An analytical description of heart muscle

A recently developed analytical model of the canine left ventricle characterizes the left heart as a pressure source that varies with time and volume. A similar approach led to an analytical model of muscle strip, embodied as a force generator that varies with time and volume. The model arises from isometric contractions and includes muscle's passive and active force components, isotonic contractions, an inverse relation between muscle load and shortening, a direct relation between initial muscle length and shortening and Hill's hyperbolic force-length relation, all with one set of constants.