Reversal in direction of the QRS complex of experimental right bundle-branch block with change in the heart's position

It can be demonstrated that the contour of experimentally produced right bundle-branch block is modified by changing the heart's position. The direction of QRS can be reversed in Leads I or III, or in both, by moving the heart's apex from left to right of the body's long axis, especially when the heart is at the same time rotated on its own long axis. This shift alone may change a seeming right to a seeming left bundle-branch block or vice versa, depending on whether the classical or Wilson's terminology is used, as is shown in the illustrations of this report. This last observation explains the apparent discrepancies between the electrocardiographic and the autopsy diagnosis of the branch involved in bundle-branch block.It is recommended that no attempt be made to designate the bundle-branch involved; instead in man all such cases should be called intraventricular block of the bundle-branch type.