目前臨床使用的人工機械心瓣可能會導致穴蝕的發生，造成心瓣本身與血球的破壞，並可能導致溶血與血栓的生成。穴蝕現象主要在葉片關閉的瞬間產生，因此與心瓣的關閉機制有很大的關聯。由於目前仍未有完美的人工心瓣，因此新型人工心瓣的設計與開發仍在不斷進行中。本研究針對穴蝕現象的生成，利用本實驗室所研發的新型三葉片機械心瓣與臨床上使用廣泛之St. Jude Medical雙葉片機械心瓣及Medtronic-Hall Standard 單葉片心瓣在體外模擬測試台中進行測試。實驗結果指出在葉片關閉速度、最大負壓(NPP)、壓力擾動之均方根值(RMS)以及左心室負載率(dp/dt)這些與穴蝕現象生成有關的各參數中，三葉片機械心瓣的表現較其他兩個心瓣為佳；而利用高速攝影機拍攝心瓣關閉瞬間的穴蝕汽泡影像的結果發現三葉片機械心瓣未有明顯的穴蝕汽泡生成，因此本實驗室所設計之三葉片機械心瓣其關閉行為應較其他單雙葉片心瓣設計為佳。

Cavitation inception caused by clinical implanted mechanical heart valve (MHV) may destroy the constitution of MHV and blood cells, and it also may induce hemolysis and thrombosis. The closing mechanisms of MHV are more relevant to cavitation inception because the cavitation bubbles often be observed at the instant of MHV closure. To date, the new design of artificial heart valves are still developing because there are no perfect artificial valves yet. In this study, we used the new design Trileaflet MHV of our laboratory to study the inception of cavitation in in vitro physiological mock loop. We also used the St. Jude medical MHV (SJM) and Medtronic Hall standard MHV (MHS), which are implanted extensively in clinical, to compare the results of Trileaflet MHV. 
Our results indicated that the valve closing velocity, the negative peak pressure (NPP), the root mean square of pressure fluctuation (RMS), and the loading rate (dp/dt), which are the important factors of cavitaion inception, were lower in Trileaflet MHV than SJM and MHS, and the cavitaion bubbles images captured from high speed CCD camera also displayed the unobvious cavitation bubbles in Trileaflet MHV than other two MHVs. This illustrate that the closing behavior of our new design trileaflet MHV is better than the monoleaflet and bileaflet MHVs.

目錄
目錄	I
圖目錄	II
表目錄	IV
第一章  緒論	1
1-1 前言	1
1-2研究動機與目的	4
1-3研究程序	6
第二章  文獻回顧	8
2-1 人工機械心瓣	8
2-2 機械心瓣的問題	10
2-3 穴蝕成因	11
2-3.1 水錘效應(Water Hammer)	12
2-3.2 文氏效應(Venturi effect)	14
2-3.3 擠壓流(squeeze flow)	15
2-3.4 渦流現象(vortex effect)	16
2-4 三葉片的相關文獻	17
第三章  實驗方法與裝置	19
3-1體外脈動模擬裝置	19
3-2 壓力計	23
3-3 拍攝及量測儀器	25
3-4 實驗方法及流程	27
第四章  結果與討論	31
4-1 主動脈與左心室壓力波形	31
4-2 PCB壓力訊號及葉片的關閉速度	42
4-3 拍攝結果	49
4-4 資料分析	74
第五章  結論與建議	77
參考文獻	80
附表	83

