Clinical Experience with Wiktor Stent Implantation: A Report from the French Multicentric Registry

Our objective was to evaluate, in a French multicenter study, the results of implantation of Wiktor tantalum wire coronary stents in stenosed or occluded coronary vessels or in saphenous vein bypass grafts. The study was a retrospective analysis of clinical and angiographic data from patients treated with tantalum wire stent implanted at five centers. Stenting of native coronary arteries or saphenous vein bypass grafts was attempted in 272 patients after acute or threatened closure of the target vessel, or because the lesions concerned were considered to be at particularly high risk of becoming restenosed, or because the result of primary angioplasty was inadequate. Successful stent deployment was achieved in 261 95.9%) of 272 patients. The incidence of major complications such as death, myocardial infarction (MI), or a condition requiring urgent bypass surgery was 8.1%. Major vascular complications occurred in 2.6% and actually decreased with a new anticoagulant regimen. Angiographic follow-up at a mean of 6 months after stenting showed restenosis in 23.6% with a more frequent restenosis in the group with stent size equal to 3 mm than in the group with stent size superior to 3 mm (46.1% vs 13.7%, P < 0.01). Stenting with the Wiktor tantalum wire stent is an effective means of treating acute complications and suboptimal results after angioplasty. This stent seems to offer hope of a significant reduction in the rate of late restenosis in native coronary vessels, but a prospective comparison of balloon angioplasty and stenting is needed .     

Clinical experience with the Wiktor stent in native coronary arteries and coronary bypass grafts.

OBJECTIVES--To evaluate the results of implantation of Wiktor tantalum wire coronary stents in stenosed or occluded coronary vessels or in saphenous vein bypass grafts. DESIGN--A retrospective analysis of clinical and angiographic data from patients treated with tantalum wire stents implanted by one operator at two centres. PATIENTS--52 patients undergoing conventional balloon angioplasty had 67 lesions treated by stents after acute or threatened closure of the target vessel, or because the lesions concerned were considered to be at particularly high risk of becoming restenosed, or because the result of primary angioplasty was inadequate. RESULTS--65 of the 67 lesions were successfully stented although in two cases the first attempt failed and a second stent was then implanted successfully. There were no cases of stent occlusion and no myocardial infarctions in hospital or in the follow up period of 1-20 months. Eight patients had haemorrhagic complications that were minor in 4. One patient later had coronary bypass surgery after failure to stent a lesion. Angiographic follow up at a mean of 6 months after stenting showed restenosis associated with 4 of 47 stents studied. All patients with chest pain had had repeat angiography, and 84% of those without symptoms also agreed to reinvestigation after about 6 months. CONCLUSIONS--The Wiktor tantalum wire stent is an effective means of treating acute complications during angioplasty and seems to offer hope of a significant reduction in the rate of late restenosis in both native coronary vessels and saphenous vein bypass grafts. A prospective comparison of balloon angioplasty and stenting is needed.     

Morphological and histological studies of in-stent restenosis in seven types of stents implanted in porcine coronary arteries]

OBJECTIVES: Differences in the mechanism of restenosis after stenting between coil and tubular stents were examined in porcine coronary arteries using histological and immunohistochemical methods. METHODS: Twenty-four pigs underwent balloon-induced injury in the left anterior descending coronary artery. Two weeks later, seven different stents clinically available in Japan (Coil stents: GR I, GR II, Wiktor, Cordis; Tubular stents: gfx, Multilink, Palmaz-Schatz) were implanted in the injured site. Four weeks after the stent implantation, the pigs were sacrificed for histological examination and for morphometrical analysis of the lumen, neointima, media and adventitia. Immunohistochemical studies using anti-proliferating cell nuclear antigen (PCNA), anti-alpha-smooth muscle actin and anti-macrophage antibody were also performed. RESULTS: The coil stents formed eccentric, and the tubular stents formed concentric neointimal proliferation. Although there was no difference in the area of neointima between the stents, the area of lumen in the tubular stents was bigger than that in the coil stents (p < 0.01), because the vascular area was bigger in the tubular stents (p < 0.05). Immunohistochemical examination found many PCNA-positive cells in the proliferated neointima, especially in the area around the stent strut. Many of these cells around the stent strut were positively stained by anti-macrophage antibody. Other cells positively stained for PCNA were confirmed as smooth muscle cells. CONCLUSIONS: Tubular stents maintained a wider lumen than coil stents, because negative remodeling after stenting was less in the tubular stents. Implantation of stents with less negative remodeling is very important to prevent restenosis after stenting.     

