CARDIAC INJURY POTENTIALS

Abstract

The potential time curve, derived from an injured region of heart muscle by the use of the suction electrode, is remarkably similar in contour and magnitude when recorded from different regions of the same heart, from different animals of the same species and even from animals widely separated in the animal scale. It represents a local potential change which does not involve the normal muscle contiguous to the injury, although a potential field develops in a conducting field which surrounds it on all sides. The contour and magnitude of the curves differ little in premature systoles as compared with normal beats, in contrast to the marked differences in unipolar and differential time curves in these two circumstances. The change in an injured region from a negative potential to a positive potential, which occurs when the muscle contiguous to the injury enters into activity is due to some process in the contiguous uninjured muscle or at the boundary between the injured and uninjured muscle. The start of this potential change at all surface regions of the ventricle precedes the rise of intra-ventricular pressure by an interval which varies with the location of the injury. At each local region, its onset precedes the onset of local or fractionate contraction of the region by an approx. constant interval. The possible relation of the start of the injury activity potential to the "excitation process" or "impulse" in the contiguous active muscle is discussed.