Semi-automated quantification of left ventricular volumes and ejection fraction by real-time three-dimensional echocardiography

<p>Abstract</p> <p>Background</p> <p>Recent studies have shown that real-time three-dimensional (3D) echocardiography (RT3DE) gives more accurate and reproducible left ventricular (LV) volume and ejection fraction (EF) measurements than traditional two-dimensional methods. A new semi-automated tool (4DLVQ) for volume measurements in RT3DE has been developed. We sought to evaluate the accuracy and repeatability of this method compared to a 3D echo standard.</p> <p>Methods</p> <p>LV end-diastolic volumes (EDV), end-systolic volumes (ESV), and EF measured using 4DLVQ were compared with a commercially available semi-automated analysis tool (TomTec 4D LV-Analysis ver. 2.2) in 35 patients. Repeated measurements were performed to investigate inter- and intra-observer variability.</p> <p>Results</p> <p>Average analysis time of the new tool was 141s, significantly shorter than 261s using TomTec (<it>p </it>< 0.001). Bland Altman analysis revealed high agreement of measured EDV, ESV, and EF compared to TomTec (<it>p </it>= <it>NS</it>), with bias and 95% limits of agreement of 2.1 ± 21 ml, -0.88 ± 17 ml, and 1.6 ± 11% for EDV, ESV, and EF respectively. Intra-observer variability of 4DLVQ vs. TomTec was 7.5 ± 6.2 ml vs. 7.7 ± 7.3 ml for EDV, 5.5 ± 5.6 ml vs. 5.0 ± 5.9 ml for ESV, and 3.0 ± 2.7% vs. 2.1 ± 2.0% for EF (<it>p </it>= <it>NS</it>). The inter-observer variability of 4DLVQ vs. TomTec was 9.0 ± 5.9 ml vs. 17 ± 6.3 ml for EDV (<it>p </it>< 0.05), 5.0 ± 3.6 ml vs. 12 ± 7.7 ml for ESV (<it>p </it>< 0.05), and 2.7 ± 2.8% vs. 3.0 ± 2.1% for EF (<it>p </it>= <it>NS</it>).</p> <p>Conclusion</p> <p>In conclusion, the new analysis tool gives rapid and reproducible measurements of LV volumes and EF, with good agreement compared to another RT3DE volume quantification tool.</p

A modelagem como um ambiente de aprendizagem para a conversão do conhecimento matemático

A investigação da modelagem como um ambiente de aprendizagem para a construção do conhecimento matemático está se tornando predominante nos meios acadêmicos. Esse ambiente facilita uma estrutura pedagógica que promove a identificação e a disseminação de ambos os conhecimentos, explícito e tácito, dos alunos, através do estudo e da codificação das ideias matemáticas presentes nos sistemas retirados da realidade. Neste artigo, discutimos as principais características da conversão dos conhecimentos matemáticos, explícito e tácito, através da utilização do ambiente de aprendizagem da modelagem

Initial assessment of protein and amino acid digestive dynamics in protein-rich feedstuffs for broiler chickens.

A study evaluating apparent digestibilities of protein and amino acids and their corresponding digestion rates in four small intestinal sites in broiler chickens was completed to further investigate dietary optimisation via synchronised nutrient digestion and absorption. A total of 288 male Ross 308 broiler chickens were offered semi-purified diets with eight protein-rich feedstuffs, including; blood meal (BM), plasma protein meal (PPM), cold pressed (CCM) and expeller-pressed (ECM) canola meal, high (SBM HCP) and low (SBM LCP) crude protein soybean meals, lupins and peas. Diets were iso-caloric, iso-nitrogenous and the test ingredient was the sole source of dietary nitrogen. Each diet was offered to 6 bioassay cages with 6 birds per cage from day 21 to 28 post hatch. On day 28, all birds were euthanized and digesta samples were collected from the proximal jejunum, distal jejunum, proximal ileum and distal ileum to determine apparent protein and amino acids digestibility coefficients, digestion rates and potential digestible protein and amino acids. Dietary protein source significantly influenced energy utilisation, nitrogen retention, apparent protein (N) digestibilities, digestion rates and potential digestible protein along the small intestine. Diets containing BM and SBM LCP exhibited the highest protein digestion rate and potential digestible protein, respectively. Digestibility coefficients and disappearance rates of the majority of amino acids in four sections of the small intestine were influenced by dietary protein source (P < 0.01) and blood meal had the fastest protein digestion rate. In general, jejunal amino acid and protein digestibilities were more variable in comparison to ileal digestibilities, and the differences in protein and amino acid disappearance rates were more pronounced between types of feedstuffs than sources of similar feedstuffs

