Endovascular aortic repair of a chronic ascending and arch aortic aneurysm

International audienc

Systematic review of native and graft-related aortic infection outcome managed with orthotopic xenopericardial grafts

International audienceObjective: Limited data are available on the use of xenopericardium in the treatment of native and graft-related aortic infections. The aim of this review was to assess outcomes of neoaortic reconstruction using xenopericardium in this challenging group of patients.Methods: Studies involving xenopericardial graft reconstruction to treat native and aortic graft infections were systematically searched and reviewed (Embase, Medline, and Cochrane databases) for the period of January 2007 to December 2017.Results: A total of 4 studies describing 71 patients treated for aortic graft (n = 54) and native aortic (n = 17) infections were included; 25 patients (35%) were operated on in an acute setting. The technical success rate was 100%. The mean 30-day mortality was 25% (range, 7.7%-31%). Only one death (1.4%) was linked to the operator-made pericardial tube graft (acute postoperative bleeding from proximal anastomosis). Septic multiorgan failure was the most common cause of perioperative death (72% [13/18]). Among the 53 patients who survived, only 3 presented with recurrent infection (5.7%), so 70.4% of patients were alive after intervention without evidence of infection (50/71). During follow-up, 2 false aneurysms (3.7% [2/53]), 1 early rupture (1.4% [1/71]), and 2 cases (3.7% [2/53]) of late rupture were reported. Other causes of late deaths unrelated to the aortic xenopericardial repair were not reported in the different series. The early reintervention rate was 1.4% (1/71), treated by open repair for rupture. The late reintervention rate was 7.5% (4/53) with thoracic endovascular aortic repair in three patients (one false aneurysm and two ruptures) and open repair in one patient (one false aneurysm). There were no cases of early or late graft thrombosis. One-year mortality rate was 38% but only 4.2% were related to the aortic repair using orthotopic xenopericardium (one early and two late ruptures).Conclusions: These data confirm the high morbidity of native and graft-related aortic infections and provide insight into the results of orthotopic xenografts as a treatment alternative. Larger series and longer follow-up will be required to compare the role of operator-made pericardial tube graft with other treatment options in infected fields

Double homemade fenestrated stent graft for total endovascular aortic arch repair.

International audienceThe aim of this retrospective analysis was to evaluate the outcomes of physician-modified double fenestrated stent grafts for total endovascular aortic arch repair: one proximal large fenestration for the brachiocephalic trunk and the left common carotid artery and one distal fenestration for the left subclavian artery (LSA)

In situ revascularization with silver-coated polyester grafts to treat aortic infection: early and midterm results

AbstractPurposeIn this prospective study we analyzed the immediate and midterm outcome in patients with abdominal aorta infection (mycotic aneurysm, prosthetic graft infection) managed by excision of the aneurysm or the infected vascular prosthesis and in situ replacement with a silver-coated polyester prosthesis.MethodsFrom January 2000 to December 2001, 27 consecutive patients (25 men, 2 women; mean age, 69 years) with an abdominal aortic infection were entered in the study at seven participating centers. Infection was managed with either total (n = 18) or partial (n = 6) excision of the infected aorta and in situ reconstruction with an InterGard Silver (IGS) collagen and silver acetate–coated polyester graft. Assessment of outcome was based on survival, limb salvage, persistent or recurrent infection, and prosthetic graft patency.ResultsTwenty-four patients had prosthetic graft infections, graft–duodenal fistula in 12 and graft-colonic fistula in 1; and the remaining 3 patients had primary aortic infections. Most organisms cultured were of low virulence. The IGS prosthesis was placed emergently in 11 patients (41%). Mean follow-up was 16.5 months (range, 3-30 months). Perioperative mortality was 15%; all four patients who died had a prosthetic graft infection. Actuarial survival at 24 months was 85%. No major amputations were noted in this series. Recurrent infection developed in only one patient (3.7%). Postoperative antibiotic therapy did not exceed 3 months, except in one patient. No incidence of prosthetic graft thrombosis was noted during follow-up.ConclusionPreliminary results in this small series demonstrate favorable outcome with IGS grafts used to treat infection in abdominal aortic grafts and aneurysms caused by organisms with low virulence. Larger series and longer follow-up will be required to compare the role of IGS grafts with other treatment options in infected fields

Silver eel downstream migration in fragmented rivers: use of a Bayesian model to track movements triggering and duration

