Publications

While assessment of metal stents by CT angiography is complicated by blooming artifacts, noninvasive follow-up should be possible after implantation of non-metal, radiolucent, bioabsorbable stents. In a multicenter, prospective, open-label study (ABSORB) 30 patients underwent implantation of a 3.0 ×12-mm (N=28) or 3.0 × 18-mm(N=2) bioabsorbable everolimus-eluting stent made of polylactic acid (Abbott Vascular, Santa Clara, CA). At 19.2 ±1.1 months 64-slice CT angiography (Siemens Somatom Definition, Germany; Philips Brilliance 64, The Netherlands; GE LightSpeed VCT, WI) was performed in 25 patients (65 ±11 years, 15 male). Five patients were lost due to target-lesion re-intervention (N=1), contrast allergy (N=1), withdrawn consent (N=3). Cross-sectional, in-stent lumen areas were measured at submillimeter intervals using quantitative CT software (Circulation®, Siemens). Minimal in-stent lumen area was compared to the reference lumen area, based on adjacent proximal and distal lumen areas. Motion artifacts excluded one CT study. Radiopaque indicators (figure ) at the egdes of the absorbed stent were the only visible remains: distance 11.4 ±0.5 mm (12-mm stents). All stents were patent. Mean lumen area 5.2 ±1.3 mm 2 (range 3.2 – 7.4 mm 2 ). Minimal lumen area 3.6 ±0.9 mm 2 (range 2.2 – 5.7 mm 2 ), compared to a reference lumen area of 5.5 ±1.0 mm 2 (range 3.3 – 7.6 mm 2 ), resulting in a lumen area stenosis of 31 ±15% (range -2 - 51%). One case showed local lumen enlargement (12.0 mm 2 ). CT angiography was feasible and demonstrated moderate in-stent lumen loss without significant obstruction after bioabsorbable stent implantation.

Smoking is common in asthma and is associated with worse asthma control and a reduced therapeutic response to corticosteroids. The present authors hypothesised that treating smokers with asthma with low-dose theophylline added to inhaled corticosteroids would enhance steroid sensitivity and thereby improve lung function and symptoms. In a double-blind, parallel group exploratory trial, 68 asthmatic smokers were randomised to one of three treatments for 4 weeks: inhaled beclometasone (200 μg·day −1 ), theophylline (400 mg·day −1 ) or both treatments combined. Outcome measures included change in lung function and Asthma Control Questionnaire (ACQ) scores. At 4 weeks, theophylline added to inhaled beclometasone produced an improvement in peak expiratory flow (39.9 L·min −1 , 95% confidence intervals (CI) 10.9–68.8) and ACQ score (-0.47, 95% CI -0.91– -0.04) and a borderline improvement in pre-bronchodilator forced expiratory volume in one second (mean difference 165 mL, 95% CI -13–342) relative to inhaled corticosteroid alone. Theophylline alone improved the ACQ score (-0.55, 95% CI -0.99– -0.11), but not lung function. In the present pilot study, the combination of low-dose theophylline and inhaled beclometasone produced improvements in both lung function and symptoms in a group of smokers with asthma. Larger trials are required to extend and confirm these findings.

Wire arc additive manufacturing (WAAM) is an efficient and cost-effective method of metal 3D printing that is well suited to structural engineering applications. Fundamental test data on the mechanical properties of WAAM materials, especially under cyclic loading, are however lacking. To address this, an experimental study into the cyclic behaviour of WAAM steel plates has been undertaken and is reported herein. Following geometric and quasi-static mechanical characterisation, a total of 40 as-built and machined coupons were tested under different cyclic loading protocols. Key results from the tests, including the full hysteresis curves, are presented and discussed. A cyclic constitutive model allowing for a yield plateau and the degradation of elastic modulus is proposed and validated against the test data. It is shown that the examined WAAM steel exhibited cyclic hardening behaviour dependent on the strain amplitude and strain history. The elastic modulus of the WAAM material was found to decrease in the first few cycles and then remain stable with increasing accumulated plastic strain. Good energy dissipation performance was also observed, indicating the potential of WAAM steels for seismic applications.

