THE REVISED VELOCITY STRAIN RELATIONSHIP - PHASE-PLANE ANALYSIS OF LEFT-VENTRICULAR FUNCTION AND DYSFUNCTION

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 (epsilon). This resul ts in individual velocity-strain (V-epsilon) parameters. For any given individual, a standard velocity-strain plots is represented by a sinu soidally varying strain and strain rate. Three standard velocity-strai n variables are then defined. The peak velocity, or peak strain rate ( V-M), the cycle strain at V-M (epsilon(M)), and the system time consta nt (tau(M)). The individual velocity-strain parameters are then divide d by these standard V-epsilon parameters to result in normalized V-eps ilon parameters for both cardiac systole and cardiac diastole. Thirty- six patients were evaluated, consisting of four groups: Normals (N = 1 5 patients), Compensated Volume Overload (CVO = 6 patients), Decompens ated Volume Overload (DVO = 9 patients) and Congestive Cardiomyopathy (CCM = 6 patients). Five individual velocity-strain parameters signifi cantly differentiate the CCM group from the N group. However, they do not differentiate CVO group and DVO group from the N group. Two standa rd V-epsilon parameters and one normalized V-epsilon parameter signifi cantly differentiated the CVO group and DVO group from the N group. Tw o standard V-epsilon parameters and one normalized V-epsilon parameter significantly differentiated the CCM group from the N group. It is re commended that future phase-plane analyses of non-linear cardiac pheno mena include both standardization and normalization techniques.