Cyclical cardiac mechanical performance has been described by plotting mid-wall left ventricular circumferential velocity, or strain rate (V) as a function of instantaneous mid-wall strain (E). This results in individual velocity-
strain (V-t-) parameters.
For any given individual, a standard velocity-strain plot is represented by a sinusoidally varying strain and strain rate. Three standard velocity-strain variables are then de$ned. The peak velocity, or peak strain rate (VA,), the cycle strain at VM (E,,,), and the system time constant (r,,,). The individual velocity-strain parameters are then divided by these standard V+ parameters to result in normalized V+ parameters for both cardiac systole and cardiac diastole. Thirty-six patients were evaluated, consisting offour groups: Normals (N= 15 patients), Compensated Volume Overload (CVO = 6 patients), Decompensated Volume Overload (DVO = 9 patients) and Congestive Cardiomyopathy (CCM = 6 patients). Five individual velocity-strain param&rs signi$cantly dfferentiate the CCM group from the N group. However, they do not diffmentiate CVO group and DVO group from the N group. Two standard V+ parameters and one normalized V-f parameter sign@antly differentiated the CVO group and the DVO group from the N group. Two standard V--E parameters and one normalized V+ parameter significantly diffmentiated the CCM group from the N group. It is recommended that future phase-plane analyses of non-linear cardiac phenomena include both standardization and normalization techniques.