Background In the anatomic SYNTAX score derived from invasive coronary angiography, the ischemic impact of each stenotic coronary segment is weighed with a fixed score based on the severity of luminal diameter narrowing and the theoretical amount of blood flow supplied to the myocardium(1). This method neither accounts for individual variation nor reflects the true extent of myocardium ischemia. Purpose We aim to provide a quantitative CT SYNTAX score derived from coronary computed tomography angiography (CCTA) with customized percent blood flow distribution to the myocardium supplied by each stenotic coronary segment to determine the myocardium at risk of ischemia. Methods Patients with 3VD and/or left main coronary artery disease (CAD) were included in the first-in-human FAST TRACK CABG trial and received surgical revascularization guided solely by CCTA and fractional flow reserve derived from CCTA (FFRCT). The recently reported anatomic CT-SYNTAX score was calculated for all cases. The FFRCT value and percent myocardial blood flow distribution(%MBF) were computed for all 16 SYNTAX score segments using the validated method of Keulards et al(2). On the pre-CABG CCTA, the segments located distal to the site where the FFRCT value dropped below 0.80 were considered at risk of ischemia, and the individual weight point per segment was calculated as 6×%MBF for each segment. The SYNTAX score derived from %MBF is compared to the anatomic and functional CT-SYNTAX score. Results Out of 114 patients enrolled, FFRCT and %MBF were analyzable in 106 patients. After excluding vessels with total occlusion, the coronary flow distribution between the right and left coronary systems was 20.5% vs 79.5%, respectively, similar to the 1:5 ratio in the anatomic SYNTAX score. The anatomic and functional CT-SYNTAX scores were 43.6 and 41.1, respectively. The average total %MBF per patient was 72.0(19.1)%, and the average SYNTAX score derived from %MBF was 38.0. There is a strong correlation between functional SYNTAX score and SYNTAX score derived from %MBF (Peason’s R=0.93). Passing-Bablock regression trends showed that the functional SYNTAX score slightly overestimated the SYNTAX score derived from %MBF (Figure 1). The coronary segment weight varied significantly per individual, especially in the presence of total occlusion. Overall, the fixed weight of the anatomic SYNTAX score is a good surrogate for the individualized weighing based on %MBF (Figure 2). Conclusion CCTA-derived %MBF enabled clinicians to quantify the individualized myocardium at risk of ischemia or injury in patients with severe CAD. Retrospectively, the fixed weight score used in the anatomical SYNTAX score appeared to be a robust surrogate for myocardial blood flow distribution.Figure 1Figure 2
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to Robert and Tim Fischell, described an "intraarterial stent with the capability to inhibit intimal hyperplasia." 1 The proponents of this patent went on to say in their proposal: "Since radiation from a radioisotope source is capable of selectively inhibiting the growth of hyperproliferating cells as compared with normal cells, a radioisotope material which forms part of the stent can be used to decrease the rate of arterial reclosure.The radioisotope could be placed inside the stent, alloyed into the metal from which the stent is made, or preferably, it can be coated onto the stent's exterior surface."So began the story of the radioactive stent.Eight years and several animal species later, we are becoming aware of the bright and dark sides of this treatment modality in the human model.
A new nickel-free austenitic stainless steel EN 1.4678 (Forta H500) with excellent corrosion resistance and significant strain hardening has been recently developed, but its elevated temperature behaviour has yet to be investigated. This paper reports an experimental study into the material properties of EN 1.4678 stainless steel at elevated temperatures. 22 coupons were extracted from 6 mm EN 1.4678 stainless steel plates and tested to failure at temperatures up to 1000°C. The average experimentally derived reduction factors and the Ramberg-Osgood material model for stainless steel were applied in the FE modelling of hybrid carbon steel-stainless steel end-plate connections in fire, with a view to exploiting the excellent elevated temperature behaviour of stainless steel to improve the response of connections in steel framed structures in fire.
Abstract. It has now become apparent that asthma, even in its mildest clinical manifestation, is a chronic inflammatory condition of the airways. There have been important advances in understanding the special features of inflammation in asthmatic airways and the role of critical inflammatory cells such as mast cells (important in the acute inflammatory response) and eosinophils, macrophages and T‐lymphocytes (involved in the chronic inflammatory response). Many inflammatory mediators have been implicated in asthma, and the development of mediator antagonists suggests that sulphidopeptide leukotrienes may play an important role in bronchoconstrictor responses. Cytokines released from many different cells in the airways are likely to be important in orchestrating and perpetuating the chronic inflammatory response. Chronic inflammation has effects on airway vessels, mucus secretion, smooth muscle and nerves, with evidence to suggest that there are structural changes which may lead to persistent airway abnormalities. The therapeutic implication of these new discoveries is that much earlier use of anti‐inflammatory treatments (such as inhaled steroids) is preferable to reliance on bronchodilators which do not control the underlying inflammatory process.
No abstract is provided for this article.