Coil-assisted retrograde transvenous obliteration of gastric varices by an inverted catheter tip technique via the pericardiophrenic vein.

A 70-year-old woman with liver cirrhosis was admitted to our hospital for treatment of growing gastric varices in the fundus. Computed tomography showed gastric varices continuously draining the pericardiophrenic vein via the inferior phrenic vein. Balloon-occluded retrograde transvenous obliteration by a transjugular approach was planned. However, a conventional balloon catheter or microballoon catheter could not be inserted into the efferent vein near the varices because of the narrowness and tortuosity of the vein. Hence, coil-assisted retrograde transvenous obliteration was performed by an inverted catheter tip technique using a single conventional microcatheter. This technique might be useful for cases in which it is difficult to insert a balloon catheter into the efferent vein.

Utility of low-dose gelatin sponge particles and 5% ethanolamine oleate iopamidol mixture in retrograde transvenous obliteration (GERTO) for gastric varices.

OBJECTIVE: To determine the utility of low-dose gelatin sponge particles and 5% ethanolamine oleate iopamidol (EOI) mixture in retrograde transvenous obliteration (GERTO) for gastric varices (GV). METHODS: 57 consecutive patients who underwent balloon-occluded retrograde transvenous obliteration (B-RTO) for GV were divided into three groups with Hirota's grade by balloon-occluded retrograde transvenous venography. Hirota's Grade 1 patients were assigned to G1 group and underwent treatment with 5% EOI. Grade ≥ 2 patients prior to August 2015 were G ≥ 2 group treated with 5% EOI, and those treated thereafter were GERTO group. The amount of EOI used per unit GV volume (EOI/GV ratio), the times to embolization and recurrence rate of GV were evaluated. RESULTS: The EOI/GV ratio was 0.66 ± 0.19 in G1, 1.5 ± 0.8 in G ≥ 2, and 0.58 ± 0.23 in GERTO (G ≥ 2 vs GERTO, p < 0.0001). The times to embolization were 26.5 ± 10.5 min for G1, 39.2 ± 26.8 for G ≥ 2, and 21.4 ± 9.4 for GERTO (G ≥ 2 vs GERTO, p = 0.005). The recurrence rate was not significantly different in any of the groups. CONCLUSION: GERTO was performed in lower amount of sclerosants and in less time compared to conventional B-RTO in Hirota's grade ≥2. ADVANCES IN KNOWLEDGE: Feasibility of low-dose gelatin sponge particles and 5% EOI mixture as sclerosants for GV.

Transapical Endovascular Repair of Thoracic Aortic Pathology.

BACKGROUND: Alternative access for thoracic endovascular aortic repair (TEVAR) has been explored for patients with unsuitable femoral and iliac access, but few cases of transapical access have been described. We report our experience with transapical access for various aortic pathologies. METHODS: We reviewed 6 cases undergoing transapical access for endovascular repair of thoracic aortic pathology between December 2013 and August 2015. Five patients had an aortic arch aneurysm and 1 patient presented with Stanford type A subacute aortic dissection. Transapical access was indicated to avoid approach through the severely atherosclerotic thoracic descending aorta in 4 patients and severely kinked aorta in 1 patient and to treat an ascending aortic dissection lesion in 1 patient. RESULTS: Transapical endografting was completed in all patients. Significant aortic valve regurgitation occurred in 3 patients when a large bore sheath was placed across the aortic valve. There was 1 death attributed to global cerebral ischemia due to carotid dissection after carotid bypass and chimney stent-graft insertion. There were no access-related complications. Computed tomography revealed complete exclusion of the aortic aneurysm in 4 patients, and shrinkage of the false lumen in 1 patient with aortic dissection. CONCLUSIONS: Transapical access for TEVAR would be a potential alternative when the anatomy is unfit for routine retrograde approach. This method might have potential benefit of reducing the risk of embolism in patients with severe atherosclerotic thoracic descending aorta. However, certain safety concerns must be addressed, including maintenance of hemodynamics, wire exteriorization for navigation of the device tip, and rapid pacing during deployment.

Prediction for Improvement of Liver Function after Balloon-Occluded Retrograde Transvenous Obliteration for Gastric Varices to Manage Portosystemic Shunt Syndrome.

