Stent-coil treatment of a distal internal carotid artery dissecting pseudoaneurysm on a redundant loop by use of a flexible, dedicated nitinol intracranial stent.
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Treatment of dissecting pseudoaneurysms of the distal cervical internal carotid artery with preservation of the parent artery by using stents or coils has become routine. Tortuosity remains a significant obstacle to successful endovascular treatment in some cases. We report the use of a stent-coil technique to treat a nonhealing dissecting pseudoaneurysm and associated stenosis with anatomic preservation of a redundant loop involving the stented arterial segment. This was accomplished by using a Neuroform dedicated intracranial stent. (+info)
Embolic protection with filtering or occlusion balloons during saphenous vein graft stenting retrieves identical volumes and sizes of particulate debris.
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BACKGROUND: Distal embolization of plaque particulate liberated during stenting may cause periprocedural complications. The number, size, and volume of debris released during stenting, however, have not been quantified, rendering embolic protection approaches empiric. We used a novel method of microparticle size assessment to measure volume and characterize individual sizes of particles captured by the PercuSurge GuardWire balloon or a vascular filter during saphenous vein graft stenting. METHODS AND RESULTS: Braided nitinol filters (average distal pore size 100 microns) were used in 47 saphenous vein grafts in 44 patients. The PercuSurge GuardWire was used in 17 saphenous vein grafts in 16 patients. Particulate debris was subjected to microparticle size analysis (RapidVue, Beckman Coulter). All samples contained particulate debris. For both filter and GuardWire populations, most particles were <100 microm in longest dimension (87% and 90% of particles, respectively), and the distribution of particle sizes was identical. Total embolic load per lesion for both filters and GuardWire aspirates was also similar: median embolic load per filter was 16 mm3 (range 2 to 84 mm3). Median embolic load per GuardWire was also 16 mm3 (range 7 to 42 mm3). Histopathologic analysis demonstrated that most samples contained plaque elements and platelet-rich thrombus. CONCLUSIONS: During saphenous vein graft interventions, particulate retrieved with a vascular filtering device or an occlusion balloon was similar in amount and character. This supports the notion that unless soluble mediators play an important role in adverse acute clinical events after stenting, the clinical efficacy of filtering devices may be equal to that of occlusion devices. (+info)
Conformity of carotid stents with vascular anatomy: evaluation in carotid models.
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BACKGROUND AND PURPOSE: Conformity between self-expanding Wallstents and vascular anatomy is limited. Because of a lack of longitudinal flexibility, straightening effects on vascular curves occur and may result in stent-induced kinking. Our purpose was to evaluate the conformity of self-expanding stents with the course and endoluminal surface of silicone models of the normal human carotid artery. METHODS: Five different types of self-expanding carotid stents were implanted into simplified pulsatile perfused silicone models of the carotid bifurcation. The models embody elastic properties of the vessel wall similar to those of normal human arteries. All stents had the same nominal diameter and length and bridged the external carotid artery origin as well as a consecutive curve at the initial segment of the internal carotid artery. Conventional radiographs of the model were compared before and after stent placement to record changes of shape and course of the silicone artery. Dehiscences between stent filaments and arterial wall were measured on digital subtraction angiograms of the model. RESULTS: Implantation of braided Wallstents or the Expander with continuous filaments induced considerable straightening effects on the bifurcation angle, as well as on the curves of the internal carotid artery. Segmented designs of modular nitinol stents complied better with vascular tortuosity and showed improved adaption between stent and the endoluminal surface of the model. CONCLUSION: Model experiments show that segmented nitinol stents improve the conformity between the prosthesis and vascular anatomy, and confirm new carotid stent concepts as an alternative to the Wallstent. (+info)
Explant analysis of AneuRx stent grafts: relationship between structural findings and clinical outcome.
