Estimation of local myocardial stress.

Two formulas are presented for estimating local average circumferential stress in the left ventricle from the cavity pressure and various quantities, available from the angiogram, which characterize the size and shape of the cavity and ventricular wall. The advantages of these formulas are as follows: 1) they are based on thick-wall shell theory; 2) they are intended for application at positions in the ventricular wall other than the base; and 3) they are based on a more general representation of ventricular geometry than a sphere, cylinder, or ellipsoid. Except for one location, both formulas predict average circumferential stresses that agree to within 25% with the corresponding stresses in a finite element model of an aneurysmal ventricle. In addition, at the equator of a thick-wall ellipsoid, the formulas are identical in form to a previously derived formula that has been shown to predict stresses that are in fair to good agreement with measured stresses in the open-chest dog heart.