No abstract available.
Hyperplasia* ; Neointima* ; Thalidomide*

No abstract available.
Hyperplasia* ; Neointima* ; Thalidomide*

The purpose of this study was to investigate the patency rates and the histologic findings of neoendothelialization according to the length of implanted polytetrafluoroethylene (PTFE) with an internal diameter of 3mm. Under the operating microscope, grafts of 8 and 24mm in length were implanted in the right carotid arteries of thirty rabbits by interrupted end-to-end microanastomosis. They were divided into two groups according to the length of implanted PTFE. Each group had fifteen rabbits. All implanted grafts were 25micro meter in fibril length and 0.39mm in wall thickness. Three grafts per group were harvested at 1, 2, 4, 8, and 12 weeks after implantation and all grafts were observed for patency rates and the histologic findings with a light microscope and scanning electron microscope. In conclusion, there was no difference in patency rates according to the length of implanted PTFE. However, the formation of neointima and subintimal tissue was delayed and incomplete in the longer implanted PTFE group.
Carotid Arteries ; Neointima ; Polytetrafluoroethylene* ; Rabbits ; Transplants

The purpose of this study was to investigate the patency rates and the histologic findings of neoen- dothelialization according to the length of implanted polytetrafluoroethylene (PTFE) with an internal diameter of 3 mm. Under the operating microscope, grafts of 8 and 24 mm in length were implanted in the right carotid arteries of thirty rabbits by interrupted end-to-end microanastomosis. They were divided into two groups according to the length of implanted PTFE. Each group compised fifteen rabbits. All implanted grafts were 25 pm in fibril length and 0.39 mm in wall thickness. Three grafts per group were harvested at 1, 2, 4, 8, and 12 weeks after implantation respectively and all grafts were observed for patency rates and the histologic findings with light microscope and scanning electron microscope. In conclusion, there was no difference in patency rates according to the length of implanted PTFE and histologically the formation of neointima and subintimal tissue was delayed and incomplete in longer implanted PTFE.
Carotid Arteries ; Neointima ; Polytetrafluoroethylene* ; Rabbits ; Transplants

Neointimal hyperplasia is the main mechanism of stent restenosis. Therefore, drug-eluting stents have replaced bare metal stents because there is less neointima and scar formation. Recently, some cases of stent restenosis after using a bare metal stent were found to involve calcification, not neointimal hyperplasia, and regarded as de novo atherosclerosis. We report unusual circular calcification inside a drug-eluting stent, which we called neointimal calcification.
Atherosclerosis ; Cicatrix ; Drug-Eluting Stents ; Hyperplasia ; Neointima ; Stents

Neointimal hyperplasia is the main mechanism of stent restenosis. Therefore, drug-eluting stents have replaced bare metal stents because there is less neointima and scar formation. Recently, some cases of stent restenosis after using a bare metal stent were found to involve calcification, not neointimal hyperplasia, and regarded as de novo atherosclerosis. We report unusual circular calcification inside a drug-eluting stent, which we called neointimal calcification.
Atherosclerosis ; Cicatrix ; Drug-Eluting Stents ; Hyperplasia ; Neointima ; Stents

BACKGROUND: One of most important mechanisms of coronary stent restenosis is neointimal hyperplasia. Although the process of neointima formation is not fully understood, a special role has been advocated for adherent platelets. Previous studies have shown a clear benefit with combined antiplatelet therapy such as aspirin plus ticlopidine in reducing the rate of thrombotic occlusions of stented vessels. The purpose of this study was to evaluate the effects of duration of antiplatelet regimens on coronary stent restenosis. METHODS: After successful placement of coronary artery stents in 222 patients, we performed follow-up coronary angiograms in 99 patients (42.3%). Forty-six patients were randomly assi-gned to receive aspirin and ticlopidine for four weeks (Group I: 54+/-9 years: M 38, F 8) and 48 patients for 6 months (Group II: 58+/-8 years: M 38, F 10). RESULTS: There were no significant differences in clinical and procedural variables or coronary lesion characteristics before and after stenting. At 6 months after stenting, minimal luminal diameter was 2.16+/-0.93mm in Group I and 2.04+/-1.07mm in Group II (p-0.57). Late lumen loss was 0.80+/-1.07mm in Group I and 0.92+/-1.11mm (p-0.58) in Group II. The stent restenosis rate of Group I at 28.3% and that of Group II at 29.2% were not statistically significant between the two groups (p-0.92). CONCLUSIONS: The therapeutic duration of combined antiplatelet regimen with aspirin and ticlopidine after coronary stent does not affect stent restenosis rate.
Aspirin* ; Coronary Vessels ; Follow-Up Studies ; Humans ; Hyperplasia ; Neointima ; Phenobarbital ; Stents* ; Ticlopidine*

