球型栓塞裝置的開發

Abstract

心血管疾病、癌症以及中風為已開發國家的主要死因。其中顱內動脈瘤破裂是造成出血性中風的主因。目前治療顱內動脈瘤的黃金標準為開顱手術以及白金線圈栓塞術。肝癌為現今全球第六大癌症，死亡人數在所有癌症中排名第三。肝癌的其中一項療法是利用栓塞肝動脈來阻斷供應癌細胞的血流。本研究提出了一項或能適用於此兩項疾病的微型醫療器材概念─球型栓塞裝置，它能夠降低通過患部的血流量，在顱內動脈瘤的應用球型栓塞裝置可以阻斷血流流入動脈瘤囊內部，使動脈瘤囊內部的血液流場較為穩定，降低動脈瘤破裂的風險。而在肝栓塞的應用可以透過部署球型栓塞裝置於肝動脈的上游，阻斷流至下游癌細胞處的血液，使肝癌細胞沒有養分來源。除了用於栓塞之外，在裝置表面塗覆抗癌藥物，可使球型栓塞裝置成為藥物載具，在降低肝動脈血液流量的同時能夠更進一步殺死癌細胞。藥物載具因為其局部性與專一性，可以將用藥量降到最低，大幅減少藥劑的毒性與副作用。本文著眼於球型栓塞裝置從設計到製程、部署過程的有限元素模型以及血液動力學模型的模型建立，並以利用此套方法驗證球型栓塞裝置的性能。參數化設計節省了曠日廢時的模型修改過程；接著利用所設計的球型栓塞裝置建立球型栓塞裝置製程的有限元素模型評估球型栓塞裝置在製造過程中材料是否失效，模擬結果則用於建立部署過程的有限元素模型。部署過程的有限元素模型分別建立了動脈瘤血管部署模型以及肝動脈分叉血管部署模型以模擬部署球型栓塞裝置於患部的情形。為確保血液動力學模型的正確性，血液動力學模型以球型栓塞裝置部署過程的模擬結果建立。最後本研究建立了部署球型栓塞裝置前後動脈瘤以及肝動脈的血液動力學模型，分析部署球型栓塞裝置前後血管中的血液流場變化。模擬結果顯示部署球型栓塞裝置能夠使通過患部的血液流量降低達成治療的目的。

Hemorrhagic stroke, with a high mortality and morbidity, is due to the rupture of intracranial aneurysms. The gold standard treatments for intracranial aneurysms include traditional craniotomy and endovascular coiling; however, these treatments has some limitations. Liver cancer is one of the most common cancer in the world and is the third leading cause of cancer death in Taiwan. One of the treatment options is hepatic artery embolization. Due to the unique dual blood supply system, liver receives blood from hepatic portal vein and hepatic arteries. The blood supply to the liver is mainly from hepatic portal vein. On the contrary, the blood supply to hepatic cancer cells is almost from hepatic arteries. As a result, liver works well even when the blood flow in hepatic arteries is cut off. In this research, an implantable medical device concept, spherical occlusion device, is proposed. By directly deploying spherical occlusion device inside the aneurysm, the device is able to reduce the blood flow into aneurysm. Also, by deploying spherical occlusion device in the upstream hepatic artery, it can cut down the blood supply to cancer cells in the downstream. Due to the excellent super-elastic property, nitinol alloy is chosen as the material of the device. Finite element models are developed to analysis the mechanical behavior of the device during manufacturing and deployment procedures. Hemodynamic models are constructed to evaluate the performance of spherical occlusion device. Finite element analysis results show that spherical occlusion device is able to withstand large deformations during all procedures. Results of the hemodynamic models show that the blood flow rate is cut down by deploying spherical occlusion device whether in aneurysm or in upstream hepatic artery.