title: Visco-elasticity of passive cardiac muscle.
abstract: A quantitative mechanical description of the heart organ requires information on the mechanical behavior of its muscle in reasonable unity and completeness. In this respect, a fundamental constitutive law for soft biological tissures was proposed by Fung in 1972. This article presents evidence to show that Fung's law is a useful law to describe the mechanical behavior of heart muscle in the unstimulated (diastolic) state with sufficient generality. A visco-elastic relaxation phenomenon is studied in the isolated cardiac muscle of cat and rabbit with the purpose of constructing a mathematical model for relaxation. Experimental results show that passive relaxation behavior of heart muscle can be adequately described by a generalized standard linear solied with a continuous distribution of relaxation times. The form of the relaxation function devised permits the application of linear visco-elasticity theory to the nonlinear cardiac muscle. The relaxation model is used to predict the force-length (stress-strain) behavior of papillary muscle with reasonable accuracy.
mesh_terms: D000818:Animals; D002415:Cats; D004548:Elasticity; D008955:Models, Cardiovascular; D009200:Myocardial Contraction; D010210:Papillary Muscles / Q000502:physiology; D011817:Rabbits; D013314:Stress, Mechanical; D013696:Temperature; D014783:Viscosity