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PubMedDate not supplied

Clinical outcomes of patients treated with the cutting balloon and Sr-90 beta-irradiation for instent restenosis.

BACKGROUND: The cutting balloon (CB) is an emerging therapy for the treatment of instent restenosis (ISR), but its impact on the clinical outcomes of patients treated with intracoronary radiation therapy (IRT) with Sr-90 compared with conventional PTCA and IRT is not clearly defined. METHODS: We compared the baseline demographics, angiographic characteristics and clinical outcomes of 102 consecutive patients with ISR treated either with CB+IRT (n=45) or with conventional PTCA+IRT (n=57). The combined endpoint was the occurrence of major adverse cardiac events (MACE), which was defined as a composite of death, myocardial infarction (MI) or target vessel revascularization (TVR) at 6 months. RESULTS: The CB+IRT group had a shorter mean lesion length (14.3+/-6.5 vs. 21.1+/-15.7, P=.009), and greater utilization of glycoprotein IIb/IIIa inhibitors during the procedure (48.9% vs. 26.3%, P=.02) compared to the PTCA+IRT group. There were no significant differences in the baseline demographics, angiographic and procedural results, or subsequent MACE at 6 months between the two groups. CONCLUSION: The strategy of CB+IRT using Sr-90 for ISR is associated with similar procedural and clinical outcomes compared to conventional PTCA+IRT. Further study is warranted to determine which patient subgroups would derive the most benefit from this approach.

Aged↗
PubMedDate not supplied

Safety and efficacy of manual stepping and overlapping of beta-emitter for diffuse in-stent restenosis lesions.

BACKGROUND: The effects of overlapping beta-emitter sources on the treatment of in-stent restenosis (ISR) lesions as a result of manual stepping are unknown. METHODS AND RESULTS: In the BETA WRIST (Beta Washington Radiation for In-stent Restenosis Trial), 17 out of the 50 patients who received radiation treatment had diffuse ISR in native coronaries that required manual stepping of the beta-emitter (90Y) source in order to cover the lesion and the edges. Fourteen of those patients received radiation with an overlap of up to 3 mm in the middle of the stented segment. The prescribed dose was 20.6 Gy to a distance of 1.0 mm from the surface of the inflated balloon, and the calculated dose to the vessel wall at the overlapped area did not exceed 75 Gy. There was no difference in late total occlusion (7.1% vs. 9.0%, P=NS) and target lesion revascularization (28.5% vs. 27.2%, P=NS) between patients with stepping and those without stepping. At 6 months, there was no evidence of perforation or aneurysm at the overlapped segments. Quantitative coronary angiographic (QCA) analysis revealed significantly reduced late loss in the overlapped segment compared to the adjacent segment (P=.04). Serial (postradiation vs. follow-up) IVUS measurement showed larger mean lumen cross-sectional area (CSA) (P=.0035) and smaller mean intimal hyperplasia (IH) CSA (P=.0010) in the overlapped segment compared to the adjacent segment. CONCLUSION: Manual stepping of beta-emitter source with a short overlapped segment is safe for diffuse ISR. Further increase in lumen dimension and reduction in IH formation are observed at the overlapped segment.

Adult↗
PubMedDate not supplied

The cost-effectiveness of beta-radiation therapy for treatment of in-stent restenosis: an analysis at 290-day follow-up.

PURPOSE: We studied the cost-effectiveness of percutaneous coronary intervention (PCI) plus beta-radiation (Radiotherapy) vs. PCI alone for treating in-stent restenosis. METHODS AND MATERIALS: We analyzed medical resource data collected at US sites during the Intimal Hyperplasia Inhibition with beta In-stent Trial (INHIBIT) to compare the incremental costs between Radiotherapy and PCI alone for each repeat target lesion revascularization (TLR) avoided. Costs were assigned for cardiac-related medical services using the Medicare payer perspective. RESULTS: Radiotherapy increased initial inpatient costs by US$3360 (P<.001). In the Radiotherapy and PCI alone groups, the mean per-patient rates for TLR were 0.13 vs. 0.30 (P=.001), and mean per-patient total costs were US$19,286 vs. US$18,349 (P<.001), respectively. The incremental cost of Radiotherapy relative to PCI alone was US$5512 per TLR avoided, which compares favorably to the observed mean per-patient cost of treating restenosis (US$16,852). CONCLUSIONS: beta-radiation is a cost-effective adjunct to PCI in treating patients with in-stent restenosis.

