Epicardial suction: a new approach to mechanical testing of myocardium

We used a nonlinear 3-D finite element method to analyze the transmural distribution of 3-D strain in the midanterior wall of the canine left ventricle (LV) that would be produced by local epicardial suction. The LV was modeled as a prolate spheroid consisting of an incompressible hyperelastic material with homogeneous exponential properties. The anisotropic properties of the passive myocardium were assumed to be locally transversely isotropic with respect to a fiber axis whose orientation varied linearly across the wall. This model suggests that local epicardial suction introduces a complex mode of deformation, with transmural variations in the magnitude and sign of nearly all six strain components. Hence, this approach to mechanical testing offers the first opportunity to quantify passive material properties of intact ventricular myocardium under loading similar to that which occurs during LV ejection.