Hypertrophy or dilatation? A vectorial analysis of echocardiographically determined left ventricular enlargement.

Echocardiograms (ECHO) and Frank vectorcardiograms (VCGs) were obtained in three groups of patients: Group I (n = 16), concentric left ventricular hypertrophy (LVH) with increased interventricular septal (IVS) and left ventricular posterior wall (LVPW) thickness in the presence of a normal left ventricular internal dimension (LVID); Group II (n = 17), left ventricular dilatation (LVD) with an enlarged LVID, normal IVS and LVPW thickness, and Group III (n = 22), no catheterization evidence of heart disease with normal IVS, LVPW and LVID. VCGs were analyzed with respect to magnitude of the QRS maximal deflection vector (MDV) and +/- 10 msec QRS vectors, horizontal plane (HP) maximal posterior force, time of HP MDV inscription, distal and proximal HP loop areas and HP loop configuration utlizing criteria of Varriale et al. The results indicate that: 1) HP QRS vector magnitude cannot reliably differentiate concentric LVH from isolated LVD and 2) proximal-distal loop area relationships and pattern of the HP QRS loop, when reviewed together, are superior to other criteria for distinguishing whether ECHO determined LVH or LVD is the primary correlate of an enlarged left ventricle.