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.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL052009-05
Application #
6537118
Study Section
Surgery and Bioengineering Study Section (SB)
Program Officer
Sopko, George
Project Start
1997-07-01
Project End
2005-06-30
Budget Start
2002-07-01
Budget End
2003-06-30
Support Year
5
Fiscal Year
2002
Total Cost
$335,893
Indirect Cost
Name
Georgia Institute of Technology
Department
Biomedical Engineering
Type
Schools of Engineering
DUNS #
097394084
City
Atlanta
State
GA
Country
United States
Zip Code
30332
Jensen, Morten O; Jensen, Henrik; Levine, Robert A et al. (2011) Saddle-shaped mitral valve annuloplasty rings improve leaflet coaptation geometry. J Thorac Cardiovasc Surg 142:697-703
Padala, Muralidhar; Sacks, Michael S; Liou, Shasan W et al. (2010) Mechanics of the mitral valve strut chordae insertion region. J Biomech Eng 132:081004
Sacks, Michael S; David Merryman, W; Schmidt, David E (2009) On the biomechanics of heart valve function. J Biomech 42:1804-24
Jensen, Morten O; Jensen, Henrik; Smerup, Morten et al. (2008) Saddle-shaped mitral valve annuloplasty rings experience lower forces compared with flat rings. Circulation 118:S250-5
Jimenez, Jorge H; Liou, Shasan W; Padala, Muralidhar et al. (2007) A saddle-shaped annulus reduces systolic strain on the central region of the mitral valve anterior leaflet. J Thorac Cardiovasc Surg 134:1562-8
Croft, Laura R; Jimenez, Jorge H; Gorman, Robert C et al. (2007) Efficacy of the edge-to-edge repair in the setting of a dilated ventricle: an in vitro study. Ann Thorac Surg 84:1578-84
Liao, Jun; Yang, Lin; Grashow, Jonathan et al. (2007) The relation between collagen fibril kinematics and mechanical properties in the mitral valve anterior leaflet. J Biomech Eng 129:78-87
Sacks, Michael S; Yoganathan, Ajit P (2007) Heart valve function: a biomechanical perspective. Philos Trans R Soc Lond B Biol Sci 362:1369-91
Grashow, Jonathan S; Sacks, Michael S; Liao, Jun et al. (2006) Planar biaxial creep and stress relaxation of the mitral valve anterior leaflet. Ann Biomed Eng 34:1509-18
Grashow, Jonathan S; Yoganathan, Ajit P; Sacks, Michael S (2006) Biaixal stress-stretch behavior of the mitral valve anterior leaflet at physiologic strain rates. Ann Biomed Eng 34:315-25

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