Aged↗
PubMedDate not supplied

Endovascular irradiation impairs vascular functional responses in noninjured pig coronary arteries.

PURPOSE: To assess the effects of endovascular irradiation on vascular structure and function in pig coronary arteries in the absence of vascular injury. METHODS AND MATERIALS: Vasomotor responses to contractions of KCl and prostaglandin F2alpha (PGF2alpha), relaxations to endothelium-dependent (substance P, A23187) and -independent (sodium nitroprusside, SNP) agents; endothelial morphology and superoxide anion (02*-) production were investigated in control (naive), sham and irradiated (20 Gy, 32P) arteries 1 month after irradiation. RESULTS: Contractions to KCl and PGF2alpha in the presence of L-NAME were significantly decreased, relaxations to substance P and A23187 were abolished and SNP-induced relaxation was potentiated in irradiated arteries compared to naive and sham-treated vessels. Scanning electron microscopy (SEM) revealed enlarged endothelial cells (ECs) exhibiting surface microvilli. O2*- production was significantly increased in irradiated vessels (437.0 +/- 37.3 vs. 126.0 +/- 11.6 RLU/s/mg tissue, P < .01). CONCLUSIONS: One month after brachytherapy, normal pig coronary arteries showed abnormal vascular reactivity, altered endothelial morphology and increased production of O2*-. Lack of relaxation to substance P and A23187 reflects ionizing radiation-mediated damage to ECs, whereas potentiation of relaxation to SNP suggests additional deleterious effects on medial smooth muscle cells (SMCs). Increased O2*- production might have contributed to endothelial dysfunction by scavenging nitric oxide (NO).

Angioplasty↗
PubMedDate not supplied

The "shielding" effect of the guide wire during coronary brachytherapy with P-32 source.

Intracoronary beta irradiation (use of beta radiation for intracoronary irradiation) is an effective method in reducing neointimal proliferation after successful angioplasty and stent implantation. However, long-term results may be influenced by absolute dose and by the homogeneity in dose distribution. In our study, we investigated dose perturbation due to the presence of a conventional guide wire during irradiation. The Galileo III centering catheter and P-32 beta source were used. The 55 MD GAF Chromic foil was positioned within a phantom made of PMMA. The dose distribution at cylindrical surfaces has been assessed using GAF Chromic dosimetric foil MD55 (Nuclear Associates, USA). Our study demonstrated the significant dose reduction of 46% in the most "shaded" area. The dose reduction to 80% or less occupy the 60 degrees sector. This phenomenon can cause progression of late restenosis. In conclusion, the results suggest that technical improvements in centering catheter construction should be made to eliminate the "shielding" effect of the guide wire.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Geographical miss and restenosis during catheter-based intracoronary beta-radiation for de novo lesions.

OBJECTIVES: We sought to determine the impact of geographical miss (GM) on restenosis rates after intracoronary beta-radiation therapy for de novo lesions. BACKGROUND: GM is the situation in which injured vessel segments (VSs) are receiving low-dose radiation and is accounted for edge restenosis. Its impact on the overall restenosis rates remains to be determined. METHODS: We analyzed 330 patients (356 vessels) treated according to the Beta Radiation in Europe (BRIE) and the Dose Finding study protocols. Using quantitative coronary angiography (QCA), the effective irradiated segment (EIRS), its edges and the total VS were analysed. The edges of the EIRS that were injured constituted the GM edges. Restenosis was defined as diameter stenosis > 50% at follow-up. GM was determined by the simultaneous electrocardiographic-matched, side-by-side projection of the source and balloons deflated and surrounded by contrast, at the site of injury, in identical angiographic projections. RESULTS: In 20.5% of the vessels, GM was non-interpretable due to inadequate filming. GM occurred at 30.4% of the interpretable edges and 53% of the interpretable vessels that were analysed. Edge restenosis was significantly increased in the GM compared to non-GM edges (13.16% vs. 4.17%, respectively, P = .001), both in the proximal (P = .03) and the distal (P = .001) edges. GM associated with stent injury significantly increased edge restenosis (P = .006). GM related to balloon injury tended to be associated with increment in edge restenosis (P = .07). The restenosis in the EIRS was similar between vessels with and without GM (17.78% and 14.85%, respectively, P = .6). GM was associated with significant increment in the restenosis at the analyzed VS (31.85% vs. 21.48%, P = .05). CONCLUSIONS: GM is strongly associated with edges and restenosis in the analysed VS. GM does not increase restenosis in the EIRS.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Visual assessment of procedural results following treatment with Sr-90 beta-radiation for instent restenosis.

