Conventional attempts to derive indices of myocardial contractility from left ventricular pump function appear to be unsound in practice and theory, and the small number of dimensional measuremets on which these computations are based obscure the regional differences in ventricular myocardial function. It is not surprising that these indices have not proved to be fully satisfactory, either in research or in clinical laboratory settings. Both theoretical considerations and laboratory results support the need for more detailed measurements of regional myocardial function. These can be obtained by use of multiplanar videoroentgenographic techniques for cross-sectional reconstructions of the epicardial and endocardial surfaces of the heart throughout the cardiac cycle and the application of computer-based sophisticated methods of analysis, such as the finiteelement technique, as a basis for more accurate assessment of myocardial function.