Artikel
Modern titanium and silicone shuntvalve implants and internal tissue obstructions by arachnoidextracellular matrix membranes
Obstruktion moderner Titan- und Silikon-Shuntventile durch arachnoidale extrazelluläre Matrix-Membranen
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Veröffentlicht: | 26. Juni 2020 |
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Objective: Shunt valves imply the demand for high performance rates and life long function. Toovercome traditional silicone materials adjustable and gravity adapted titanium valves still occlude and cause dysfunction.Even high experienced departments treating the most delicate and vulnerable preterm with PHHC, valve complications in this group occur quite often. The aim of the present study was to investigate silicone and titanium valves for occupation with cellular and proteinous materials inside the housings.
Methods: 19 explanted shunt valves from children between 2 and 182 months of age were investigated following obstruction. After fixation in formalin and embedding in hardresin, the specimens were cut and slices were ground to a thickness of 5-30 microns. Histology and immunohistochemistry was performed using antibodies with markers for microglia, astrocytes, platelets, monocytes and the matrix proteins laminin, fibronectin, collagen IV.
Results: Traces, layers and plaques could be demonstrated in every investigated silicone or titanium valve with animplantation time of more than 6 days. Most of the tissue was found adjacent to silicone and titanium surfaces of the inner housing, the rotor for the adjustment and the ball in cone system. Stainingwith markers for micro- and astroglia was positive in 40%-60% of the specimen, mostly demonstrating a proteinous layer positive for laminin (80%), fibronectin (30%) and collagen IV (30%).
Conclusion: Tissue reactions and colonisations with cellular and proteinous material are common in silicone and inside titanium shunt valves causing serious obstruction in PHHC. Obstructive layers consisting of extracellular matrix resemble astrocytic repair mechanisms of subventricular polarized astrocytes adjacent to the basal membrane. The knowledge of these typical arachnoid pattern of tissue colonisation is a prerequisite for developing future shunt devices.