each end. Sexual morph of P. aureum differs from other species of Phaeoacremonium by having ascomata with relatively long (300–380 μm) conical necks and being saprobic on Rhizophora mucronata. This is the first record of Phaeoacremonium species from a mangrove habitat. We also provide a key to sexual morphs of Phaeoacremonium species.

Advanced endografting techniques: snorkels, chimneys, periscopes, fenestrations, and branched endografts.

The anatomy of aortic aneurysms from the proximal neck to the access vessels may create technical challenges for endovascular repair. Upwards of 30% of patients with abdominal aortic aneurysms (AAA) have unsuitable proximal neck morphology for endovascular repair. Anatomies considered unsuitable for conventional infrarenal stent grafting include short or absent necks, angulated necks, conical necks, or large necks exceeding size availability for current stent grafts. A number of advanced endovascular techniques and devices have been developed to circumvent these challenges, each with unique advantages and disadvantages. These include snorkeling procedures such as chimneys, periscopes, and sandwich techniques; "homemade" or "back-table" fenestrated endografts as well as manufactured, customized fenestrated endografts; and more recently, physician modified branched devices. Furthermore, new devices in the pipeline under investigation, such as "off-the-shelf" fenestrated stent grafts, branched stent grafts, lower profile devices, and novel sealing designs, have the potential of solving many of the aforementioned problems. The treatment of aortic aneurysms continues to evolve, further expanding the population of patients that can be treated with an endovascular approach. As the technology grows so do the number of challenging aortic anatomies that endovascular specialists take on, further pushing the envelope in the arena of aortic repair.

Building 3D anatomical model of coiling of the internal carotid artery derived from CT angiographic data.

The purpose of this study is to recreate live patient arterial anomalies using new recent application of three-dimensional (3D) printed anatomical models. Another purpose of building such models is to evaluate the effectiveness of angiographic data. With the help of the DICOM files from computed tomographic angiography (CT-A), we were able to build a printed model of variant course of the internal carotid artery (ICA). Images of coiling of the ICA taken by CT-A, were then converted into 3D images using Google SketchUp free software, and the images were saved in stereolithography format. Imaging helped us conduct the examination in details with reference to geometrical features of ICA, degree of curve, its extension, location and presence of loop. Challenging vascular anatomy was exposed with models of adverse curve of carotid anatomy, including highly angulated necks, conical necks, short necks, tortuous carotid arteries, and narrowed carotid lumens. It assisted us to comprehend spatial anatomy configuration of life-like models. 3D model can be very effective in cases when anatomical difficulties are detected through the CT-A, and therefore, a tactile approach is demanded preoperatively. 3D life-like models serve as an essential office-based tool in vascular surgery as they assist surgeons in preoperative planning, develop intraoperative guidance, teach both the patients and the surgical trainees, and simulate to show patient-specific procedures in medical field.

A Pilot Study Assessing the Impact of 3-D Printed Models of Aortic Aneurysms on Management Decisions in EVAR Planning.

Endovascular repair of aortic aneurysms with difficult anatomy is challenging. There is no consensus for planning such procedures. Six cases of aortic aneurysms with challenging anatomical features, such as short, angulated, and conical necks and tortuous iliacs were harvested. The computed tomography (CT) scans were anonymized. Lifesize 3-dimensional (3-D) printed models were created of the lumen. Endovascular operators were asked to review the CT angiography (CTA), make a management plan, and give an indication of their confidence. They were then presented with the equivalent model and asked to review their decision. Their attitudes to such models were briefly surveyed. A total of 28 endovascular operators reviewed 144 cases. After review of the physical model, the management plan changed in 29 (20.1%) of 144 cases. Initial plan after CTA review was endovascular 73.6%, open repair 22.9%, and second opinion 3.5%. After model review, this became endovascular 67.4%, open repair 19.4%, and second opinion 4.8%. Although the general trend was toward more open procedures, off-label techniques reduced from 19.4% to 15.2% following model review. When the management plan did not change, level of confidence did increase in 37 (43.5%) of 85 cases. The majority of operators stated that they would find models useful for planning in some procedures. For 1 case, the change in the percentage of participants being sure in the management plan was statistically significant (P = .031). The 3-D printed models may be potentially useful in planning cases with EVAR. It is a paradigm that warrants further investigation.

Abstract No. 210: Outcomes of EVAR in Patients with Conical Necks

Abstract No. 210: Outcomes of EVAR in Patients with Conical Necks

Improving Endograft Stability by Accommodation onto the Aortic Bifurcation

To report the technique for deploying a 3-part endovascular graft onto the native aortic bifurcation for greater stent-graft stability. The Zenith Composite Endovascular Graft is a 3-part system consisting of a proximal tubular body with an uncovered Gianturco Z stent, a distal bifurcated body, and a contralateral leg. Proximally, 8-mm flexible interstent gaps facilitate precise infrarenal aortic placement, even in angulated necks. Technically, the bifurcated part is deployed first and pulled down to the aortic bifurcation, while the tubular main body and contralateral leg deployment follow. Using this technique to accommodate the graft onto the natural aortic bifurcation, distal stability can be enhanced and graft migration minimized. The Composite configuration can be an alternative to ensure a higher security index in difficult anatomies. It may be beneficial in patients with short (10-15 mm), angulated (>60 degrees ), or conical necks and deserves investigation in these patient populations.

Fenestrae in golgi and endoplasmic reticulum cisternae of human brain tumours

Fenestrae were found in freeze-fractured cisternae of the Golgi apparatus and endoplasmic reticulum of glioblastoma, oligodendroglioma, ependymoma, medulloblastoma, medulloepithelioma, meningioma, cerebellar sarcoma, hemangioblastoma, and chromophobe adenoma. They were about 200--400 A in diameter and often diffusely distributed or concentrated in groups in Golgi cisternae, while they were around 300--600 A in size and scattered in distribution in cisternae of endoplasmic reticulum. They appeared as conical protrusions or circular broken-off necks of face A and as circular holes on face B in tangential fractures, and as several constrictions of cisternae in cross fractures.