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Background/Objectives: Carbon dioxide digital-subtraction angiography (CO2-DSA) is an increasingly adopted technique in endovascular aortic repair (EVAR) and fenestrated/branched EVAR (F/B-EVAR); it is used to reduce the amount of iodinate contrast medium (ICM) and prevent postoperative renal function worsening (PO-RFW). Our aim is to report results from the literature on EVAR and F/B-EVAR procedures using CO2-DSA, together with wider applications in aortic endovascular treatment. Methods: We performed a literature review by searching electronic databases for published data on CO2-DSA during EVAR and F/B-EVAR procedures. The endpoints were postoperative renal function worsening (PO-RFW) and efficacy of intraoperative arterial visualization. Further, applications of CO2 for thoracic endovascular aortic repair (TEVAR) were described. Results: Seventeen studies reporting results on CO2-DSA in EVAR (644 patients) were retrieved. Overall, 372 (58%) procedures were performed with CO2 alone, and 272 (42%) were performed with CO2+ICM. Eight studies analyzed the effect of CO2-DSA angiography on PO-RFW; four studies showed a significantly lower rate of PO-RFW compared to ICM. Five studies (153 patients) analyzed intraoperative arterial visualization with CO2-DSA; renal and hypogastric arteries were effectively visualized in 69% and 99% of cases, respectively. The use of CO2-DSA in F/B-EVAR has not been widely investigated. The largest series reported that PO-RFW was lower in the CO2 vs. ICM group. Conclusions: Carbon dioxide is widely applied in modern aortic endovascular treatment. CO2-DSA for EVAR and F/B-EVAR is an efficient technique for reducing PO-RFW while allowing acceptable arterial intraoperative visualization. [ABSTRACT FROM AUTHOR]

Multilevel secret sharing schemes are used in cryptography when a responsibility has to be delegated to qualified groups of participants rather than to a single one. In the present paper we propose a mathematical model for such a scheme based on projective geometry over a finite field. The main ingredients are normal rational curves and their osculating subspaces. [ABSTRACT FROM AUTHOR]

Background: Popliteal artery aneurysms (PAAs) need urgent treatment in case of acute thrombosis, distal embolization, or rupture. Few data are available in the literature about the treatment results in these scenarios. The aim of the present study was to evaluate an 11-year multicenter experience in the urgent treatment of PAAs. Methods: All symptomatic PAAs surgically treated in two vascular centers between 2010 and 2021 were retrospectively analyzed. In the postoperative period periodical clinical and Duplex-Ultrasound evaluation were performed. The evaluated endpoint was the outcome of urgent PAAs treatment according to their clinical presentation. Statistical analysis was performed by Kaplan-Meier log-rank evaluation and multivariable Cox regression tests. Results: Sixty-six PAAs needed an urgent repair. Twelve (18%) patients had a PAA rupture and 54 (82%) had an acute limb ischemia (ALI) due to either distal embolization or acute thrombosis. Patients with ALI underwent bypass surgery in 51 (95%) cases, which was associated with preoperative thrombolysis in 18 (31%) cases. A primary major amputation was performed in 3 (5%) cases. The mean follow-up was 52 ± 21 months with an overall 5-year limb salvage of 83 ± 6%. Limb salvage was influenced only by the number of patent tibial arteries (pTA) [5-years limb salvage 0%, 86 ± 10%, 92 ± 8% and 100% in case of 0, 1, 2 or 3 pTA, respectively (P =.001)]. An independent association of number of pTA and limb loss was found [hazard ratio (HR): 0.14 (95% confidence interval (CI) 0.03–0.6), P =.001]. Overall 5-year survival was 71 ± 7%. Ruptured PAAs were associated with lower 5-year survival compared with the ALI group (48 ± 2% vs. 79 ± 7%, P =.001). The number of pTA (33 ± 20%, 65 ± 10%, 84 ± 10% and 80 ± 10% for 0, 1, 2 and 3 pTA, respectively, P =.001) and the thrombolysis (94 ± 6% vs. 62 ± 10%, P =.03) were associated with higher survival in patients with ALI. There was an independent association of number of pTA and long-term survival [HR 0.15 (95% CI 0.03–0.8), P =.03]. Conclusions: PAA rupture is the cause of urgent PAA treatment in almost one fifth of cases, and it is associated with lower long-term survival. ALI can benefit from thrombolysis, and long-term limb salvage and survival are associated with the number of pTA. [ABSTRACT FROM AUTHOR]