Efficacy of a Paclitaxel-Eluting Nitinol Stent on the Inhibition of Pseudointimal Hyperplasia in a Transjugular Intrahepatic Portosystemic Shunt: An Experimental Study in a Swine Model

PURPOSE: To evaluate the efficacy of a paclitaxel-eluting nitinol stent on the inhibition of pseudointimal hyperplasia in a transjugular intrahepatic portosystemic shunt. MATERIALS AND METHODS: Twelve pigs were used in this study. Two types of 10-mm diameter and 60-mm long nitinol stents were made for a transjugular intrahepatic portosystemic shunt by coating them with a polyurethane solution, with and without paclitaxel. Each transjugular intrahepatic portosystemic shunt was created successfully in the 12 swine with 7 paclitaxel-eluting stents and 5 polyurethane stents. Five swine in each group were followed-up for 14 days due to the death of 2 swine given the paclitaxel-eluting stents. The proliferation of the pseudointima was evaluated on both follow-up portograms and histopathology examinations. The mean maximum pseudointimal hyperplasia is expressed as the percentage of the stent radius. RESULTS: On the portograms, all the transjugular intrahepatic portosystemic shunts using the paclitaxel-eluting stents maintained patency despite there being a complete occlusion of the polyurethane stents in all the animals. The histopathology analysis revealed the mean maximum pseudointimal hyperplasia to be 25% and 76% in the paclitaxel-eluting and control stents, respectively. CONCLUSION: A transjugular intrahepatic portosystemic shunt with a paclitaxel-eluting nitinol stent appears to significantly inhibit the formation of pseudointimal hyperplasia.

Efficacy of a Dexamethasone-Eluting Nitinol Stent on the Inhibition of Pseudointimal Hyperplasia in a Transjugular Intrahepatic Portosystemic Shunt: An Experimental Study in a Swine Model

OBJECTIVE: We wanted to evaluate the feasibility and efficacy of using a dexamethasone (DM) -eluting nitinol stent to inhibit the pseudointimal hyperplasia following stent placement in the transjugular intrahepatic portosystemic shunt tract (TIPS) of a swine. MATERIALS AND METHODS: Fifteen stents were constructed using 0.15 mm-thick nitinol wire; they were 60 mm in length and 10 mm in diameter. The metallic stents were then classified into three types; type 1 and 2 was coated with the mixture of 12% and 20%, respectively, of DM solution and polyurethane (PU), while type 3 was a bare stent that was used for control study. In fifteen swine, each type of stent was implanted in the TIPS tract of 5 swine, and each animal was sacrificed 2 weeks after TIPS creation. The proliferation of the pseudointima was evaluated both on follow-up portogram and pathologic examination. RESULTS: One TIPS case, using the type 1 stent, and two TIPS cases, using the type 2 stent, maintained their luminal patency while the others were all occluded. On the histopathologic analysis, the mean of the maximum pseudointimal hyperplasia was expressed as the percentage of the stent radius that was patent, and these values were 51.2%, 50% and 76% for the type 1, 2, and 3 stents, respectively. CONCLUSION: The DM-eluting stent showed a tendency to reduce the development of pseudointimal hyperplasia in the TIPS tract of a swine model with induced-portal hypertension.

Glue Embolization of Aneurysm after Stenting in Canine Carotid Arteries - Technical Feasibility

PURPOSE: Coiling or infusion of embolic materials into a wide necked aneurysm can be performed with stenting. The purpose of our study is to assess the technical feasibility of aneurysm treatment with glue embolization after stenting. MATERIALS AND METHODS: We used four Wallstents for surgically repairing eight canine carotid aneurysms. After confirmation of the aneurysms on the angiogram, we introduced a 6-7 F guiding catheter in order to deploy the stents. After stenting, we passed a microcatheter into the aneurysm lumen through the stent mesh. 28% glue was slowly injected until the glue cast completely filled the lumen. We evaluated the passage of a microcatheter through the stent meshwork, formation of the glue cast and the stents' ability to protection for any leakage of glue. The follow-up angiogram was obtained for two dogs, one to three times until 8 weeks, and then we sacrificed the dogs and performed pathologic examinations. RESULTS: Stenting was successful in all cases except one in which the vessel was occluded because the stent was not completely expanded within the lumen. The microcatheter could not pass through the stent mesh in one aneurysm. The two week follow-up angiogram showed complete occlusion of the aneurysm and a patent carotid lumen in a case after successful stenting and glue embolization without distal migration of glue. Tungsten in the glue was noted to migrate out of aneurysm into the soft tissue of the neck. Histopathologic examination showed successful obliteration and stable organization of the aneurysmal lumen with ingrowth of fibroblasts and a foreign body reaction. In contrast, the aneurysms without the glue embolization being performed showed partially thrombosed aneurysmal lumens that became smaller and indistinct on the 8 week follow-up angiograms. Histopathologic examination showed a disorganized thrombus with numerous recanalizations. CONCLUSION: Glue embolization after stenting could be performed for aneurysm without distal migration of the glue or gluing of the catheter. This concept appears to be useful for applications to the further research and the treatment of aneurysm.

