eb96407b22572e465621022395aa97e6 pmc_33445418.pdf 036cc224fa51a71b52b02d23928163ce914ff0bb pmc_33445418.pdf c6f4e6d595f7a6e4120516e683d23c87be4741f6099003a517dcc5c2a959aa0e pmc_33445418.pdf Title: Considerations in the Use of Gravitational Valves in the Management of Hydrocephalus. Some Lessons Learned with the Dual-Switch Valve Subject: In the past decade, there has been a clear trend towards better outcomes in patients with hydrocephalus, especially those with normal pressure hydrocephalus (NPH). This is partly due to the availability of more sophisticated hardware and a better understanding of implants. However, there is little evidence to show the superiority of a specific type of valve over another. The most commonly reported consequence of hydrodynamic mismatch is shunt over-drainage. Simple differential pressure valves, with a fixed opening pressure or even adjustable valves, lead to non-physiologic intraventricular pressure (IVP) as soon as the patient moves into an upright posture. These valves fail to maintain IVP within physiological limits due to the changes in hydrostatic pressure in the drainage system. To solve this problem more complex third-generation hydrostatic valves have been designed. These gravitational devices aim to reduce flow through a shunt system when the patient is upright but there are important technical differences between them. Here we review the main characteristics of the Miethke® Dual-Switch valve, which includes two valve chambers arranged in parallel: a low-opening pressure valve, designed for working in the supine position, and a second high-opening pressure valve, which starts working when the patient assumes the upright position. This paper specifies the main advantages and drawbacks of this device and provide a series of recommendations for its use. The discussion of this specific gravitational valve allows us to emphasize the importance of using gravitational control in implanted shunts and some the caveats neurosurgeons should take into consideration when using gravitational devices in patients with hydrocephalus. The correct function of any gravitational device depends on adequate device implantation along the vertical body axis. Misalignment from the vertical axis equal to or more than 45 might eliminate the beneficial effect of these devices. Keywords: complications; Dual-Switch valve; gravitational valves; hydrocephalus; hydrostatic valves; shunt dysfunction Author: Maria A. Poca, Dario F. Gándara, Katiuska Rosas, Aloma Alcina, Diego López-Bermeo and Juan Sahuquillo Creator: LaTeX with hyperref Producer: pdfTeX-1.40.21 CreationDate: Tue Jan 12 07:18:13 2021 CET ModDate: Tue Jan 12 07:26:41 2021 CET Tagged: no UserProperties: no Suspects: no Form: none JavaScript: no Pages: 14 Encrypted: no Page size: 595.276 x 841.89 pts (A4) Page rot: 0 File size: 1943738 bytes Optimized: no PDF version: 1.7 name type encoding emb sub uni object ID ------------------------------------ ----------------- ---------------- --- --- --- --------- DDMOHK+VnURWPalladioL Type 1 Custom yes yes no 10 0 AFVCIA+URWPalladioL-Ital Type 1 Custom yes yes no 15 0 KPPWYZ+URWPalladioL-Bold Type 1 Custom yes yes no 20 0 ZNKHWF+URWPalladioL-Roma Type 1 Custom yes yes no 24 0 YIVWYZ+CMSY10 Type 1 Builtin yes yes no 28 0 ENXZUH+VnURWPalladioL-Bold Type 1 Custom yes yes no 32 0 XPUSBJ+TimesNewRomanPS-BoldItalicMT Type 1C WinAnsi yes yes no 40 0 BSDWLC+TimesNewRomanPSMT Type 1C WinAnsi yes yes no 43 0 MCBCCI+SourceSansRoman-Regular Type 1C Custom yes yes no 65 0 MCBCCM+SourceSansRoman.613wght Type 1C Custom yes yes no 69 0 MCBCCO+SourceSansRoman-Bold Type 1C Custom yes yes no 73 0 BMBJKB+PalatinoLinotype,Bold TrueType WinAnsi yes yes no 95 0 BMBJOC+PalatinoLinotype TrueType WinAnsi yes yes no 98 0 BMBJOE+PalatinoLinotype,Italic TrueType WinAnsi yes yes no 101 0 OVNEXW+EURM10 Type 1 Builtin yes yes no 111 0 BMBJKB+PalatinoLinotype,Bold TrueType WinAnsi yes yes no 127 0 BMBJOB+PalatinoLinotype CID TrueType Identity-H yes yes yes 130 0 BMBJOC+PalatinoLinotype TrueType WinAnsi yes yes no 136 0 BMBJOE+PalatinoLinotype,Italic TrueType WinAnsi yes yes no 139 0 BMBJKB+PalatinoLinotype,Bold TrueType WinAnsi yes yes no 156 0 BMBJOC+PalatinoLinotype TrueType WinAnsi yes yes no 159 0 BMBJOE+PalatinoLinotype,Italic TrueType WinAnsi yes yes no 162 0 BMBJKB+PalatinoLinotype,Bold TrueType WinAnsi yes yes no 176 0 BMBJOC+PalatinoLinotype TrueType WinAnsi yes yes no 179 0 BMBJOE+PalatinoLinotype,Italic TrueType WinAnsi yes yes no 182 0 BMBJKB+PalatinoLinotype,Bold TrueType WinAnsi yes yes no 202 0 BMBJOC+PalatinoLinotype TrueType WinAnsi yes yes no 205 0 BMBJOE+PalatinoLinotype,Italic TrueType WinAnsi yes yes no 208 0 BMBJKB+PalatinoLinotype,Bold TrueType WinAnsi yes yes no 223 0 BMBJOC+PalatinoLinotype TrueType WinAnsi yes yes no 226 0 BMBJOE+PalatinoLinotype,Italic TrueType WinAnsi yes yes no 229 0 Jhove (Rel. 1.22.1, 2019-04-17) Date: 2023-05-27 02:49:44 CEST RepresentationInformation: pmc_33445418.pdf ReportingModule: PDF-hul, Rel. 1.12.1 (2019-04-17) LastModified: 2023-03-31 12:08:34 CEST Size: 1943738 Format: PDF Version: 1.7 Status: Well-Formed and valid SignatureMatches: PDF-hul MIMEtype: application/pdf PDFMetadata: Objects: 394 FreeObjects: 1 IncrementalUpdates: 0 DocumentCatalog: PageLayout: SinglePage PageMode: UseNone Outlines: Item: Title: Introduction Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@44c8afef Item: Title: The Miethke® Dual-Switch Valve Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@7b69c6ba Item: Title: Dual-Switch Valve Performance Reported by the Manufacturer Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@46daef40 Item: Title: Independent Evaluation of the Performance of the Dual-Switch Valve Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@12f41634 Item: Title: The Effect of MRI on the Function of M-DSV Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@13c27452 Item: Title: Pressure Selection of the Two Valves in the M-DSV Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@262b2c86 Item: Title: Intracranial Pressure Changes after M-DSV Implantation Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@371a67ec Item: Title: Surgical Aspects in the Implantation of the M-DSV Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@5ed828d Item: Title: Clinical Experience with M-DSV Use Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@50d0686 Item: Title: The Problem of Catheter Dislocation/Fracture in the M-DSV Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@7a3d45bd Item: Title: Final Considerations and Recommendations Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@1e7c7811 Item: Title: References Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@77ec78b9 Info: Title: Considerations in the Use of Gravitational Valves in the Management of Hydrocephalus. Some Lessons Learned with the Dual-Switch Valve Author: Maria A. Poca, Dario F. Gándara, Katiuska Rosas, Aloma Alcina, Diego López-Bermeo and Juan Sahuquillo Subject: In the past decade, there has been a clear trend towards better outcomes in patients with hydrocephalus, especially those with normal pressure hydrocephalus (NPH). This is partly due to the availability of more sophisticated hardware and a better understanding of implants. However, there is little evidence to show the superiority of a specific type of valve over another. The most commonly reported consequence of hydrodynamic mismatch is shunt over-drainage. Simple differential pressure valves, with a fixed opening pressure or even adjustable valves, lead to non-physiologic intraventricular pressure (IVP) as soon as the patient moves into an upright posture. These valves fail to maintain IVP within physiological limits due to the changes in hydrostatic pressure in the drainage system. To solve this problem more complex third-generation hydrostatic valves have been designed. These gravitational devices aim to reduce flow through a shunt system when the patient is upright but there are important technical differences between them. Here we review the main characteristics of the Miethke® Dual-Switch valve, which includes two valve chambers arranged in parallel: a low-opening pressure valve, designed for working in the supine position, and a second high-opening pressure valve, which starts working when the patient assumes the upright position. This paper specifies the main advantages and drawbacks of this device and provide a series of recommendations for its use. The discussion of this specific gravitational valve allows us to emphasize the importance of using gravitational control in implanted shunts and some the caveats neurosurgeons should take into consideration when using gravitational devices in patients with hydrocephalus. The correct function of any gravitational device depends on adequate device implantation along the vertical body axis. Misalignment from the vertical axis equal to or more than 45 might eliminate the beneficial effect of these devices. Keywords: complications; Dual-Switch valve; gravitational valves; hydrocephalus; hydrostatic valves; shunt dysfunction Creator: LaTeX with hyperref Producer: pdfTeX-1.40.21 CreationDate: Tue Jan 12 07:18:13 CET 2021 ModDate: Tue Jan 12 07:26:41 CET 2021 ID: 0x01c04bf138e61ef0eca6919b9ca2d5c9, 0x01c04bf138e61ef0eca6919b9ca2d5c9 Filters: FilterPipeline: FlateDecode Fonts: Type1: Font: BaseFont: ENXZUH+VnURWPalladioL-Bold FontSubset: true FirstChar: 161 LastChar: 226 FontDescriptor: FontName: ENXZUH+VnURWPalladioL-Bold Flags: Symbolic FontBBox: -152, -301, 1000, 935 FontFile: true EncodingDictionary: Differences: true Font: BaseFont: KPPWYZ+URWPalladioL-Bold FontSubset: true FirstChar: 3 LastChar: 174 FontDescriptor: FontName: KPPWYZ+URWPalladioL-Bold Flags: Symbolic FontBBox: -152, -301, 1000, 935 FontFile: true EncodingDictionary: Differences: true Font: BaseFont: ZNKHWF+URWPalladioL-Roma FontSubset: true FirstChar: 2 LastChar: 252 FontDescriptor: FontName: ZNKHWF+URWPalladioL-Roma 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