In vitro and in vivo degradation of poly(D, L-lactide-co-glycolide)/amorphous calcium phosphate copolymer coated on metal stents.
ABSTRACT The purpose of this study was to optimize a novel biodegradable polymer for drug eluting stent (DES) applications. Degradation profiles of different poly(D,L-lactide-co-glycolide)/amorphous calcium phosphate (PLGA/ACP) composites coated on stents were studied both in vitro and in vivo for three months. For the in vitro study, stents were immersed into the phosphate buffered saline (37 °C, pH 7.4) with constant shaking. The polymer weight loss was measured weekly and morphological changes were analyzed. The results demonstrated that approximately 60% of polymer was degraded within the three-month period and there was no significant difference between the different PLGA/ACP composites. However, the composite of 50% PLGA (65/35) with 50% ACP showed a slightly faster degradation rate than other composites. Morphologically, all stent surfaces changed from a micro-porous before degradation to a corrugated solid micro-net-like structure at two months post degradation. Based on in vitro results, 65% PLGA (65/35) with 35% ACP) coated stents were selected and implanted into rat aortas (n = 12) for the in vivo study. Microscopic observation showed that no composite was found on any of the implanted stents at 12 weeks post implantation, which indicated the selected PLGA/ACP composite is desired for DES applications.
Article: Sirolimus-eluting stents for treatment of patients with long atherosclerotic lesions in small coronary arteries: double-blind, randomised controlled trial (E-SIRIUS).[show abstract] [hide abstract]
ABSTRACT: Sirolimus-eluting stents have been developed to prevent restenosis in the treatment of coronary artery disease. We investigated the risk of restenosis with use of sirolimus-eluting stents compared with bare-metal stents to assess possible differences. We enrolled 352 patients in whom one coronary artery required treatment, with diameter 2.5-3.0 mm and lesion length 15-32 mm. We randomly assigned patients sirolimus-eluting stents (n=175) or bare-metal stents (control, n=177). At 8 months we assessed differences in minimum lumen diameter and binary restenosis within the lesion (restenosis of > or =50% diameter, including 5 mm vessel segments proximal and distal to stented segment). Patients were also followed up for 9 months for major adverse cardiac events. Analysis was by intention to treat. Stent implantation was successful in 100% of sirolimus-stent patients and 99.4% of controls. The mean diameter of treated coronary arteries was 2.55 mm (SD 0.37) and mean lesion length was 15.0 mm (6.0). Multiple stents were implanted in 170 (48%) patients. At 8 months, minimum lumen diameter was significantly higher with sirolimus-eluting stents than with control stents (2.22 vs 1.33 mm, p<0.0001). The rate of binary restenosis was significantly reduced with sirolimus-eluting stents compared with control stents (5.9 vs 42.3%, p=0.0001). Significantly fewer patients with sirolimus-eluting stents had major adverse cardiac events at 9 months than did controls (8.0 vs 22.6%, p=0.0002), due mainly to a lower need for target-lesion revascularisations (4.0 vs 20.9%, p<0.0001). Sirolimus-eluting stents are better than bare-metal stents for treatment of single long atherosclerotic lesions in a coronary vessel smaller than 3 mm in diameter.The Lancet 10/2003; 362(9390):1093-9. · 38.28 Impact Factor
Article: Clinical outcome of stent implantation in small coronary arteries using different types of coronary stents.[show abstract] [hide abstract]
ABSTRACT: We evaluated the results of stent placement in small coronary arteries. The subjects were divided into 2 groups: the first contained 911 lesions treated with stenting in the coronary arteries (stent group), and the second contained 1,203 background- and patient-matched lesions treated with balloon angioplasty (POBA group). There was no significant difference in the background of patients or lesions between the groups. A "small coronary artery" was defined as a coronary artery with a reference vessel diameter < 3.0 mm. There was no significant difference in incidence of acute myocardial infarction (AMI), coronary artery bypass grafting, or death between the groups. In the stent group, acute occlusion (0.8%) and subacute thrombosis (2.1%) occurred. The restenosis rate of 29.8% in the stent group was significantly lower than in the POBA group (38.2%; p < 0.01). The restenosis rate of 19.4% in stented vessels 3.0 mm diameter was significantly lower than in vessels < 3.0 mm diameter (29.8%; p < 0.01). The rate of restenosis was 22.9% for the Multi-Link stent, 24.4% for the NIR stent, 34.1% for the GFX stent, and 35.3% for the PS stent. The restenosis rate of 23.8% in stented vessels > 2.5 mm diameter and < or = 20 mm length was significantly lower than in vessels , < or = 2.5 mm diameter and > 20 mm length (32.7%; p < 0.01). Factors associated with restenosis, analyzed using a stepwise multivariate logistic regression model, included ostial lesions and post-procedural minimum lumen diameter. Stent implantation in vessels < 3.0 mm diameter using a newly designed coronary stent yielded favorable clinical results, while there was a high prevalence of restenosis, leading to diffused stenotic lesions, in vessels < 2.5 mm diameter.The Journal of invasive cardiology 09/2001; 13(9):634-9. · 1.84 Impact Factor
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ABSTRACT: The results of stent implantation for small coronary disease have been inconclusive. The purpose of the present study was to evaluate the factors in predicting the risk of angiographic restenosis after 2.5-mm stent implantation for small coronary arteries. The study group comprised 134 consecutive patients who had a reference small coronary artery with diameter from 1.8 mm to 2.5 mm on quantitative coronary angiography and who had been successfully treated by stent implantation with a 2.5-mm stent. Of the 134 patients, 55 had angiographic restenosis (41%). The rate of target lesion revascularization was 32%. Diabetes mellitus, acute coronary syndrome, lesion length, bifurcation lesion, lower left ventricular ejection fraction (LVEF), stent strut, stent/artery ratio, and stent length were identified as predictors of restenosis by univariate analysis. Subsequent multivariate analysis revealed that lower LVEF (odds ratio (OR) 3.37, p=0.01), bifurcation lesion (OR 2.47, p=0.04), thicker stent strut (OR 2.30, p=0.04), and longer stent length (OR 1.05, p=0.02) were significant predictors of restenosis. Two pre-interventional factors (reduced left ventricular function and bifurcated lesion) and 2 procedure-related factors (thickness of stent strut and total stent length) were identified as predictors of restenosis. These factors should be taken into account when deciding on the percutaneous coronary intervention strategy for small coronary artery disease.Circulation Journal 04/2004; 68(3):236-40. · 3.77 Impact Factor