Fixation Methods for Implantable Port Chamber: Comparative Study Using Glue, Self-stabilizing Leg and Suture Fixations in Rabbits

OBJECTIVE: To evaluate the fixation strength and tissue reaction of the glue fixation and self-stabilizing leg fixation methods and to compare the results with those of the conventional tagging suture fixation method. MATER AND METHODS: Twelve healthy rabbits were selected and three different methods of implanting the port chamber were employed on the back of each rabbit. A total of thirty six port chambers were implanted with these three different methods, viz. the glue fixation method using tissue adhesive, the self-stabilizing leg method using a self-expandable stabilizing leg, and the suture fixation method. The fixation strength and the gross and histopathologic changes of each fixation method were evaluated at three days, one week, two weeks and four weeks after port implantation. RESULTS: The glue fixation method showed a good fixation strength, which was similar to that of the tagging suture method (p=0.3486). Five of the six ports (83%) implanted with the glue fixation method which were examined after two weeks showed cracks on the external surface, but this had no adverse effects on their function. A large amount of granulation tissue reaction was found at the bottom of the chamber (p=0.0025). The fixation with the self-stabilizing leg showed relatively lower fixation strength (p=0.0043), but no turning-over of the chamber occurred. The fixation strength improved with time after the first week, and minimal granulation tissue reaction was observed with this method. CONCLUSION: The glue fixation method exhibited equal fixation strength compared to the suture fixation, but showed cracking and a large amount of granulation tissue, whereas the fixation with a self-stabilizing leg showed weaker fixation strength.

Reduction of Tissue Hyperplasia with a 188Re-MAG3-filled Balloon Dilation: Experimental Study with a Rabbit Esophageal Model

PURPOSE: The purpose of this study was to evaluate the feasibility and efficacy of beta-radiation therapy with a rhenium-188-mercaptoacetyltriglycine ((188)Re-MAG(3)) filled balloon to prevent tissue hyperplasia secondary to stent placement in a rabbit esophageal model. MATERIALS AND METHODS: Fifteen rabbits were divided into the three study groups. The ten rabbits having the radioactive balloon dilation performed immediately after stent placement were scheduled to be sacrificed at six weeks; the 20 Gy (Group I, n=5) or 40 Gy (Group II, n=5) at 1 mm away from the balloon surface were also sacrificed at six weeks. The remaining five rabbits that had conventional balloon dilation done immediately after stent placement were scheduled to be sacrificed six weeks later; this was the control group (Group III). At follow-up, we obtained esophagography and the histologic findings (epithelial layer thickness, degree of destruction of the muscularis propria, and degree of submucosal inflammatory cell infiltration) at both the normal area and the mid-stent area for each esophageal specimen after sacrificing each rabbit. The differences among the three groups were statistically assessed using Kruskal-Wallis and Mann-Whitney U tests. RESULTS:There were no complications such as migration after stent placement. Nine of the rabbits died 1-3 weeks after stent placement and the stents were partially obstructed with a lot of residue, so it was impossible to compare the esophagographic findings among the three groups. Esophageal perforation (n=6) and mucosal reddish changes (n=5) of the esophagus adjacent to the stent were observed only for rabbits of group I or II. The esophageal mucosa displayed smoothness in group I and II, and the esophageal mucosa displayed nodularity in group III. The degree of destruction of the muscularis propria was significantly higher in group I or II when compared to group III (p<0.05). CONCLUSION: Beta-irradiation using a (188)Re-MAG(3)-filled balloon dilation has the potential for preventing tissue hyperplasia secondary to stent placement in a rabbit esophageal model.

