CLINICAL SIGNIFICANCE OF ELECTROCARDIOGRAMS WITH LARGE Q WAVES IN LEAD III

Abstract

The occurrence of a large Q wave in lead III of the electrocardiogram in certain cardiac conditions has been noted recently by some observers. Parkinson and Bedford¹ noted its presence in 9 of 29 patients (31 per cent) with a coronary thrombosis. In a series of 200 cases of heart disease of various types, Pardee² found 30 patients with the anginal syndrome. Of these, 8, or 27 per cent, were found to have a large Q wave in lead III. In the other 170 cases he found only 6 such records, or 3.5 per cent. In reviewing the records of 277 normal hearts from other clinics, he found only 2 with large Q waves in lead III. He believes that this finding is closely associated with pathologic changes that involve coronary narrowing, and that the larger the Q wave in relation to the voltage of Q-R-S, the closer