Cardiovascular radiation medicine最新文献

Background

The effects of brachytherapy performed 24 h postintervention in de novo native coronary artery lesions.

Methods and Results

Thirty-nine patients with 39 de novo coronary artery lesions were randomised to prompt (immediately after intervention, n=21) or delayed (24 h later, n=18) beta brachytherapy (⁹⁰Sr/⁹⁰Y) after been successfully revascularized with stenting. Clinical follow-up data up to 21 months (median time) were compared. After irradiation and at 6-month follow-up, paired volumetric analysis of the stented segment and the 5-mm proximal and distal reference segments was performed; this included measurements of the external elastic membrane, lumen, plaque, and media (external elastic membrane minus lumen), stent and intima hyperplasia (stent minus lumen).

Baseline clinical and angiographic characteristics were similar in the two groups. Postintervention measurements of stent, lumen, and intima hyperplasia volumes as well as postintervention minimum lumen cross-sectional areas were not different. In the stented segments and in the segments 5 mm proximal and distal to the stent, similar changes of all IVUS measurements were measured in the two patient groups, but in the lumen volume at the proximal stent edge of patients irradiated 24 h postinjury. At 21 months median follow-up time, target lesion revascularization (TLR) was performed in 8 patients (38%) in the prompt irradiation group compared with 3 (17%) in the delayed (P=.17).

Conclusion

Beta irradiation is similarly effective whether performed immediately after percutaneous coronary intervention or 24 h later.

Background

Parallel, thin (<100 μm) planes of synchrotron-generated X rays, have been shown to spare normal tissues and preferentially damage tumors in animal models. The aim of the present study was to assess the effect of such microbeams directed unidirectionally on angioplasted rat carotid arteries.

Methods and materials

Three groups of Sprague–Dawley rats were studied: (a) rats with normal, untreated arteries, (b) rats treated by balloon angioplasty, but not irradiated, and (c) rats treated with balloon angioplasty and exposed to single fraction, unidirectional, parallel, microbeams an hour after angioplasty. The microbeam array, 15 mm wide×7.6 mm high, consisting of 27-μm-wide beam slices, spaced 200 μm center-to-center laterally traversed the damaged artery. The in-depth in-beam dose was 150 Gy, the “valley” dose (dose midway between microbeams resulting mainly from X-ray scattering) was 4.5 Gy on average, and the “integrated” (averaged) dose was 26 Gy.

Results

Microbeam irradiation, as given in the present study, was tolerated, but was insufficient to significantly suppress the neointimal hyperplasia.

Discussion

The microbeam dose used is considered low. Dose escalation would be necessary to reach conclusive results regarding the X-ray microbeam efficacy to control restenosis.

We report the case of an unusual complication for Cutting Balloon Angioplasty (CBA) during treatment for instent restenosis (ISR), which resulted in inadvertent intracoronary stent extraction 10 months after implantation. In this case report, CBA was utilized to treat an ISR lesion in the distal right coronary artery (RCA). Due to difficulty in withdrawing the cutting balloon into the guide after treatment of the lesion, the entire system (guide, cutting balloon, and guidewire) was removed as a unit from the body. Upon examination of the system, the previously placed stent in the distal RCA was attached to the microtomes of the cutting balloon. Although the precise mechanisms for stent extraction in this case remain speculative, the initial stent used in the distal RCA may have been undersized, and this may have played a major role in this complication. Although there is limited data regarding the optimal strategy to treat the site of the inadvertent stent extraction, we opted to re-stent the area with a properly-sized coronary stent. Following the intervention, there was no residual stenosis with TIMI 3 flow through the vessel. The patient remained asymptomatic and a serum troponin drawn 18 hours after the procedure was normal, and he was discharged the next day. The interventionist must be vigilant about this rare but serious complication when applying CBA in the treatment of ISR, particularly when an undersized or underdeployed stent is suspected.

Background

Brachytherapy is the only effective treatment for in-stent restenosis (ISR). The preliminary data regarding cutting balloon angioplasty (CBA) are encouraging and suggest a possible additive effect of CBA with combination with vascular brachytherapy. Hence, in this study, we evaluated the efficacy, feasibility and safety of cutting balloon angioplasty followed by intracoronary Holmium (¹⁶⁶Ho) brachytherapy for the treatment of in-stent restenosis.

Methods and Materials

Fifty-six patients with in-stent restenosis were treated with cutting balloon angioplasty and intracoronary ¹⁶⁶Ho brachytherapy. For irradiation, a balloon approximately 10 mm longer than the initially deployed stent was filled with liquid ¹⁶⁶Ho and placed at the in-stent restenosis lesion. The patients were followed angiographically at 6 months and clinically for 19.0±9.8 months.

Results

The initial procedures were successful in all of the patients. The preprocedural average minimal luminal diameter (MLD) and stenosis rate were 0.57±0.30 mm and 80.2±11.6%, respectively. The MLD and residual stenosis immediately after the procedure was 2.43±0.37 and 13.8±9.9%, respectively. Thirty-nine (69.6%) patients have completed their angiographic follow-up at 6 months. The MLD, late loss and loss index at follow-up were 1.97±0.79 mm, 0.72±0.69 mm and 0.36±0.34, respectively. The target lesion restenosis rate was 20.5% and the target lesion revascularization rate was 3.6%. None of these patients presented with adverse coronary events such as MI, sudden cardiac death or stent thrombosis during the follow up period.

Conclusion

The combination therapy using cutting balloon angioplasty and intracoronary ¹⁶⁶Ho brachytherapy may be an effective new treatment modality for in-stent restenosis.

Purpose

Human observations provide rich soil for making hypotheses, but good animal models are essential for understanding the disease and to test treatment modalities. Currently, there is no standard animal model of vulnerable plaque; therefore, the purpose of this study is to develop a pathophysiologically relevant vulnerable plaque model.

Methods

New Zealand White rabbits were fed with 1% hypercholesterolemic (HC) diet for 7 days, followed by balloon denudation of both the iliac arteries, and continued on 1% HC diet. Four weeks later, in 12 rabbits one of the iliac arteries was radiated (192-Ir, 15 Gy), and in five rabbits both the iliac arteries were sham treated. Following that, rabbits were fed with 0.15% HC diet. Four weeks later, arteries were processed for histomorphometry or immunohistochemistry.

Results

Serum cholesterol levels were similar in all the groups. In radiated arteries, plaque area was significantly larger (32% larger then in sham). Macrophage-positive area in radiated arteries was 2.4 times greater than the macrophage-positive area in the nonradiated arteries. The area positive for macrophages is also positive for metalloproteinases (MMP)-1. The extent of α-actin positive area was significantly less (2.3-fold) in radiated arteries.

Conclusion

The atherosclerotic plaque developed in the current model is predominantly composed of macrophages expressing metalloproteinases with few smooth muscle cells (SMC)—a characteristic of vulnerable plaque. The animal model presented in this study can elucidate at least part of the mechanism of plaque vulnerability and could be used to test treatment modalities to test plaque stability.