Transluminal Radio-Frequency Thermal Ablation Using a Stent-Type Electrode: an Experimental Study

PURPOSE: To assess the feasibility of transluminal radiofrequency thermal ablation using a stent-type electrode and to determine, by means of in-vitro and in-vivo animal studies, the appropriate parameters. MATERIALS AND METHODS: In vitro: The radiofrequency electrode used was a self-expandable nitinol stent with 1cm insulated ends. A stent was placed in the portal vein of bovine liver, and ablations at target temperatures of 70, 80, 90, and 100degrees C were performed. Ablated sizes were measured longitudinally. In vivo: Four mongrel dogs were anesthetized, and a stent was inserted in the common bile duct under fluoroscopic guidance through an ultrasound-guided gall bladder puncture site. The ablation temperature was set at 80 degrees C, and each dog underwent proximal and distal esophageal ablations lasting 12 minutes. They were sacrificed immediately. RESULTS: In-vitro: Ablated sizes showed significant correlation with target temperatures (r>0.04; p<0.05). Although most lesions were fusiform, dumbbell-shaped lesions with central thinning were found in two cases in the 70degrees C group. In all cases in the 70 degrees C and 80 degrees C group, the length of the insulated segment was less than 1 cm. In-vivo: At microscopy, tissues at the center of the biliary stent showed more prominent pathological change than those at the periphery while those remote from the stent showed minimal or no change. In esophageal ablations, the mean highest temperature was 48.6 degrees C. Microscopy demonstrated the destruction and shedding of mucosa, edema, and coagulation necrosis of submucosa, but in muscle layers no abnormalities were apparent. CONCLUSION: Transluminal radio-frequency thermal ablation using a stent-type electrode may be useful for elongating patency. The appropriate target temperature for biliary ablation is 80 degrees C.

Radiofrequency Ablation of the Gastrointestinal Tract with a Stent-Like Electrode: Experimental Study

OBJECTIVE: To assess the technical feasibility of a newly designed stent-like electrode in rabbits. MATERIALS AND METHODS: A stent-like electrode was knitted from a single thread of nitinol wire and interconnected to a generator using similar wire. In order to gauge the extent of radiofrequency ablation (RFA), we measured the depth of the ablated area in cow liver using a combination of 180-sec time intervals and 20-watt power increments. For data processing, Cox regression analysis was used. RFA was also applied to the small intestine of rabbits using this stent-like electrode under six different sets of conditions: 10 watts for 1 min, 10 watts for 2 mins, 20 watts for 1 min, 20 watts for 2 mins, 30 watts for 1 min, and 30 watts for 2 mins. To determine the gross and microscopic findings, six animals were sacrificed immediately after the procedure and the results obtained under the different sets of conditions were correlated. Eight rabbits were monitored for 4 weeks prior to sacrifice. RESULTS: For both ex-vivo and in-vivo ablations, the depth of the thermal lesion showed linear correlation with both the duration of RFA and the power applied. RFA of the duodenum was technically successful in all 14 rabbits. The acute changes occurring in the rabbits' small intestine included color change, cytoplasmic denaturation, fibrin deposition and hemorrhage, among which hemorrhage of the mucosal layer was the earliest finding. RF ablation for 2 mins at 30 watts caused serosal hemorrhage. The gross and histologic changes occurring showed close correlation under all six sets of conditions. CONCLUSION: Use of the stent-like electrode proves technically feasible but to determine the nature of the chronic change occurring in the gastrointestinal tract after RF ablation, further investigation and long-term follow-up in animals are required.

A Study about Histopathological Change of NBCA Injected into Subarachnoid Space of the Cat

PURPOSE: To determine the histopathological changes occurring after the injection of NBCA(n-butyl cyanoacrylate) into the subarachnoid space of the cat. MATERIALS AND METHODS: A 1: 4 NBCA-Lipiodol mixture was injected into the subarachnoid space of ten cats by cervical spinal tap. Two weeks later all cats were sacrificed, and histopathological examination of the cerebrospinal leptomeninges, blood vessels and parenchyma was undertaken. RESULTS: 1. Changes in leptomeninges: Foreign body giant cells were noted in five cases, fibrosis in six and acute inflammation in all ten. Chronic inflammatory change accompanied 7 of 10 acute inflammations. 2. Changes in blood vessels: One case was excluded because blood vessels were not included in pathologic tissue. Acute vasculitis was noted in six cases, thrombosis in one, and one showed fibrotic change without necrosis in the media of the vessel wall. Among the six with acute vasculitis, severe change was noted in one and mild change in five. 3. Changes in parenchyma: Mild parenchymal inflammation was discovered in two cases and mild infarction in one. Parenchymal changes were limited to the outer cortex. CONCLUSION: The injection of NBCA into the subarachnoid space of the cat caused toxic histopathological changes in the cerebrospinal meninges, blood vessels, and parenchyma.