Optical coherence tomography-guided stenting of a large coronary aneurysm: images at implantation and at 6 months

Intravascular imaging with optical coherence tomography (OCT) can produce high-resolution images (10-20 μm) of the coronary vessel wall and is being increasingly used to provide insight into coronary pathology and neointima formation following coronary stenting. Fourier domain OCT (FD-OCT) permits a greater scan diameter than time domain OCT and enables larger-caliber coronary structures to be effectively imaged. We present a case of a large, symptomatic and expanding right coronary artery aneurysm treated with FD-OCT-guided pericardial covered stenting and describe the OCT findings immediately after stent deployment and at 6 months.     

Use of a second buddy wire during percutaneous coronary interventions: a simple solution for some challenging situations

The buddy wire technique, i.e. the use of a second 0.014 inch guide wire placed alongside the one employed to advance balloons and stents inside the coronary artery during percutaneous coronary intervention (PCI), may help in a series of procedural challenges during PCI. Indeed, by improving both the stability of the guiding catheter and the support for balloon and stent, a buddy wire use is sometimes the simplest way to accomplish a successful procedure. In this paper, we discuss technical aspects of some specific circumstances frequently encountered during PCI, in which a buddy wire may be helpful. These include: 1) The reduction of balloon slippage during angioplasty for in-stent restenosis; 2) insufficient back-up of the guiding catheter; 3) stenting of lesions located in vessels with proximal tortuosities/angulations; 4) stenting of lesions distally located in the vessel; 5) facilitation in the positioning of distal protection devices; 6) stenting of a lesion distally located from a previously implanted stent or from a coronary segment with both calcification and sharp bend; 7) PCI on coronary arteries with anomalous origin. Because of its simplicity, low cost, and availability, the use of a buddy wire should be considered when dealing with the aforementioned conditions during PCI procedures.     

A new rat model of small vessel stenting

Objectives: Restenosis is the major complication of coronary angioplasty and stenting. In addition, the small vessel diameter represents a major limitation to the wide use of the technology. The aim of this study was to assess the feasibility and the vascular response of stent deployment in rat small vessels. Methods: In 40 Wistar rats (500–550 g) a Nir stent crimped on a 1.5 mm Comet angioplasty balloon catheter was deployed at high pressure in the common carotid artery. Neointimal area, neointima/media ratio and the arterial dimension were assessed immediately and at 7, 14, 21, and 28 days after stenting. Results: After stent deployment, the neointimal area and the neointima/media ratio increased progressively and peaked at 14 days (p < 0.05 vs 0 and 7 days). Alpha-actin-positive cells were found circumferentially organized on the lumen surface. At 21 and 28 days after stenting, the neointima and the neointima/media ratio were not statistically different compared with the results obtained fourteen days after stent deployment. No significant differences in the area of external elastic lamina were observed during the study period. In contrast, the internal lumen area was reduced significantly at 14, 21, and 28 days after the stent deployment. Subacute thrombosis rate after stent implantation was 26.5%. Conclusions: The results of this study demonstrated that the balloon expandable stents can be safely placed into rat arteries and the reduction of the internal arterial lumen observed after stent deployment was only due to the neointima formation whereas remodeling did not occur. Received: 5 August 1999, Returned for 1. revision: 6 October 1999, 1. Revision received: 23 November 1999, Returned for 2. revision: 7 December 1999, 2. Revision received: 22 December 1999, Accepted: 6 January 2000     

冠状动脉内置入自制钽丝支架的实验研究

目的为了评估冠状动脉内自制支架的生物学效应。方法将１７枚自制的钽丝支架置入１２头小型猪的冠状动脉内，并观察了置入后６个月的结果。实验表明，置入支架后冠状血管未见局部组织排异反应，新生内膜的增殖呈时相性过程；在３个月时，新生内膜的增殖达到峰值，其成份主要是大量增殖的平滑肌细胞和细胞外基质；并且，新生内膜增殖的程度与血管损伤程度成正相关。结论这种自制钽丝支架具有良好的Ｘ光下可视性，能够快速、准确、定点释放     

Six-month Follow-up of Successful Stenting for Acute Dissection After Coronary Angioplasty: Comparison Between Slotted Tube (Palmaz-Schatz) and Flexible Coil (Gianturco-Roubin) Stent Designs

