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Hydrodynamic properties of the Certas hydrocephalus shunt.
MedLine Citation:
PMID:  23215818     Owner:  NLM     Status:  Publisher    
Object Independent testing of hydrocephalus shunts provides information about the quality of CSF drainage after shunt implantation. Moreover, hydrodynamic parameters of a valve assessed in the laboratory create a comparative pattern for testing of shunt performance in vivo. This study sought to assess the hydrodynamic parameters of the Certas valve, a new model of a hydrocephalus shunt. Methods The Certas valve is an adjustable ball-on-spring hydrocephalus valve. It can be adjusted magnetically in vivo in 7 steps, equally distributed within the therapeutic limit for hydrocephalus, and the eighth step at high pressures intended to block CSF drainage. The magnetically adjustable rotor is designed to prevent accidental readjustment of the valve in a magnetic field, including clinical MRI. Results The pressure-flow performance curves, as well as the operating, opening, and closing pressures, were stable, fell within the specified limits, and changed according to the adjusted performance levels. The valve at settings 1-7 demonstrated low hydrodynamic resistance of 1.4 mm Hg/ml/min, increasing to 5.1 mm Hg/ml/min after connection of a distal drain provided by the manufacturer. At performance Level 8 the hydrodynamic resistance was greater than 20 mm Hg/ml/min. External programming of the valve proved to be easy and reliable. The valve is safe in 3-T MRI and the performance level of the valve is unlikely to be changed. However, with the valve implanted, distortion of the image is substantial. Integration of the valve with the SiphonGuard limits the drainage rate. Conclusions In the laboratory the Certas valve appears to be a reliable differential-pressure adjustable valve. Laboratory evaluation should be supplemented by results of a clinical audit in the future.
Zofia Czosnyka; John D Pickard; Marek Czosnyka
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-12-7
Journal Detail:
Title:  Journal of neurosurgery. Pediatrics     Volume:  -     ISSN:  1933-0715     ISO Abbreviation:  J Neurosurg Pediatr     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-12-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101463759     Medline TA:  J Neurosurg Pediatr     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Neurosurgical Unit, Department of Clinical Neurosciences, University of Cambridge, United Kingdom.
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