title: Computational Investigation of Transmural Differences in Left Ventricular Contractility.
abstract: Myocardial contractility of the left ventricle (LV) plays an essential role in maintaining normal pump function. A recent ex vivo experimental study showed that cardiomyocyte force generation varies across the three myocardial layers of the LV wall. However, the in vivo distribution of myocardial contractile force is still unclear. The current study was designed to investigate the in vivo transmural distribution of myocardial contractility using a noninvasive computational approach. For this purpose, four cases with different transmural distributions of maximum isometric tension (Tmax) and/or reference sarcomere length (lR) were tested with animal-specific finite element (FE) models, in combination with magnetic resonance imaging (MRI), pressure catheterization, and numerical optimization. Results of the current study showed that the best fit with in vivo MRI-derived deformation was obtained when Tmax assumed different values in the subendocardium, midmyocardium, and subepicardium with transmurally varying lR. These results are consistent with recent ex vivo experimental studies, which showed that the midmyocardium produces more contractile force than the other transmural layers. The systolic strain calculated from the best-fit FE model was in good agreement with MRI data. Therefore, the proposed noninvasive approach has the capability to predict the transmural distribution of myocardial contractility. Moreover, FE models with a nonuniform distribution of myocardial contractility could provide a better representation of LV function and be used to investigate the effects of transmural changes due to heart disease.
authors: Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40506-0503.
authors: Hua
authors: H
authors: Wang
authors: Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40506-0503.
authors: Xiaoyan
authors: X
authors: Zhang
authors: Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104-6321.
authors: Shauna M
authors: SM
authors: Dorsey
authors: Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA 19104-5156;Department of Surgery, University of Pennsylvania, Philadelphia, PA 19104.
authors: Jeremy R
authors: JR
authors: McGarvey
authors: Department of Physiology, University of Kentucky, Lexington, KY 40536-0298.
authors: Kenneth S
authors: KS
authors: Campbell
authors: Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104-6321.
authors: Jason A
authors: JA
authors: Burdick
authors: Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA 19104-5156;Department of Surgery, University of Pennsylvania, Philadelphia, PA 19104.
authors: Joseph H
authors: JH
authors: Gorman
authors: Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA 19104-5156;Department of Surgery, University of Pennsylvania, Philadelphia, PA 19104;Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104.
authors: James J
authors: JJ
authors: Pilla
authors: Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA 19104-5156;Department of Surgery, University of Pennsylvania, Philadelphia, PA 19104.
authors: Robert C
authors: RC
authors: Gorman
authors: Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40506-0503;Department of Surgery, University of Kentucky, Lexington, KY 40536-0298 e-mail: jonathan.wenk@uky.edu.
authors: Jonathan F
authors: JF
authors: Wenk
mesh_terms: D000818:Animals; D016880:Anisotropy; D019245:Compressive Strength / Q000502:physiology; D003198:Computer Simulation; D055119:Elastic Modulus / Q000502:physiology; D056966:Excitation Contraction Coupling / Q000502:physiology*; D006329:Heart Conduction System / Q000502:physiology*; D006352:Heart Ventricles / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000502:physiology*; D013314:Stress, Mechanical; D013552:Swine; D013718:Tensile Strength / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*