Early time course of neointima formation and vascular remodelling following percutaneous coronary intervention and vascular brachytherapy of in-stent restenotic lesions as assessed by intravascular ultrasound analysis.

In-stent restenosis (ISR) represents the major limitation of stent implantation. Treatment, although of relative technical ease, is unsatisfactory due to a high incidence of recurrent restenosis. Vascular brachytherapy (VBT) has emerged as a powerful adjunct therapeutic modality to treat ISR. Inhibition of neointima formation has been regarded as the relevant mechanism of action. Yet, positive remodelling has been suspected as another contributing factor. Since only very few precise analyses of the extent, distribution and time course of the respective mechanims exist, the goal of the present study was to describe the changes of the vessel geometry at the target lesion and at the reference site following angioplasty and VBT of ISR in 42 patients by means of quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS) before and after the index procedure and at the 3 and 6 month follow-up. By QCA the acute lumen gain measured 2.2+/-0.8 mm, the late lumen loss at 3 months was 0.1+/-0.5 mm and at 6 months 0.4+/-0.7 mm. By IVUS luminal cross-sectional area increased from 1.5+/-1.2 mm(2) to 7.9+/-1.9 mm(2) (p<0.001). The intima hyperplasia cross-sectional area at 3 months was only 0.2+/-1.0 mm(2) (p=0.191), but increased to 0.7+/-0.6 mm(2) (p<0.001) at 6 months resulting in a lumen cross-sectional area of 7.1+/-1.7 mm(2). Stent dimensions did not show any significant changes over time. The external elastic membrane cross-sectional area at 3 months increased by 1.3+/-1.9 mm(2) (p<0.001), and showed a further increase by 0.7+/-2.9 mm(2) at 6 months. Positive remodelling could be demonstrated also at the reference segment. In conclusion the absolute amount of intima hyperplasia during a 6-month follow-up period after VBT of ISR is low and most pronounced between the third and sixth month. Besides this, predominantly within the first 3 months of follow-up, significant positive remodelling could be demonstrated at the target lesion and at the reference site. Both observed effects may contribute to the preservation of the vessel lumen.

[Clinical and angiographic one-year follow-up of vascular beta-brachytherapy for coronary lesions treated by a stent with a very high risk for restenosis]. / Klinischer und angiographischer Ein-Jahres-Verlauf nach vaskulärer Beta-Brachytherapie von Instent-Restenosen mit sehr hohem Rezidivrisiko.

BACKGROUND: Vascular brachytherapy (VBT) has been proven to reduce restenosis rate and unwanted cardiac events in several randomized trials. Long-term data on populations at high risk for re-interventions are few. The aim of this study was to assess the acute and one-year outcome of beta-radiation in coronary in-stent restenoses with a high likelihood of recurrence. METHODS: In 79 patients, VBT using 90Yttrium/Strontium or 32Phosphorus, was performed. Clinical and angiographic follow-up was carried out after 6 months and 1 year. RESULTS: 44.4 % of patients had three-vessel coronary artery disease and a high prevalence of cardiovascular risk factors and comorbidity. Mean lesion length was 36.8+/-18.9 mm. VBT was successful in all patients. Fractionation of VBT was necessary in 2,5 %. Acute gain of luminal diameter was 2.15+/-0.89 mm. During the hospital stay one acute myocardial infarction (AMI) not associated with VBT occurred. After 6 months loss of luminal diameter measured 0.39+/-0.47 mm, equaling a restenosis rate (RR) of 16.8 % (1 year: 0.60+/-0.56 mm, RR 33.5 %). 18.9 % of patients required revascularization of the target lesion (1 year: 29.5 %). After 6 months, all patients survived, three had an AMI after discontinuation of clopidogrel, one of them was asymptomatic (1 year: 1 cardiac death, 2 symptomatic AMI). CONCLUSION: Beta-VBT in patients at a high risk for recurrence after angioplasty is feasible and safe. Though the clinical and angiographic results at 1 year showed some impairment as opposed to the 6-months-follow-up, they nevertheless are largely superior to those patients from historic controls not treated with VBT.

