Fluid Mechanics of the Mitral Valve: In Vitro Studies

Summary

Principal Investigator: AJIT P contact YOGANATHAN
Abstract: DESCRIPTION (Provided by Applicant): A 5 year in-vitro investigation of the mechanics of the natural mitral valve (MV) is proposed to continue our previous work examining normal valve mechanics, and changes that occur in cases of disease or following valve chemical fixation. The normal fluid and leaflet dynamics will be studied to examine the effects of annular planarity, and annular size on overall valve function. The relative changes in the fluid and leaflet mechanics will be assessed by measuring the transmitral flow directly, and the valve leaflet dynamics by high-speed video imaging, force measurements, and Doppler ultrasound. The hemodynamics and leaflet dynamics will be tied to leaflet tissue mechanics through a graphite marker tracking technique to assess the leaflet strain fields and flexure under dynamic conditions. This study will also address diseased states by examining a range of annular orifice areas along with planarity and altered papillary muscle (PM) position. Information regarding valvular function with respect to annular planarity will assist surgeons in critical decisions when performing valvular repair procedures, such as ring annuloplasty and chordal replacement. Further examination of chemical fixation techniques is also proposed to study static fixation processes. This will provide a better understanding of how structural modifications that occur during chemical fixation influence valve dynamics. The significance and clinical relevance of the proposed research is to improve our fundamental understanding of mitral valve function transmitral fluid mechanics and leaflet dynamics) under normal anatomical conditions and pathological changes to the mitral apparatus, especially due to the effects of chronic and acute ischemic mitral regurgitation. The goal is to enhance our understanding of valve dynamics through controlled in vitro MV testing under physiologic conditions by development of advanced in vitro modeling techniques. This will provide surgeons and cardiologists scientific data on the response of the MV to changes in annular planarity and size and PM positioning. This will result in improved diagnosis and treatment of MV disease by physicians, and provide surgeons information about the effect that repair techniques have on overall valve functionality. In the case of MV replacements, investigating fixation processes will help in their manufacture by providing data on valve dynamics following fixation. A comprehensive in vitro study utilizing both flexible and rigid left ventricular models and human and porcine mitral valves is planned. The experiments will be performed in a controlled environment providing isolation of specific parameters without artifacts introduced by competing factors. The use of state of the art measurement systems unavailable for in vivo use will yield significant results.
Funding Period: 1997-07-01 - 2007-12-31
more information: NIH RePORT

Top Publications

  1. pmc Saddle-shaped mitral valve annuloplasty rings improve leaflet coaptation geometry
    Morten O Jensen
    Department of Cardiothoracic and Vascular Surgery, Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark
    J Thorac Cardiovasc Surg 142:697-703. 2011
  2. ncbi Mechanics of the mitral valve strut chordae insertion region
    Muralidhar Padala
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 315 Ferst Drive, Atlanta, GA 30332 0535, USA
    J Biomech Eng 132:081004. 2010
  3. pmc On the biomechanics of heart valve function
    Michael S Sacks
    Department of Bioengineering, Engineered Tissue Mechanics and Mechanobiology Laboratory, The McGowan Institute, University of Pittsburgh, Pittsburgh, PA, United States
    J Biomech 42:1804-24. 2009
  4. ncbi Saddle-shaped mitral valve annuloplasty rings experience lower forces compared with flat rings
    Morten O Jensen
    Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby, 8200 Aarhus N, Denmark
    Circulation 118:S250-5. 2008
  5. ncbi A saddle-shaped annulus reduces systolic strain on the central region of the mitral valve anterior leaflet
    Jorge H Jimenez
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
    J Thorac Cardiovasc Surg 134:1562-8. 2007
  6. ncbi Efficacy of the edge-to-edge repair in the setting of a dilated ventricle: an in vitro study
    Laura R Croft
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 0535, USA
    Ann Thorac Surg 84:1578-84. 2007
  7. pmc Heart valve function: a biomechanical perspective
    Michael S Sacks
    Engineered Tissue Mechanics and Mechanobiology Laboratory, Department of Bioengineering and the McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
    Philos Trans R Soc Lond B Biol Sci 362:1369-91. 2007
  8. ncbi The relation between collagen fibril kinematics and mechanical properties in the mitral valve anterior leaflet
    Jun Liao
    Engineered Tissue Mechanics Laboratory, Department of Bioengineering, and the McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
    J Biomech Eng 129:78-87. 2007
  9. ncbi Planar biaxial creep and stress relaxation of the mitral valve anterior leaflet
    Jonathan S Grashow
    Department of Bioengineering, Engineered Tissue Mechanics Laboratory, University of Pittsburgh, 100 Technology Drive, Room 234, PA 15219, USA
    Ann Biomed Eng 34:1509-18. 2006
  10. ncbi In-vivo dynamic deformation of the mitral valve anterior leaflet
    Michael S Sacks
    Engineered Tissue Mechanics Laboratory, Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15219, USA
    Ann Thorac Surg 82:1369-77. 2006