參考文獻
1.	http://www.chinesetoday.com/news/show/id/28964.
2.	Chou YC, The study of the functional characteristics of the hinge of a trileaflet Mechanical Heart Valve,MS,Thesis,Tamkang University of Taiwan. 2006.
3.	Yoganathan AP, Cardiac Vakve Prostheses,The Biomedical Engineering Handbook. Bronzino J, 2000: p. 1847-1870.
4.	Hammond GL, e.a., Biological versus mechanical valves. . Thorac Cardiovasc Surg, 1987. 93: p. p. 182-198.
5.	Yan LY, The Design and In-Vitro Testing of a New Trileaflet Prosthetic Heart Valve,MS,Thesis,Tamkang University of Taiwan 1997.
6.	Hwang NH, Design Criteria for the Trileaflet Mechanical Heart Valve,MS,Thesis,Tamkang University of Taiwan 2007.
7.	Bokros JC, L.L., Schoen FJ control of structure of carbon for use in bioengineering. Chemisy and physics of Carbon, 1972: p. 103-171.
8.	Gu L, S.W., Evaluation of computational models for hemolysis estimation. ASAIO J., 2005. 51(3): p. 202-207.
9.	Kafesjian, R., D. Wirting, and J. Ely, Characterization of Cavitation Potential of Pyrolytic Carbon, In : Bodanr E(ed). Surgery for Heart Valve Disease, 1990: p. 509-516.
10.	Zapanta CM, Correlation of prosthetic heart valve dynamics with cavtation: in vitro and in vivo studies. Ph. D. Thesis,The Pennsylvania State University. 1997.
11.	Graf T, e.a., Cavitation potential of mechanical heart valve prostheses. Int J Artif Organs., 1991. 14: p. 169-174.
12.	Wu ZJ, Cavutation in mechanical heart valve prostheses: an in-vitro study,Ph.D.Thesis,University of Miami1996. 1996.
13.	Lo CW, Causes of cavitation phenomena in mechanical heart valves, Ph.D. ,Thesis,Tamkang University of Taiwan 2008.
14.	Vardy A.E, A weighting function model of transient turbulent pipe friction. Jou. of Hyd. Res., 1993: p. 533-548.
15.	Tokuno.T., Cavitation inception of deceleration surfaces, Ph.D. ,Thesis,Tamkang University of Rice. 1978.
16.	Su RN, Measurement of backflow and pressure transients with mechanical heart valves closure,MS,Thesis,Tamkang University of Taiwan 2005.
17.	Lee H, T.T., Homma A, Kamimura T, Takewa Y, Nishinaka T, Tatsumi E, Taenaka Y, Takano H, Kitamura S., Observation of cavitation in a mechanical heart valve in a total artificial heart. ASAIO J., 2004. 50(3): p. 205-210.
18.	Lee H, Mechanism for cavitation in the mechanical heart valve with an artificial heart: nuclei and viscosity dependence. Artif Organs., 2005. 29(1): p. 41-46.
19.	Lee H, T.Y., Kitamura S., Mechanisms of mechanical heart valve cavitation in an electrohydraulic total artificial heart. ASAIO J., 2005. 51(3): p. 208-213.
20.	kini.V, e.a., Flow visualization in mechanical heart valve: occluder rebound and cavitation potential. Ann Biomed Eng, 2000. 28: p. 431-441.
21.	Keefe B. Manning, e.a., Regurgitatant flow field characteristics of St.Jude bileaflet mechanical heart valve under physiologic pulsatile flow using particle image velocimetry. Artif Organs., 2003. 27(9): p. 840-846.
22.	Li CP, An in vitro study of mechanical heart valve closure fluid dynamics,MS,Thesis,Tamkang University of Taiwan 2005.
23.	Li CP, L.P., Liu JS, Lo CW, Hwang NH., Role of vortices in cavitation formation in the flow across a mechanical heart valve. J Heart Valve Dis., 2008. 17(4): p. 435-445.
24.	Rambod, E., et al, A Physical Model Describing the Mechanism for Formation of Gas Microbubbles in Patients with Mitral Mechanical Heart Valves. . Ann Biomed Eng, 1999. 27: p. p774-792.
25.	Brücker Ch, Unsteady flow through a new mechanical heart valve prosthesis analyzed by DPIV. 2001: p. 17-19.
26.	Liu JS, L.P., Lo CW, Lai HC, Hwang NH., An experimental study of steady flow patterns of a new trileaflet mechanical aortic valve. ASAIO J., 2005. 51(4): p. 336-341.
27.	Lu PC, L.J., Huang RH, Lo CW, Lai HC, Hwang NH., The closing behavior of mechanical aortic heart valve prostheses. ASAIO J. , 2004. 50(4): p. 294-300.
28.	Reul.H, Hydraulic Analog Model of Systemic Circulation – Designed for Fluid Mechanical Studies in the Left Heart and Systemic Arteries. 1983. 5: p. p. 43-54.
29.	Rambod, E., et al, Role of vortices in growth of microbubbles at mitral mechanical heart valve closure. . Ann Biomed Eng., 2007. 35(7): p. p. 1131-1145.