Examination of the coatings of coronary stents

In our study the main properties of coated coronary stents are shown, such as foreshortening, recoil, surface features and failures and the expansion properties. The types and the effects of active and passive coatings are introduced. The results of our examinations with different coated coronary stents are shown as well

Different properties of coronary stents

Stents are mesh structured implants which are used to support the vessel wall in the balloon expanded vessel part. Several methods were developed and applied for the determination of mechanical properties of coronary stents, as a part of a complex pre-clinical in vitro diagnostic system: radiopacity, flaring, metallic surface area and fatigue tests. Three pieces of equipment were assembled for the examination of fatigue properties. The first method simulates the bending stress in the coronary arteries; the second method simulates the effect of the cylindrical mechanical strain which is equivalent to the systolic and diastolic pulse in the coronary arteries; and the third method is using the energy of the ultrasound concentrating to the stent. After fatigue tests stereomicroscopy, optical microscopy, scanning electron microscopy were used for the determination of surface quality and condition. The most frequent failures were scratches, pits and small shrinkage of materials originated from the manufacturing and finishing processes. Because of fatigue tests slip lines occurred in the critical curves, grain boundaries were outlined, the surface of the struts become rough, but these mutations do not affect the functionality of the stents

Development and Examination of Coated Coronary Stents

The aim of this study is to show the developments carried out by us with coated stents, expansion properties, furthermore the failures of the coatings. The coating was examined before and after expansion, paying special attention to the curves. The quality and the changing of the coatings were examined by different methods: optical microscopy, atomic force microscopy, scanning electron microscopy and EDS analysis. The results show that the expansion to a higher pressure did not change the coating. Polyurethane coating was given to TentAur stents. The coatings were produced by a method of dipping. The sterile and dust free environment is crucial to produce a suitable coating. Electro-polished and non-electro-polished sheets and stents were used for these experiments. The quality and the changing of the coatings were examined by different methods after drying. The fatigue tests showed that the polyurethane coating had suitable adherence

Investigation of coated coronary stents

In this study the main properties of coated coronary stents are shown, such as recoil, foreshortening, surface features and failures and the expansion properties. The types and the effects of active and passive coatings are introduced. The results of our examinations with different coated coronary stents are shown as well. The quality and the changing of the coatings were examined by different methods (stereomicroscopy, atomic force microscopy, scanning electron microscopy and EDS analysis)

Mechanical Behaviours of Coronary Stents

The role of the stents is to prevent restenosis. The rapid growth of stents’ application in the treatment of cardiovascular diseases resulted in the unique development of these implants. This is mainly due to the effective clinical trials, the success of which determined the use of these endoprostheses. In this study the surface properties of the coronary stents were described by using different methods (stereomicroscopy, scanning electron microscopy and energy dispersive analysis) before and after balloon expansion. Furthermore, the most frequent failures caused by the expansion were introduced. For investigating fatigue properties two high cycle fatigue test equipments were used: the first one simulates the bending stress, and the second one simulates the effect of the pulsating mechanical strain. Surface features of the stents were examined after the fatigue tests as well: macroscopic damages were not originated on the stents, and the implants were not broken down. Only small traces of fatigue occurred on the surface, which became rough; and slip lines and grain boundaries were outlined

Haemocompatible Coatings of Coronary Stents

The main goal of the present study was to determine the surface features, surface failures and fatigue properties of coated coronary stents. The quality and the changing of the coatings were examined by different methods. In this paper, the results of the examinations with different coated coronary stents are introduced and the results of the coating experiments are shown as well

Polyurethane Coating on Coronary Stents

Stents are special metallic or polymer endoprostheses of meshed structure and tube shape. Their function is to prevent restenosis in the arteries. Stents can be coated or uncoated. In the expanded part of the artery the chance of restenosis is bigger even without a stent so it is practical to coat the stents. The aim of this work is to present the results of the coating experiments made on the coronary stents. Three types of commercially available polyurethanes were used for these experiments. The coatings were produced by a dipping method. Electro-polished and non-electro-polished metallic sheets and stents were used for these experiments. Contact angle measurements were done to examine the wetting properties of the three different polyurethane coatings. The quality and the changing of the coatings were examined by different methods (stereomicroscope, scanning electron microscope and energy dispersive spectrometry)

CD39 and CD73 in immunity and inflammation

The enzymatic activities of CD39 and CD73 play strategic roles in calibrating the duration, magnitude, and chemical nature of purinergic signals delivered to immune cells through the conversion of ADP/ATP to AMP and AMP to adenosine, respectively. This drives a shift from an ATP-driven proinflammatory environment to an anti-inflammatory milieu induced by adenosine. The CD39/CD73 pathway changes dynamically with the pathophysiological context in which it is embedded. It is becoming increasingly appreciated that altering this catabolic machinery can change the course or dictate the outcome of several pathophysiological events, such as AIDS, autoimmune diseases, infections, atherosclerosis, ischemia-reperfusion injury, and cancer, suggesting these ectoenzymes are novel therapeutic targets for managing a variety of disorders