Elastic modulus of the human intact left ventricle-determination and physiological interpretation

The left ventricle (l.v.) is represented as a shell of muscle whose performance is characterised in terms of the chamber pressure and stress/strain in the ventricular wall; the effective elastic modulus of the l.v. relates these peerformance variables, and hence represents the transfer function of the left ventricular physiological system. A method is presented for indirectly determining the effective modulus E for the left ventricle. The method employs a thick-walled mathematical model of the l.v. having a homogeneous isotropic medium. Instantaneous values of E are determined for subjects with heart diseases of varied etiologies, in order to assess the responses of the l.v. to chronic overloads of pressure and volume. Resulting values for E are used diagnostically to characterise the physiological state of the l.v. Normal values of E, at systole, indicate that the strength of contraction exercised by the l.v. is normal, and hence is an indication of the l.v. having adjusted to the heart disease. © 1975 International Federation for Medical & Biological Engineering.