Scientific Experts

  • Muralidhar Padala
  • Zhaoming He
  • M S Sacks
  • Ajit P Yoganathan
  • Jennifer Ritchie
  • Jorge H Jimenez
  • Morten O Jensen
  • Jonathan S Grashow
  • Jorge Hernan Jimenez
  • Laura R Croft
  • Jun Liao
  • Hans Nygaard
  • J Michael Hasenkam
  • Robert A Levine
  • Sten L Nielsen
  • Henrik Jensen
  • Robert C Gorman
  • Joseph H Gorman
  • Dennis Dam Soerensen
  • Niels Trolle Andersen
  • Morten Smerup
  • Shasan W Liou
  • Jonathan Grashow
  • Lin Yang
  • Lisa Small
  • Jorge Jimenez
  • Joseph Forbess
  • James N Warnock

Detail Information

Publications17

  1. pmc Saddle-shaped mitral valve annuloplasty rings improve leaflet coaptation geometry
    Morten O Jensen
    Department of Cardiothoracic and Vascular Surgery, Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark
    J Thorac Cardiovasc Surg 142:697-703. 2011
    ..It is hypothesized that saddle-shaped annuloplasty rings cause less distortion of the physiologic leaflet geometry than do flat rings...
  2. ncbi Mechanics of the mitral valve strut chordae insertion region
    Muralidhar Padala
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 315 Ferst Drive, Atlanta, GA 30332 0535, USA
    J Biomech Eng 132:081004. 2010
    ....
  3. pmc On the biomechanics of heart valve function
    Michael S Sacks
    Department of Bioengineering, Engineered Tissue Mechanics and Mechanobiology Laboratory, The McGowan Institute, University of Pittsburgh, Pittsburgh, PA, United States
    J Biomech 42:1804-24. 2009
    ..While we focus on the work from the author's laboratories, relevant works of other investigators have been included whenever appropriate. We conclude with a summary of important future trends...
  4. ncbi Saddle-shaped mitral valve annuloplasty rings experience lower forces compared with flat rings
    Morten O Jensen
    Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby, 8200 Aarhus N, Denmark
    Circulation 118:S250-5. 2008
    ..We tested the hypothesis that saddle-shaped annuloplasty rings have superior uniform systolic force distribution compared with a nonuniform force distribution in flat annuloplasty rings...
  5. ncbi A saddle-shaped annulus reduces systolic strain on the central region of the mitral valve anterior leaflet
    Jorge H Jimenez
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
    J Thorac Cardiovasc Surg 134:1562-8. 2007
    ..Mitral valve repair for degenerative diseases has shown suboptimal results in selected patients. Improved postinterventional mitral valve mechanics are essential to increase repair durability...
  6. ncbi Efficacy of the edge-to-edge repair in the setting of a dilated ventricle: an in vitro study
    Laura R Croft
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 0535, USA
    Ann Thorac Surg 84:1578-84. 2007
    ..The edge-to-edge repair to correct mitral regurgitation (MR) has shown substandard results in cases of ischemic MR or dilated cardiomyopathy...
  7. pmc Heart valve function: a biomechanical perspective
    Michael S Sacks
    Engineered Tissue Mechanics and Mechanobiology Laboratory, Department of Bioengineering and the McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
    Philos Trans R Soc Lond B Biol Sci 362:1369-91. 2007
    ..While we focus on the work from the authors' respective laboratories, the works of most investigators known to the authors have been included whenever appropriate. We conclude with a summary and underscore important future trends...
  8. ncbi The relation between collagen fibril kinematics and mechanical properties in the mitral valve anterior leaflet
    Jun Liao
    Engineered Tissue Mechanics Laboratory, Department of Bioengineering, and the McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
    J Biomech Eng 129:78-87. 2007
    ..These unique mechanical characteristics are likely necessary for normal valvular function...