[Edge effect and late thrombosis -- inevitable complications of vascular brachytherapy?]. / Edge effect und späte Thrombose -- Notwendiges Ubel oder vermeidbare Nebenwirkung der intrakoronaren Brachytherapie?

Restenosis is the limiting entity after percutaneous coronary angioplasty. Vascular brachytherapy for the treatment of in-stent restenosis has been shown to reduce the repeat restenosis rate and the incidence of major adverse events in several randomized trials. Besides the beneficial effects, brachytherapy yielded some unwanted side effects. The development of new stenoses at the edges of the target lesion treated with radiation is termed edge effect. It occurs after afterloading brachytherapy as well as after implantation of radioactive stents. It is characterized by extensive intimal hyperplasia and negative remodeling. As contributing factors the axial dose fall-off, inherent to all radioactive sources, and the application of vessel wall trauma by angioplasty have been identified. The combination of both factors, by insufficient overlap of the radiation length over the injured vessel segment, has been referred to as geographic miss. It has been shown to be associated with a very high incidence of the edge effect. Avoidance of geographic miss is strongly recommended in vascular brachytherapy procedures. Late thrombosis after vascular brachytherapy is of multifactorial origin. It comprises platelet recruitment, fibrin deposition, disturbed vasomotion, non-healing dissection and stent malapposition predisposing to turbulent blood flow. The strongest predictors for late thrombosis are premature discontinuation of antiplatelet therapy and implantation of new stents during the brachytherapy procedure. With a consequent and prolonged antiplatelet therapy, the incidence of late thrombosis has been reduced to placebo levels. Edge effect and late thrombosis represent unwanted side effects of vascular brachytherapy. By means of a thorough treatment planning and prolonged antiplatelet therapy their incidences can be largely reduced. With regard to the very favorable net effect, they do not constitute relevant limitations of vascular brachytherapy.

Vascular brachytherapy for treatment of cardiac allograft vasculopathy.

A high restenosis rate often follows treatment of coronary stenoses in cardiac allograft vasculopathy. We report successful coronary brachytherapy of a second in-stent restenosis in a patient after heart transplantation.

[Endoluminal irradiation of tracheobronchial tumors using a high dose rate iridium-192 afterloading device]. / Endoluminale Bestrahlung mit dem HDR-Iridium-192-Afterloadingverfahren bei tracheobronchialen Tumoren.

We report about 50 patients with inoperable bronchus tumors treated since March 1986 in a prospective non randomized study with high dose rate iridium-192 afterloading (AL) irradiation in 140 applications. 26 patients were treated combined with external irradiation. 32 were treated before with laser therapy, one with chemotherapy (small cell carcinoma). The actuarial survival rate (Kaplan-Meier) was 26% after 36 weeks for all patients; 38% for combined endoluminal and external irradiation and 9% for patients treated with AL alone. Death was caused by the local tumor in 85%. In 41% lethal bleeding was seen.

[Clinical result of thyroid scintigraphy and iodine estimations using a fluorescent technique (author's transl)]. / Klinische Ergebnisse der Schilddrüsenszintigraphie und Jodbestimmung mit Fluoreszenztechnik.

The new technique of quantitative fluorescent scintigraphy was used for determining the regional distribution and concentration of stable intrathyroid iodine (127 I) in 96 patients. Average iodine concentration in normal people (20 individuals) without thyroid enlargement living in the Bavarian iodine-deficiency area was 0.38 +/- 0.07 mg/g. In 32 patients with simple goitres it was significantly lower at 0.17 +/- 0.06 mg/g. With this technique it was possible to separate two types of hyperthyroidism amongst 21 patients: those with low iodine concentration in the thyroid (0.15 +/- 0.08 mg/g) and those with high iodine concentration (0.42 +/- 0.12 mg/g) after iodine administration. The iodine concentration in decompensated autonomous adenomas in twelve patients was usually low (0.12 +/- 0.12 mg/g). On the other hand iodine concentration was high in the paranodular tissues and could be demonstrated on the fluorescent scintigram. The quality of the scintigram using this technique for concentrations below 0.1 mg/g is inadequate. In this situation good imates can be obtained by radionucleid scintgrams. The situation is reversed by previous administration of iodine.