BACKGROUND: Visual assessment (VA) of postprocedural % diameter stenosis (DS) is used routinely in clinical practice to determine the adequacy of coronary intervention. Although VA has been shown to underestimate final %DS after balloon angioplasty compared to quantitative coronary angiography (QCA), the impact of this effect on clinical outcomes following treatment with intracoronary radiation therapy (IRT) with Sr-90 for instent restenosis (ISR) is unknown. METHODS: To determine the effect of VA on the rate of major adverse cardiac events (MACEs) after IRT for ISR, we compared the clinical outcomes of 102 consecutive patients based on postprocedural %DS by QCA vs. %DS by VA. MACE was defined as death, M1 or need for target vessel revascularization (TVR). RESULTS: MACE rates for the 102 consecutive patients grouped according to postprocedural %DS by QCA and VA were compared. The mean %DS by QCA was 30.7%, while the mean %DS by VA was 12.5%. The mean %DS by VA across the QCA subgroups were 13.67%, 10.71% and 13.37%, respectively (P = .244). Fifty-two patients (51.0%) had %DS > 30% by QCA with the highest MACE percentage occurring in this subgroup. CONCLUSION: VA underestimated the %DS compared to QCA, and it was associated with worse MACE following treatment with Sr-90 for ISR.

Beta Particles↗
PubMedDate not supplied

Measured TG-60 dosimetric parameters of the Novoste Beta-Cath 90Sr/Y source trains for intravascular brachytherapy.

Measurements were performed on the 30, 40 and 60-mm 90Sr/Y beta-emitter source trains used in the Novoste Beta-Cath system to determine the dosimetric characteristics of the sources at millimeter distances and provide the necessary TG-60 dosimetry parameters for mapping the dose distributions. These measurements were carried out in a Solid Water phantom where MD-55-2 Gafchromic films were placed in direct contact with a 5 French (F) catheter used for the 30 and 60-mm source trains and a 3.5 F catheter used for a thinner 40-mm source train. The dosimetric analysis was performed according to the AAPM TG-60 formalism. For the 30-mm source train, data were collected with the source axis at distances of 0.41 and 1.19 mm from the film surface, respectively, in order to investigate possible dosimetric effects due to the intrinsic off centering of the source train lumen within the 5 F catheter. Absolute dose rates at 2 mm were determined by calibrating the radiochromic film in a high energy electron beam from a radiotherapy accelerator. The dose rates at a radial distance of 2 mm were found to be within 10% of the values provided by Novoste. Radial dose functions from this study were in good agreement (< or = 10%) with a 30-mm, 90Sr/Y source train dose data generated from C. G. Soares et al. 90Sr/Y single seed data. However, larger differences were observed at distances shorter than 1 mm when compared to radial dose functions from the Novoste Monte Carlo data.

Beta Particles↗
PubMedDate not supplied

Clinical beta radiation dosimetry for brachytherapy in terms of absorbed dose to water: ISO new work item proposal for international standardization.

PURPOSE: Beta radiation has found increasing interest in intravascular brachytherapy for successfully overcoming the severe problem of restenosis after interventional treatment of arterial stenosis. Prior to initiating procedures applying beta radiation there is a common need to specify methods for the determination and specification of the absorbed dose to water or tissue and their spatial distributions. The DIN-NAR standardization in radiology task group Dosimetry has initiated an international ad hoc working group for an ISO new work item proposal on the standardization of procedures in clinical beta radiation dosimetry. METHODS: The intent of this standard is to review methods and to give recommendations for the calibration of therapeutic beta sources, a code of practice for clinical beta radiation dosimetry and guidance for estimating the uncertainty of the absorbed dose to water delivered. The standard will be confined to "scaled" radioactive sources such as single seeds, source trains, line, shell and volume sources for which only the beta radiation emitted is of therapeutic relevance. The topics will include dosimetric quantities; source data; calibration and traceability; general principles and requirements for absorbed dose measurements; in phantom dosimetry; theoretical modeling; presentation of dose distributions; clinical dosimetry; clinical quality control; irradiation treatment planning; as well as uncertainties. The document is geared to organizations wishing to establish reference methods in dosimetry aiming at clinical demands for appropriate small measurement uncertainties. Existing normative documents as well as international recommendations, such as those from AAPM, DGMP, ESTRO, NCS, ICRU, or IAEA will be taken into account. RESULTS: The first meetings of the new international working group took place in March and September 2002 at Essen, Germany [IAEA-cn-96-73, 2002]. CONCLUSIONS: Based on the DGMP Report 16, the AAPM TG 60 up-date draft, other recommendations and normative documents, the DIN-NAR project has collected and prepared detailed material on the calibration and dosimetry of beta radiation brachytherapy sources in terms of absorbed dose to water. The ISO new work item proposal will be completed in spring 2003.

