A coordinate axis transformation study of spatial QRS loop in hypertrophic cardiomyopathy.

To obtain an overall view of the QRS loop on vectorcardiograms (VCG) of hypertrophic cardiomyopathy (HCM), the coordinate axis was transformed using the resolver method. The morphological features and planarity of the loop were compared with hypertrophic patterns and hypertensive heart disease (HHD). The subjects in the present study included 30 normal individuals, 40 patients with HCM and 30 with HHD. The HHD group was selected from patients showing left ventricular hypertrophy on VCG similar to that of HCM patients. The HCM group showed significantly greater values than the HHD group in the thickness/length ratio, which represents the planarity of the spatial QRS loop. The above finding suggests that the HCM group had greater deformation in the QRS loop than the HHD group. This may provide a useful indicator for the differential diagnosis of the two diseases.