A case of interpolated extrasystoles in an otherwise normal human heart,illustrated by electrocardiograms

Abstract

At the meeting of this Society on October 16, 1912, we presented a case of interpolated extrasystoles in an otherwise normal human heart, pointing out several interesting features in the polygraphic records of the case. These records were of such a nature that interpretation of them was very difficult and led to doubtful conclusions. Since that meeting we have been fortunate in securing excellent electrocardiograms of this heart through the kindness of Dr. H. B. Williams. These records show that the interpolated beats arise constantly in the right ventricle, and probably in the right branch of the A-V bundle; the curves indicate that the abnormal impulse travels to the basal part of the left ventricle and thence to the apex, and that this path is always the same; there is no evidence of retrogression to the auricle, as was suspected from the mechanical tracings, but there is evidence of depression of the conduction system, for the P-R intervals of normal beats following the extrasystoles are often considerably lengthened (we could not be certain of lengthened As-Vs intervals in the polygrams). Phonocardiograms show divided second sounds produced by the abnormal beats and lengthened first sounds. A few compensating pauses have been seen in the electrocardiograms.

Aside from these new facts about the case, our previous report needs no alteration.