Diagnostic implications of figure-of-eight and clockwise QRS loop rotation on the horizontal vectorcardiogram in...

In chronic aortic valve disease the left ventricular (LV) volumes, mass and ejection fraction (EF), as well as selected Frank ECG measurements of patients with a normal counterclockwise rotation (Type A) of the horizontal QRS vector loop are compared with those of patients showing an abnormal figure-of-eight or clockwise configuration (Type B) to investigate whether the different QRS patterns reflect ventriculographic alterations or depends on a conduction delay. In aortic stenosis (AS,n = 21) and combined AS and aortic insufficiency (AS + AI,n = 23) the Type B vectorcardiograms (VCGs) correlate with significantly increased LV end-diastolic volumes (p. .01, .01, respectively) and depressed EF (p .07, .009, respectively). In pure AI (n = 39) LV volumes, mass and EF do not differ between the Type A and Type B patterns. As compared to Type B VCGs of AS (n = 6), the LV end-diastolic volume index is clearly higher in Type A VCGs of pure AI (n = 21)(p .028). The only ECG change which is significant at the p .01 level in each group is the increase of the R peak time in lead X in the Type B VCGs. This can be related to greater volume and mass only in AS and AS+ AI, but is not substantiated by equivalent ventriculographic alterations in pure AI. The findings indicate that Type B VCGs are very likely caused by a left ventricular conduction delay since they cannot be strictly correlated with increases in LV volume and mass alone.