Diagnostic import of QRS notching in high-frequency electrocardiograms of living subjects with heart disease.

In a 10-month period 92 patients have been studied for the occurrence of highfrequency notching in orthogonal electrocardiographic leads X, Y, and Z obtained by high-frequency, high-speed techniques. The same patients were studied radiographically with barium, with routine electrocardiograms, hemodynamically at cardiac catheterization and, in many instances, with left ventricular angiograms. Sixty-nine patients had not had cardiac surgery prior to recording and had normal duration of ventricular activation. These patients were placed into groups which included those with no ventricular enlargement, isolated right ventricular enlargement, isolated left ventricular enlargement, and biventricular enlargement. The patients with no ventricular enlargement had a mean of 2.9 notches and never exceeded a total notch count of 6. Those with single ventricular enlargement had a mean of between 5 and 6, while those with biventricular enlargement frequently exceeded 6 notches and had a mean of 8.6. The differences were statistically significant. We concluded, then, that notch count correlates well with the dynamic evidence of ventricular enlargement in a living population. Since the effect is additive, biventricular enlargement elevates the counts sufficiently to remove the overlap with normal