PURPOSE: To investigate predictive factors and cutoff value of transient elastography (TE) measurements for assessing improvement in liver function after balloon-occluded retrograde transvenous obliteration (BRTO) for gastric varices (GV). MATERIALS AND METHODS: Retrospective analysis was performed of 50 consecutive patients followed for > 3 months after BRTO, who had undergone TE before BRTO between January 2011 and February 2015. The correlation between change in liver function (total bilirubin, albumin, and prothrombin time) and baseline liver function values and liver stiffness measurement (LSM) by TE was evaluated by Pearson correlation test. Receiver operating characteristic curves were used to determine cutoff values for discriminating between patients who had improved liver function and patients who did not. The time interval from BRTO to aggravation of esophageal varices (EV) (worsening morphology, development of new varices, or variceal rupture) grouped by cutoff values was also analyzed. RESULTS: Serum albumin was significantly improved at 3 months after BRTO (3.57 g/dL vs 3.74 g/dL, P < .001). There was a significant negative correlation between change in albumin and baseline LSM (r = -0.50, P < .001). The best cutoff point for LSM was ≤ 22.9 kPa, with sensitivity and specificity of 78.4% and 69.2%, respectively, for predicting which patients would have improved albumin after BRTO. Among 33 patients, 29 (88%) patients had improved albumin. The 1-year progression rate of EV after BRTO was 13.6% in patients with LSM ≤ 22.9 kPa. CONCLUSIONS: The predictive factor for improvement in albumin after BRTO was lower LSM (≤ 22.9 kPa) using TE.

Mid-term Results of Endovascular Treatment for Infrarenal Aortic Stenosis and Occlusion.

BACKGROUND: Focal stenosis or occlusion of the infrarenal aorta is rare, and treatment is usually conventional bypass or endarterectomy. However, endovascular treatment has advanced in recent years. The purpose of this retrospective study is to report the results of primary stenting for focal infrarenal aortic occlusive disease and clarify the usefulness of endovascular treatment. METHODS: This study includes 6 consecutive patients (3 men, 3 women; mean age, 59.3 years) with infrarenal aortic stenosis or occlusion who underwent endovascular intervention at our hospital between April 2009 and February 2014. All patients had bilateral intermittent claudication. The mean preoperative ankle-brachial index (ABI) showed a slight to moderate decrease: right 0.668 and left 0.636. The mean lesion site length was 12.5 mm, the percent stenosis was 90.7%, and calcification was present in 3 patients. Primary stenting was performed in all patients. The stent selected was generally a self-expanding stent (SES). For patients with severe calcification, the stent selected was a balloon-expandable stent (BES). RESULTS: Four patients received an SES and two patients received a BES. The technical success rate was 100%, no complications occurred, and the mean pressure gradient disappeared or decreased. Symptoms resolved in all patients and the postoperative ABI improved: right 0.923 and left 0.968. During a mean follow-up period of 27 months, there were no recurrent symptoms and no restenosis on CT angiography. CONCLUSIONS: Endovascular treatment should be considered as a first line treatment for focal infrarenal aortic stenosis and occlusion.

Efficacy and safety of intra-arterial steroid infusions in patients with steroid-resistant gastrointestinal acute graft-versus-host disease.

There is no established second-line treatment for steroid-resistant acute graft-versus-host disease (GVHD). We prospectively assessed the safety and efficacy of intra-arterial steroid infusions (IASIs) for steroid-resistant acute gastrointestinal (GI) GVHD and compared the outcomes with those of historical controls at our institution. Nineteen consecutive, allogeneic hematopoietic stem cell transplantation subjects aged 31-67 years (median 52) were enrolled between October, 2008, and November, 2012. Acute GVHD was confirmed by biopsy in all cases. The enrolled patients were treated with infusions of methylprednisolone into the mesenteric arteries and/or gastroduodenal and left gastric arteries. Fourteen consecutive patients who developed steroid-resistant acute GI GVHD between 2001 and 2008 were used as controls. For the primary endpoint at day 28, the overall and complete responses in the IASI group trended higher (79% vs. 42%, p = 0.066) and were significantly higher (63% vs. 21%, p = 0.033) than those in the control group. Although not statistically significant, owing to the small population, the crude day-180-nonrelapse mortality rate was about 20% lower and the day-180-overall-survival rate tended to be higher than the control (11% vs. 29%, p = 0.222; 79% vs. 50%, p = 0.109, respectively). There were no serious IASI-related complications. Our results suggest that IASI can safely provide excellent efficacy for refractory acute GI GVHD without increasing infection-related complications and may improve prognosis.

