Cardiovascular radiation medicine最新文献

Purpose

Edge restenosis in stenotic lesions treated by implantation of a conventional stent followed (or preceded) by a catheter-based brachytherapy is often attributed to “geographic miss” (GM). We propose a complementary (or, possibly, alternative) explanation based on the concept that a clear postprocedural mismatch between the in-stent lumen and the normal (undilated) lumens of the proximal and/or distal vessel segments results in an excessive, damageable increase of axial wall stress in these segments.

Methods

The possible poststenting situations at both margins of a stent are examined, and based on the presence or absence of an increase in axial wall stress, predictions are made about the lesion evolution. The concept is then also examined in the light of published observations.

Results

None of the analyzed observations appeared to be incompatible with the proposed morphological–mechanical explanation.

Conclusion

From a mechanical point of view, optimal matching of the proximal and distal stent diameters to the corresponding normal diameters of the adjacent arterial segment is likely to reduce the rate of edge restenosis.

Staphylococcus aureus is a leading cause of septicaemia and infective endocarditis. The overall incidence of staphylococcal bacteraemia is increasing, contributing to 16% of all hospital-acquired bacteraemias. The use of cardiac pacemakers has revolutionized the management of rhythm disturbances, yet this has also resulted in a group of patients at risk of pacemaker lead endocarditis and seeding in the range of 1% to 7%. We describe a 26-year-old man with transposition of the great arteries who had a pacemaker implanted and presented with S. aureus septicaemia 2 years postpacemaker implantation and went on to develop pacemaker lead endocarditis. This report illustrates the risk of endocarditis in the population with congenital heart disease and an intracardiac device.

To reduce in-stent restenosis rates, we developed a novel drug-eluting covered stent with a microporous elastometric covered film, in which its luminal surface was flat and immobilized with heparin for anticoagulation and its outer surface immobilized with FK506 to prevent neointimal hyperplasia. One month after implantation into the bilateral common carotid arteries, all stented arteries were patent and the luminal surfaces were fully covered with a confluent of endothelial cells irrespective of the drug immobilization. In the control group, which consisted of covered stents without drug immobilization, intensive inflammatory cells adjacent to the stents and neointimal hyperplasia, indicating vascular injury, were observed. In contrast, in the developed drug-eluting stents, only a few inflammatory cells around the stent strut and covered film were observed, and there was no significant neointimal thickening.

Objective

Vascular access for hemodialysis is often achieved with an arterial–venous graft (AVG). Brachytherapy is being explored for prevention of stenosis within these grafts. The objective was to develop treatment planning (TP) capability for dialysis implants.

Material and methods

Fluoroscopic images are used to identify position of sources and irradiated vessel. An Sr⁹⁰/Y⁹⁰ beta source, jacketed in a CO₂-filled balloon, is used to irradiate the AVG. A single-seed Sr⁹⁰ dose kernel was generated using Monte Carlo. The single-seed dose kernel was employed to calculate the dose surrounding the implant accounting for the path length of the beta particles through the gas-filled balloon.

Results

Dose distributions are displayed superimposed on the fluoroscopic image of the AVG. Dose–area histograms were also generated.

Conclusion

TP for dialysis implants can be performed using radiographic localization of the graft. The TP tools could be used to correlate clinical outcome with dose delivery.

Background: Oxidation of lipoproteins is considered to be a key contributor to atherogenesis. Antioxidants are potential antiatherogenic agents because they can inhibit lipoprotein oxidation. Radiation has been shown to increase oxidative stress leading to increased atherogenesis. This study is designed to test the potential of antioxidants to inhibit atherosclerotic plaque progression in balloon-denuded and -radiated rabbits. Methods and Results: Two groups of New Zealand white rabbits (n=36) were fed with 1% cholesterol diet (control diet) or with 1% cholesterol diet containing a mixture of various antioxidants for 1 week. Iliac arteries in all the animals were balloon denuded and continued to fed with 0.15% cholesterol diet or 0.15% cholesterol diet containing antioxidants (antioxidant diet). Four weeks after balloon denudation one iliac artery in 12 animals from each group was radiated and all the animals were continued to be fed with the same diet. Four weeks after radiation animals were sacrificed and morphometric analysis of iliac arteries (n=12) in nonradiated and radiated animals were performed. Plaque area (PA) in the rabbits that were fed with cholesterol diet is 0.2±0.12 mm², and it is increased by 2.75-fold (P<.05) in the radiated arteries of animals fed with cholesterol diet. Plaque area in the animals fed with antioxidant diet is 50% less then the one in the animals fed with cholesterol diet. Similarly, plaque area in radiated arteries of the animals fed with antioxidant diet is 50% less then the animals fed with cholesterol diet. Conclusion: Antioxidants significantly attenuate atherosclerotic plaque progression in balloon-injured and -radiated hypercholesterolemic rabbits.

Introduction: Inflammatory and immunological responses of vascular cells are known to play significant roles in atherosclerotic plaque development. Rapamycin with antiinflammatory, immunosuppressive and antiproliferative properties has been shown to reduce neointima formation when coated on stents. This study is designed to test the potential of oral rapamycin to inhibit atherosclerotic plaque development. Methods: Eight-week-old apoE knock-out mice were fed with 0.25% cholesterol supplemented diet (control diet), control diet containing 50 μg/kg rapamycin (low-dose rapamycin) or 100 μg/kg rapamycin (high-dose rapamycin) for 4 or 8 weeks. Subsets of mice from each group (n=10) were weighed and euthanized. Whole blood rapamycin levels were determined using HPLC–MS/MS, and histological analyses of atherosclerotic lesions in the aortic root were performed. Results: Mice fed with high-dose rapamycin did not gain weight (18.5±1.5 vs. 20.6±0.9 g, P=.01). Blood levels of rapamycin 117±7 pg/ml were detected in the blood of mice fed with high-dose rapamycin for 8 weeks. The plaque area in mice fed with high dose oral rapamycin is significantly less as compared to control (0.168±0.008 vs. 0.326±0.013 mm², P=.001 at 4 weeks; 0.234±0.013 vs. 0.447±0.011 mm², P=.001 at 8 weeks). Lumen area was inversely proportional to the plaque area. Conclusions: The results indicate that oral rapamycin is effective in attenuating the progression of atherosclerotic plaque in the mice.