The calculation of the intramyocardial stress

Abstract

A mathematical approach is given by which the intramyocardial stress σ induced in the passive medium of the myocardium is expressed as the sum of the stress ${\mathrm{(}\mathit{\sigma }\mathrm{)}}_{\mathit{p}}$ induced in the passive medium by the left ventricular pressure P and the external pressure ${\mathit{P}}_{\mathit{o}}$ , and the stress ${\mathrm{(}\mathit{\sigma }\mathrm{)}}_{\mathit{d}}$ induced in the passive medium by the active force generated by the muscular fibers of the myocardium. Relations between $\mathit{\sigma }={\mathrm{(}\mathit{\sigma }\mathrm{)}}_{\mathit{p}}+{\mathrm{(}\mathit{\sigma }\mathrm{)}}_{\mathit{d}}$ , the left ventricular elastance E and the residual volume ${\mathit{V}}_{\mathit{d}}$ are also derived. Applications to experimental data are given and clinical implications of the results are discussed.