ALTERATIONS IN THE ELECTRICAL FIELD PRODUCED BY CHANGES IN THE CONTACTS OF THE HEART WITH THE BODY

Abstract

Expts. are reported in which various regions of the heart were connected to various parts of the chest by a good electrical non-polarizable shunt. The alterations obtained were of 2 sorts (or intermediate or mixed forms) : diphasic additions when the region under the shunt electrode was not injured, and monophasic additions when the region under the shunt electrode was injured. Regions of the heart may gain a decided advantage over the rest of the heart merely because they are in contact with a good electrical conductor, provided the contact is electrically nearer to one than the other of the 2 recording electrodes. The point on the chest to which the heart currents are shunted determines the advantage of the heart region so shunted over the rest of the heart. This depends on the "electrical distances" between the recording electrodes and the point of shunt on the chest. The electrical resistance of the shunting circuit determines the degree of advantage gained by the heart region shunted; the less the electrical resistance of the shunt, the greater the advantage. The shunted region of the heart probably sets up its own electrical field in the body which sum-mates with that set up by the heart through its natural contacts. These expts. support the concept that the nature of the electrical conductors in contact with the heart are an important, if not the most important, element in determining the nature of the electrical field set up by the heart and thereby in determining the contour of the electrocardiogram obtained with recording electrodes at a distance from the heart. They also support the concept that alterations in the relation of various regions of the heart to the good electrical conductors and alterations in the location of the latter are important factors in modifying the ordinary electrocardiogram.