Despite the recent accumulation of a large hemodynamic data base describing myocardial infarction and cardiogenic shock, precise characterization of patient subsets has been elusive. This paper represents an attempt to identify the major factors contributing to this wide hemodynamic spectrum, and their interrelation using a theoretical model based upon currently emerging concepts of this disease. It is proposed that the hemodynamic alterations associated with acute infarction are a consequence both of reduction in contractile mass and alteration in left ventricular compliance. In addition, mitral insufficiency, altered contractility, and the peripheral circulation interact to produce wide divergence between clinical and hemodynamic features from case to case and during the progression of the course of the illness. This model may more rationally explain the genesis and natural history of “heart failure’ and the “shock syndrome’ associated with acute myocardial infarction and in addition explain the extremely variable responses to both drug therapy and to more aggressive modes of treatment of power failure.