MR Imaging-Histopathologic Correlation of Radiofrequency Thermal Ablation Lesion in a Rabbit Liver Model: Observation during Acute and Chronic Stages

OBJECTIVE: To determine the ability of MR imaging to detect the pathological changes occurring in radiofrequency (RF) thermal lesions and to assess its accuracy in revealing the extent of tissue necrosis. MATERIALS AND METHODS: Using an RF electrode, thermal lesions were created in the livers of 18 rabbits. The procedure involved three phases. In the acute phase, six animals were killed the day after performing thermal ablation with RF energy, and two on day 3. In the subacute and chronic phases, eight rabbits underwent percutaneous hepatic RF ablation. After performing MR imaging, two animals were sacrificed at 1, 2, 4, and 7 weeks after the procedure, and MR-pathologic correlation was performed. RESULTS: In the acute phase, the thermal ablation lesions appeared at gross examination as well-circumscribed, necrotic areas, representing early change in the coagulative necrosis seen at microscopic examination. They were hypointense on T2-weighted images, and hyperintense on T1-weighted images. Gadolinium-enhanced MR imaging showed that a thin hyperemic rim surrounded the central coagulative necrosis. In the subacute phase, ablated lesions also showed extensive coagulative necrosis and marked inflammation at microscopic examination. Beyond two weeks, the lesions showed gradual resorption of the necrotic area, with a peripheral fibrovascular rim. The size of lesions measured by MR imaging correlated well with the findings at gross pathologic examination. CONCLUSION: MR imaging effectively demonstrates the histopathological tissue change occurring after thermal ablation, and accurately determines the extent of the target area.

Changes of Incompletely Embolized Aneurysm with Tungsten Coils: An Experimental Study in Dogs

PURPOSE: To evaluate changes of residual aneurysms according to the size of aneurysmal neck andthrombogenicity of a tungsten coil after incomplete embolization of experimental lateral aneurysms. MATERIALS AND METHODS: Eleven experimental lateral aneurysms with different aneurysmal neck size were created in the commoncarotid arteries of mongrel dogs. They were then divided into narrow-neck(n=3), wide-neck(n=6) and spontaneouslythrombosed control(n=2) groups. After confirmation of aneurysmal patency, incomplete embolizations of varyingdegrees (about 30% to near total occlusion) were performed using 5mm-diameter tungsten coils. Angiography wasperformed immediately before and after, and one and six weeks after embolizations. The size of residual aneurysmwas measured on each angiogram. After the last angiography, embolized aneurysms were excised and examined underlight and electron microscopes. RESULTS: On angiograms obtained 6 weeks after embolization, all residual narrowneck aneurysms were completely occluded, whereas in those with a wide-neck, therre was either no change (n=4) or aslight increase in size(n=2). On light microscopy, all narrow-neck aneurysms showed total organized fibrosis whileall control aneurysms and half those with a wide neck showed unorganized thrombi. The embolized group showed ahigher degree of organization in the aneurysmal cavity than did the control group. Neointima formation was seen inall embolized aneurysms, but no aneurysm showed foreign body reaction. On electron microscopy, uniform thicknessof plasma coatings was noted on the surface of the tungsten coils. CONCLUSION: A wide-neck residual aneurysm maypersist or increase in size, while one with a narrow-neck can be thrombosed after incomplete embolization withtungsten coils in a lateral aneurym. Careful consideration might be necessary in the embolization of wide-neckaneurysms. With plasma coatings on its surface and organized fibrosis, tungsten coil can be an useful forembolization of an aneurysm.

