Publications

Magnetic guidewire assisted percutaneous coronary interventions (MPCI) could have certain advantages in coronary bifurcation lesions. We aimed to report the angiographic characteristics of the bifurcation lesions, as well as the procedural and clinical outcomes of the MPCI patients.The lesion characteristics and the treatment effect were assessed by performing diagnostic and quantitative coronary angiography with dedicated bifurcation software. A total of 76 patients (age 65 years, 78% male) were assigned to undergo MPCI, in which two-thirds of the lesions were located in LAD/D1. Fifty-seven out of 78 lesions (73%) had a diseased side branch and complex stenting techniques were used in the majority of the lesions (64%). All 59/78 (76%) fenestration attempts were successfully performed and only 13 dedicated bifurcation stents were implanted. The average acute gain in minimal luminal diameter was 1.08±0.81 mm, 0.80±0.70 mm and 0.59±0.56 mm for the proximal, distal and side branch, respectively. The procedural success was 69% with a procedure time of 107±43 minutes, fluoroscopy time of 34±24 minutes and contrast use of 338±136 ml. At a mean of 1.8-years follow-up, 15 patients (20%) had a cardiac event.MPCI is associated with good angiographic, fenestration and procedural success rates in the treatment of coronary bifurcation lesions.

Background and aims Coronary angiography-derived wall shear stress (WSS) may enable identification of vulnerable plaques and patients. A new recently introduced software allows seamless three-dimensional quantitative coronary angiography (3D-QCA) reconstruction and WSS computation within a single user-friendly platform carrying promise for clinical applications. This study examines for the first time the efficacy of this software in detecting vulnerable lesions in patients with intermediate non-flow limiting stenoses. Methods This multicentre retrospective study included patients who had coronary angiography showing at least one lesion with borderline negative fractional flow reserve (FFR: 0.81–0.85). In these lesions, 3D-QCA reconstruction and blood flow simulation were performed using the CAAS Workstation WSS prototype (Pie Medical Imaging, Maastricht, Netherlands). Time averaged and multidirectional WSS were extracted across the lesion at every 3 mm segments. The primary endpoint of the study was lesion-oriented clinical events (LOCE), defined as the composite of cardiac death, target lesion related myocardial infarction (MI) or clinically indicated target lesion revascularization. Results 352 patients (355 lesions) were included in the analysis. Over a median follow-up of 4.1 years, 57 LOCE were recorded. Lesions causing events had a larger area stenosis (AS) [59.4 (54.6–67.7)% vs 52.8 (43.8–60.1)%, p < 0.001], maximum time averaged WSS (TAWSS) [11.56 (8.25–13.64)Pa vs 7.73 (5.41–11.51)Pa, p < 0.001], mean TAWSS at the minimum lumen area (MLA) [9.30 (5.44–11.94)Pa vs 6.19 (3.96–9.00)Pa, p < 0.001] and maximum transverse WSS [0.30 (0.21–0.45)Pa vs 0.23 (0.17–0.32)Pa, p=0.002] than those remaining quiescent. In multivariable models, AS was the only independent predictor of LOCE. Kaplan-Meier curves demonstrated that lesions with elevated maximum TAWSS and AS had a higher rate of LOCE than those with low TAWSS and AS values (26 % vs 7 %, p < 0.001). Conclusions For non-flow limiting lesions with borderline negative FFR, fast WSS computation using a dedicated software is feasible and holds potential for cardiovascular risk stratification.

No abstract is provided for this article.

Wire arc additive manufacturing (WAAM), a method of metal 3D printing, has the capacity to create large scale elements suitable for construction applications with a high degree of design freedom and structural efficiency. There is currently however a lack of fundamental experimental data on the material and structural performance of such elements. Towards addressing this limitation, the tensile behaviour of WAAM high strength steel produced using different printing strategies is the focus of the present study. WAAM steel plates and tubular tension members manufactured with different interpass temperatures and toolpaths using ER110S-G welding wire were examined. A total of 60 tensile coupons, consisting of 40 as-built and 20 machined specimens, and 8 as-built circular hollow section (CHS) tension members, were tested. The examined WAAM materials were found to exhibit very little anisotropy, corroborated by a nearly homogeneous crystallographic texture observed by microstructural analysis, while the inherent surface undulations were shown to result in a varying degree of reduction in the material stiffness, strength and ductility at different angles to the print layer orientation. The different printing strategies led to varying surface geometries; combined with different interpass temperatures, they also resulted in different thermal histories and thus different mechanical properties. The tension members showed good structural resistance, but a considerable reduction in ductility compared to the coupon tests, due to the greater geometric variability and manufacturing defects.