Injectable cell scaffold restores impaired cell-based therapeutic angiogenesis in diabetic mice with hindlimb ischemia.

The clinical success of cell-based therapeutic angiogenesis has been limited in diabetic patients with critical limb ischemia. We previously reported that an injectable cell scaffold (ICS), which is a nano-scaled hydroxyapatite (HAp)-coated polymer microsphere, enhances therapeutic angiogenesis. Subsequently, we developed a modified ICS for clinical use, measuring 50 µm in diameter using poly(l-lactide-co-ε-caprolactone) as a biodegradable polymer, which achieved appropriately accelerated absorption in vivo. The aim of the present study was to evaluate the effectiveness of this practical ICS in diabetic hindlimb ischemia. Bone-marrow mononuclear cells (BMNCs) were intramuscularly injected, without or with a practical ICS, into the ischemic hindlimbs of mice (BMNCs or ICS+BMNCs group, respectively). Kaplan-Meier analysis demonstrated that the beneficial effects of BMNC transplantation for limb salvage after ischemic surgery were almost entirely abrogated in streptozotocin-induced diabetic mice. In contrast, injection of ICS+BMNCs revealed significant limb salvage in diabetic mice to a similar extent as in non-diabetic mice. The number of apoptotic transplanted BMNCs was 1.8-fold higher in diabetic mice 10 days after transplantation compared to non-diabetic mice, while that in the ICS+BMNCs group was markedly lower (8.3% of that in the BMNCs group) even in diabetic mice. The proangiogenic factors VEGF and FGF2, also known as antiapoptotic factors, mostly co-localized with transplanted GFP-positive BMNCs that were closely aggregated around the ICS in ischemic tissue. In conclusion, the practical ICS significantly augmented cell-based therapeutic angiogenesis even in diabetic animals, through local accumulation of proangiogenic factors and antiapoptotic effects in transplanted cells.

Neointimal hyperplasia after stent placement across size-discrepant vessels in an animal study.

PURPOSE: To examine differences in neointimal hyperplasia (NIH) after placing a self-expanding (SE) stent across size-discrepant vessels. MATERIALS AND METHODS: The subjects were 6 beagles, and the target vessels were the abdominal aorta and the external iliac artery (EIA). A nitinol SE stent was placed which was normal-sized in the aorta and oversized in the EIA. Angiography and intravascular ultrasound (IVUS) were performed immediately and after 1 and 3 months; histopathologic examinations were then performed. Furthermore, the chronic outward force (COF) on the same type of stent was investigated in vitro. RESULTS: On IVUS, thickened intima was seen on the EIA at 1 month (5.1 ± 4.2 mm(2)) and at 3 months (7.8 ± 2.5 mm(2)). For the aorta, thickening of the intima was negligible at any time. Histopathologically, the percentage of the vessel obliterated by NIH was significantly greater on the iliac side than on the aortic side (33.2 ± 10.4 vs. 13.4 ± 4.4 %). The COF exerted when stent diameter reached that of the EIA and the aorta was 0.73 and 0.17 N/mm(2), respectively. CONCLUSIONS: When a non-tapered stent is placed in vessels with a large discrepancy in diameter, attention must be paid to increased NIH in the oversized side.

Factors associated with aggravation of esophageal varices after B-RTO for gastric varices.

PURPOSE: To retrospectively evaluate risk factors for aggravation of esophageal varices (EV) within 1 year after balloon-occluded retrograde transvenous obliteration (B-RTO) of gastric varices (GV) and to clarify suitable timing for upper endoscopy to detect EV aggravation after B-RTO. METHODS: Participants included 67 patients who underwent B-RTO for GV between January 2006 and December 2010. Whether EV aggravation occurred within 1 year was evaluated, and the time interval from B-RTO to aggravation was calculated. Factors potentially associated with EV aggravation were analyzed. RESULTS: B-RTO was successfully performed in all patients. EV aggravation at 1 year after B-RTO was found in 38 patients (56.7 %). Multivariate logistic regression analysis showed that total bilirubin (T-bil) (P = 0.032) and hepatic venous pressure gradient (HVPG) (P = 0.011) were significant independent risk factors for EV aggravation after B-RTO. Cutoff values of T-bil and HVPG yielding maximal combined sensitivity and specificity for EV aggravation were 1.6 mg/dL and 13 mmHg, respectively. The patients with T-bil ≥ 1.6 mg/dL or HVPG ≥ 13 mmHg had a median aggravation time of 5.1 months. All five patients with ruptured EV belonged to this group. In contrast, patients with T-bil < 1.6 mg/dL and HVPG < 13 mmHg had a median aggravation time of 21 months. CONCLUSION: T-bil and HVPG were significant independent risk factors for EV aggravation after B-RTO. The patients with T-bil ≥ 1.6 mg/dL or HVPG ≥ 13 mmHg require careful follow-up evaluation, including endoscopy.

