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系統識別號 U0026-1708201115520600
論文名稱(中文) 利用改良的血管支架進行末端吻合術
論文名稱(英文) End-to-End Anastomosis Using Improved Stent Graft
校院名稱 成功大學
系所名稱(中) 醫學工程研究所碩博士班
系所名稱(英) Institute of Biomedical Engineering
學年度 99
學期 2
出版年 100
研究生(中文) 曾育婕
研究生(英文) Yu-Chieh Tseng
學號 P86984015
學位類別 碩士
語文別 英文
論文頁數 46頁
口試委員 指導教授-葉明龍
口試委員-張志涵
口試委員-羅偉誠
口試委員-甘宗旦
中文關鍵字 血管支架  末端吻合  模擬分析 
英文關鍵字 stent graft  aorta  end-to-end anastomosis  numerical modeling 
學科別分類
中文摘要 傳統血管末端吻合手術主要還是以縫線法為主,但縫線吻合還是有費時、縫線距離不一、針孔流血等缺點。 為了改善這些缺點,發展了許多改良的非縫線吻合方式,但大多數在使用上還是有其限制和缺點,例如較適用在管徑比較小的血管,對於血管壁容易造成傷害以及接合強度的不足。所以目前還有適合的非縫線吻合的方式可以適用在主動脈弓的部位。而本研究目的主要是設計改良式的血管支架來進行非縫線的末端吻合,而此改良式的血管支架可適用在主動脈弓的部位並且降低對血管壁的傷害及破壞。研究方向主要分成兩部分: 1.體外實驗: 觀察每分鐘在吻合處的滲水量。 2.電腦模擬分析:分析在進行無縫線吻合後,血管上的力學分佈。
體外實驗的部分:將距離人工血管末端3公分和5公分的地方縫入316L不銹鋼支架,而人工血管的直徑略大於豬的主動脈15-20%。透過不同的接合長度,觀察接合處的滲水量,藉以了解人工血管和主動脈管壁之間是否有完整的密封性。並於接合處外部包覆一段的Dacron。比較接合處有包覆和沒有包覆的滲水量,觀察之間的差異性。實驗分別測試(A)人工血管和主動脈不同的接合固定長度;(B)接合長度固定在5cm,但在接合處有包覆3mm的Dacron,另外一組沒有,觀察接合處的滲水量和主動脈外直徑的變化量。
另外電腦模擬分析的部分:依據CT的圖檔建立豬的主動脈模型;以及實際的原型建立改良式的血管支架模型。而分析方式主要分成固體分析和流體分析兩部分,透過流固耦合(FSI)模擬體內放置此改良式的血管支架的實際狀況。分析出來的結果可以提供之後動物實驗的參考。
實驗的結果顯示(A)人工血管和主動脈在接合長度5cm時,滲水量為24ml/min,明顯小於接合長度3cm和4cm的滲水量。(B)接合處有包覆3cm Dacron的滲水量幾乎為零;接合處沒有包覆的滲水量則隨著管內壓力的提高而增加約80ml/min。而血管的外徑也隨著壓力的上升而變大,但壓力在到達120mmHg時,血管外徑趨於一定值。
在電腦模擬的結果方面,顯示已置換人工血管支架在接合處沒有渦流的產生,這代表在接合處產生血栓栓塞的機會降低。另外一方面從von Mises stress和shear stress分布圖上可觀察出,受力較大的區域主要發生在血管支架處。但因血管支架的材料楊氏係數很大,所以其變形量相對來說比較小。而由於shear stress的分佈與變形量有很大的關係,所以比較觀察shear stress分佈圖和網格位移量可推測得知,較大的變形量發生在吻合處的下方。 綜合體外實驗和電腦模擬分析的結果,此改良式的無縫線末端吻合血管支架是可應用的。
英文摘要 Currently, the major method in vessel anastomosis is suture method, but there are some drawbacks, such as time-consuming, uneven suture distances, and suture hole bleeding, and so on. In order to overcome the problems, many non-suture methods have been designed; however, they still have their limits and drawbacks in limited in smaller vascular and destruction on vessel wall. There was no appropriate non-suture device to apply on aortic arch portion. Therefore, the purpose of this study is to investigate the direct sutureless end-to-end anastomosis by using stent graft by ex vivo study and numerical simulation. This device would decrease the damage on vessel wall could be potentially applied in aortic arch. An ex-vivo study was conducted to evaluate the oversizing effect on water leakage and finite element analysis was used to simulate force and stress distribution on stent graft and blood vessel.