Stent Placement in Arteriovenous Fistula: An Experimental study

PURPOSE: To determine the efficacy of metalic stents in the treatment of experimentally createdcarotid-jugular fistulas. MATERIALS AND METHODS: Carotid-jugular fistulas were constructed surgically in fourmongrel swines. Three Wallstents (Schneider, Bulbanch, Switzerland), 6mm in diameter and 23mm in length, and oneNir stent (Boston Scientific Corporation, Boston, U.S.A.), 3-5mm in diameter and 16mm in length, were placedendovascularly across the fistula holes within the carotid artery. Carotid angiography was performed before,immediately after, and 1-3 months after stent placement. Fistula specimens were ohtained after final angiographyand gross and microscopic examination was performed. RESULTS: Angiography demonstrated decreased flow through thefistula immediately after stent placement. During follow-up, flow through the fistula decreased progressively butcomplete closure did not occur. Carotid arteries p in which Wallstents were placed were patent throughout thefollow-up period. A carotid artery in which a Nir stent was used showed no decreased flow during follow-upangiography lasting two months. Pathologically, a thin layer of endothelium covered the stent wires;there was atransitional zone between the fibrous connective tissue of organizing thrombus, and endothelial proliferationoccurred in the overlying fistula hole. CONCLUSIONS: Stent placement effectively reduced flow through thefistulas but during the ensuing three months closure did not occur. Occlusion was then progressive.Pathologically, intimal proliferntion arose from the oranizing thrombus on the surface of the stent mesh.

Reaction Difference of Glue-Lipiodol Mixture According to the Different Lot Number

PURPOSE: We noted that in a catheter, glue-lipiodol mixtures (GLM) prematurely turned into a cast duringembolization of brain arteriovenous maliformation, and to avoid this problem, added tungsten to GLM. The reactiontime and hardness of GLM were then evaluated in vitro. MATERIALS AND METHODS: Six lots of Lipiodol (Nos.97LU009A, 96LU018A, 96LU017A, 96LUollA and 95Lu020A)(Laboratoire Guerbet, Cedex, France) and three lots HistoacrylBlue (2/7121, Ex. Date 03/99 (993);2/6263, 06/98 (986);2/6132 03/98 (983))(B. Brown, Melsungen, Germany) weremixed in a 5cc bottle at concentrations of 25-50%(glue:lipiodol=1:1 to 1:3) and observed for two weeks. Thehardness of polymerized GLM was classified as liquid, gel, semi-solid or solid. After the addition of tungsten ortantalum powder (0.2gm) and a drop of blood to GLM, different series of experiments were performed. pH wasmeasured in distilled water mixed with tungsten of tantalum(0.1 to 0.5 gm). RESULTS: At a concentration of 50%,most GLM turned into solid casts within 48 hours;at one of 25%, most GLM gelled within 24hrs. At concentrations of28 and 33%, hardness was between that of a solid and that of a gel. After the addition of tungsten to 50% and 25%GLM, this remained in a liquid state until two weeks later, regardless of lipiodol products. In 5cc distilledwater with 0.1 to 0.5 gm tungsten, pH changed from 3.5 to 2.6, and on the addition of tantalum from 6.4 to 5.7.The addition of blood to the mixture immediately turned the cast solid at a GLM concentration of 50%, andsemi-solid at one of 25%. CONCLUSION: The reaction time of GLM differed according to the lot number of lipiodol.The addition of tungsten seemed to prevent premature cast formation by decreasing pH;the mechanism was similar tothat observed when acetic acid was added.

Percutaneous Embolization Using Histoacrylic Blue(N-butyl 2-cyanoacrylate) in VX-2 Carcinoma in the Orbit of Rabbits

PURPOSE: To investigate the efficacy of percutaneous embolization of hypervascular VX-2 carcinoma in the retroorbital area of the rabbits using Histoacrylic Blue(N-butyl 2-cyanoacrylate, NBCA) and to establish as an experimental model. MATERIALS AND METHODS: Retroorbital VX-2 carcinoma was made in 10 rabbits by injection of carcioma cells. At 2 and 4 weeks following the tumor cell injection, carotid angiography was performed before and after percutaneous embolization using 50% NBCA diluted with Lipiodol. Doppler ultrasonography was also performed to evaluate the vascularity of the mass. Light microscopic examination was used to evaluate the effect of embolization on the tumor mass. RESULTS: Angiography following percutaneous embolization showed filling of embolic materials in the tumor beds. Ultrasonographic findings showed tumor necrosis and increased Doppler signal in the tumor. Histopathological examinations showed extensive necrosis of tumor cells with remaining viable cells surrounding the capillaries. There were no NBCA emboli in arterioles and capillaries of tumor beds in multiple sections. CONCLUSION: Since 50% diluted NBCA used as percutaneous embolus into the retroorbital VX-2 carcinoma dose not get into small blood vessels of tumor beds. using NBCA in lower concentration in the hypervascular tumor would be the next step to figure out its usefulness. This study also serves as an experimental model of percutaneous embolization of hypervascular tumor.

