An Ex Vivo Model of Left Ventricular Dilation and Functional Mitral Regurgitation to Facilitate the Development of Surgical Techniques
Objective: Functional mitral regurgitation (FMR) is a common sequelae of myocardial ischemic disease. It results from annular dilation and outward rotation of the posterior papillary muscle. Different surgical techniques are under investigation for the treatment of FMR. However, an ex vivo model of FMR would be valuable to develop and compare the effect of techniques on the geometry of the left ventricle and the correction of FMR.
Methods: FMR was induced in explanted ovine hearts (n = 12) by manual dilation of the mitral annulus or by posterior papillary muscle repositioning with a patch. Left ventricular dimensions were measured. Mitral regurgitant volume (MRV) was measured in a continuous flow system.
Results: Annular dilation significantly increased MRV from 93.0 ± 110.4 to 472.2 ± 211.8 mL/min (P = 0.031), and the patch increased it from 37.8 ± 55.2 to 365 ± 189.6 mL/min (P = 0.031), with no significant differences between the 2 groups. When both techniques were applied, MRV significantly increased to 1383.5 ± 567.0 mL/min (P = 0.0005). The left ventricular sphericity index decreased from 3.25 ± 0.7 to 2.34 ± 0.6 (P = 0.0025) after application of the patch. The posterior papillary muscle was displaced after patch placement, following an outward rotation.
Conclusion: This ex vivo model reproduces annular dilation and outward rotation of the posterior papillary muscle, which are both present during FMR after ischemic myocardial disease. This model could be used to evaluate and compare interventions to treat FMR.
Ahmed MI, McGiffin DC, O'Rourke RA, Dell'italia LJ. 2009. Mitral regurgitation. Curr Probl Cardiol 34:93-136.nAlfieri O, De Bonis M. 2010. Mitral valve repair for functional mitral regurgitation: is annuloplasty alone enough? Curr Opin Cardiol 25:114-8.nCiarka A, Braun J, Delgado V, et al. 2010. Predictors of mitral regurgitation recurrence in patients with heart failure undergoing mitral valve annuloplasty. Am J Cardiol 106:395-401.nEnriquez-Sarano M, Akins CW, Vahanian A. 2009. Mitral regurgitation. Lancet 373:1382-94.nFukamachi K, Popovic ZB, Inoue M, et al. 2004. Changes in mitral annular and left ventricular dimensions and left ventricular pressure-volume relations after off-pump treatment of mitral regurgitation with the Coapsys device. Eur J Cardiothorac Surg 25:352-7.nGorman JH 3rd, Jackson BM, Gorman RC, Kelley ST, Gikakis N, Edmunds LH Jr. 1997. Papillary muscle discoordination rather than increased annular area facilitates mitral regurgitation after acute posterior myocardial infarction. Circulation 96(9 Suppl):II-124-7.nIsomura T, Suma H, Yamaguchi A, Kobashi T, Yuda A. 2003. Left ventricular restoration for ischemic cardiomyopathy: comparison of presence and absence of mitral valve procedure. Eur J Cardiothorac Surg 23:614-9.nKatoh T, Ikeda N, Nishi K, et al. 1999. A newly designed adapter for testing an ex vivo mitral valve apparatus. Artif Organs 23:920-3.nLevine RA, Schwammenthal E. 2005. Ischemic mitral regurgitation on the threshold of a solution: from paradoxes to unifying concepts. Circulation 112:745-58.nMcCarthy PM, Takagaki M, Ochiai Y, et al. 2001. Device-based change in left ventricular shape: a new concept for the treatment of dilated cardiomyopathy. J Thorac Cardiovasc Surg 122:482-90.nMessas E, Guerrero JL, Handschumacher MD, et al. 2001. Chordal cutting: a new therapeutic approach for ischemic mitral regurgitation. Circulation 104:1958-63.nNielsen SL, Nygaard H, Fontaine AA, et al. 1999. Papillary muscle misalignment causes multiple mitral regurgitant jets: an ambiguous mechanism for functional mitral regurgitation. J Heart Valve Dis 8:551-64.nOtsuji Y, Handschumacher MD, Liel-Cohen N, et al. 2001. Mechanism of ischemic mitral regurgitation with segmental left ventricular dysfunction: three-dimensional echocardiographic studies in models of acute and chronic progressive regurgitation. J Am Coll Cardiol 37:641-8.nPoglajen G, Harlander M, Gersak B. 2010. Ex vivo study of altered mitral apparatus geometry in functional mitral regurgitation. Heart Surg Forum 13:E172-6.nRichards AL, Cook RC, Bolotin G, Buckner GD. 2009. A dynamic heart system to facilitate the development of mitral valve repair techniques. Ann Biomed Eng 37:651-60.nTakagaki M, McCarthy PM, Ochiai Y, et al. 2001. Novel device to change left ventricular shape for heart failure treatment: device design and implantation procedure. ASAIO J 47:244-8.nTibayan FA, Rodriguez F, Zasio MK, et al. 2003. Geometric distortions of the mitral valvular-ventricular complex in chronic ischemic mitral regurgitation. Circulation 108(Suppl 1):II116-21.n
How to Cite
Author Disclosure & Copyright Transfer Agreement
In order to publish the original work of another person(s), The Heart Surgery Forum® must receive an acknowledgment of the Author Agreement and Copyright Transfer Statement transferring to Forum Multimedia Publishing, L.L.C., a subsidiary of Carden Jennings Publishing Co., Ltd. the exclusive rights to print and distribute the author(s) work in all media forms. Failure to check Copyright Transfer agreement box below will delay publication of the manuscript.