The aim of this study was to evaluate the influence that two different stent designs may have in late outcome following successful coronary stent implantation for acute dissection after balloon angioplasty. In the present study, 50 consecutive patients were matched to compare late outcome between the use of slotted tube (Palmaz-Schatz) and flexible coil (Gianturco-Roubin) stent designs (25 in each group). Group matching was performed according to vessel size, location of target lesion, and dissection type among patients undergoing successful coronary stenting to treat an acute dissection following balloon coronary angioplasty. Poststent minimal luminal diameter (2.46 ± 0.49 mm vs 2.35 ± 0.47 mm, not significant [NS]) and acute luminal gain (2.02 ± 0.61 mm vs 1.85 ± 0.56 mm, NS) were similar in slotted tube and flexible coil stent groups, respectively. However, at 6-month follow-up, late loss in luminal diameter was larger in lesions treated with a flexible coil stent (0.96 ± 0.75 mm vs 0.62 ± 0.55 mm, P = 0.05), and minimal luminal diameter was smaller in those lesions treated with a flexible coil stent (1.38 ± 0.87 mm vs 1.84 ± 0.63 mm, P < 0.05). Angiographic restenosis (> 50% diameter narrowing) occured in four lesions treated with a slotted tube stent (16%) compared to ten lesions treated with a flexible coil stent (40%, P < 0.05). The design of the coronary stent may have significant influence in the late lesion outcome. In patients with acute dissection following balloon coronary angioplasty, use of a slotted tube stent design (Palmaz-Schatz) may result in lower late loss and larger luminal diameter at 6-month follow-up than use of a flexible coil stent design (Gianturco-Roubin).     

冠状动脉支架置入后局部内膜增生模式的探讨

目的探讨冠状动脉支架置入局部血管内膜的增生模式。方法建立冠状动脉支架置入的广西种的微型猪模型。分别于支架置入后3,7,28,90和180 d截取支架段血管连同临近的近端正常血管段,进行病理组织学检查和聚合酶链反应检测支架局部血管内膜增生情况。结果正常血管段表达增殖细胞核抗原(proliferating cell nuclear antigen,PCNA)mRNA在各个时间段没有显著性差异。支架置入后3 d局部血管壁PCNA mRNA的表达明显增高。并在术后7 d达到高峰。术后90 d PCNA mRNA的表达呈现下降的趋势,但仍显著高于正常血管段,并且差异一直持续到术后180 d。术后7～180 d支架段内膜及中膜面积明显大于正常血管段。结论冠状动脉支架置入后局部内膜呈现了一种持续过度的增生反应。     

Coronary artery aneurysm after implantation of an endothelial progenitor cell capturing stent

The Genous? stent coated with anti-CD34 antibodies has been designed to accelerate healing of the vessel by attracting circulating endothelial progenitor cells. Rapid restoration of a functional endothelial layer with a full coverage of the stent struts aims to minimise arterial injury after coronary stenting and to prevent thrombus formation and neointima proliferation. We report a case of a 56 year-old man who developed a coronary artery aneurysm after the implantation of a Genous? stent due to an edge restenosis in sirolimus-eluting stent. We present diagnostics of our patient with the application of intravascular ultrasound and coronary computed tomography angiography, discuss his management, and hypothesise about the pathomechanism of aneurysm formation.     

Coronary morphologic findings after stent implantation

Clinical studies demonstrated a reduction of acute complications by high-pressure stenting. This study was performed to correlate the histomorphologic changes of the vessel wall after coronary stenting with stent expansion pressure. We studied the effects of intravital and postmortem stenting on coronary morphology in human hearts. Artifact-free analysis and morphometry of the artery segments' cross section was performed after plastic resin embedding and cutting and grinding sectioning. By comparing intra- and postmortem findings we demonstrated that postmortem stent implantation can serve as an adequate model to study the mechanical effects of coronary stenting. A consistent histologic feature was eccentric stent expansion. Larger calcified areas of the vessel wall were not deformed by implanted stents. The highest degree of vessel injury and deformation was apparent in anatomically "nondiseased" or only slightly fibrotic parts of the arterial wall. Dissections were predominantly located directly adjacent to calcified plaques and appeared as "half-moon"-like tears reaching into the arterial media. A statistically significant stent lumen gain was found when the implantation pressure was increased up to 15 atm. Stent symmetry was not influenced by the applied implantation pressure but depended mostly on local coronary morphology. Thus, increasing implantation pressures during coronary stenting seemed to improve the stenting result up to 15 atm. When applying histomorphologic criteria, the higher pressures (>15 atm) did not cause further optimization of stent expansion. Morphometric analysis of stents implanted postmortemly and intravitally revealed comparable results. Postmortem stenting seems to be an appropriate model for studying stent expansion and stenting results in human coronary arteries.     

