Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

In Memoriam

.

.

.

In the Chilean Frontal Cordillera between 28.5 and 30.5° S, two volcano-sedimentary succesions of Late Guadalupian to Middle Triassic age croup out: the El Tapado (Late Guadalupian-Lopingian) and Guanaco Sonso (Late Lopingian-Middle Triassic) formations, representing the westernmost exposures of the Choiyoi Group and post-Choiyoi magmatism. Recently, these two units have been characterized in detail, shedding light into the tectonic and climatic context of the late stages of the Choiyoi magmatism, and, more generally, the geology of intra-arc successions in the southwestern Gondwana margin. In this work, we present a stratigraphy and lithofacies analysis of three stratigraphic sections studied in the La Laguna sector (30-30.5° S), comprising rocks of the El Tapado and Guanaco Sonso formations. The former is dominated by caldera-related rhyolitic to dacitic ignimbrites accumulated in depocenters associated with the extensional activity of major structures. Lacustrine and fluvial-alluvial deposits interbedded in this rock unit were mainly controlled by volcaniclastic input and subsidence dynamics, and record the transition from relatively humid conditions to semi-arid or even arid conditions during the Late Guadalupian-Lopingian, consistent with regional paleoclimatic observations. On the other hand, the Guanaco Sonso Formation presents mainly intermediate, proximal (near-vent) volcanic products that denote a varied volcanism in terms of composition and eruptive style, likely controlled by structures and tectonics. We conclude the southwestern Gondwana margin sustained high-explosivity, silicic volcanism (El Tapado) that transitioned into a more varied, mainly intermediate volcanism (Guanaco Sonso). This activity ultimately gave way to the basaltic-andesitic to bimodal products that characterized the final part of the pre-Andean stage during the Triassic in this region.

A small body of orbicular granodiorite crops out on the Recoba Hill, immediately east of the town of Chaitén, in the mainland area called Chiloé continental, in southern Chile. The rock comprises cm-sized igneous cores with a single shell of fine-grained plagioclase-quartz-K-feldspar assemblages. It is hosted in a Miocene granodiorite, and it is crosscut by aplite and mafic dikes. No other mention of orbicular rocks has to date been reported for the >1,000 km long North Patagonian Batholith, suggesting that the conditions necessary for their formation were infrequent. Thermobarometric determinations indicate pressures lower than 2 kbar (less than 6 km depth) for its formation, a level much shallower than the estimated source depth of the older rocks of the batholith.

-

INTRODUCTION: Type 2 endoleaks (T2EL) are common complications following endovascular aneurysm repair (EVAR), potentially leading to adverse outcomes such as aneurysm sac growth and reintervention. Although current guidelines recommend surveillance and conservative management for most T2EL cases, there's growing interest in prophylactic measures, including embolization of lumbar (LA) and inferior mesenteric arteries (IMA) during EVAR. This study aims to investigate the impact of LA and IMA on the development of T2EL after EVAR and to identify associated risk factors. METHODS: A retrospective analysis was conducted on patients who underwent elective EVAR for infrarenal aortic aneurysms at our institution between January 2020 and December 2022, without embolization of LA or IMA. All patients had preoperative and one-month post-operative computed tomography angiography (CTA). Patient demographics, aneurysm characteristics, LA and IMA patency and diameter were registered. Evidence of T2EL was assessed at one and 12 months after surgery, in addition to sac growth. RESULTS: Fifty-eight patients were included, with a median age of 75 and mean aneurysm size of 64mm at the time of treatment. Most patients were male (n=56). Eighteen patients (31%) exhibited a T2EL on follow-up. Aneurysm shape was associated with T2EL, with 62% of saccular aneurysms developing T2EL, whilst only 26% in fusiform aneurysms (p=0.039). Patients with T2EL had a higher number of covered LA than patients without (5.33 and 5 vs 4.6 and 3.45, respectively), yet only patent covered LA achieved statistical significance for T2EL (p=0.195 and p=0.025, respectively). Additionally, T2EL showed significant association with covering > three patent LA (78%, p=0.020); similarly, IMA patency was associated with T2EL (100% vs 65% without T2EL, p=0.003). Presence of lumbar and inferior mesenteric arteries with ≥ 3 mm, mean LA and IMA diameter, as well as sum of combined diameters did not reach significance, despite being slightly higher in the T2EL group. Among the 18 patients with T2EL, three (17%) had sac growth and two (11%) sac shrinkage (defined as variation ≥ 5mm) at 12 months, none of which required reintervention. One patient had concomitant type 3 endoleak, and underwent endograft relining. CONCLUSION: This study reveals a substantial incidence of T2EL following elective EVAR, emphasizing the importance of further understanding associated risk factors. Saccular aneurysm morphology, more than three patent covered LA, and patent IMA were identified as significant predictors of T2EL, whilst collateral vessel diameter did not achieve significance. While prophylactic embolization of LA and IMA may benefit certain patients, the lack of association between vessel diameter and T2EL warrants additional investigation to refine embolization strategies.

INTRODUCTION: In recent years, endovascular stenting has emerged as a promising palliative therapeutic modality for carefully selected patients with Superior Vena Cava Syndrome (SVCS) secondary to intra-thoracic malignancies. However, a lack of data hinders procedure standardization, particularly regarding the dichotomy of covered versus uncovered stents. This study aims to compare the outcomes of malignant SVCS treated with covered versus uncovered stents. To the best of our knowledge, no past review has directly attained this dichotomy in malignant SVCS. METHODS: A systematic review and meta-analysis were performed based in the PRISMA guidelines. COCHRANE and PUBMED databases were searched up to February 2024. Only original studies including 10 or more patients were considered. Primary outcomes were defined as technical and clinical success. Secondary outcomes were defined as primary and secondary patency, complications, recurrence of symptoms, reinterventions, and mean survival. RESULTS: Our search yielded 17 studies, encompassing 1123 participants (109 submitted to covered stents and 1014 to uncovered stents). Technical success was very high in covered and uncovered stents: pooled data 100% (95% confidence interval [CI] not estimable [NE]) versus 97.9% (95% CI 96.5-99.3), respectively. A single study compared clinical success with a trend towards best results in the covered group, but it was not significant: OR 1.59 (95% CI 0.25-10.13). The complication rate was 0% (95% CI NE) versus 6.2% (95% CI 0.6-11.8), and the re-intervention rate was 1.7% (95% CI 0.0-28.2) versus 9.0% (95% CI 2.7-15.4) for covered and uncovered stents, respectively. A single study directly compared primary patency between groups, with no difference at one month: OR 1.03 (95% CI 0.06-17.09). However, the difference became statistically significant at 6 and 12 months, favoring covered stents: OR 8.75 (95% CI 1.79-42.67) and OR 19.56 (95% CI 4.08-93.82), respectively. Pooled primary patency at 12 months was 90.9% (95% CI 45.9-100) and 77.1% (95% CI 46.0-100) for covered and uncovered stents, respectively. CONCLUSIONS: Our findings suggest that endovascular implant of covered stents represents a promising approach with superior primary patency rates (versus uncovered). However, limited data from heterogeneous studies hinders definite conclusions, and further investigation is necessary.