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OBJECTIVE: We reviewed the structural findings of explanted AneuRx stent grafts used to treat abdominal aortic aneurysms, and relate the findings to clinical outcome measures. METHODS: We reviewed data for all bifurcated AneuRx stent grafts explanted at surgery or autopsy and returned to the manufacturer from the US clinical trial and worldwide experience of more than 33,000 implants from 1996 to 2003. Devices implanted for more than 1 month with structural analysis are included in this article. Explant results were analyzed in relation to cause of explantation and pre-explant evidence of endoleak, enlargement, or device migration. RESULTS: One hundred twenty explanted stent grafts, including 37 from the US clinical trial, were analyzed. Mean implant duration was 22 +/- 13 months (range, 1-61 months). Structural abnormalities included stent fatigue fractures, fabric abrasion holes, and suture breaks. The mean number of nitinol stent strut fractures per explanted device was 3 +/- 4, which represents less than 0.2% of the total number of stent struts in each device. The mean number of fabric holes per explanted device was 2 +/- 3, with a median hole size of 0.5 mm(2). Suture breaks were seen in most explanted devices, but composed less than 1.5% of the total number of sutures per device. "For cause" explants (n = 104) had a 10-month longer implant duration (P =.007) compared with "incidental" explants (n = 16). "For cause" explants had more fractures (3 +/- 5; P =.005) and fabric holes (2 +/- 3; P =.008) per device compared with "incidental" explants, but these differences were not significant (P =.3) when adjusted for duration of device implantation. Among clinical trial explants the number of fabric holes in grafts in patients with endoleak (2 +/- 3 per device) was no different from those without endoleak (3 +/- 4 per device; P = NS). The number of fatigue fractures or fabric holes was no different in grafts in clinical trial patients with pre-explant aneurysm enlargement compared with those without enlargement. Pre-explant stent-graft migration was associated with a greater number of stent strut fractures (5 +/- 7 per device; P =.04) and fabric holes (3 +/- 3 per bifurcation; P =.03) compared with explants without migration. Serial imaging studies revealed inadequate proximal, distal, or junctional device fixation as the probable cause of rupture or need for conversion to open surgery in 86% of "for cause" explants. Structural device abnormalities were usually remote from fixation sites, and no causal relationship between device findings and clinical outcome could be established. CONCLUSIONS: Nitinol stent fatigue fractures, fabric holes, and suture breaks found in explanted AneuRx stent grafts do not appear to be related to clinical outcome measures. Longer term studies are needed to confirm these observations. (+info)
Determination of nickel in alloys and plant leaves with salicylaldehyde 3-oxobutanoylhydrazone by spectrophotometry.
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A simple and highly sensitive reagent of salicylaldehyde 3-oxobutanoylhydrazone (salicylaldehyde acetoacetic acid hydrazone, SAAH) was synthesized and studied for the spectrophotometric determination of nickel in detail. In the pH range 6, which greatly increased the selectivity, nickel reacted with SAAH to form a 1:1 yellow complex, having a sensitive absorption peak at 405 nm. Under the optimal conditions, Beer's law was obeyed over the range from 0.0117 to 0.1174 microg cm(-3). The apparent molar absorptivity was 3.025 x 10(5) dm3 mol(-1) cm(-1). The detection limit and the variation coefficient were found to be 1.752 ng cm(-3) and 1.0%, respectively. The method has been applied to the quantitative determination of nickel in different alloys and leaves. (+info)
Clinical evaluation of radiotherapy for advanced esophageal cancer after metallic stent placement.
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AIM: To evaluate the therapeutic effect of radiotherapy for esophageal cancer after expandable metallic stent placement. METHODS: Ten cases of advanced esophageal cancer were evaluated, 7 having complete obstruction and 3 with digestive-respiratory fistula. Ten nitinol stents were placed at the site of stenosis. Patients were treated with a total dose of 1 200 cGy divided into 3 fractions of 400 cGy 4-7 d after stents placement. RESULTS: All the 10 stents were placed successfully at one time. After radiotherapy for advanced esophageal cancer, the survival period of the cases ranged from 14 to 22 mo, with a mean survival of 17 mo. No re-stenosis occurred among all the 10 cases. CONCLUSION: Stent placement combined with radiotherapy for esophageal cancer is helpful to prolong patients' survival and reduce occurrence of re-stenosis. (+info)
H-point standard addition method for the selective simultaneous determination of nickel and copper using 1-(2-pyridylazo)-2-naphthol in Tween 80 micellar media.
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The H-point standard addition method (HPSAM) has been applied for the simultaneous determination of nickel and copper in trace levels, using 1-(2-pyridylazo)-2-naphthol (PAN) as a chromogenic reagent in aqueous Tween 80 micellar media. Under the optimum condition, the simultaneous determinations of nickel and copper by HPSAM were performed. The absorbances at one pair of wavelengths, 548 and 579 nm, were monitored with the addition of standard solutions of copper. The method is able to accurately determine copper-to-nickel ratios of 15:1 to 1:10 (Wt/Wt). The effects of diverse ions on the determination of nickel and copper to investigate the selectivity of the method were also studied. The recommended procedure was successfully applied to some water and alloy samples. (+info)
Dental devices; dental noble metal alloys and dental base metal alloys; designation of special controls. Final rule.
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The Food and Drug Administration is amending the identification and classification regulations of gold-based alloys and precious metal alloys for clinical use and base alloys devices in order to designate a special control for these devices. FDA is also exempting these devices from premarket notification requirements. The agency is taking this action on its own initiative. This action is being taken under the Federal Food, Drug, and Cosmetic Act (the act), as amended by the Safe Medical Devices Act of 1990 (SMDA), and the Food and Drug Administration Modernization Act of 1997 (FDAMA). Elsewhere in this issue of the Federal Register, FDA is announcing the availability of the draft guidance documents that would serve as special controls for these devices. (+info)