Inhibition of neointima formation by tranilast in pig coronary arteries after balloon angioplasty and stent implantation

OBJECTIVES: We evaluated the effect of orally administered tranilast, N-(3,4-dimethoxycinnamoyl) anthranilic acid, on histologic and histomorphometric changes after angioplasty or stent implantation in pig coronary arteries. BACKGROUND: Tranilast, which has antikeloid and antiallergic properties and therefore may modulate the fibrotic and inflammatory tissue responses to angioplasty and stenting, has been shown to inhibit angiographic restenosis in small clinical trials. However, its effect on histomorphometric changes in coronary arteries after angioplasty and stenting is unknown. METHODS: Following initial pharmacokinetic studies in two pigs to determine desirable plasma levels of orally administered tranilast, 36 crossbred juvenile pigs were randomized to placebo or tranilast before undergoing balloon angioplasty in both the left anterior descending and left circumflex plus stent implantation in the right coronary artery. Oral tranilast was administered at 3 g/day starting 3 days before coronary injury and continued for 28 days until euthanasia. Injured vessels were harvested and sections analyzed by computer-assisted microscopic planimetry. RESULTS: In balloon-injured vessels, tranilast was associated with a 37% reduction in neointimal area normalized to fracture length (0.47 +/- 0.01 vs. 0.74 +/- 0.03 mm; p < 0.001) and a 23% reduction in adventitial area normalized to vessel size (0.43 +/- 0.02 vs. 0.56 +/- 0.03; p = 0.003). In stented arteries, neointimal area normalized to injury score was 32% lower in the tranilast-treated group compared to control (1.94 +/- 0.17 vs. 2.86 +/- 0.29; p = 0.01). CONCLUSIONS: In pig coronary arteries, tranilast was associated with a reduction in neointima formation and adventitial reaction after balloon injury. In stented vessels, tranilast was associated with a reduction in neointima formation normalized to injury score.     

Histologic comparison of coronary and iliac atherectomy tissue from cases of in-stent restenosis

Pathologically, restenotic lesions after stenting were investigated by use of atherectomized tissues of seven coronary and seven iliac arteries. The mean interval of the stent deployment to restenosis was 9.1 months for the coronary artery and 33.7 months for the iliac artery, indicating a 3.7-fold longer interval for the latter. This study does not include cases of acute thrombotic occlusion. The atherectomized tissue from restenotic coronary arteries showed abundant neointima with alpha-actin-positive and ultrastructually synthetic-type smooth muscle cells in a rich myxomatous extracellular matrix. In the iliac arteries, the predominant component of restenosis consisted of organized thrombi. The neointima of the iliac arteries was mature, and only a small amount of spindle cells were observed in the hyalinized matrix. The tissue that developed restenosis after stenting was different in the coronary and iliac arteries included in this series. This study on the atherectomized tissue suggests that even in the chronic stage, a major cause of in-stent restenosis among the larger caliber vessels such as the iliac artery is not neointima but stent thrombosis.     

光学相干断层成像在冠心病介入治疗中的应用价值

目的应用光学相干断层成像（OCT）技术评价冠状动脉内粥样硬化斑块、血管对置入支架后即刻和中远期的反应。方法20例冠心病患者,有22支血管在完成冠状动脉造影或介入治疗后进行OCT成像。同时获取23个支架OCT成像,在23个支架中有15个为支架术后4～35个月随访,其中7个为雷帕霉素药物洗脱支架,8个为金属裸支架,另外8个为支架置放后即刻成像。结果入选的20例患者均成功进行OCT检查,并获取22支血管和23个支架满意的图像。通过OCT成像清晰地显示8处纤维斑块、3处钙化斑块、9处富含脂质斑块、2处血栓形成、斑块破裂3处及血管壁上夹层、粥样硬化斑块微小裂口和夹层等。7个置入雷帕霉素药物洗脱支架后OCT随访,均未发现有明显再狭窄,支架表面有少量内膜覆盖,部分支架表面没有内膜覆盖,其中1个支架血管出现瘤样扩张、支架与血管壁分离、支架表面没有内膜覆盖,有1个支架没有充分扩张。8个金属裸支架后用OCT随访发现,所有置入金属裸支架后支架表面内膜增殖明显,其中有3个支架因为内膜过度增殖而出现再狭窄,并再次接受介入治疗。8个支架术后即刻OCT检查显示,与血管贴壁均良好、支架扩张充分有3个支架,4个支架充分扩张,但可见到斑块裂片通过支架网眼突入管腔,1个支架支撑杆分布不均,可见支架与血管壁分离,在8个支架中有2个为支架内套叠支架。结论OCT成像技术可清晰显示各种冠状动脉粥样斑块情况,并可用于评价冠状动脉介入治疗的效果。     

