Transmural Course of Stress and Sarcomere Length in the Left Ventricle Under Normal Hemodynamic Circumstances

In this paper the dynamic behaviour of mechanical stresses and strains in the wall of the left ventricle is described. Though several investigators are rather optimistic (1), direct determination of stresses in the wall of the left ventricle is difficult and unreliable (2). A better approach is calculation of these stresses by the use of a mathematical model of the mechanics of the left ventricle (3). Following this principle, several investigators (2, 4, 5) have computed wall stress from left ventricular pressure, assuming a certain geometry of the left ventricle and certain mechanical properties of the wall. However, none of these models can be used to study the dynamic behaviour of the stresses in the wall of the left ventricle since these models are based on unrealistic approximations, such as isotropic myocardial material or inadequate geometry, while usually fibre orientation in the wall of the left ventricle and physiological contractile behaviour of the myocardial material are not taken into account. Therefore, a new model was developed in which all of these factors are considered (3).