Radiofrequency ablation of liver tumors in combination with local OK-432 injection prolongs survival and suppresses distant tumor growth in the rabbit model with intra- and extrahepatic VX2 tumors.

PURPOSE: To evaluate survival and distant tumor growth after radiofrequency ablation (RFA) and local OK-432 injection at a single tumor site in a rabbit model with intra- and extrahepatic VX2 tumors and to examine the effect of this combination therapy, which we termed immuno-radiofrequency ablation (immunoRFA), on systemic antitumor immunity in a rechallenge test. METHODS: Our institutional animal care committee approved all experiments. VX2 tumors were implanted to three sites: two in the liver and one in the left ear. Rabbits were randomized into four groups of seven to receive control, RFA alone, OK-432 alone, and immunoRFA treatments at a single liver tumor at 1 week after implantation. Untreated liver and ear tumor volumes were measured after the treatment. As the rechallenge test, tumors were reimplanted into the right ear of rabbits, which survived the 35 weeks and were followed up without additional treatment. Statistical significance was examined by log-rank test for survival and Student's t test for tumor volume. RESULTS: Survival was significantly prolonged in the immunoRFA group compared to the other three groups (P < 0.05). Untreated liver and ear tumor sizes became significantly smaller after immunoRFA compared to controls (P < 0.05). In the rechallenge test, the reimplanted tumors regressed without further therapy compared to the ear tumors of the control group (P < 0.05). CONCLUSION: ImmunoRFA led to improved survival and suppression of distant untreated tumor growth. Decreases in size of the distant untreated tumors and reimplanted tumors suggested that systemic antitumor immunity was enhanced by immunoRFA.

Radiofrequency ablation and immunostimulant OK-432: combination therapy enhances systemic antitumor immunity for treatment of VX2 lung tumors in rabbits.

PURPOSE: To evaluate whether antitumor immunity is enhanced systemically by combining radiofrequency ablation (RFA) and local injection of an immunostimulant, OK-432. MATERIALS AND METHODS: Experiments were approved by the institutional animal care committee. Experimental Japanese rabbits inoculated with VX2 tumors in the lung and the auricle were randomized into four groups of eight: control (supportive care), RFA (RFA of lung tumor), OK-432 (direct injection of OK-432 into lung tumor), and combination therapy (lung RFA and direct OK-432 injection into lung tumor). All procedures were performed 1 week after implantation of VX2 tumors (week 1). In addition, a VX2 tumor rechallenge test was performed in the RFA and combination therapy groups. Survival time was evaluated by means of the Kaplan-Meier method and by using the log-rank test for intergroup comparison. Mean auricle tumor volumes were calculated every week. Specific growth rates (SGRs) were calculated and compared by using the Mann-Whitney test. RESULTS: The median survival times of the control, RFA, OK-432, and combination therapy groups were 23, 36.5, 46.5, and 105 days, respectively. Survival was significantly prolonged in the combination therapy group when compared with the other three groups (P <.05). The mean auricle tumor volume decreased only in the combination therapy group. The mean auricle tumor volumes of the combination therapy group from week 1 to week 7 were 205, 339, 264, 227, 143, 127, and 115 mm(3). SGR in the combination therapy group became significantly smaller than those in the other three groups (P < .05). In the rechallenge test, the volume of all reimplanted tumors decreased. CONCLUSION: Combining RFA with local injection of immunostimulant OK-432 may lead to indirectly activation of systemic antitumor immunity.

Systemic artery to pulmonary artery fistula associated with mitral regurgitation: successful treatment with endovascular embolization.

