title: A computationally efficient formal optimization of regional myocardial contractility in a sheep with left ventricular aneurysm.
abstract: A non-invasive method for estimating regional myocardial contractility in vivo would be of great value in the design and evaluation of new surgical and medical strategies to treat and/or prevent infarction-induced heart failure. As a first step towards developing such a method, an explicit finite element (FE) model-based formal optimization of regional myocardial contractility in a sheep with left ventricular (LV) aneurysm was performed using tagged magnetic resonance (MR) images and cardiac catheterization pressures. From the tagged MR images, 3-dimensional (3D) myocardial strains, LV volumes and geometry for the animal-specific 3D FE model of the LV were calculated, while the LV pressures provided physiological loading conditions. Active material parameters (T(max_B) and T(max_R)) in the non-infarcted myocardium adjacent to the aneurysm (borderzone) and in myocardium remote from the aneurysm were estimated by minimizing the errors between FE model-predicted and measured systolic strains and LV volumes using the successive response surface method for optimization. The significant depression in optimized T(max_B) relative to T(max_R) was confirmed by direct ex vivo force measurements from skinned fiber preparations. The optimized values of T(max_B) and T(max_R) were not overly sensitive to the passive material parameters specified. The computation time of less than 5 hours associated with our proposed method for estimating regional myocardial contractility in vivo makes it a potentially very useful clinical tool.
authors.affiliation: Department of Surgery, University of California, San Francisco, USA.
authors.forename: Kay
authors.initials: K
authors.lastname: Sun
authors.forename: Nielen
authors.initials: N
authors.lastname: Stander
authors.forename: Choon-Sik
authors.initials: CS
authors.lastname: Jhun
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Takamaro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Guan-Ying
authors.initials: GY
authors.lastname: Wang
authors.forename: Maythem
authors.initials: M
authors.lastname: Saeed
authors.forename: Arthur W
authors.initials: AW
authors.lastname: Wallace
authors.forename: Elaine E
authors.initials: EE
authors.lastname: Tseng
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Baker
authors.forename: David
authors.initials: D
authors.lastname: Saloner
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Einstein
authors.forename: Mark B
authors.initials: MB
authors.lastname: Ratcliffe
authors.forename: Julius M
authors.initials: JM
authors.lastname: Guccione
mesh_terms: D000818:Animals; D006328:Cardiac Catheterization; D006322:Heart Aneurysm / Q000150:complications / Q000503:physiopathology; D006333:Heart Failure / Q000150:complications; D006352:Heart Ventricles / Q000503:physiopathology; D008297:Male; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000150:complications* / Q000503:physiopathology*; D011312:Pressure; D012756:Sheep; D013599:Systole