5-Year clinical follow-up of the COBRA (complex coronary bifurcation lesions: Randomized comparison of a strategy using a dedicated self-expanding biolimus A9-eluting stent vs. a culotte strategy using everolimus-eluting stents) study.

OBJECTIVES: We evaluated healing responses with optical coherence tomography, and long-term clinical outcomes after treatment with a dedicated stent versus a conventional culotte technique. BACKGROUND: Dedicated bifurcation stents have been proposed as an alternative treatment for coronary bifurcation lesions. The long-term performance of dedicated stents versus conventional dual-stent techniques for the treatment of complex coronary bifurcation lesions is unknown. METHODS: Forty patients with true coronary bifurcation lesions were randomized to treatment with a dedicated Axxess bifurcation stent in the proximal main vessel and additional Biomatrix stents in branches versus culotte stenting using Xience stents. RESULTS: The percentage of uncovered struts in each bifurcation segment at 9 months (primary endpoint) was similar between groups. Five-year clinical follow-up was available for all patients and included major adverse cardiac events [MACE; a composite of cardiac death, myocardial infarction (MI) and ischemia-driven target lesion revascularization (TLR)], target-vessel (TVR) and non-target-vessel revascularization (non-TVR), non-TLR and stent thrombosis. At 5 years, in the culotte group, one patient had undergone TLR and another suffered a clinical MI, resulting in 10% MACE versus none in the Axxess group. TVR (5% vs. 10%, P = 0.54) and non-TVR (5% vs. 20%, P = 0.39) rates were similar between the Axxess and culotte groups, respectively. There was no stent thrombosis. CONCLUSION: Compared with culotte stenting with Xience, complex coronary bifurcation stenting using a dedicated strategy combining the Axxess and Biomatrix stents results in similar stent strut coverage at 9 months, and excellent clinical outcomes at 5 years.

Complex bifurcation lesions: Randomized comparison of a fully bioresorbable modified t stenting strategy versus bifurcation reconstruction with a dedicated self-expanding stent in combination with bioresorbable scaffolds, an OCT study: Rationale and design of the COBRA II trial.

OBJECTIVE: There is an ongoing controversy regarding the efficacy and safety of different percutaneous stenting techniques for coronary bifurcation lesions needing >1 stent. The promise of safe vessel restoration with bioresorbable scaffolds (BRS) may not be transferable to complex double BRS bifurcation techniques, and permanent metallic scaffolding of the bifurcation core may be needed. We identified modified-T stenting as the most promising fully bioresorbable 2-stent strategy in a preclinical setting. The objective of this study is to assess acute performance and compare long-term vessel healing with this strategy, versus an approach combining BRS with a dedicated metallic drug-eluting bifurcation stent. STUDY DESIGN: In a single center, 60 consecutive patients with true and complex coronary bifurcation lesions will be randomly assigned to treatment with the dedicated self-expanding Axxess™ biolimus-eluting bifurcation stent in the proximal main vessel and additional Absorb™ everolimus-eluting BRS in the branches versus a modified T technique using Absorb™ only. Angiography and optical coherence tomography (OCT) will be performed immediately after implantation and at 30 months, and clinical follow-up is foreseen up to 5 years after implantation. The primary endpoint is the change in minimal luminal area assessed with OCT from baseline to 30 months in pre-specified bifurcation segments. CONCLUSION: To date the use of Absorb™ BRS in complex coronary bifurcations has not been evaluated in a randomized clinical trial setting. The COBRA II study will examine the role and safety of a double BRS strategy in coronary bifurcations, alone or in combination with a metallic dedicated bifurcation device. © 2016 Wiley Periodicals, Inc.

Comparison of sirolimus eluting stent with bioresorbable polymer to everolimus eluting stent with permanent polymer in bifurcation lesions: Results from CENTURY II trial.

OBJECTIVE: To demonstrate the safety and efficacy of a new sirolimus eluting stent with bioresorbable polymer, Ultimaster, (BP-SES) compared with everolimus-eluting, permanent polymer, Xience stent (PP-EES) in bifurcation lesions with respect to the freedom from Target Lesion Failure at 1-year. METHODS: Within 1,119 patients enrolled in the CENTURY II randomized controlled multicenter trial, 194 patients were treated for bifurcation lesions and randomized to either BP-SES (n = 95) or PP-EES (n = 99). The primary endpoint was freedom from target lesion failure (TLF) composite endpoint [cardiac death, MI not clearly attributable to a non-target vessel, and clinically driven target lesion revascularization (TLR)] at 1-year. RESULTS: Baseline patient demographic, angiographic, and stenting characteristics were similar in both study arms. A single stent technique with provisional or "cross over" stenting were the most widely used in both arms (93.2% BP-SES vs. 92.4% PP-EES). Freedom from TLF at 1-year was 94.7% for BP-SES and 91.9% for PP-EES (P for noninferiority 0.031). The rate of clinically driven target lesion revascularization (TLR) at 1-year was 3.2% for BP-SES and 3.0% for PP-EES (P = 0.95). There were no significant differences detected in any of the individual clinical endpoints or other secondary clinical endpoints between the study arms at 1-year follow up. CONCLUSIONS: The new bioresorbable polymer sirolimus-eluting stent showed safety and efficacy profiles similar to durable polymer everolimus-eluting in the treatment of patients with bifurcation lesions at 1-year follow up. © 2015 Wiley Periodicals, Inc.

