Experiments on the Origin and Conduction of the Cardiac Impulse

The experiments to be described in this paper were undertaken in an attempt to determine the normal path or paths of conduction of the cardiac impulse from its origin in the upper part of the sino-auricular node to the right auricle and to the auriculoventricular node. The problem was attacked in two ways : first, by an attempt to map out the path of the spread of electronegativity from the sino-auricular node to surrounding parts in the intact heart ; and second, the determination of the influence on conduction from the sino-auricular node to the right auricle and auriculoventricular node produced by a gradual and progressive isolation of the sino-auricular node from the surrounding tissues. So far as we have been able to find, no previous work has been done in which the sino-auricular node has been gradually isolated from the surrounding tissues in the heart in situ, with the exception