The SYNTAX score (SXscore), an anatomical-based scoring tool reflecting the complexity of coronary anatomy, has established itself as an important long-term prognostic factor in patients undergoing percutaneous coronary intervention (PCI). The incorporation of clinical factors may further augment the utility of the SXscore to longer-term risk stratify the individual patient for clinical outcomes. Patient-level merged data from >6000 patients in seven contemporary coronary stent trials was used to develop a logistic regression model—the Logistic Clinical SXscore—to predict 1-year risk for all-cause death and major adverse cardiac events (MACE). A core model (composed of the SXscore, age, creatinine clearance, and left ventricular ejection fraction) and an extended model [incorporating the core model and six additional (best performing) clinical variables] were developed and validated in a cross-validation procedure. The core model demonstrated a substantial improvement in predictive ability for 1-year all-cause death compared with the SXscore in isolation [area under the receiver operator curve (AUC): core model: 0.753, SXscore: 0.660]. A minor incremental benefit of the extended model was shown (AUC: 0.791). Consequently the core model alone was retained in the final the Logistic Clinical SXscore model. Validation plots confirmed the model predictions to be well calibrated. For 1-year MACE, the addition of clinical variables did not improve the predictive ability of the SXscore, secondary to the SXscore being the predominant determinant of all-cause revascularization. The Logistic Clinical SXscore substantially enhances the prediction of 1-year mortality after PCI compared with the SXscore, and allows for an accurate personalized assessment of patient risk.

Early and late modifications of stenosis geometry after stenting of coronary arteries were assessed. Morphologic changes were evaluated by quantitative coronary angiography (automated edge-detection) and theoretical pressure drop across the dilated and stented stenosis was calculated from the Poiseuille formula, with turbulent resistances assuming a coronary blood flow of 1 or 3 ml/s. Eleven patients (ages 41 to 69 years, mean 55) were studied before and after angioplasty, and immediately after stent implantation. The stented coronary artery was the left anterior descending artery in 9 patients and the left circumflex in 2. Following stent implantation, an additional increase in minimal luminal crosssectional area of the dilated vessel was observed, suggesting that the self-expanding stainless-steel endoprosthesis used had a dilating function in addition to its stenting role. Repeat angiography in 6 patients 3 months after stent implantation showed a decrease in the minimal luminal cross-sectional area without a significant change in theoretic pressure decrease. This slight reduction in vessel caliber had no hemodynamically significant repercussions. Thus, stenting of coronary arteries following dilatation is a potentially valuable technique for preventing both abrupt closure and late reduction in lumen diameter.

Aims: To study the expression of mucins in peripheral airways in patients with chronic obstructive pulmonary disease (COPD). Methods and results: Peripheral lung sections from smokers with COPD ( n = 9) and age‐matched controls including smokers ( n = 11) and lifelong non‐smokers with normal lung function ( n = 6) were stained with alcian blue, periodic acid–Schiff (PAS) and by immunohistochemistry of mucins (MUC): MUC2, MUC4, MUC5AC, MUC5B and MUC6. Histochemical staining and immunoreactivity of bronchiolar epithelium were graded and the presence or absence of stained mucus in the bronchiolar lumen was evaluated. There were no differences in alcian blue and PAS epithelial staining between the three groups. Intraluminal PAS staining was significantly more frequent among COPD subjects ( P < 0.05). The expression of MUC5AC was significantly higher in the bronchiolar epithelium of patients with COPD ( P < 0.05). Within the bronchiolar lumen, the predominant mucin was MUC5B. Intraluminal MUC5B was significantly more frequent among COPD patients ( P < 0.05). Conclusions: COPD is specifically associated with increased expression of MUC5B in the bronchiolar lumen and of the mucin MUC5AC in the bronchiolar epithelium. These changes in mucin production in the peripheral airways may contribute to the pathophysiology of COPD.