PURPOSE: To evaluate the effect of dexamethasone(DM) and polyurethane(PU)-coated nitinol stent on neointimal formation in the canine great vessels. MATERIALS AND METHODS: Thirty-six nitinol wire stents were implanted in the abdominal aorta and inferior vena cava(IVC) of six dogs. In each animal, six different types of stent (NC, non-coated; PU, polyurethane coated; DM, DM and polyurethane coated) were serially positioned in permutationally possible order in the aorta below the renal arteries and in the IVC below the renal veins. For DM stent an in-vitro drug release test was performed to determine the stability of DM release. The thickness of the intima and media of the aorta and of the intima of the IVC were measured three (n=3) or six months (n=3) after stent placement at and between the wires. RESULTS: In the in-vitro study, 25% of DM was released during the first week, and the subsequent release rate was 3 microgram/day for 6 months. The intima-to-media ratio of DM-stented aorta was less than in aortas where PU or NC stents were used (p<0.05). The neointima thickness of DM stent in the IVC was less than that of PU stent (p<0.05). These differences were less prominent between the wires than at them, and there was no significant difference between the three-and six-month groups (p>0.05). CONCLUSION: In this canine great vessel model, newly designed DM-coated nitinol stent decreased neointimal formation.
Animals ; Aorta ; Aorta, Abdominal ; Dexamethasone* ; Dogs ; Neointima ; Polyurethanes ; Renal Artery ; Renal Veins ; Stents*

BACKGROUND AND OBJECTIVES: Radiation therapy is one of the promising new treatment for restenosis, which is a major problem for the long-term success after angioplasty. We compared radiation therapy only and combined therapy of paclitaxel and radiation on neointimal hyperplasia after injury of rat carotid artery to see whether we can reduce the effective dosage of radiation and thus diminish untoward consequence of radiation if paclitaxel could function as a cell-cycle selective radiosensitizer. MATERIAL AND METHODS: A standardized carotid balloon catheter arterial injury was produced in 65 rats. First group was composed of a single dose of paclitaxel 1 mg/kg body weight, 2 mg/kg or 4 mg/kg, which was administrated intraperitoneally at 2 hours after injury. Second group received external radiation at doses of 2.5 or 5 Gy at 24 hours after injury. Third group was treated with combined paclitaxel-radiation: paclitaxel was injected at 2 hours after injury and then external radiation was delivered 24 hours later. At 21 days after injury, the cross-sectional area of neointima and the ratio of intima/medial area were determined from axial sections using image analysis. RESULTS: Single dose of paclitaxel had no effect in reducing smooth muscle cell proliferation. Minimum effective single dose to inhibit neointimal hyperplasia was 5 Gy. Combined paclitaxel-radiation group except subgroup with paclitaxel 1 mg/kg and 2.5 Gy radiation showed significant reduction of neointimal area compared to group with 2.5 Gy radiation. CONCLUSION: Low-dose external radiation combined with paclitaxel can more effectively inhibit smooth muscle cell pro-liferation and neointimal hyperplasia than radiation only in the rat carotid injury model.
Angioplasty ; Animals ; Body Weight ; Carotid Arteries ; Catheters ; Hyperplasia* ; Myocytes, Smooth Muscle ; Neointima ; Paclitaxel* ; Radiation Dosage ; Rats*

BACKGROUND AND OBJECTIVES: Artemisinin and dihydroartemisinin are drugs used to treat malaria. These drugs suppress inflammatory reactions. The aim of this study was to examine the anti-intima hyperplasia effect of a novel drug-eluting stent with artemisinin or dihydroartemisinin in a porcine coronary restenosis model. MATERIALS AND METHODS: Pigs were randomized into four groups; in the first, the coronary arteries (20 pigs, a total of 40 coronary arteries, with 10 coronary arteries in each group) was implanted with bare metal stents (BMS, n=10); the second group was given polymer-coated stents (PCS, n=10); the third group was treated with artemisinin-eluting stents (AES, n=10); and the fourth group was given dihydroartemisinin-eluting stents (DAES, n=10). Histopathologic analysis was performed 28 days after stenting. RESULTS: The injury and fibrin scores among the four groups were not significantly different. However, the internal elastic lamina, lumen area, and neointima area were significantly different. Moreover, the percent area of stenosis (46.2±18.66% in BMS vs. 89.4±10.92% in PCS vs. 83.3±17.07% in AES vs. 36.7±11.20% in DAES, p<0.0001) and inflammation score (1.0 [range: 1.0-1.0] vs. 3.0 [range: 2.25-3.0] vs. 3.0 [range: 1.0-3.0] vs. 2.0 [range: 1.75-3.0] in BMS, PCS, AES, and DAES, respectively; p<0.001) were markedly decreased in the DAES group compared to the PCS group. CONCLUSION: DES, which uses a natural substance, dihydroartemisinin, showed a neointima and inflammatory suppressive effect in a porcine coronary restenosis model.
Constriction, Pathologic ; Coronary Restenosis* ; Coronary Vessels ; Drug-Eluting Stents ; Fibrin ; Hyperplasia ; Inflammation ; Malaria ; Neointima ; Stents* ; Swine