The effect of position of the heart on the electrocardiogram: I. The electrocardiogram in revived perfused human hearts in normal position

Eight cases of revived human heart in which a reasonably normal type of electrocardiographic curve was obtained have been studied with regard to both the localization of extrasystoles and bundle-branch block.With the heart in normal position it is found that the extrasystoles were similar to those described by Barker, Macleod and Alexander.The right and left bundles were cut in five instances, and the results indicate with the heart in normal position that a lesion of the right bundle is characterized by a deflection that is downward in Lead I and upward in Lead III.When the left bundle was cut with the heart in normal position or with left axis deviation, the electrocardiographic curve was characterized by an upward deflection of the complex in Lead I and a downward deflection in Lead III.Changes in position of the heart greatly modify the character of the curves of both extrasystoles and bundle-branch block.Shifting of the human heart to the left in one instance gave a right axis deviation (old terminology); shifting of it to the right gave a left axis deviation. Rotation of the heart also causes variation in the electrical axis.