Production of Carotid Artery Aneurysm in Pigs

PURPOSE: To establish the method of constructing an experimental aneurysm model in porcine carotid artery. MATERIALS AND METHODS: Fourteen aneurysms were created in the carotid arteries of eight pigs. After paramedian incision under intravenous anesthesia, the common carotid artery and external jugular vein were separated. A portion of the latter was cut to make an aneurysmal sac and this was sutured to the side wall of the common carotid arterial wall (end to side). Within one week, an arteriogram was obtained in all pigs and color Doppler study was performed in four. Digital subtraction arteriograms were serially obtained three images/sec, and these were analyzed to determine the size of the sac and the neck, flow pattern in the aneurysm, and stenosis in the common carotid artery. RESULTS: Arteriographic findings were obtained in ten of 14 aneurysms. Six aneurysms were saccular in shape, and the mean size of the sac and neck was 16x10 mm and 5.3 mm, respectively. Four aneurysms were lobulated, and in these cases, the mean size of the sac and neck was 9x3 mm and 3.7 mm, respectively. The mean size of the proximal common carotid artery was 4.5 mm, and at the operation site, mean stenosis was 40%. CONCLUSION: In 10/14 cases (71%), we successfully established an aneurysm model in the porcine carotid artery, and believe that it is suitable for use in interventional neuroradiology experiments.

An Experimental Study for Efficacy of Acetic Acid as a Sclerosing Agent

PURPOSE: To evaluate the efficacy of acetic acid as a sclerosing agent by observation of histologic change in urinary bladder epithelium after the instillation of acetic acid. MATERIALS AND METHODS: Urinary bladder of the rabbit was catheterized with a Foley catheter, and acetic acid of 10%, 20%, 30%, 40% and 50% concentration was instilled for 5 minutes. After evacuation of the acid, the bladder was irrigated three times with normal saline. After two days, gross and histologic examinations of the bladder were performed. RESULTS: A bladder into which10% acetic acid had been instilled revealed a nearly normal epithelium without denudation. In two cases, 20% acetic acid was instilled; one revealed partial denudation of the epithelium and the other revealed complete denudation. Mild to moderate interstitial edema and vascular congestion of the bladder wall were evident in all cases in which acid at a concentration of 30% or more had been instilled. In all cases in which the concentration of acid was greater than 30%, the epithelium was completely denuded. CONCLUSION: An acetic acid concentration of 40% or more is sufficient to completely destroy the epithelium of rabbit urinary bladder, and may be effective as a new sclerosing agent in cases of renal or hepatic cyst.

An Experimental Study on Hanaro Self-expanding Metallic Stent in Porcine Carotid Arteries

PURPOSE: To evaluate the patency of the Hanaro self-expanding stainless steel stent in the common carotidartery of the pig. MATERIALS AND METHODS: Sixteen stents(6mm in diameter/3.5mm in length) were inserted in one orboth common carotid arteries of nine pigs. Carotid angiography was performed before and after stent insertion, and at the end of the follow-up period(which ranged from 4 to 13 weeks), to evaluate stent patency and change of stent location. Histopathologic study was carried out to assess the endothelial proliferation. RESULTS: Of nine pigs with 16 successfully-inserted stents, follow-up angiography was obtained in seven pigs with 13 stents. The stents inserted were patent in 12 cases and occluded in one. Stenosis was noted in nine of the 12 stents. In three stents, there was angiographic evidence of recanalization such as non-filling or collateral filling of the rete. In no case was there any change of stent location. Endothelial proliferation was more severe in two of four occluded stents(mean thickness : 0.43mm) than in the other 11 stents(mean thickness : 0.08mm). CONCLUSION: Because the Hanaro stent was successfully inserted in porcine carotid arteries and showed a rather good patency(92%), the stent can be used in the small arteries. However, before it is used clinically, futher study and development appear to be necessary.