  9. ncbi Planar biaxial creep and stress relaxation of the mitral valve anterior leaflet
    Jonathan S Grashow
    Department of Bioengineering, Engineered Tissue Mechanics Laboratory, University of Pittsburgh, 100 Technology Drive, Room 234, PA 15219, USA
    Ann Biomed Eng 34:1509-18. 2006
    ..Moreover, insight into these specialized characteristics can help guide and inform efforts directed toward surgical repair and engineered valvular tissue replacements...
  10. ncbi In-vivo dynamic deformation of the mitral valve anterior leaflet
    Michael S Sacks
    Engineered Tissue Mechanics Laboratory, Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15219, USA
    Ann Thorac Surg 82:1369-77. 2006
    ..However, these data do not presently exist. In the present study, a sheep model and sonomicrometry were used to compute the in-surface Eulerian strain tensor of the anterior leaflet over the cardiac cycle at varying afterloads...
  11. ncbi Effects of annular size, transmitral pressure, and mitral flow rate on the edge-to-edge repair: an in vitro study
    Jorge H Jimenez
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 0535, USA
    Ann Thorac Surg 82:1362-8. 2006
    ..Although edge-to-edge repair is an established adjunctive procedure, there is still debate on its long-term durability and efficacy...
  12. ncbi The material properties of the native porcine mitral valve chordae tendineae: an in vitro investigation
    Jennifer Ritchie
    Wallace H Coulter, Department of Biomedical Engineering, Cardiovascular Fluid Mechanics Laboratory, Georgia Institute of Technology, Emory University, 313 Ferst Drive, Room 2119, Atlanta, GA 30332, USA
    J Biomech 39:1129-35. 2006
    ..In conclusion, a non-destructive technique was developed to measure in vitro chordal strain in the mitral valve. This technique allows the investigation of the behavior of biological tissues under physiologic loading conditions...
  13. ncbi Biaixal stress-stretch behavior of the mitral valve anterior leaflet at physiologic strain rates
    Jonathan S Grashow
    Engineered Tissue Mechanics Laboratory, Department of Bioengineering, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
    Ann Biomed Eng 34:315-25. 2006
    ..The mechanisms underlying this quasi-elastic behavior are as yet unknown, but are likely an important functional aspect of native mitral valve tissues and clearly warrant further study...
  14. ncbi In vitro dynamic strain behavior of the mitral valve posterior leaflet
    Zhaoming He
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 315 Ferst Drive, Atlanta, GA 30332 0535, USA
    J Biomech Eng 127:504-11. 2005
    ..We conclude that PM positions may influence the posterior strain in a different way as compared to the anterior leaflet...
  15. ncbi Mitral valve function and chordal force distribution using a flexible annulus model: an in vitro study
    Jorge Hernan Jimenez
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 0535, USA
    Ann Biomed Eng 33:557-66. 2005
    ..2) The tension on the intermediate and marginal chords is relatively insensitive to annular motion, whereas tension on the basal chords is directly affected by annular motion...
  16. ncbi Structural characterization of the chordae tendineae in native porcine mitral valves
    Jennifer Ritchie
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332 0535, USA
    Ann Thorac Surg 80:189-97. 2005
    ..This study was aimed to characterize the different mitral valve chordae tendineae to provide additional understanding of their function...
  17. ncbi Effects of papillary muscle position on chordal force distribution: an in-vitro study
    Jorge Hernan Jimenez
    Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
    J Heart Valve Dis 14:295-302. 2005
    ..Therefore, further understanding of the effects of PM displacement on chordal force distribution is required...