We present the case of a 60-year-old woman with symptomatic mitral regurgitation caused by a left-to-right shunt via anastomoses consisting of microfistulae, most likely of inflammatory origin, between the right subclavian artery and the right pulmonary artery. The three arteries responsible for fistulous formation, including the internal mammary, thyrocervical, and lateral thoracic arteries, were successfully occluded by transcatheter embolization using superabsorbent polymer microsphere (SAP-MS) particles combined with metallic coils. No complications have been identified following treatment with SAP-MS particles. This approach significantly reduced the patient's mitral regurgitation and she has remained asymptomatic for more than 4 years.

Homemade endovascular treatment of postoperative aortobronchial fistulas.

Successful treatments of aortobronchial fistulas were achieved in two cases using a homemade endovascular stent graft. In one, a 75-year-old man was operated on for a distal arch aneurysm 11 years previously. In the other, a 73-year-old woman was operated on for a ruptured type B aortic dissection 2 months previously. In both cases, the chief complaint was repeated hemoptysis, and the communication between the aorta and the airway tract was at the distal anastomotic site in the descending aorta. To minimize risks associated with reoperation, endovascular stent grafting was selected electively. Postoperative courses were uneventful and there were no recurrences of hemoptysis.

An animal model for type II endoleaks with use of a tsuzumi drum-shaped stent-graft.

PURPOSE: To create an animal model of type II endoleaks after endoluminal deployment of a specially designed stent-graft (SG). MATERIALS AND METHODS: Five swine were used. A tsuzumi drum-shaped SG consisting of a covered Z stent with its diameter narrowed at the center was deployed in the midthoracic aorta. In this way, a residual space (RS) was created between the aortic wall and the graft to simulate an aneurysm sac. A 5-F catheter was placed into the RS, and then aortography, RS angiography, and pressure measurements were performed. Follow-up was performed at 3 and 10 days after the procedure. Mean pressure indexes (MPIs) were calculated as the ratio of the mean RS pressure to the aortic pressure. Histologic examination was also performed. RESULTS: RSs with two or three pairs of intercostal arteries were successfully created in all cases. Aortography showed two type II endoleaks in five swine just after SG deployment and four type II endoleaks at 10 days. RS angiography showed circulation between the RS and the intercostal arteries in all cases. The mean MPI was 69.4% +/- 10.4% just after SG deployment and increased to 87.8% +/- 5.2% at 10 days. By gross examination, RS patency was retained. CONCLUSIONS: A swine model of type II endoleaks was successfully created endoluminally. This model does not require direct surgery to the aorta and its side branches and promises to be useful to study the mechanism of and therapy for type II endoleaks.

The influence of radiofrequency ablation on hepatic vessels in porcine liver.

BACKGROUND/AIMS: The objective of this study was to clarify the influence of radiofrequency ablation on the portal and hepatic vein. METHODOLOGY: Hepatic radiofrequency ablation was performed on 18 swine (mean weight, 22 kg). The livers were removed immediately, 1 week or 3 weeks following ablation. Vessel patency and diameter were determined by computed tomography, and the severity of endothelial injuries was determined histopathologically. RESULTS: The patency rate for portal and hepatic veins with diameters less than 3.0 mm decreased sequentially. At three weeks following ablation, the patency rate for vessels with diameters more than 3.0 mm was significantly higher (P<0.05) compared to those with diameters less than 2.0 mm. In portal and hepatic veins contiguous to ablated hepatic parenchyma, the endothelium with intimal thickening was found at 1 to 3 weeks following ablation, although its detection rate was decreased until 3 weeks. CONCLUSIONS: The portal and hepatic vein with diameters more than 3.0 mm in radiofrequency lesions maintained high patency. The endothelium seems to play an important role for maintaining vessels patency and the distal hepatic tissue following ablation. We believe that this maintained vascular patency may be the advantage of radiofrequency ablation over the PEIT.

Balloon-occluded retrograde transvenous obliteration of gastric varices with gastrorenal shunt: long-term follow-up in 78 patients.