Obstacles in rivers are considered to be one of the main threats to diadromous fish. As a result of the recent collapse of the European eel, the European Commission introduced a Regulation, requiring to reduce all sources of anthropogenic mortality, including those caused by passing through hydropower turbines. Improving knowledge about migration triggers and processes is crucial to assess and mitigate the impact of obstacles. In our study, we tracked 97 tagged silver eels in a fragmented river situated in the Western France (the River Dronne). Using the movement ecology framework, and implementing a Bayesian state-space model, we confirmed the influence of river discharge on migration triggering and he distance travelled by fish. We also demonstrated that, in our studied area, there is a small window of opportunity for migration. Moreover, we found that obstacles have a significant impact on distance travelled. Combined with the small window, this suggests that assessment of obstacles impact on downstream migration should not be limited to quantifying mortality at hydroelectric facilities, but should also consider the delay induced by obstacles, and its effects on escapement. The study also suggests that temporary turbines shutdown may mitigate the impacts of hydropower facilities in rivers with migration process similar to those observed here

Efficiency of fish-friendly intakes, bypasses associated with low bar-spacing trashracks, for downstream migration of Atlantic salmon smolts

Lessons learned about the efficiency of fish-friendly water intakes at 4 power plants in France

Photosynthetic growth despite a broken Q-cycle

Central in respiration or photosynthesis, the cytochrome bc1 and b6f complexes are regarded as functionally similar quinol oxidoreductases. They both catalyse a redox loop, the Q-cycle, which couples electron and proton transfer. This loop involves a bifurcated electron transfer step considered as being mechanistically mandatory, making the Q-cycle indispensable for growth. Attempts to falsify this paradigm in the case of cytochrome bc1 have failed. The rapid proteolytic degradation of b6f complexes bearing mutations aimed at hindering the Q-cycle has precluded so far the experimental assessment of this model in the photosynthetic chain. Here we combine mutations in Chlamydomonas that inactivate the redox loop but preserve high accumulation levels of b6f complexes. The oxidoreductase activity of these crippled complexes is sufficient to sustain photosynthetic growth, which demonstrates that the Q-cycle is dispensable for oxygenic photosynthesis

Ultrafast Dynamics of the Photo-Excited Hemes b and cn in the Cytochrome b6f Complex

The dynamics of the heme b and cn within the cytochrome b6f complex are investigated by means of ultrafast broad-band transient absorption spectroscopy. On one hand, the data reveals that, subsequent to visible light excitation, part of the b hemes undergo a pulse limited photo-oxidation, with the liberated electron supposedly being admited in one of the adjacent aromatic amino acid. The photo-oxidation is followed by a charge recombination in about 8.2 ps. Subsequent to the charge recombination, the heme is promoted to an vibrationally excited ground state that relaxes in about 4.6 ps. On the other hand, the heme cn undergoes an ultrafast ground state recovery in about 140 fs. Interestingly, the data also shows that, contrarely to previous beliefs, Chl a is involved in the hemes photochemistry. Indeed, subsequently to the hemes excitation, the Chl a bleaches and recovers its ground state in 90 fs and 650 fs, respectively. The Chl a bleaching allegedly corresponds to the formation of a short lived Chl a anion. Beyond the previously suggested structural role, this study gives unique evidences that Chl a is directly involved in the photochemistry of the hemes

A Map of Dielectric Heterogeneity in a Membrane Protein: the Hetero-Oligomeric Cytochrome b 6 f Complex

The cytochrome b6f complex, a member of the cytochrome bc family that mediates energy transduction in photosynthetic and respiratory membranes, is a hetero-oligomeric complex that utilizes two pairs of b-hemes in a symmetric dimer to accomplish trans-membrane electron transfer, quinone oxidation–reduction, and generation of a proton electrochemical potential. Analysis of electron storage in this pathway, utilizing simultaneous measurement of heme reduction, and of circular dichroism (CD) spectra, to assay heme–heme interactions, implies a heterogeneous distribution of the dielectric constants that mediate electrostatic interactions between the four hemes in the complex. Crystallographic information was used to determine the identity of the interacting hemes. The Soret band CD signal is dominated by excitonic interaction between the intramonomer b-hemes, bn and bp, on the electrochemically negative and positive sides of the complex. Kinetic data imply that the most probable pathway for transfer of the two electrons needed for quinone oxidation–reduction utilizes this intramonomer heme pair, contradicting the expectation based on heme redox potentials and thermodynamics, that the two higher potential hemes bn on different monomers would be preferentially reduced. Energetically preferred intramonomer electron storage of electrons on the intramonomer b-hemes is found to require heterogeneity of interheme dielectric constants. Relative to the medium separating the two higher potential hemes bn, a relatively large dielectric constant must exist between the intramonomer b-hemes, allowing a smaller electrostatic repulsion between the reduced hemes. Heterogeneity of dielectric constants is an additional structure–function parameter of membrane protein complexes