Beta Particles↗
PubMedDate not supplied

Beta-radiation therapy for long lesions in native coronary vessels: a matched comparison between de novo and in-stent restenotic lesions.

OBJECTIVE: The purpose of this study was to evaluate effectiveness and to compare clinical outcome of intracoronary beta-radiation to treat long lesions (>20 mm) in patients with de novo stenosis vs. patients with in-stent restenosis (ISR). METHODS: A matched comparison of 44 patients with 63 de novo lesions and 48 patients with 63 ISR lesions (>20 mm) treated with intracoronary beta-radiation was performed. RESULTS: Stents were implanted in 65.1% of de novo and 19% of ISR lesions (P=.001). Radiation doses delivered were 17.2+/-3.0 vs. 20.3+/-3.0 Gy at 2 mm from the source center for de novo and ISR lesions. There was no difference in the incidence of in-hospital events. Clinical follow-up at 16.4+/-6.7 months showed no difference in major adverse cardiac events (MACE) between de novo and ISR patients (27.3% vs. 25%, P=.8). Late total occlusions (LTOs) occurred in eight patients (four in each group) treated with stents at the time of radiation and after discontinuation of ticlopidine. By multivariate analysis, stent implantation was the only predictor of late occlusions (OR 8.25, 95% CI 1.73-38.46, P<.008). Restenosis rates were similar for de novo and ISR lesions (29.3% vs. 23.2%, P=.46), as well as target lesion revascularization (TLR) and target vessel revascularization (TVR) rates (22.7% vs. 22.9% and 29.5% vs. 29.2%, respectively). CONCLUSIONS: Intracoronary beta-radiation gives comparable results when used to treat de novo or ISR lesions provided new stent implantation can be avoided. Long-term combined antiplatelet therapy is mandatory for patients who receive new stents at the time of radiation treatment.

Adult↗
PubMedDate not supplied

32P liquid sources--comparison of the effectiveness of postangioplasty versus poststenting intravascular brachytherapy in hypercholesterolemic rabbits. Adjunctly implanted titanium stent does not attenuate the effect of endovascular irradiation.

PURPOSE: Endovascular application of ionizing radiation is a promising but still not sufficiently studied means of restenosis prevention. To test the effects of radiation on restenosis, and especially their dependence on whether the angioplasty was followed by stent implantation or not, we performed an in-stent versus no-stent intravascular brachytherapy study in an animal model. Balloon-based, continuous and self-centering, liquid 32P sources seemed the most convenient for the purpose. METHOD: The radial dose distribution around angioplasty balloons filled with solutions of Na(2)H32PO(4) was calibrated by thermoluminescence dosimetry, both in the absence and presence of stents. The animal experiments were performed on rabbits with induced hypercholesterolemia. The balloons containing 32P were introduced into iliac artery immediately after stent implantation or after angioplasty alone. Radiation effects were evaluated postmortem by comparing thickness of various components of the artery wall. RESULTS: In the presence of titanium stents (TTS), irradiation with 16 Gy dose at 1.0 mm from the balloon surface was no less effective in reducing hypertrophy in every active layer of the artery wall than without a stent. CONCLUSION: In the animal model, IVBT basing on P(32) liquid sources was no less effective in the stented arteries than in the nonstented ones.

Angioplasty, Balloon↗
PubMedDate not supplied

Beta emitter systems and results from clinical trials. state of the art.

Vascular brachytherapy has been established as the standard of care for the treatment of in-stent restenosis (ISR). Both beta and gamma emitters are currently in use for the prevention of ISR recurrence. The use of beta sources for vascular application is attractive from both the radiation exposure and safety points of view, and a wide variety of beta sources are available for this application. This review is intended to summarize the clinical trials utilizing beta emitter systems for the treatment of ISR and de novo lesions and their subsequent results.

