COMPARISON OF ELECTROCARDIOGRAMS AND VECTORCARDIOGRAMS IN CONGENITAL AORTIC STENOSIS

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Abstract
A comparison was made of the accuracy of the vectorcardiogram, both uncorrected (cube) and corrected (Frank), and the standard electrocardiogram in the assessment of left ventricular hypertension in 30 patients with aortic stenosis. Peak pressure, gradient, valve area, and stroke work were used as reference points rather than heart weight or wall thickness. There was a linear relation between left ventricular peak pressure and the maximum spatial vector (r=0. 88; 0<0. 001) as well as the sum of selected spatial vectors (r=0. 89; 0<0. 001). When the series was extended to 50 patients comparable coefficients were obtained (r=0. 85 and 0. 89). Similar correlation with data derivedby the cube systemwas less significant (r=0. 72 and 0. 75 for 50 patients) while the sum of SV2 and RV5 yielded a coefficient of 0. 48 and 0. 49, respectively. Another hemodynamic parameters gave less significant correlations and appeared not to reflect the electrical changes in a direct way. The usefulness of T wave changes was compared to alterations of the spatial QRS-T angle and the non- specificity of both was demonstrated, when used as an estimation of severity. These results correspond to previous studies establishing the superiority of the Frank lead system above the cube system or standard electrocardiography and extend it to the assessment of left ventricular hypertension. They also indicate that measurement of specific spatial vectors permits the estimation of left ventricular peak pressure with a high degree of accuracy. Thus, in aortic stenosis in the adolescent and young adult age-group, this technique forms a worth-while adjunct in the assessment of its severity, which may reduce the need for indiscriminate cardiac catheterization.