Problems Concerning the Application of Concepts of Muscle Mechanics to the Determination of the Contractile State of the Heart

THERE HAS BEEN much recent interest by clinical cardiologists in the question of myocardial "contractility" or "contractile state." To the clinician, the quest for a measure of "contractility" or "contractile state" becomes the quest for an early indication of myocardial disease that may be of prognostic value and open up the possibility of preventive measures to forestall serious myocardial disease and failure. Braunwald1 has pointed out that there is a dissociation between the heart's output and its contractile state. In the normal intact dog, an increase in end-diastolic volume (i.e. initial fiber length) increases stroke volume and cardiac output whereas an increase in contractility does not.2 How then