Abstract
Change in papillary muscle motion as a result of left ventricular (LV) remodeling after posterolateral myocardial infarction is thought to contribute to ischemic mitral regurgitation. A finite element (FE) model of the LV was created from magnetic resonance images acquired immediately before myocardial infarction and 8 weeks later in a cohort of 12 sheep. Severity of mitral regurgitation was rated by two-dimensional echocardiography and regurgitant volume was estimated using MRI. Of the cohort, six animals (DC) received hydrogel injection therapy shown to limit ventricular remodeling after myocardial infarction (Rodell, Christopher B., Circ. Cardiovasc. Interv. 9:e004058 2016) while the control group (MI) received a similar pattern of saline injections. LV pressure was determined by direct invasive measurement and volume was estimated from MRI. FE models of the LV for each animal included both healthy and infarct tissue regions as well as a simulated hydrogel injection pattern for the DC group. Constitutive model material parameters for each region in the FE model were assigned based on results from previous research. Invasive LV pressure measurements at end diastole and end systole were used as boundary conditions to drive model simulations for each animal. Passive stiffness (C) and active material parameter (Tmax) were adjusted to match MRI estimations of LV volume at end systole and end diastole. Nodal positions of the chordae tendineae (CT) were determined by measurements obtained from the excised heart of each animal at the terminal time point. Changes in CT nodal displacements between end systole and end diastole at 0- and 8-week time points were used to investigate the potential contribution of changes in papillary muscle motion to the progression of ischemic mitral regurgitation after myocardial infarction. Nodal displacements were broken down into radial, circumferential, and longitudinal components relative to the anatomy of the individual animal model. Model results highlighted an outward radial movement in the infarct region after 8 weeks in untreated animals, while radial direction of motion observed in the treated animal group was preserved relative to baseline. Circumferential displacement decreased in the remote region in the untreated animal group after 8 weeks but was preserved relative to baseline in the treated animal group. MRI estimates of regurgitant volume increased significantly in the untreated animal group after 8 weeks but did not increase in the treated group. The results of this analysis suggest that hydrogel injection treatment may serve to limit changes in papillary muscle motion and severity of mitral regurgitation after posterolateral myocardial infarction.
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References
M.G.S.J. Sutton, N. Sharpe, Left ventricular remodeling after myocardial infarction. Circulation 101(25), 2981–2988 (2000). https://doi.org/10.1161/01.cir.101.25.2981
F. Bursi et al., Mitral regurgitation after myocardial infarction: a review. Am. J. Med. 119(2), 103–112 (2006). https://doi.org/10.1016/j.amjmed.2005.08.025
G.A. Lamas, Clinical significance of mitral regurgitation after acute myocardial infarction. Survival and ventricular enlargement investigators. Circulation 96(3), 827–833 (1997)
J.F. Wenk et al., First finite element model of the left ventricle with mitral valve: insights into ischemic mitral regurgitation. Ann. Thorac. Surg. 89(5), 1546–1553 (2010). https://doi.org/10.1016/j.athoracsur.2010.02.036
H. Wang et al., Effects of hydrogel injection on borderzone contractility post-myocardial infarction. Biomech. Model. Mechanobiol. 17(5), 1533–1542 (2018). https://doi.org/10.1007/s10237-018-1039-2
C.B. Rodell et al., Injectable shear-thinning hydrogels for minimally invasive delivery to infarcted myocardium to limit left ventricular remodeling. Circ. Cardiovasc. Interv. 9(10), e004058 (2016). https://doi.org/10.1161/circinterventions.116.004058
J.M. Guccione et al., Passive material properties of intact ventricular myocardium determined from a cylindrical model. J. Biomech. Eng. 113(1), 42 (1991). https://doi.org/10.1115/1.2894084
J.M. Guccione, A.D. McCulloch, Mechanics of active contraction in cardiac muscle: part I—constitutive relations for fiber stress that describe deactivation. J. Biomech. Eng. 115(1), 72 (1993). https://doi.org/10.1115/1.2895473
J.M. Guccione et al., Mechanics of active contraction in cardiac muscle: part II—cylindrical models of the systolic left ventricle. J. Biomech. Eng. 115(1), 82 (1993). https://doi.org/10.1115/1.2895474
K.S. Dujardin et al., Grading of mitral regurgitation by quantitative doppler echocardiography. Circulation 96(10), 3409–3415 (1997). https://doi.org/10.1161/01.cir.96.10.3409
W.G. Hundley et al., Magnetic resonance imaging assessment of the severity of mitral regurgitation. Circulation 92(5), 1151–1158 (1995). https://doi.org/10.1161/01.cir.92.5.1151
M.W. Kon, J. Heart Valve Dis. 13(4), 600–607 (2004)
M. Soleimani et al., Moderate mitral regurgitation accelerates left ventricular remodeling after posterolateral myocardial infarction. Ann. Thorac. Surg. 92(5), 1614–1620 (2011). https://doi.org/10.1016/j.athoracsur.2011.05.117
J.F. Obadia et al., Mitral subvalvular apparatus. Circulation 96(9), 3124–3128 (1997). https://doi.org/10.1161/01.cir.96.9.3124
Acknowledgements
This study was supported by National Institutes of Health grants R01 HL063954 (R. Gorman) and U01 HL133359 (J. Wenk).
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Ferguson, C.R., Gorman, R.C., Wenk, J.F. (2020). Quantification of Papillary Muscle Motion and Mitral Regurgitation After Myocardial Infarction. In: Grady, M. (eds) Mechanics of Biological Systems and Materials & Micro-and Nanomechanics, Volume 4. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, Cham. https://doi.org/10.1007/978-3-030-30013-5_4
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DOI: https://doi.org/10.1007/978-3-030-30013-5_4
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