Space and Time Shape Constrained Deformable Surfaces for 4D Medical Image Segmentation

Abstract. The aim of this work is to automatically extract quantitative parameters from time sequences of 3D images (4D images) suited to heart pathology diagnosis. In this paper, we propose a framework for the reconstruction of the left ventricle motion from 4D images based on 4D deformable surface models. These 4D models are represented as a time sequence of 3D meshes whose deformation are correlated during the cardiac cycle. Both temporal and spatial constraints based on prior knowledge of heart shape and motion are combined to improve the segmentation accuracy. Incontrast to many earlier approaches, our framework includes the notion of trajectory constraint. We have demonstrated the ability of this segmentation tool to deal with noisy or low contrast images on 4D MR, SPECT, and US images.

Dosis baja de apixabán en pacientes con implante transcatéter de prótesis valvular aórtica y fibrilación auricular

Introduction and objectives: A significant amount of patients undergoing transcatheter aortic valve implantation (TAVI) have an indication for oral anticoagulation due to atrial fibrillation. In these patients the bleeding risk is often high. The purpose of this study was to compare the clinical outcomes of patients treated with low doses of apixaban or the vitamin K antagonist (VKA) acenocumarol in this setting. Methods: Multicenter observational registry including patients treated after TAVI with low doses of apixaban (2.5 mg/12 hours) or VKA both without associated antiplatelet therapy. Propensity score matching was conducted to select 2 comparable cohorts. Data were gathered for 12 months following the procedure. Coprimary endpoints of efficacy (death, myocardial infarction, and stroke) and safety (bleeding BARC ≥ 2) were considered. Results: A total of 236 patients were included. They were divided into 2 comparable groups of 64 patients each. Only 19 patients (30%) strictly met the dose adjustment criteria for apixaban. The rate of death, myocardial infarction, and stroke was similar at the 12-month follow-up (12.5% with VKA vs 9.3% with apixaban, P = .5), but the rate of bleeding BARC ≥ 2 was significantly higher in the VKA group (7.8% vs 0%; P = .02). Most of the events seen in the apixaban group occurred in patients with incorrect dose titration. Conclusions: In this registry of patients treated with TAVI and atrial fibrillation the use of low-dose apixaban compared to VKA—both without antiplatelet agents—was associated to a lower rate of actionable bleeding and a similar rate of thrombotic events.Introducción y objetivos: Una proporción significativa de pacientes sometidos a implante percutáneo de válvula aórtica (TAVI) presenta indicación de anticoagulación oral por fibrilación auricular. En estos pacientes, con frecuencia el riesgo hemorrágico es alto. El objetivo del estudio fue comparar los resultados clínicos en pacientes tratados con dosis baja de apixabán o con acenocumarol, un antagonista de la vitamina K (AVK). Métodos: Registro observacional multicéntrico que incluyó pacientes sometidos a TAVI tratados con dosis baja de apixabán (2,5 mg/12 h) o AVK, en ambos casos sin tratamiento antiplaquetario asociado. Se llevó a cabo un emparejamiento por puntuación de propensión para seleccionar dos cohortes comparables. Se recabó la información de los 12 meses posteriores al procedimiento. Se consideraron objetivos coprimarios de eficacia (muerte, infarto de miocardio e ictus) y de seguridad (hemorragias BARC ≥ 2). Resultados: Se incluyeron 236 pacientes y se obtuvieron 2 grupos de 64 pacientes comparables en cuanto a características basales. Solo 19 (30%) cumplieron estrictamente los criterios de ajuste a la baja de la dosis de apixabán. A los 12 meses, la incidencia de muerte, infarto de miocardio e ictus fue comparable (12,5% con AVK frente a 9,3% con apixabán; p = 0,5), pero la incidencia de hemorragia BARC ≥ 2 fue significativamente mayor en el grupo de AVK (7,8 frente a 0%; p = 0,02). La mayoría de los eventos trombóticos en el grupo de apixabán se observaron en pacientes con reducción de dosis no ajustada a criterios. Conclusiones: En este registro de pacientes con TAVI y fibrilación auricular, el uso de la dosis baja de apixabán en comparación con el uso de AVK, sin antiagregantes concomitantes, se asoció a una menor incidencia de hemorragias mayores con una incidencia similar de eventos tromboembólicos