[Implementation of reperfusion therapy in ST segment elevation myocardial infarction (STEMI). A policy statement from the Belgian Society of Cardiology and its working group of acute cardiology and interventional cardiology]. / Mise en pratique du traitement de reperfusion dans les infarctus du myocarde avec élévation du segment ST.

Myocardial infarction remains a major healthcare problem. Reperfusion therapy has been shown to influence favourably short- and long-term patient survival. The authors reviewed the data of early recognition of STEMI (ST Elevation Myocardial Infarction), the reperfusion modalities including a flowchart management, as proposed by the Belgian working groups (BIWAC and BWGIC), and the lessons learned from European and American registries. Primary PCI often remains the treatment of choice. A national policy is still required to implement the guidelines and improve clinical practice for our STEMI patients.

[Implementation of reperfusion therapy in ST segment elevation myocardial infarction (STEMI). A policy statement from the Belgian Society of Cardiology and its working group of acute cardiology and interventional cardiology]. / Mise en pratique du traitement de reperfusion dans les infarctus du myocarde avec élévation du segment ST (STEMI). Recommandations actualisées de la Société Belge de Cardiologie et de ses groupes de travail: le Groupe Interdisciplinaire de Cardiologie Aiguë (BIWAC) et le Groupe de Cardiologie Interventionnelle (BWGIC).

Myocardial infarction remains a major healthcare problem. Reperfusion therapy has been shown to influence favourably short- and long-term patient survival. The authors reviewed the data of early recognition of STEMI (ST Elevation Myocardial Infarction), the reperfusion modalities including a flowchart management, as proposed by the Belgian working groups (BIWAC and BWGIC), and the lessons learned from European and American registries. Primary PCI often remains the treatment of choice. A national policy is still required to implement the guidelines and improve clinical practice for our STEMI patients.

Dynamic Performance of an Oil Starved Squeeze Film Damper Combined With a Cylindrical Roller Bearing.

Squeeze film dampers (SFDs) are widely used to dissipate mechanical energy caused by rotor vibrations as well as to improve overall stability of the rotor system. Especially turbomachine rotors, supported on little damped rolling element bearings (REBs), are primarily sensitive to unbalance excitation and thus high amplitude vibrations. To ensure safe operation, potential failure modes, such as an oil starved damper state, need to be well examined prior to the introduction in the ultimate industrial application. Hence, the aim of this research project is to evaluate the performance of the rotor support for a complete oil starvation of the SFD. An academic rotor dynamic test bench has been developed and briefly presented. Experimental testing has been conducted for two static radial load cases resembling the full load and idle condition of a certain turbomachine. Evidently, the measurement results exposed severe vibration problems. Even a split first whirl mode arises due to a pronounced anisotropic bearing stiffness. Moreover, for the least radially loaded bearing, highly nonlinear behavior emerged at elevated unbalance excitation. Consequently, the rollers start to rattle which will have a negative effect on the overall bearing lifetime. To explain the nature of the nonlinear behavior, advanced quasi-static bearing simulations are exploited. A number of possible solutions are proposed in order to help mitigate the vibration issues.

An investigation of flat panel equipment variables on image quality with a dedicated cardiac phantom.

Image quality (IQ) evaluation plays a key role in the process of optimization of new x-ray systems. Ideally, this process should be supported by real clinical images, but ethical issues and differences in anatomy and pathology of patients make it impossible. Phantom studies might overcome these issues. This paper presents the IQ evaluation of 30 cineangiographic films acquired with a cardiac flat panel system. The phantom used simulates the anatomy of the heart and allows the circulation of contrast agent boluses through coronary arteries. Variables investigated with influence on IQ and radiation dose are: tube potential, detector dose, added Copper filters, dynamic density optimization (DDO) and viewing angle. The IQ evaluation consisted of scoring 4 simulated calcified lesions located on different coronary artery segments in terms of degree of visualization. Eight cardiologists rated the lesions using a five-point scale ((1) lesion not visible to (5) very good visibility). Radiation doses associated to the angiograms are expressed in terms of incident air kerma (IAK) and effective dose that has been calculated with PCXMX software (STUK, Finland) from the exposure settings assuming a standard sized patient of 70 Kg. Mean IQ scores ranged from 1.68 to 4.88. The highest IQ scores were obtained for the angiograms acquired with tube potential 80 kVp, no added Cu filters, DDO 60%, RAO and LAO views and the highest entrance detector dose that has been used in the present study, namely 0.17 microGy/im. Radiation doses (IAK approximately 40 mGy and effective dose of 1 mSv) were estimated for angiograms acquired at 15 frames s(-1), detector field-of-view 20 cm, and a length of 5 s. The following parameters improved the IQ factor significantly: a change in tube potential from 96 to 80 kVp, detector dose from 0.10 microGy/im to 0.17 microGy/im, the absence of Copper filtration. DDO variable which is a post-processing parameter should be carefully evaluated because it alters the quality of the images independently of radiation exposure settings. The SAM anthropomorphic phantom has the advantage of visualization of stenotic lesions during the injection of a contrast agent and using an anatomical background. In the future, this phantom could potentially bridge the gap between physics tests and the clinical reality in the catheterization laboratory.

