Effect of transmurally heterogeneous myocyte excitation-contraction coupling on canine left ventricular electromechanics.
The excitation-contraction coupling properties of cardiac myocytes isolated from different regions of the mammalian left ventricular wall have been shown to vary considerably, with uncertain effects on ventricular function. We embedded a cell-level excitation-contraction coupling model with region-dependent parameters within a simple finite element model of left ventricular geometry to study effects of electromechanical heterogeneity on local myocardial mechanics and global haemodynamics. This model was compared with one in which heterogeneous myocyte parameters were assigned randomly throughout the mesh while preserving the total amount of each cell subtype. The two models displayed nearly identical transmural patterns of fibre and cross-fibre strains at end-systole, but showed clear differences in fibre strains at earlier points during systole. Haemodynamic function, including peak left ventricular pressure, maximal rate of left ventricular pressure development and stroke volume, were essentially identical in the two models. These results suggest that in the intact ventricle heterogeneously distributed myocyte subtypes primarily impact local deformation of the myocardium, and that these effects are greatest during early systole.
Campbell
Stuart G
SG
Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA.
Howard
Elliot
E
Aguado-Sierra
Jazmin
J
Coppola
Benjamin A
BA
Omens
Jeffrey H
JH
Mulligan
Lawrence J
LJ
McCulloch
Andrew D
AD
Kerckhoffs
Roy C P
RC
D000200:Action Potentials; D000818:Animals; D001696:Biomechanical Phenomena; D004285:Dogs; D055724:Electrophysiological Phenomena; D020342:Finite Element Analysis; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000502:physiology; D032383:Myocytes, Cardiac / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*