OBJECTIVE: Our aim was to evaluate the long-term clinical results after balloon-occluded retrograde transvenous obliteration (B-RTO) for gastric varices with spontaneous gastrorenal shunt. MATERIALS AND METHODS: A total of 78 patients with cirrhosis and with gastric varices, successfully treated by B-RTO, were enrolled in this study. Recurrence and bleeding of gastric varices and worsening of esophageal varices were endoscopically evaluated. Univariate and multivariate analyses were used to assess the prognostic factors for worsening of esophageal varices and survival. RESULTS: Recurrence of gastric varices was found in two patients; the 5-year recurrence rate was 2.7%. Bleeding of gastric varices occurred in only one patient after B-RTO; the 5-year bleeding rate was 1.5%. Worsening of esophageal varices was observed in 29 patients, and the worsening rates at 1, 3, and 5 years were 27%, 58%, and 66%, respectively. These esophageal varices were endoscopically treated to prevent rupture. Multivariate analysis showed the presence of esophageal varices before B-RTO was a prognostic factor for worsening (relative risk, 4.956). At a median follow-up of 700 days (range, 137-2,339 days), the survival rates at 1, 3, and 5 years were 93%, 76%, and 54%, respectively. The prognostic factors associated with survival were presence of hepatocellular carcinoma (relative risk, 24.342) and the Child-Pugh classification (relative risk, 5.780). CONCLUSION: B-RTO is an effective method for gastric varices with gastrorenal shunt and provides lower recurrence and bleeding rates. We believe that B-RTO can become a standard treatment for gastric varices with gastrorenal shunt, although treatment of worsened esophageal varices may be necessary after B-RTO.

Dual balloon-occluded retrograde transvenous obliteration of gastric varix draining into the left adrenal vein and left inferior phrenic vein.

A 66-year-old woman with a gastric varix, draining into a dilated left adrenal vein and a left inferior phrenic vein, was treated with dual balloon-occluded retrograde transvenous obliteration (B-RTO). Under balloon occlusion of the left adrenal vein and the left inferior phrenic vein, retrograde injection of a sclerosant (5% ethanolamine oleate) into the gastric varix was performed. Two weeks later, disappearance of flow in the gastric varix was confirmed on endoscopic ultrasound examination.

TIPS versus transcatheter sclerotherapy for gastric varices.

OBJECTIVE: The purpose of our study was to compare the efficacy and long-term results of transjugular intrahepatic portosystemic shunt (TIPS) with those of transcatheter sclerotherapy for the treatment of gastric varices. MATERIALS AND METHODS: A total of 139 cirrhotic patients with gastric varices underwent endovascular treatment. Of the 139 patients, 104 without hepatocellular carcinoma were enrolled; 27 patients were treated with TIPS, and 77 patients with transcatheter sclerotherapy. Bleeding of gastric varices and survival rates were compared between the TIPS and transcatheter sclerotherapy groups. Multivariate analysis was used to identify the prognostic factors for gastric variceal bleeding and survival. Changes in liver function were evaluated in each group. RESULTS: The cumulative gastric variceal bleeding rate at 1 year was 20% in the TIPS group and 2% in the transcatheter sclerotherapy group (p < 0.01). The prognostic factor associated with gastric variceal bleeding was the treatment method. The cumulative survival rates at 1, 3, and 5 years were, respectively, 81%, 64%, and 40% in the TIPS group and 96%, 83%, and 76% in the transcatheter sclerotherapy group (p < 0.01). The prognostic factors for survival were the treatment method and the Child-Pugh classification of liver disease. For patients categorized in Child-Pugh class A, the survival rate was higher in the transcatheter sclerotherapy group than in the TIPS group (p < 0.01). For patients in Child-Pugh classes B and C, no significant difference was seen between the two groups. Liver function tended to improve in the transcatheter sclerotherapy group. CONCLUSION: Transcatheter sclerotherapy may provide better control of gastric variceal bleeding than TIPS. Transcatheter sclerotherapy may contribute to a higher survival rate than TIPS in patients with Child-Pugh class A disease.

Brachytherapy for the prevention of neointimal hyperplasia in the canine inferior vena cava after stent placement.

The aim of this study was to evaluate the efficacy of brachytherapy for preventing neointimal hyperplasia in the inferior vena cava (IVC) after stent placement. Sixteen beagles underwent Z-stent placement in the IVC and the aorta. For 8 of 16 beagles, irradiation (15 Gy) was delivered endoluminally to the stented segments of each vessel immediately after stent placement using the 192Ir. All animals were sacrificed after 6 weeks for morphometric and histopathologic examination. Morphometrically, neointimal thickness in the IVC of the radiation group was significantly decreased compared with the control group as well as that in the aorta (p < 0.05). Histopathologic findings showed the neointima in the IVC of the control group contained markedly organization of thrombus and neovascularization though that in the IVC of the radiation group consisted mainly of smooth muscle cells without organization of thrombus and neovascularization. From these data intravenous irradiation may prevent clinical restenosis after stent placement.