EFFECTS OF INERTIA AND VISCOELASTICITY IN LATE RAPID FILLING OF THE LEFT-VENTRICLE

A theoretical solution for circumferential stress in the left ventricle is determined when wall mass is considered. Cavity pressure starts at lowest diastolic value in late rapid filling and follows a parabolic arc in the pressure-time plane. The myocardium is composed of a viscoelastic material whose shear relaxation function is specified by an elastic solution for material stiffness in diastole. The dynamic stress oscillates about the quasi-static stress with 2 frequencies. Inertia produces the high frequency; shear relaxation function yields the low frequency. For a representative example fashioned from published canine data, the maximum absolute value of the difference between dynamic and quasi-static stresses is not significant. Considering stress, in this case constitutive considerations are not important.