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In Vitro Modeling of Mitral Valve Hemodynamics: Significance of Left Atrium Function in the Normal and Repaired Mitral Valve with Simulated MitraClip

Gooden, Shelley Chee-Mei
http://rave.ohiolink.edu/etdc/view?acc_num=osu1545069944650814

Abstract Details

2019, Master of Science, Ohio State University, Biomedical Engineering.
With the advent of transcatheter based therapies for mitral regurgitation (MR), such as MitraClip NT, there is a need to develop a new in vitro model with full ventricular and atrial function, to help optimize the use of such devices. The objective of this study is to investigate the effect of left atrial (LA) pumping function (LA kick) and the number of MitraClips on mitral valve (MV) hemodynamics for various degenerative mitral regurgitation (MR) severities. The overarching hypotheses of this study are: (1) physiological mitral flow is achievable only with LA kick and (2) MitraClip benefits a regurgitant MV only by decreasing regurgitation. In order to test these hypotheses, (a) an in vitro model was developed utilizing a custom designed MV chamber with full control of papillary muscles to hold the porcine MV being tested. The flow setup involved addition of a computer controlled LA pump. This setup allowed for physiological and pathophysiological modeling of the MV with various degrees of regurgitation, each without and with LA kick. The setup also allowed for high fidelity pressure and flow hemodynamic measurements to quantify parameters, including effective orifice area (EOA) and mitral regurgitant fraction (MRF). (b) 24 experiments were conducted using a MitraClip analog in various configurations. Configurations included the absence and presence of LA kick, number of clips (0, 1, and 2), and state of the mitral valve (native and mild, moderate, and severe MR). In validation of the mitral flow loop, the presence of atrial kick yielded a representative mitral flow curve similar to what is seen physiologically. Overall, LA kick did not affect valve hemodynamics to a degree clinically relevant. Clipping the native and mild MR valves did not benefit valve hemodynamics to a degree clinically relevant, as MRF was decreased by a maximum of 0.009, if at all. However, clipping moderate and severe MR valves greatly improved MRF. MRF decreased with the use of clips from roughly 0.40 to 0.15 for the moderate case (p < 0.001 without LA kick, p < 0.0001 with LA kick). The use of one clip decreased EOA from the order of 0.9 to 0.7 cm2 (p < 0.0001). The use of two clips instead of one gave no added benefit to MRF but continued to decrease EOA to about 0.45 cm2 (p < 0.0001). MRF decreased drastically with clips for the severe case. The use of one clip decreased MRF from the order of 0.5 to 0.3 (p < 0.0001), while EOA decreased from roughly 1 to 0.5 cm2 (p < 0.001). The use of two clips decreased MRF to around 0.27 (p < 0.0001), while EOA decreased to 0.42 cm2 (p < 0.0001). The use of two clips further improved MRF (p < 0.0001), while EOA continued to worsen (p < 0.0001). This study clearly shows that validated in vitro models can be used to explore the full therapeutic effect of MitraClip. The use of MitraClip greatly benefits MRF in moderate and severe MR cases, where one clip is optimal, as two clips did not further improve MRF much but further impaired EOA.
Lakshmi Dasi (Advisor)
Cynthia Roberts (Committee Member)
83 p.
Biomedical Engineering
mitral valve; mitral regurgitation; MitraClip; atrial kick; papillary muscles; two MitraClips

Recommended Citations

Citations

  • Gooden, S. C.-M. (2019). In Vitro Modeling of Mitral Valve Hemodynamics: Significance of Left Atrium Function in the Normal and Repaired Mitral Valve with Simulated MitraClip [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1545069944650814

    APA Style (7th edition)

  • Gooden, Shelley. In Vitro Modeling of Mitral Valve Hemodynamics: Significance of Left Atrium Function in the Normal and Repaired Mitral Valve with Simulated MitraClip. 2019. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1545069944650814.

    MLA Style (8th edition)

  • Gooden, Shelley. "In Vitro Modeling of Mitral Valve Hemodynamics: Significance of Left Atrium Function in the Normal and Repaired Mitral Valve with Simulated MitraClip." Master's thesis, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1545069944650814

    Chicago Manual of Style (17th edition)

osu1545069944650814
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This open access ETD is published by The Ohio State University and OhioLINK.