Performance of left ventricle based on pressure-volume relation.

The concept of body force (force per unit volume) is used to derive an expression for the radial force developed by the myocardium (active force) in a model of the left ventricle represented as an elastic thick-walled cylinder contracting symmetrically. This approach leads to a novel equation to describe the pressure-volume relation in the Suga-Sagawa model. New indices to describe the mechanics of the left ventricular contraction are derived. Results tend to demonstrate that the radial active force generated by the myocardium will reach its peak value near end-systole, and that this peak is related to the peak isovolumic pressure. The study was carried out within a quasi-static approximation of the contraction (inertia forces neglected).