Arteriovenous fistula creation with VasQTM device: A feasibility study to reveal hemodynamic implications.

BACKGROUND: Arteriovenous fistula (AVF) is the preferred vascular access (VA) for hemodialysis, but it is still affected by high non-maturation and early failure rates due to stenosis development. Increasing evidence suggests that the presence of turbulent-like flow may play a key role, therefore, to stabilize the flow in the venous segment, an external support device (VasQTM) has been designed. The aim of this study was to provide preliminary evidence of VasQTM impact on AVF hemodynamics as compared to AVFs created with conventional surgery. METHODS: In this pilot single-center prospective randomized study six patients were enrolled, three in the VasQ group and three in the control group. Contrast-free magnetic resonance imaging (MRI) scans were acquired at 3 days, 3 months and 1 year after AVF surgery and were used to generate 3D patient-specific models. Computational fluid dynamic (CFD) simulations were performed using pimpleFoam, imposing patient-specific flow waveforms derived from ultrasound (US) examinations at the inlet of the proximal and distal artery, and a traction-free condition at the venous outflow. Morphologic and hemodynamic changes occurring over time were compared between VasQ and control AVFs. RESULTS: Our MRI protocol provided high-quality images suitable for reliable segmentation and reconstruction of patient-specific 3D models of AVFs at all three timepoints in four out of six patients. The VasQTM device maintained the angle between the artery and the vein almost unchanged over time, with a more stable flow in the AVFs supported by the device. In contrast, one of the AVFs of the control group evolved to an extreme dilatation of the vein and highly disturbed flow, while the other developed a stenosis in the juxta-anastomotic region. CONCLUSIONS: This study demonstrated the feasibility of characterizing the morphological and hemodynamic changes occurring over time in AVFs created using the VasQTM device and provided preliminary evidence of the potential hemodynamic benefits of its use.

Heavy metal tolerance and polychlorinated biphenyl oxidation in bacterial communities inhabiting the Pasvik River and the Varanger Fjord area (Arctic Norway).

Heavy metals (HMs) and polychlorobiphenyls (PCBs) enter the Arctic environment through a variety of anthropogenic sources with deleterious effects towards biota and public health. Bacteria first transfer toxic compounds to higher trophic levels and, due to the tight link existing between prokaryotic community functions and the type and concentration of contaminants, they may be useful indicator of pollution events and potential toxicity to other forms of life. The occurrence and abundance of HM-tolerant and PCB-oxidizing bacteria in the sub-Arctic Pasvik river area, heavily impacted by anthropogenic modifications, was related to HM and PCB contamination. This latter more likely derived from local inputs rather than a global contamination with higher PCB and HM amounts (and higher bacterial viable counts) that were determined in inner and middle sections of the River. Finally, a panel of bacteria with potential applications in the bioremediation of cold environments were selected and phylogenetically identified.

Endovascular Treatment of Popliteal Artery Aneurysms: A Word of Caution after Long-Term Follow-up.

BACKGROUND: The aim of this work was to evaluate the long-term patency of endografting in the treatment of popliteal artery aneurysms (PAAs) and to identify which factors may be predictors of graft occlusion. METHODS: All the patients who underwent endovascular repair of PAA were analyzed from 2006 until 2014 on the basis of symptoms, comorbidities, limb salvage, and long-term patency. The predictive value of the different variables was assessed in univariate analysis for primary patency and, for factors resulted significant, a multivariate analysis was performed. The Kaplan-Meier life table method was used to calculate patency and limb salvage. RESULTS: We treated 65 PAAs in 57 patients (53 men and 4 women). PAAs were symptomatic in 26 cases (40%) and 34% were the emergency cases; the mean aneurysm size was 33.8 ± 17 mm. Mean follow-up was 35 months ± 25. Graft occlusion occurred in 22 limbs (35%). We had 9 amputations (14.5%). The late conversion to open surgery was 6.4%. The cumulative estimated 60-month primary patency, secondary patency, and limb salvage were respectively 57% (standard error [SE] ±0.7), 73% (SE ±0.7), and 83% (SE ±0.5). We found that diabetes (hazard ratio [HR] 2.936, 95% confidence interval [CI] 0.993-8.683), associated percutaneous transluminal angioplasty (PTA) procedures (HR 2.534, 95% CI 1.115-5.757), symptoms (HR 2.492, 95% CI 1.127-5.510), and runoff scores (HR 2.069, 95% CI 0.942-4.544) were the most important risk factors for long-term patency at univariate analysis. When considering a multivariate analysis symptoms (HR 2.066, 95% CI 0.862-4.952) become the principal risk factor followed by diabetes (HR 1.808, 95% CI 0.531-6.157)], runoff scores (HR 1.716, 95% CI 0.757-3.893) and associated PTA procedures (HR 1.441, 95% CI 0.519-3.839), but no one reached a statistical significance. CONCLUSIONS: On the base of our experience it seems that several factors affect durability in PAA endovascular repair, especially the presence of acute symptoms, diabetes, and runoff. Therefore until further refined clinical studies, we believe that the actual role of this technique must be yet clarified.

A case of atherosclerotic inferior mesenteric artery aneurysm secondary to high flow state.

Inferior mesenteric artery aneurysms are very rare and they are among the rarest of visceral artery aneurysms. Sometimes, the distribution of the blood flow due to chronic atherosclerotic occlusion of some arteries can establish an increased flow into a particular supplying district (high flow state). A high flow state in a stenotic inferior mesenteric artery in compensation for a mesenteric occlusive disease can produce a rare form of aneurysm. We report the case of an atherosclerotic inferior mesenteric aneurysm secondary to high flow state (association with occlusion of the celiac trunk and severe stenosis of the superior mesenteric artery), treated by open surgical approach.