Ex vivo study: The graft with 14mm inner diameter which is 10-20% oversizing with respect to porcine aortic diameter was chosen and sutured with stainless stents on one end. The landing distances between stent graft and aorta were 3, 4 and 5cm respectively. The anastomotic leakage at water pressure from 54 to 100 mmHg was measured to evaluate the security of this anastomosis. Two parameters were evaluated for water leakage, (1) the water leakage change with landing zone from 3 to 5 cm at incremental water pressure; (2) the function of 3cm wide Dacron outside banding on the anastomotic site with 5 cm landing zone on water leakage. Besides the water leakage, changes in aortic diameters were also observed through this experiment.
Numerical modeling: The geometry of the thoracic aorta was built through a series of images of CT scans of porcine. In other hands, the stent graft model was also built according to our improved stent graft. The stress distribution on aorta wall and improved stent-graft were calculated by using CFD of ANSYS. The simulation results could provide this design to examine the feasibility.
The ex vivo experiment results showed: (A) the leakage from 5cm landing zone was the least among those 3, 4 and 5cm landing region groups; (B) almost no leakage was found when outer 3mm band was applied. Therefore, the outer band had the ability of fixation. The outer diameter of porcine aorta increased with the raising up of pressure, but it tended a gradual value when the pressure reached 120mmHg.
On the other hands, the simulation results showed: there was no vortex at the anastomotic site. Therefore, it had less opportunity to appear thromboembolism. Otherwise, the shear stress and von Mises stress distribution were large around the stent. However the Young’s modulus of stent wa large, so that the deformation was relatively small. Comparing the contour of wall shear stress with mesh displacement, it showed that the bigger deformation would occur below the anastomotic site. Above all, the direct sutureless end-to-end anastomosis by using stent graft seems to be feasibile from the ex vivo experiment and numerical computation.
論文目次 中文摘要 I
ABSTRACT III
致謝 V
CONTENTS VII
LIST OF FIGURES X
LIST OF TABLES XII
CHAPTER 1 INTRODUCTION 1
1.1 BACKGROUND 1
1.2 NEEDLE SUTURE METHOD 1
1.3 NON-SUTURE METHODS 2
1.3.1 Graft 4
1.4 MECHANICAL PROPERTIES OF PORCINE AORTA 4
1.5 NUMERICAL MODELING 5
1.6 MOTIVATION AND PURPOSE 6
CHAPTER 2 MATERIALS AND METHODS 7
2.1 FLOW CHART 7
2.2 EX VIVO EXPERIMENT 8
2.2.1 Improved stent graft and porcine artery 8
2.2.2 Setting of the ex vivo experiment 8
2.2.3 The different distal landing zone 11
2.2.4 Banding and no-banding on anastomosis 11
2.3 NUMERICAL MODELING 12
2.3.1 Geometry 13
2.3.2 Mechanical property 15
2.3.3 Governing equations 16
2.3.4 Boundary conditions 17
CHAPTER 3 RESULTS 19
3.1 EX VIVO EXPERIMENT 19
3.1.1 The different distal landing zone 19
3.1.2 Banding and no-banding on anastomosis 20
3.1.3 Changes in aortic diameter 21
3.2 FINITE ELEMENT ANALYSIS 22
3.2.1 Streamline 22
3.2.2 Mesh displacement 23
3.2.3 Stress distribution 25
3.2.3.1Pressure 25
3.2.3.2 Von Mises stress 27
3.2.3.3 Wall shear stress 29
3.2.3.4 Radial force 30
CHAPTER 4 DISCUSSION 32
4.1 STABILITY ON ANASTOMOSIS OF STENT-GRAFT 32
4.1.1 Size of diameter 32
4.1.2 Landing length of stent-graft 32
4.1.3 Banding on anastomatic site 33
4.2 FLOW PATTERN AND MESH DISPLACEMENT 33
4. 3 STRESS DISTRIBUTION 34
4.3.1 Wall shear stress 35
4.3.2 Radial force 36
4.3.3 Fluid structure interaction and solid mechanics 37
4.4 LIMITATIONS 38
4.4.1 Experimental limitations 38
4.4.2 Limitations of numerical simulation 39
CHAPTER 5 CONCLUSION AND FUTURE PROSPECTIVE 40
5.1 CONCLUSION 40
5.2 FUTURE PROSPECTION 41
REFERENCES 42
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