The assessment of coronary flow reserve from the instantaneous distribution of the contrast agent within the coronary vessels and myocardial muscle at the control state and at maximal flow has been limited by the superposition of myocardial regions of interest in the two-dimensional images. To overcome these limitations, we are in the process of developing a three-dimensional (3D) reconstruction technique to compute the contrast distribution in cross sections of the myocardial muscle from two orthogonal cineangiograms. To limit the number of feasible solutions in the 3D- reconstruction space, the 3D-geometry of the endo- and epicardial boundaries of the myocardium must be determined. For the geometric reconstruction of the epicar-dium, the centerlines of the left coronary arterial tree are manually or automatically traced in the biplane views. Next, the bifurcations are detected automatically and matched in these two views, allowing a 3D-representation of the coronary tree. Finally, the circumference of the left ventricular myocardium in a selected cross section can be computed from the intersection points of this cross section with the 3D coronary tree using B-splines. For the geometric reconstruction of the left ventricular cavity, we envision to apply the elliptical approximation technique using the LV boundaries defined in the two orthogonal views, or by applying more complex 3D-reconstruction techniques including densitometry. The actual 3D-reconstruction of the contrast distribution in the myocardium is based on a linear programming technique (Transportation model) using cost coefficient matrices. Such a cost coefficient matrix must contain a maximum amount of a priori information, provided by a computer generated model and updated with actual data from the angiographic views. We have only begun to solve this complex problem. However, based on our first experimental results we expect that the linear programming approach with advanced cost coefficient matrices and computed model will lead to acceptable solutions in the 3D-reconstruction of the myocardial contrast distribution from biplane cineangiograms.

Coronary balloon angioplasty has become standard treatment for ischemic coronary artery disease. Major limitations of angioplasty are the inferior results obtained with unfavorable lesions, the occurrence of abrupt occlusion responsible for in‐hospital mortality and morbidity, and the high restenosis rate at 6 months. New techniques for stents, laser, and atherectomy have been developed to overcome these limitations. Until now, although the initial results are encouraging, these new techniques have not as yet shown to be clearly superior to balloon angioplasty. However, due to the limitations of balloon angioplasty, further development of new techniques should be stimulated so that nonsurgical treatment of coronary artery disease will become safer, more effective, and applicable to a wider spectrum of coronary artery disease.

Abstract This paper presents an experimental study into the behaviour of concrete filled double skin tubular (CFDST) stub columns. A total of eight axial compression tests were carried out, half of which were filled with conventional concrete and the remainder had recycled aggregate concrete. The columns were circular in cross‐section and comprised an austenitic stainless steel outer tube and a carbon steel inner tube, of varying dimensions. Accordingly, hollow ratios of 0.67 and 0.55 were considered. The recycled coarse aggregate was made by crushing test specimens from a previous research project. A replacement ratio of 50% was adopted in these tests. Both the natural coarse aggregates and the recycled aggregates had a maximum diameter of 9.5 mm. During the tests, similar structural behaviour and failure modes were observed between the columns with conventional and recycled aggregate concrete, and the faiure modes were identical. The experimental results are compared with available design procedures and it is ultimately shown that using recycled aggregate concrete rather than regular concrete in CFDST stub columns does not have a significant effect on the performance.

The aim of this study was to compare the strut coverage of the XIENCE stent with that of the BuMA Supreme sirolimus-eluting cobalt-chromium stent, which has a shorter drug elution, on optical coherence tomography (OCT) one or two months after implantation.The PIONEER-II OCT trial was a multicentre, two-arm randomised trial, which comprised two cohorts: cohort-1 underwent an OCT imaging one month after coronary intervention (BuMA: 16 patients with 18 lesions, XIENCE: 15 patients with 17 lesions), whereas cohort-2 underwent OCT at two months (BuMA: 21 patients with 21 lesions, XIENCE: 23 patients with 28 lesions). The primary hypotheses were non-inferiority of the BuMA stent to the XIENCE stent in percent strut coverage at one month (cohort-1) or two months (cohort-2). In cohort-1, the BuMA stent was non-inferior to the XIENCE stent in terms of the strut coverage (83.8±10.4% for BuMA vs. 73.0±17.5% for XIENCE, pfor noninferiority <0.001), and was also significantly higher than the XIENCE (pfor superiority 0.037). In cohort-2, the BuMA stent was non-inferior to the XIENCE stent in OCT strut coverage (80.3±18.3% vs. 73.3±21.3%, pfor noninferiority 0.006, pfor superiority 0.24). Healing scores showed better healing in the BuMA stent in cohort-1 (32.36±21.59 vs. 54.88±34.65, p=0.027), whereas there was comparable healing between the BuMA and XIENCE stents in cohort-2 (39.86±37.77 vs. 53.75±42.84, p=0.25).The BuMA Supreme had a faster coverage than the XIENCE at one month, presumably due to faster and shorter sirolimus elution. The difference in tissue coverage became less evident at two months.