High-frequency components in the electrocardiogram. A comparative study of normals and patients with myocardial disease.

SUMMARY Expanding the frequency response of the electrocardiogram and its derivative to 1,000 cps revealed notching in certain parts of the QRS complex which correlates with the presence of primary myocardial disease. Chi-square analysis of data from 169 patients with myocardial involvement indicated that notching on the downstroke of leads X, V4, and V6 separated abnormal from normal patients at the 1% level of significance , whereas fine and coarse slurring showed reverse correlation at the 1% level of significance. This suggests that notching and not slurring is the important evidence of disease. Neither notching nor slurring was significant at the peak of the R wave in any lead. Study of individual cases revealed that complete right and left bundle-branch blocks do not mask high-frequency components caused by myocardial disease nor do they produce high-frequency components. Conclusions regarding specific diagnostic criteria, however, should serve only as guidelines. ADD,ITIONAL INDEXING WORDS: Bundle-branch block Right ventricular hypertrophy M UCH of the clinically useful information derived from the electrocardio-gram comes from gross alterations in the QRS complexes and T waves. These changes involve frequencies mostly below 100 cps' or in the low-frequency range, but patients with diffuse myocardial disease often will show reduced voltage and many high-frequency components in the QRS complexes. Oppenheimer and Rothschild2 first correlated these changes with a disseminated patchy sclerosis involving the subendocardial layer of the heart, and Intraventricular conduction defect they concluded that the abnormal electrocar-diograms were due to lesions in the Purkinje network. They suggested that the condition be known as arborization block. Unfortunately, conventional electrocardio-graphic equipment with its poor high frequency response and slow paper speed is incapable of recording these phenomena.3 Recognizing this, Langner and associates4-10 have used the cathode-ray oscilloscope and an expanded time scale to demonstrate these high-frequency waves in patients with coronary artery disease. Franke and associates"1 have shown frequency components up to 3,000 cps, which was well above the noise level in some subjects , and have noted abnormal power spectra in ischemic heart disease. The two large studies reported to date8 11 have dealt solely with coronary artery disease. The present study was designed to determine criteria which permit separation of three abnormal 195