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 (ε). This results in individual velocity-strain (V-ε) 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 defined. The peak velocity, or peak strain rate (V M ), the cycle strain V M (ε M ), and the system time constant (μ M ). The individual velocity-strain parameters are then divided by these standard V-ε parameters to result in normalized V-ε parameters for both cardiac systole and cardiac diastole. Thirty-six patients were evaluated, consisting of four 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 parameters significantly differentiate the CCM group from the N group. However, they do not differentiate CVO group and DVO group from the N group. Two standard V-ε parameters and one normalized V-ε parameter significantly differentiated the CVO group and the DVO group from the N group. Two standard V-ε parameters and one normalized V-ε parameter significantly differentiated 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.NOMENCLATURET period of cardiac cycle (second)V peak (per second)V V normalized by V M V M V for a standard sinusoidal cycle (per second)ε mid-wall circumferential strain at whichV occurs mid-wall circumferential strain rate (per second) ε normalized by ε M ε M ε for a standard sinusoidal cycleε M A X maximum mid-wall circumferential strain which occurs between end-systole and protodiastoleτ system time constant (second) τ normalized by τ M τ M τ for a standard sinusoidal cycle (second)Subscripts:S systole (systolic)D diastole (diastolic)