A current form follows:
The author(s) hereby transfer(s), assign(s), or otherwise convey(s) all copyright ownership of the manuscript submitted to Forum Multimedia Publishing, LLC (Publisher). The copyright transfer covers the exclusive rights to reproduce and distribute the article and the material contained therein throughout the world in all languages and in all media of expression now known or later developed, including but not limited to reprints, photographic reproduction, microfilm, electronic data processing (including programming, storage, and transmission to other electronic data record(s), or any other reproductions of similar nature), and translations.
However, Publisher grants back to the author(s) the following:
- The right to make and distribute copies of all or part of this work for use of the author(s) in teaching;
- The right to use, after publication in The Heart Surgery Forum, all or part of the material from this work in a book by the author(s), or in a collection of work by the author(s);
- The royalty-free right to make copies of this work for internal distribution within the institution/company that employs the author(s) subject to the provisions below for a work-made-for-hire;
- The right to use figures and tables from this work, and up to 250 words of text, for any purpose;
- The right to make oral presentations of material from this work.
Publisher reserves the right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. To republish, such third parties must obtain written permission from the Publisher. (This is in accordance with the Copyright Statute, United States Code, Title 17. Exception: If all authors were bona fide officers or employees of the U.S. Government at the time the paper was prepared, the work is a “work of the US Government” (prepared by an officer or employee of the US Government as part of official duties), and therefore is not subject to US copyright; such exception should be indicated on signature lines. If this work was prepared under US Government contract or grant, the US Government may reproduce, royalty-free, all or portions of this work and may authorize others to do so, for official US Government purposes only, if the US Government contract or grant so requires.
I have participated in the conception and design of this work and in the writing of the manuscript and take public responsibility for it. Neither this manuscript nor one with substantially similar content under my authorship has been published, has been submitted for publication elsewhere, or will be submitted for publication elsewhere while under consideration by The Heart Surgery Forum, except as described in an attachment. I have reviewed this manuscript (original version) and approve its submission. If I am listed above as corresponding author, I will provide all authors with information regarding this manuscript and will obtain their approval before submitting any revision. I attest to the validity, accuracy, and legitimacy of the content of the manuscript and understand that Publisher assumes no responsibility for the validity, accuracy, and legitimacy of its content. I warrant that this manuscript is original with me and that I have full power to make this Agreement. I warrant that it contains no matter that is libelous or otherwise unlawful or that invades individual privacy or infringes any copyright or other proprietary right. I agree to indemnify and hold Publisher harmless of and from any claim made against Publisher that relates to or arises out of the publication of the manuscript and agree that this indemnification shall include payment of all costs and expenses relating to the defense of any such claim, including all reasonable attorney’s fees.
I warrant that I have no financial interest in the drugs, devices, or procedures described in the manuscript (except as disclosed in the attached statement).
I state that the institutional Human Subjects Committee and/or the Ethics Committee approved the clinical protocol reported in this manuscript for the use of experimental techniques, drugs, or devices in human subjects and appropriate informed consent documents were utilized.
Furthermore, I state that any and all animals used for experimental purposes received humane care in USDA registered facilities in compliance with the “Principles of Laboratory Animal Care” formulated by the National Society for Medical Research and the “Guide for the Care and Use of Laboratory Animals” prepared by the Institute of Laboratory Animal Resources and published by the National Institutes of Health (NIH Publication No. 85-23, revised 1985).