Comparison of Carotid Stents: An In-Vitro Experiment Focusing on Stent Design
Department of Diagnostic and Interventional Radiology / Neuroradiology, Academic Hospitals Flensburg, Germany. Journal of Endovascular Therapy
(Impact Factor: 3.35).
05/2009; 16(2):168-77. DOI: 10.1583/08-2539.1
To examine and compare different carotid stent designs with regard to flexibility, adaptability (adjustability), conformability (compliance) to the vessel, and scaffolding to reduce plaque prolapse and embolization.
Six stents of different design were compared (Precise, Acculink, Protégé, Xact, Wallstent, and Cristallo Ideale). Optical microscopy was used to determine exact dimensions and scaffolding of each stent. Radial force was tested using a parallel plate setup, and flexibility (torsion and bending) was measured in water at body temperature. Particle penetration simulation was performed using plastic spheres from 1.5- to 6.0-mm outer diameter.
Stent dimensions met the manufacturers' data; none of the products showed any failure during the test program. Cell sizes in the middle part of the stents ranged from 1.36 mm(2) (Wallstent) to 15.10 mm(2) (Acculink). Bending forces at 20 degrees /30 degrees ranged from 0.063 N / 0.074 N (Cristallo Ideale) to 0.890 N / 0.616 N (Xact); forces to achieve torsion at 10 degrees /15 degrees ranged from 0.032 N / 0.043 N (Acculink) to 0.905 N / 1.071 N (Xact). According to the parallel plate method, mean lowest force was measured for Xact (0.765 N), while the Wallstent had the highest force (2.136 N). Mean radial force measurements were lowest for Cristallo Ideale (9.06 N at mid part) and highest for Protégé (24.09 N). The Cristallo Ideale stent at mid part resisted penetration by all but the smallest plastic spheres (1.5-mm spheres penetrated only at 0.65 N); the Precise and Protégé stent had the highest variation in sphere penetration (1.5- to 4.0-mm spheres). Only the Acculink let 6-mm spheres penetrate.
Despite comparable stent sizes, these carotid stents showed differences in behavior due to stent design. The open-cell design displayed the greatest flexibility and adaptability to the vessel but easily allowed particle penetration due to the open structure. Closed-cell designs had low flexibility and thus low adaptability to the vessel but high resistance to particle penetration due to the closed-cell design and high scaffolding. The hybrid stent design (Cristallo Ideale) was able to combine both the flexibility of an open-cell structure and the resistance to particle penetration of closed-cell structures.
Available from: PubMed Central
- "Most embolic complications occur after the procedure and are probably caused by late emboli through the struts of the stent, as described above.11 A closed cell stent has smaller struts than an open cell stent.12 Bosiers et al11 reported that the rate of post-procedural events was higher when using the open cell stent than when using the closed cell stent. "
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ABSTRACT: To evaluate the clinical outcome and MRI findings after carotid artery stenting (CAS) without post-dilatation.
Between May 2005 and April 2012, a total of 169 consecutive patients (61.4% symptomatic) underwent 176 CAS procedures performed with an embolic protection device (GuardWire, n=116; FilterWire EZ, n=60). All stents were deployed without post-dilatation. Periprocedural complications and mid-term outcomes were analyzed.
The stroke rate was 2.3% within 30 days post-CAS (asymptomatic patients 2.8%; symptomatic patients 2.8%). Cerebral infarction occurred in one asymptomatic patient (2.8%) and one symptomatic patient (0.9%). Intracranial hemorrhage occurred in two symptomatic patients (1.9%). Post-CAS diffusion-weighted imaging (DWI) revealed a high-intensity area in 26 of 176 procedures (14.8%). Ipsilateral stroke after 31 days occurred in two patients (1.1%) and restenosis occurred in six (3.4%). A post-CAS comparison of the embolic protection devices revealed no difference in stroke incidence within 30 days and in DWI high-intensity area.
Our CAS procedure without post-dilatation is feasible, safe and associated with a low incidence of stroke and restenosis.
Journal of Neurointerventional Surgery 09/2013; 6(7). DOI:10.1136/neurintsurg-2013-010873 · 2.77 Impact Factor
Available from: ncbi.nlm.nih.gov
- "Such interaction facilitates enough space for full expansion of the second stent as well as minimizes decline in the radial force of the stent. Müller-Hülsbeck et al. (21) reported that an open cell nitinol stent has more flexibility and adaptability compared to a closed cell design. Due to these physical properties, open cell stents appeared more suitable for bifurcating lesions or tortuous anatomy and have been widely used, especially in vascular system (16). "
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ABSTRACT: To evaluate the feasibility, safety and the effectiveness of the complex assembly of open cell nitinol stents for biliary hilar malignancy.
During the 10 month period between January and October 2007, 26 consecutive patients with malignant biliary hilar obstruction underwent percutaneous insertion of open cell design nitinol stents. Four types of stent placement methods were used according to the patients' ductal anatomy of the hilum. We evaluated the technical feasibility of stent placement, complications, patient survival, and the duration of stent patency.
Bilobar biliary stent placement was conducted in 26 patients with malignant biliary obstruction-T (n = 9), Y (n = 7), crisscross (n = 6) and multiple intersecting types (n = 4). Primary technical success was obtained in 24 of 26 (93%) patients. The crushing of the 1st stent during insertion of the 2nd stent occurred in two cases. Major complications occurred in 2 of 26 patients (7.7%). One case of active bleeding from hepatic segmental artery and one case of sepsis after procedure occurred. Clinical success was achieved in 21 of 24 (87.5%) patients, who were followed for a mean of 141.5 days (range 25-354 days). The mean primary stent patency period was 191.8 days and the mean patient survival period was 299 days.
Applying an open cell stent in the biliary system is feasible, and can be effective, especially in multiple intersecting stent insertions in the hepatic hilum.
Korean journal of radiology: official journal of the Korean Radiological Society 11/2012; 13(6):795-802. DOI:10.3348/kjr.2012.13.6.795 · 1.57 Impact Factor
Available from: Sangmin Lee
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ABSTRACT: To be functional in a practical sense for real-time control of
assistive devices, a myoprocessor must successfully integrate both
detection and estimation systems. This paper describes an approach for
classifying electromyographic (EMG) signals using a multilayer
perceptrons (MLPs) and hidden Markov models (HMMs) hybrid classifier and
force estimation. Instead of using MLPs as probability generators for
HMMs the authors propose to use MLPs as the second classifiers to
increase discrimination rates of myoelectric patterns. This strategy is
proposed to overcome weak discrimination and to consider dynamic
properties of EMG signals. Two discrimination strategies (HMM, and HMM
with three subnet MLPs) for discriminating signals representative of 6
primitive class of motions are described and compared. The proposed
strategy increase the discrimination results considerably. Results are
presented to support this approach
Circuits and Systems, 1996., IEEE Asia Pacific Conference on; 12/1996
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