Title page for ETD etd-03252003-124256


Type of Document Master's Thesis
Author Mace, Amber
Author's Email Address amace@vt.edu
URN etd-03252003-124256
Title A Comparative In Vitro Study of the Flow Characteristics Distal to Mechanical and Natural Mitral Valves
Degree Master of Science
Department Engineering Science and Mechanics
Advisory Committee
Advisor Name Title
Telionis, Demetri P. Committee Chair
Grant, John Wallace Committee Member
Pyle, Robert Lee Committee Member
Vlachos, Pavlos P. Committee Member
Keywords
  • mitral leaflets
  • DPIV
  • St. Jude Medical
  • chordae tendineae
  • vorticity
  • mechanical heart valves
Date of Defense 2002-12-16
Availability unrestricted
Abstract
Mechanical heart valve (MHV) flows are characterized by high shear stress, regions of recirculation, and high levels of turbulent fluctuations. It is well known that these flow conditions are hostile to blood constituents, which could lead to thromboembolism. In the ongoing effort to reduce long-term complications and morbidity, it is imperative that we better understand the flow characteristics of the natural valve as well as that of the mechanical valve. In this study, we overcome many of the limitations imposed by other measurement techniques by employing a powerful, high-speed Time-Resolved Digital Particle Image Velocimetry (TRDPIV) system to map the flow field. We compare the flows downstream from a St. Jude Medical bileaflet MHV, a porcine mitral valve (MV), and a combination of both valves to simulate the technique of chordal preservation. Instantaneous velocity fields and vorticity maps are presented, which provide detailed information about the development of the flow. Time-averaged velocity, vorticity, and turbulent kinetic energy measurements are also discussed. Asynchronous leaflet behavior was observed in all cases involving the mechanical valve. Extensive vortex formation and propagation are present distal to the MHV, which leads to high levels of jet dispersion. The porcine mitral jet exhibits lateral oscillatory behavior, but it does not disperse like the MHV. In the MHV/porcine combination system, the native tissue limits vortex propagation and jet dispersion. The results presented provide insight on the hemodynamic characteristics of natural and MHVs, reveal the detrimental character of asynchronous leaflet opening, document the mechanism of vortex formation and interaction distal to the valve, and illustrate the importance of chordal preservation. These results may improve MHV replacement clinical practice and/or motivate and aid the design of MHVs that better mimic natural mitral flow patterns.
Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  bileaflet_vorticity.avi 22.62 Mb 01:44:44 00:53:51 00:47:07 00:23:33 00:02:00
  combination_vorticity.avi 22.75 Mb 01:45:19 00:54:10 00:47:23 00:23:41 00:02:01
  porcine_vorticity.avi 21.28 Mb 01:38:31 00:50:40 00:44:20 00:22:10 00:01:53
  thesis_mace.pdf 18.12 Mb 01:23:52 00:43:08 00:37:44 00:18:52 00:01:36

Browse All Available ETDs by ( Author | Department )

dla home
etds imagebase journals news ereserve special collections
virgnia tech home contact dla university libraries

If you have questions or technical problems, please Contact DLA.