Pressure wire guide provisional coronary stent implantation

OBJECTIVES: Whether coronary artery lesion successfully dilated by balloon angioplasty should be stented or not is unclear. The purpose of this study is to evaluate the provisional stent implantation method assessing residual ischemia by pressure wire. METHODS: Thirty-one patients with de-novo lesions suitable for stenting were enrolled in a pressure wire guided provisional stent study. The pressure wire was used to assess the fractional flow reserve(FFR) before and after balloon angioplasty. When the FFR after angioplasty was less than 0.75, stent implantation was planned. Patients with lesions consisting of an intermediate stenosis proximal to the target lesion, chronic total occlusion, bypass graft and left main lesion were excluded from the study. Stent implantation was permitted even if the FFR was more than 0.75 when the operator thought stenting was necessary. Medical treatment was given with aspirin 162 mg/day, cilostazol 200 mg/day for 6 months and additional ticlopidine 200 mg/day for a month after stenting the lesion. RESULTS: Target vessel was the left anterior descending coronary artery in 19 lesions, the right coronary artery in 3, and the circumflex coronary artery in 9. Stent implantation was performed in seven (23%) of 31 lesions and the other 24(77%) lesions were treated with only balloon angioplasty. The FFR before intervention was 0.58 +/- 0.16, and improved to 0.87 +/- 0.07 (p < 0.0001). Percentage diameter stenosis before intervention was 70.7 +/- 12.6% and improved to 20.1 +/- 13.3% (p < 0.0001) after intervention. There was no major cardiac event (death, coronary artery bypass grafting, myocardial infarction, stent thrombosis). Six months follow-up angiography was performed in 27 patients (87%). Angiographic restenosis (percentage diameter stenosis > or = 50%) was found in four patients (15%). A new lesion was found in two patients. Target vessel revascularization was performed in six patients (21%). CONCLUSIONS: Lesions successfully dilated by balloon angioplasty with FFR > or = 0.75 do not require stenting.     

Scanning electron microscopic analysis of vessel wall reactions after coronary stenting

High restenosis rates are still a major factor limiting the use of minimal invasive coronary stenting. Tissue reactions to the implanted alloplastic endoprostheses are still barely understood. 18 coronary artery segments 32 hours up to 340 days after stent implantation of 16 patients were post-mortem investigated. The pathomorphological findings of the vessel wall after stent insertion were studied by scanning electron microscopy (SEM). Stent integration can be divided with intraindividual differences in three phases: In the acute phase (<6 weeks) the border between vascular lumen and arterial wall is constituted by a thin, multi-layered thrombus. During the time course of integration, increasing amounts of Smooth Muscle Cells (SMC) and extracellular matrix can be detected. No endothelial cells can be found in the implantation zone. In the intermediate phase (6 weeks to 12 weeks) the neointima consists of extracellular matrix and increasing numbers of SMC. The borderline between lumen and neointima is generated by SMC and extracellular matrix. Increasing amounts of endothelial cells are found on the luminal surface of the stent neointima. Complete reendothelization is first noted in the chronic phase three months after stenting. Matrix structures are increasing whereas the amount of SMC decreases. In all phases of stent incorporation, the alloplastic stent material is covered by a thin (few nanometer) proteinaceous layer.     

Preventive effect of an antiallergic drug,pemirolast potassium,on restenosis after stent placement: quantitative coronary angiography and intravascular ultrasound studies