Beta Particles↗
PubMedDate not supplied

On the depth of penetration of photons and electrons for intravascular brachytherapy.

PURPOSE: To investigate the depth dose characteristics of various radionuclides under consideration for intravascular brachytherapy (IVB). MATERIALS AND METHODS: In the past few years, various preclinical studies have shown that 10-30 Gy of ionizing radiation delivered by a brachytherapy treatment may inhibit restenosis following angioplasty. A number of new delivery systems using various radionuclides have been developed and are being investigated for IVB. Typical target size for IVB is in the range of millimeters, in contrast to conventional brachytherapy for cancer in which the target may be 1-5 cm in size. The question addressed in this paper is: whether lower energy photon emitters and even beta emitters, which are not commonly used for intracavitary brachytherapy of cancer, may provide a depth of penetration adequate for IVB. To explore this issue, radial dose functions for photons and electrons in the range of 1-10 mm in water were calculated using Monte Carlo simulation. Reference depth for normalization of the radial dose funtion was chosen to be 2 mm. RESULTS: Radial dose functions have been calculated for monoenergetic photons with energies of 0.01, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.40, and 1.00 MeV and monoenergetic electrons with energies of 0.5, 1.0, 1.5 and 2.0 MeV. Also, the same calculations have been performed for 192Ir, 125I, and 103Pd gamma or x-ray sources as well as 90Sr-90Y, 32P, and 188Re beta-emitting sources. Results are also provided for selected cases in a simulated calcified lesion in water. CONCLUSIONS: It is concluded that photons above an energy of 20 keV and electrons above an energy of 1.0 MeV are acceptable from the point of view of adequate depth of penetration for IVB in tissue.

Animals↗
PubMedDate not supplied

Gamma vs beta irradiation: which is superior?

BACKGROUND: The debate over which radioisotope, gamma-emitting or beta-emitting, is ideal for vascular brachytherapy, is as old as the field itself. Gamma isotopes such as Ir-192 have been successfully used in large-scale clinical trials. However, radiation protection and safety remains a practical issue when high energy gamma rays are used in interventional suites. METHODS: In this report, we have evaluated dosimetric properties of currently available radiation sources, gamma and beta, in terms of their utility in vascular brachytherapy. Published data have been analyzed in comparing the depth doses of these two radiation modalities. RESULTS AND CONCLUSIONS: Our evaluation shows that significant dosimetric differences do exist between gamma and beta sources. The superiority of one over the other in clinical utility will more likely be determined by the outcome of human trials.

Beta Particles↗
PubMedDate not supplied

Intracoronary radiation therapy for restenosis prevention: status of the clinical trials.

BACKGROUND: Vascular brachytherapy is an evolving field for the prevention of restenosis. The rationale for such therapy is that radiation prevents neointimal proliferation and vessel constriction following vascular injury. In recent years, numerous animal experiments have demonstrated that low doses of radiation when applied following intracoronary intervention reduces proliferation and alters the restenosis rate. This novel approach introduced specific vascular radiation biology and radiation physics aspects, new devices, and platforms to deliver the radiation intraluminally. METHODS: A variety of beta or gamma isotopes for use in vascular brachytherapy has been suggested. These isotopes need to be delivered intracoronarily to provide the therapeutic dose to the target cell via a safe and user-friendly platform. Two platforms of delivery are available and in practice: catheter-based systems and radioactive stenting. However, these novel applications have to be proven in the clinical arena. RESULTS: We have been conducting clinical trials with intracoronary brachytherapy since 1994 and are gathering information regarding the feasibility, safety, and effectiveness of this technology. Currently we are in the midst of an intensive clinical investigation using various devices, isotopes doses, and techniques. This report summarizes all the clinical work that has been conducted so far and is currently under investigation in this field. CONCLUSIONS: Without having the results of the majority of the trials described in this paper, it is difficult at this stage to draw firm conclusions regarding the future of this technology. However, the information presented will serve as a tool for the reader to judge the direction of vascular brachytherapy for prevention of restenosis.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Effects of low-dose-rate beta-irradiation on vascular smooth muscle cells: comparison with high-dose-rate exposure.

