Due to the enormous burden of disease and escalating healthcare costs, there is now renewed interest in the underlying cellular and molecular mechanisms of chronic obstructive pulmonary disease (COPD) [1, 2] and a search for new therapies [3]. The definition of COPD was adopted by the Global Initiative on Chronic Obstructive Lung Disease and for the first time this definition encompassed the idea that COPD is a chronic inflammatory disease [4]. Much of the recent research has focused on the nature of this inflammatory response.
Local stent-based drug delivery (drug-eluting stent - DES) is a new technology aimed to prevent the development of neointimal hyperplasia and restenosis following percutaneous coronary interventions. A number of DESs have been developed using different carrier stents, different kind of coatings, and different drugs. However, to date only two polymer-coated DESs (the Cypher sirolimus-eluting stent from Cordis, Johnson & Johnson, Miami Lake, FL, USA; and the Taxus paclitaxel-eluting stent, Boston Scientific, Natick, MA, USA) have become commercially available after a number of randomized trials showed their ability to reduce late luminal loss, binary restenosis and the need for repeat revascularization when compared to bare metal stents. This review describes the general concept of DES and summarizes the results of the principal clinical trials on DESs, both approved for clinical use or under development. For the marketed stents, we also report the results of the first clinical evaluations in real life and a few insights into the most controversial issues.
In a model of early and aggressive vein graft stenosis in pigs, an intervention was performed with a single stent (n = 12 grafts), multiple stents (n = 6), or balloon angioplasty (n = 6), while grafts with mild stenoses were left untreated (n = 8). Four weeks after intervention, angiography showed that grafts with single stents, balloon angioplasty, or untreated grafts had patency rates of 92%, 83%, and 83%, respectively. Grafts receiving multiple stents, however, showed only a 17% patency rate (p < 0.05). Balloon dilatation or placement of a single stent improved the angiographic minimal diameter by 0.6 ± 0.2 and 0.8 ± 0.3 mm, respectively, over the short term, but this gain was lost during the follow-up period. Multiple stents showed a similar gain (0.5 ± 0.2 mm) but more loss occurred during the follow-up period (2.4 ± 0.2 mm). Histology revealed no significant differences between the treatment groups except for the prolonged presence of thrombus remnants in association with the stent wires. In conclusion, single stents and balloon angioplasty show good patency in early saphenous vein graft narrowing but multiple stents show a high occlusion rate.
The success rates of coronary angioplasty for the treatment of chronic total occlusions are less favorable than for coronary stenosis. Therefore, a new laser guidewire (LW) was designed to facilitate the crossing of chronic total occlusions. We report on the results of a European multicenter surveillance study, evaluating the laser guidewire performance. Between May 1994 and July 1996, 345 patients (age 59 ± 10 years, 291 men) with chronic total occlusions were enrolled in 28 European centers. The median age of occlusion was 29 weeks (range 2 to 884), the occlusion length 19 ± 10 mm. LW recanalization was successful in 205 patients (59%). LW perforation occurred in 73 patients (21%), with hemodynamic consequences in 4 (1%). There were no deaths, emergency coronary artery bypass graft surgery, or Q-wave myocardial infarctions. In a multivariate regression analysis an occlusion age of <40 weeks (p = 0.001, RR = 1.34) and an occlusion length <30 mm (p = 0.01, RR = 1.59) were independent predictors of success. Results indicate that the LW is an effective and safe tool in the treatment of chronic total occlusion refractory to conventional guidewires.
