Different types of left-ventricular wall movement were demonstrated in normal subjects and coronary patients, the differences being due to different degrees of reduction in the equatorial diameter of the cavity in the ejection phase. Rationale are given for using the mean diameter for left-ventricular volume calculations. A linear relationship has been demonstrated between the degree of diameter reduction and the ejection fraction. The latter is shown to be dependent on left-ventricular end diastolic volume. Regional myocardial contractility, a parameter of high diagnostic value, based on segmental ejection fraction, is introduced.