OBJECTIVES: The preventive effect of pemirolast against restenosis after coronary stent placement was evaluated. METHODS: Eighty-four patients with 89 de novo lesions who underwent successful coronary stenting were assigned to the pemirolast group(40 patients, 45 lesions) and the control group(44 patients, 44 lesions). Administration of pemirolast(20 mg/day) was initiated from the next morning after stenting and continued for 6 months of follow-up. Quantitative coronary angiography was performed immediately after stenting and at follow-up. Angiographic restenosis was defined as diameter stenosis > or = 50% at follow-up. Intravascular ultrasound study conducted at follow-up angiography was used to measure vessel cross-sectional area(CSA), stent CSA, lumen CSA, neointima CSA(stent CSA--lumen CSA), and percentage neointima CSA(neointima CSA/stent CSA x 100%) at the minimal lumen site. RESULTS: There were no significant differences in baseline characteristics between the two groups. Restenosis rate was significantly lower in the pemirolast group than in the control group(15.0% vs 34.1% of patients, 13.3% vs 34.1% of lesions, p < 0.05, respectively). The intravascular ultrasound study at follow-up(36 lesions in the pemirolast group, 33 in the control group) found no significant differences in vessel CSA and stent CSA between the two groups(17.3 +/- 2.2 vs 16.8 +/- 2.4 mm2, 8.6 +/- 1.9 vs 8.4 +/- 1.7 mm2, respectively). However, lumen CSA was significantly larger in the pemirolast group than in the control group(5.5 +/- 1.3 vs 4.4 +/- 1.1 mm2, p < 0.05). Moreover, neointima CSA and percentage neointima CSA were significantly smaller in the pemirolast group(3.1 +/- 1.1 vs 4.0 +/- 1.2 mm2, p < 0.05 and 36.2 +/- 15.9% vs 47.4 +/- 15.6%, p < 0.01). CONCLUSIONS: Pemirolast has a preventive effect against restenosis after stent placement, possibly by inhibiting neointimal hyperplasia.     

Predictors of thrombotic complications after placement of the flexible coil stent

The balloon-expandable, stainless steel, flexible coil stent is a useful device for managing acute or threatened closure after percutaneous transluminal coronary angioplasty.^1–5 Use of the device is associated with thrombosis of the stented vessel in a small but important group of patients.^3,6–10 The clinical, angiographic, and procedural factors associated with stent thrombosis with this device are still unknown. The objective of this study was to define predictors of stent thrombosis occurring within the ftrst month after stenting with this device.     

OCT对冠状动脉介入术后即刻支架周围组织结构改变的评价

目的通过光学相干断层成像(OCT)初步评价冠状动脉内支架术后即刻支架周围组织结构特点。方法随机入选15例冠状动脉粥样硬化性心脏病(冠心病)行支架置入术患者,在患者置入支架后用OCT成像系统评价术后即刻支架释放情况及支架贴壁情况。结果15例患者共置入36枚支架,OCT检查得到满意图像并显示有14例患者冠状动脉内支架各部分充分释放,支架与血管壁贴合良好,无斑块组织向血管腔内突入,支架连接处贴合好;有1例患者支架部分节段释放不充分,支架与血管壁贴合不良,支架连接处贴合欠佳。结论OCT检查可充分评价支架释放及血管壁贴合和支架连接处管壁贴合情况,是检查支架术后支架周围组织结构的一种重要方法。     

Restenosis following placement of an intracoronary heparin treated tantulum stent in the hyperlipidemic miniature swine model

Restenosis persists as an important factor limiting a favorable long term outcome following mechanical revascularization. The objective of the present study was to compare the effects of an intracoronary heparin treated tantalum prototype stent and balloon angioplasty on intimal hyperplasia, luminal diameter, and thrombosis in a porcine restenosis model. Male miniswine maintained on a high cholesterol diet and 325 mg aspirin per day underwent cardiac catheterization and oversized balloon injury to the right and left circumflex coronary arteries. Two weeks later one artery was either balloon injured again or implanted with a stent. No additional anticoagulation following stent placement was given, however aspirin was continued throughout the study. At four weeks, the coronary arteries were harvested and prepared for histologic examination and blinded quantitative morphometric analysis. The prototype stent was successfully deployed in 10 coronary arteries. Histological examination at explant revealed no evidence for thrombus or platelet aggregation. The angiographic luminal diameter of stented vessels was not significantly different from the diameter measured prior to implantation. In contrast, the angiographic diameter of balloon injured vessels was significantly decreased (4.4 +/- 0.4 mm2, balloon injured, vs. 5.8 +/- 3.3 mm2, control; p < 0.05). Stented arteries showed significantly more intimal hyperplasia, compared to balloon injured vessels (2.99 +/- 0.58 mm2 intimal area, stented arteries vs. 0.38 +/- 0.15 mm2 intimal area, control arteries; p < 0.05). In conclusion, heparin treated tantalum wire prototype intracoronary stents were successfully deployed in swine coronary arteries with no evidence for thrombus formation. Despite a significant intimal response, luminal diameter was preserved in stented vessels. The data suggest that a heparin treated tantalum wire prototype intracoronary stent may be an effective method of coronary revascularization that results in the preservation of luminal diameter without thrombotic occlusion.