PURPOSE: Radiation therapy is undergoing extensive preclinical and clinical testing as a new tool to reduce restenosis after vessel injury. To date, however, no definite dose threshold has been identified after radioactive stent implantation. In this study, we compared the in vitro response of pig vascular smooth muscle cells (SMC) to conventional high-dose-rate (HDR) irradiation with the response to continuous low-dose rate (LDR) that could result from exposure to a radioactive stent. MATERIALS AND METHODS: Catheter-based radiotherapy delivers single doses at HDR whereas radioactive stents use a continuous LDR approach. Single doses in excess of 10 Gy have clearly shown a reduction in neointima formation and negative vessel remodeling in several animal models. Because dose rate is an important parameter modulating the overall biological response to ionizing radiation, we have compared the in vitro response of pig aortic SMC at conventional HDR (1.5 Gy/min) and at LDR (0.675 Gy/h). RESULTS: SMC showed significant repair of sublethal DNA damage and about twice the dose was necessary at the LDR to produce the same effect as that seen at the HDR. CONCLUSION: In vitro SMC exhibit a significant dose-rate effect that indicates that radioactive stents could deliver the dose at a sufficiently high dose rate to compensate for cell proliferation while at the same time the total dose should be increased to account for sublethal damage repair. This finding has important implications for the design of a radioactive stent.

Animals↗
PubMedDate not supplied

Low-energy 103Pd gamma (X-ray) source for vascular brachytherapy.

PURPOSE: This article describes the merits of 103Pd, a low energy x-ray emitter, as a new and potentially superior candidate for intraluminal brachytherapy. 103Pd can be ion implanted into different materials, designs, and devices for vascular brachytherapy. METHODS: The mass-analyzed ion implantation process has been used to embed the desired activity of 103Pd into the surface of 316L stainless steel stents. The low-energy, 21-keV x-ray from 103Pd delivers reasonably homogeneous radiation to the vessel wall and loses intensity rapidly beyond the immediate vicinity of the source. Shielding for 103Pd x-rays is trivial and the issues regarding safety, health hazards, storage, and handling are easily manageable. RESULTS: Experimental data on 103Pd ion-implanted stents show a clean gamma-ray spectrum devoid of any radioimpurity. Activity measurements within a batch demonstrate little stent-to-stent variation (approximately 2%), excellent axial and radial uniformity (<10%), and minimal dissolution in a saline environment (approximately 0.02%). The dosimetry shows the focused radiation field for 103Pd stents and rapid fall-off beyond a few millimeters of the stent. Furthermore, the 103Pd dosimetry indicates that a 350 muCi stent will deliver approximately 14 Gy at 1-mm distance, over its lifetime. CONCLUSION: 103Pd is an appropriate source for vascular brachytherapy. It has an appropriate combination of half-life (16.93 days) and energy (21 keV). The half-life of 103Pd delivers the dose with an acceptable dose rate for stent applications while, at the same time, allowing for manageable shipping, storage, and/or disposal.

Animals↗
PubMedDate not supplied

Radioactive beta-emitting solution-filled balloon treatment prevents porcine coronary restenosis.

PURPOSE: Intracoronary gamma or beta radiation from centrally located sources at the time of overstretch balloon injury inhibits neointimal proliferation. In an effort to deliver homogeneous, centered radiation fields in a technically straightforward fashion, we studied the effects of a beta-emitting solution used as a balloon inflation fluid to deliver radiation at the time of coronary injury. METHODS: Twenty-one coronary arteries in 13 juvenile swine underwent irradiation (control and 11 or 25 Gy media dose). Radiation was delivered using a perfusion balloon inflated with an Re-188 solution. Subsequently, overdilatation percutaneous transluminal coronary angioplasty was performed at the pretreated segment. Histopathologic and histomorphometric analysis was performed at 30 days after injury on the entire irradiated artery. RESULTS: Balloon overdilation was associated with significant vascular injury and marked neointimal proliferation in control and low-dose (11 Gy)-treated arteries. High-dose radiation (25 Gy) significantly inhibited neointima formation compared with controls (neointimal area: 0.49 +/- 0.29 mm2 vs. 1.51 +/- 0.22 mm2, respectively; p = 0.02) and low-dose radiation (neointimal area 1.75 +/- 0.54 mm2, p > 0.1 compared with controls). CONCLUSIONS: Liquid Re-188 is an effective beta-emitting vehicle to deliver intracoronary radiation and prevent restenosis in this model. Intracoronary radiation treatment using aqueous radioisotope sources is technically straightforward and provides the optimally achievable radiation dose distribution.

Animals↗