A computationally efficient formal optimization of regional myocardial contractility in a sheep with left ventricular aneurysm.
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.
Sun
Kay
K
Department of Surgery, University of California, San Francisco, USA.
Stander
Nielen
N
Jhun
Choon-Sik
CS
Zhang
Zhihong
Z
Suzuki
Takamaro
T
Wang
Guan-Ying
GY
Saeed
Maythem
M
Wallace
Arthur W
AW
Tseng
Elaine E
EE
Baker
Anthony J
AJ
Saloner
David
D
Einstein
Daniel R
DR
Ratcliffe
Mark B
MB
Guccione
Julius M
JM
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