External beam irradiation and restenosis following femoral stenting: long-term results of a prospective randomized study.

PURPOSE: To assess the long-term outcome of external beam irradiation (EBI) for the prevention of restenosis due to neointimal hyperplasia, following percutaneous transluminal angioplasty (PTA) and stenting of the superficial femoral artery. METHODS: Sixty consecutive patients with peripheral arterial disease, who were treated with "bail-out" stent implantation in the superficial femoral artery due to suboptimal PTA, were included in this study. Patients were randomly allocated into two groups, receiving either external beam irradiation (6 MV photons, total dose 24 Gy in a hypofractionated schedule) plus antiplatelet therapy (EBI group) or antiplatelet therapy alone (control group). RESULTS: No procedure-related complications occurred, and all patients of the EBI group received the full dose of 24 Gy. During the long-term follow-up, an overall statistically significant difference was demonstrated in favor of the EBI group patients, regarding both the in-stent (log-rank test, p = 0.0072) and the in-segment binary restenosis (log-rank test, p = 0.0103). The primary patency rates were also significantly better in the EBI group at specific time-points, such as in the first (74.2% vs 46.5%, p = 0.019), second (62.5% vs 33.8%, p = 0.020), and third (54.6% vs 29.0%, p = 0.039) year, respectively. Moreover, the overall clinically driven reintervention rate was significantly lower among patients of the irradiated group (log-rank test, p = 0.038). CONCLUSION: Our long-term follow-up analysis revealed that EBI following femoral artery PTA and stenting significantly reduces restenosis and reintervention rates, while improving primary patency.

Clinical trials of vascular brachytherapy for in-stent restenosis: update.

Vascular brachytherapy has become the therapeutic strategy of choice for in-stent restenosis. Clinical trials evaluating the effectiveness and safety of this technology have enrolled nearly 4000 patients using both gamma and beta emitters. At present, ongoing controversies include optimal dosimetry, whether beta emitters are as effective as gamma and whether centering delivery systems perform better than non-centering systems. Complications of brachytherapy such as edge effect, late thrombosis and late restenosis have received increasing attention. This review provides an update of the current status of clinical trials utilizing vascular brachytherapy to prevent the recurrence of in-stent restenosis.

Successful treatment of intimal hyperplasia in renal arteries by endovascular brachytherapy.

PURPOSE: The present study shows the possibility of preventing restenosis of renal arteries by endovascular brachytherapy. METHODS AND MATERIALS: We present a patient suffering from rapid restenosis of both renal arteries with decreasing renal function. Percutaneous transluminal angioplasty (PTA) and stent implantation were unable to stop hypertension and to stabilize renal function. Both renal arteries and the right pole artery were treated by endovascular brachytherapy in one session. RESULTS: Six months after intervention, intraarterial digital subtraction angiography (DSA) showed no evidence of recurrence, and the blood pressure remained normal without medical treatment. CONCLUSION: Endovascular brachytherapy can help to prevent restenosis in renal arteries. It is possible to treat both renal arteries and one pole artery in one session without any disadvantage.

Samarium-153 for intravascular irradiation therapy with liquid-filled balloons to prevent restenosis: acute and long-term results in a hypercholesterolemic rabbit restenosis model.

BACKGROUND: It has been shown that irradiation with either beta and gamma sources inhibit neointimal formation. Samarium-153 ((153)Sm) is an isotope with 0.8 MeV, subdivided in three different beta energies and 103 keV of gamma energy. This compound has been tested and used in humans for palliation of pain from bone metastases. The aim of the present study was to evaluate the feasibility and efficacy of brachytherapy with (153)Sm-filled balloon to inhibit neointimal formation in rabbits after balloon overstretch injury. METHODS: Nineteen rabbits underwent balloon injury in their iliac arteries. In 12 animals (control), oversized balloons filled with saline solution were inflated up to 5 atm for a period of 5 min. In 7 rabbits, the same procedure was performed but using balloons filled with (153)Sm. In all cases, both iliac arteries were treated. The prescribed radiation dose was 15 Gy at 1 mm depth. After 30 days, the animals were sacrificed and their arterial segments were analyzed. Radiation exposure at the animal chest to the table and at a distance of 1 m from the table was measured. RESULTS: Histopathologic analysis showed a striking reduction in the amount of neointima in the irradiated arteries compared with control vessels (0.36+/-0.21 vs. 1.07+/-0.56 mm(2), P<.01). The dose delivered to the animal chest was 21.5 mR/h, whereas only 1.9 mR/h was measured at the table and virtually no radiation could be detected at a distance of 1 m from the table. CONCLUSIONS: Brachytherapy with (153)Sm was feasible with minimal personnel exposure radiation and effectively inhibited neointimal formation in this experimental model. These results warrant further experimental and clinical investigations.

[Endovascular radioprevention of intimal hyperplasia after percutaneous transluminal angioplasty of peripheral blood vessels]. / Endovaskuläre Radiatioprophylaxe der Intimahyperplasie nach perkutaner transluminaler Angioplastie in peripheren Gefässen.

The prognosis of interventionally treated arterial occlusive vessel disease in peripheral arteries is not significantly better with the use of stents than with percutaneous transluminar angioplasty. The rate of restenosis or reocclusion in dilated or recanalized and stented peripheral arteries is reported as up to 40%, depending on location and author. In the early phase thrombotic processes are responsible which then demonstrate histologically confirmed intimal hyperplasia. On the basis of many years of radiotherapy experience in the treatment of benign hyperplastic tissue alterations, brachytherapy could be introduced as a method for prophylaxis of vessel restenoses. The early difficulties with this method were due to the inadequacies of the equipment. The development of small radiation sources with high specific activity now enables these target volumes to be reached. The clinical experience so far indicates high efficiency of this method. It can be expected that the range of indications for adjuvant endoluminal irradiation will broaden in the future.

[Intervention and clinical aspects combined with endovascular irradiation of intimal hyperplasia of the vascular system]. / Intervention und Klinik im Zusammenhang mit der endovaskulären Radiatio intimaler Hyperplasien im Gefässsystem.

After implantation of stents in femoropopliteal arteries we found restenosis or occlusions by intimal hyperplasia in up to 40% especially in the hunter's channel. Repeated balloon angioplasty and prophylactic endovascular radiotherapy with a surface dose of 12 Gy in the vessel wall using an iridium 192 source in the same investigational session is a new technique to reduce or eliminate further recurrence. All 18 patients had developed recurrent stenoses or occlusions 6-8 months after original stent implantations. The patients have not redeveloped recurrent obstructions after this treatment, which up to date showed no short term or long term complications. We conclude that the encouraging results of this pilot study justify further randomized trials.