Intravascular Ultrasound in the Detection of Bridging Stent Graft Instability During Fenestrated and Branched Endovascular Aneurysm Repair Procedures: A Multicentre Study on 274 Target Vessels

Objective: The use of intravascular ultrasound (IVUS) reduces contrast medium use and radiation exposure during conventional endovascular aneurysm repair (EVAR). The aim of this study was to evaluate the safety and efficacy of IVUS in detecting bridging stent graft (bSG) instability during fenestrated and branched EVAR (F/B-EVAR). Methods: This was a prospective observational multicentre study. The following outcomes were evaluated: (1) technical success of the IVUS in each bSG, (2) IVUS findings compared with intra-operative angiography, (3) incidence of post-operative computed tomography angiography (CTA) findings not detected with IVUS, and (4) absence of IVUS related adverse events. Target visceral vessel (TVV) instability was defined as any branch or fenestration issues requiring an additional manoeuvre or re-intervention. Any IVUS assessment that detected stenosis, kinking, or any geometric TVV issue was considered to be branch instability. All procedures were performed in ad hoc hybrid rooms. Results: Eighty patients (69% males; median age 72 years; interquartile range 59, 77 years) from four aortic centres treated with F/B-EVAR between January 2019 and September 2021 were included: 70 BEVAR (21 off the shelf; 49 custom made), eight FEVAR (custom made), and two F/B-EVAR (custom made), for a total of 300 potential TVVs. Two TVVs (0.7%) were left unstented and excluded from the analysis. The TVVs could not be accessed with the IVUS catheter in seven cases (2.3%). Furthermore, 17 (5.7%) TVVs could not be examined due to a malfunction of the IVUS catheter. The technical success of the IVUS assessment was 91.9% (274/298), with no IVUS related adverse events. Seven TVVs (2.5%) showed signs of bSG instability by means of IVUS, leading to immediate revisions. The first post-operative CTA at least 30 days after the index procedure was available in 268 of the 274 TVVs originally assessed by IVUS. In seven of the 268 TVVs (2.6%) a re-intervention became necessary due to bSG instability. Conclusion: This study suggests that IVUS is a safe and potentially valuable adjunctive imaging technology for intra-operative detection of TVV instability. Further long term investigations on larger cohorts are required to validate these promising results and to compare IVUS with alternative technologies in terms of efficiency, radiation exposure, procedure time, and costs

Effects of Temperature and Mobile Phase Condition on Chiral Recognition of Poly(l-phenylalanine) Chiral Stationary Phase

Characteristics of the chiral stationary phase with poly(l-phenylalanine) peptide selector, which was in α-helical state, was reported. Since environmental factors affect peptide conformation, the changes in enantioselectivity were examined depending on column temperature and mobile phase conditions (ionic strength, pH, mobile phase composition). Column temperature and pH drastically affected the enantioselectivity. Based on these changes, the relation between chiral recognition and secondary structure of the peptide selector was discussed. The column stability during sequential analysis under different separation conditions was also evaluated

Documenting the Recovery of Vascular Services in European Centres Following the Initial COVID-19 Pandemic Peak: Results from a Multicentre Collaborative Study

Objective: To document the recovery of vascular services in Europe following the first COVID-19 pandemic peak. Methods: An online structured vascular service survey with repeated data entry between 23 March and 9 August 2020 was carried out. Unit level data were collected using repeated questionnaires addressing modifications to vascular services during the first peak (March – May 2020, “period 1”), and then again between May and June (“period 2”) and June and July 2020 (“period 3”). The duration of each period was similar. From 2 June, as reductions in cases began to be reported, centres were first asked if they were in a region still affected by rising cases, or if they had passed the peak of the first wave. These centres were asked additional questions about adaptations made to their standard pathways to permit elective surgery to resume. Results: The impact of the pandemic continued to be felt well after countries’ first peak was thought to have passed in 2020. Aneurysm screening had not returned to normal in 21.7% of centres. Carotid surgery was still offered on a case by case basis in 33.8% of centres, and only 52.9% of centres had returned to their normal aneurysm threshold for surgery. Half of centres (49.4%) believed their management of lower limb ischaemia continued to be negatively affected by the pandemic. Reduced operating theatre capacity continued in 45.5% of centres. Twenty per cent of responding centres documented a backlog of at least 20 aortic repairs. At least one negative swab and 14 days of isolation were the most common strategies used for permitting safe elective surgery to recommence. Conclusion: Centres reported a broad return of services approaching pre-pandemic “normal” by July 2020. Many introduced protocols to manage peri-operative COVID-19 risk. Backlogs in cases were reported for all major vascular surgeries

Structure and dynamics of Penetratin’s association and translocation to a lipid bilayer

Penetratin belongs to the important class of small and positively charged peptides, capable of entering cells. The determination of the optimal peptidic structure for translocation is challenging; results obtained so far are varied and dependent on several factors. In this work, we review the dynamics of association of Penetratin with a modeled dioleoyl-phosphatidylcholine (DOPC) lipid membrane using molecular dynamics simulations with last generation force fields. Penetratin’s structural preferences are determined using a Markov state model. It is observed that the peptide retains a helical form in the membrane associated state, just as in water, with the exception of both termini which lose helicity, facilitating the interaction of terminal residues with the phosphate groups on the membrane’s outer layer. The optimal orientation for insertion is found to be with the peptide’s axis forming a small angle with the interface, and with R1 stretching toward the bilayer. The interaction between arginine side-chains and phosphate groups is found to be greater than the corresponding to lysine, mainly due to a higher number of hydrogen bonds between them. The free energy profile of translocation is qualitatively studied using Umbrella Sampling. It is found that there are different paths of penetration, that greatly differ in size of free energy barrier. The lowest path is compatible with residues R10 to K13 leading the way through the membrane and pulling the rest of the peptide. When the other side is reached, the C-terminus overtakes those residues, and finally breaks out of the membrane. The peptide’s secondary structure during this traversal suffers some changes with respect to the association structure but, overall, conserves its helicity, with both termini in a more disordered state

Retrograde Totally Endovascular Recanalization of Occluded Mesenteric Arteries Through the Pancreaticoduodenal Arcade

: Introduction: Failed antegrade endovascular recanalization of occluded mesenteric arteries has traditionally been dealt with by open mesenteric bypass or by hybrid solutions. This article describes a totally endovascular retrograde approach for recanalization of occluded mesenteric arteries through the pancreaticoduodenal arcade. Surgical technique: A femoral or brachial approach is used to gain access to the patent visceral artery. A micro-catheter is advanced in a retrograde fashion into the distal main stem of the occluded artery through the gastroduodenal artery and inferior pancreaticoduodenal arcade. A combination of .014″ and .018″ wires is used to cross the occlusion in a retrograde fashion and to land into the aortic lumen. The guide wire is then snared through the brachial access, establishing a through and through wire. A micro-catheter is then advanced on the through and through wire across the occlusion from the brachial access. The distal occluded artery is then catheterized by advancing a second wire parallel to the through and through wire. The remaining procedure is performed as a standard antegrade approach. Discussion: The totally endovascular retrograde approach through collaterals can be helpful for the recanalization of mesenteric artery occlusions. This technically complex procedure should be reserved for cases in which the traditional antegrade approach has failed. Keywords: Superior mesenteric artery, Endovascular, Celiac artery/trunk, Retrograde approach, Chronic total occlusio