Prediction of the sound field above a patchwork of absorbing materials.

The aim of this paper is to investigate the acoustic performance of sound absorbing materials through a numerical wave based prediction technique. The final goal of this work is to get insight into the acoustic behavior of a combination of sound absorbing patches. In order to address a wide frequency range, a model based on the Trefftz approach is adopted. In this approach, the dynamic field variables are expressed in terms of global wave function expansions that satisfy the governing dynamic equations exactly. Therefore, approximation errors are associated only with the boundary conditions of the considered problem. This results in a computationally efficient technique. The main advantage of this method is the fact that the sound absorbing patches do not have to be locally reacting. In this article, the wave based method is described and experimentally validated for the case of normal incidence sound absorption identification in a standing wave tube. Afterwards, the method is applied to simulate some interesting setups of absorbing materials.

Radiation dose survey in a paediatric cardiac catheterisation laboratory equipped with flat-panel detectors.

Flat-panel X-ray detectors for fluoroscopy represent a modern imaging equipment that is being implemented in paediatric cardiac catheterisation laboratories. Infants and children represent a group of patients with a high radiosensitivity. A survey of 273 (126 diagnostic and 147 therapeutic) paediatric catheterisations was performed to investigate the radiation doses delivered by the new X-ray system. Statistical parameters (75th, 50th and 25th percentiles) of dose-area product (DAP) and fluoroscopy time are reported for patients divided into six age groups: 0-30 d, >1-12 m, >1-3, >3-5, >5-10 and >10-15 y. For accurate risk estimation, effective dose (E) has been determined for all patients using the PCXMC software. For diagnostic procedures, the third quartile of E ranges from 11.3 mSv for newborns to 7 mSv for children of 10-15 y. Therapeutic procedures are more complex than diagnostic. Consequently, the third quartile of E is 22.6 mSv (0-30 d), 18.6 (>1-12 m), 13.3 (>1-3 y), 21.5 (>3-5 y), 17.8 (>5-10 y) and 34.1 mSv (>10-15 y). Dose conversion factors, which relate the DAP and E, have been estimated for each age group. The results of this study may serve as a first step in the optimisation process, in order to make full use of the dose reduction potential of flat-panel systems.

Evaluation of automatic dose rate control for flat panel imaging using a spatial frequency domain figure of merit.

Current automatic dose rate controls (ADRCs) of dynamic x-ray imaging systems adjust their acquisition parameters in response to changes in patient thickness in order to achieve a constant signal level in the image receptor. This work compares a 3 parameter (3P) ADRC control to a more flexible 5-parameter (5P) method to meet this goal. A phantom composed of 15 composite poly(methyl) methacrylate (PMMA)/aluminium (Al) plates was imaged on a Siemens Artis Q dynamic system using standard 3P and 5P ADRC techniques. Phantom thickness covered a water equivalent thickness (WET) range of 2.5 cm to 37.5 cm. Acquisition parameter settings (tube potential, tube current, pulse length, copper filtration and focus size) and phantom entrance air kerma rate (EAKR) were recorded as the thickness changed. Signal difference to noise ratio (SDNR) was measured using a 0.3 mm iron insert centred in the PMMA stack, positioned at the system isocentre. SDNR was then multiplied by modulation transfer function (MTF) based correction factors for focal spot penumbral blurring and motion blurring, to give a spatial frequency dependent parameter, SDNR(u). These MTF correction factors were evaluated for an object motion of 25 mm s-1 and at a spatial frequency of 1.4 mm-1 in the object plane, typical for cardiac imaging. The figure of merit (FOM) was calculated as SDNR(u)²/EAKR for the two ADRC regimes. Using 5P versus 3P technique showed clear improvements over all thicknesses. Averaged over clinically relevant adult WET values (20 cm-37.5 cm), EAKR was reduced by 13% and 27% for fluoroscopy and acquisition modes, respectively, while the SDNR(u) based FOM increased by 16% and 34% for fluoroscopy and acquisition. In conclusion, the generalized FOM, taking into account the influence of focus size and object motion, showed benefit in terms of image quality and patient dose for the 5-parameter control over 3-parameter method for the ADRC programming of dynamic x-ray imaging systems.