Photo-cross-linking of PVA in concentrated aquous solution, and application to liquid embolic of cerebral aneurysms for subarachnoid hemorrhage

蛛网膜下腔出血（SAH）是大脑表面出血，通常是由大脑底部血管破裂引起的。血管通常在一个被称为动脉瘤的薄弱部位破裂。这会导致非常严重的神经损伤甚至死亡。传统上，这包括一个大的脑部手术，用手术夹关闭动脉瘤。这种动脉瘤的封闭现在通常可以通过铂GDC〇栓塞来完成。R线圈和液体栓子。本课题的目的是通过光敏PVA栓塞动脉瘤体外模拟系统，获得光敏PVA的控制和行为的客观数据。研究了含有尿嘧啶、胸腺嘧啶、苯乙烯基吡啶（SbQ）等光活性单位的光敏聚乙烯醇（PVA）作为液体栓剂的作用。作为脑动脉瘤的液体栓剂，要求：1)与动脉瘤有较强的粘连性，2)粘连持续2周直到新血管形成，3)溶液粘度低，注射率高。附着力强的PVA中光活性单元的含量要高，溶液粘度低的PVA中光活性单元的含量要低。本研究使用脑动脉瘤玻璃模拟管，通过光交联法测量其粘度和粘附性。对于高光敏性，光活性单位的含量应高。然而;光活性单元的高含量降低了PVA在水中的溶解度。因此，在聚乙烯醇中引入了聚乙二醇单元（TEG：三（乙二醇）单甲醚）。通过引入TEG单元，PVA含有约10%的SbQ单元可溶于水，具有较高的光敏性。PVA在脑动脉瘤模型上的粘附在紫外线照射3秒内完成，生理盐水流2周未见脱离。

A subarachnoid hemorrhage (SAH) is bleeding onto the surface of the brain, most often caused by a break in a blood vessel at the base of the brain. A blood vessel usually breaks at a weak spot called an aneurysm. This can cause a very severe neurological injury or even death. Traditionally this has involved a major brain operation with closure of the aneurysm using a surgical clip. Closure of such aneurysms can often be accomplished now through embolization using platinum GDC ○!R coils, and liquid embolics.The purpose of this project was to obtain objective data on control and behavior of photosensitive PVA with an in vitro simulation system of photosensitive PVA embolization for aneurysm. Photosensitive polyvinyl alcohols (PVA) containing photoactive units such as uracil, thymine, styryl pyridium (SbQ) were investigated as liquid embolics. As liquid embolics for cerebral aneurysm, the requirements are 1) strong adhesion to aneurysm, 2) the adhesion continue until formation of new blood vessel for 2 weeks, 3) viscosity of the solution is low for high injection rate. The contents of the photoactive unit in PVA should be high for the strong adhesion, but the content of the photoactive units should be low for low viscosity of the solution. In this study, glass simulation tube of cerebral aneurysm was used for measurements of viscosity and adhesion by photo-cross linking.For the high photosensitivity, the contents of the photoactive unit should be high. However; the high contents of the photoactive units made decrease the solubility of PVA in water. Therefore, polyethylene glycol units (TEG: tri(ethylene glycol)monomethylether) were introduced in PVA. By introduction of TEG unites, PVA contain about 10% units of SbQ units were soluble in water and gave high photosensitivity. The adhesion of PVA on cerebral aneurysm model was complete within 3-second irradiation of UV light, and no detachment was observed for 2 weeks under flow of physiological saline.