Background: Partial resection of left ventricle (LV) wall, denoted as partial left ventriculectomy (PLV), was suggested as a novel alternative for heart transplantation in cases of severe heart failure. Reasonable reduction of LV radii reduces the wall stresses according to Laplace law and increases the cardiac output. However, reducing LV radii decreases the LV mass. Currently, no defined guidelines are used to determine the resected wedge size.
Aims: To define the criteria for optimizing the excised wall size.
Methods: The effects of PLV on ventricular performance are determined by the effects of loading conditions on sarcomere functions. The failing heart function is simulated by describing the sarcomere control of contraction and coupling calcium kinetics with cross-bridge (motor unit) dynamics. The effects of PLV are evaluated at the sarcomere (micro) and global LV (macro) levels, for various postoperative radii. The LV performance before and immediately after the operation are evaluated assuming no changes in tissue characteristics.
Results: Although reducing the LV size increases the ejection fraction, there are bi-modal effects, with clear optima in the stroke volume, systolic pressure, stroke work and sarcomere external work. These optima are achieved at different postoperative LV radii. The optima are determined by geometrical parameters and by the sarcomere control of the force-velocity relation and regulation of cross-bridge recruitment. Reducing LV radii decreases the sarcomere energy consumption and improves sarcomere efficiency, mainly due to the decrease in the (pseudo) potential energy.
Conclusions: The optimal resected wedge size is determined by the sarcomere control of contraction.