An experimental study of the electromotive forces of the heart

Propagated wavefronts were produced by mechanical stimulation at points located deeply within the myocardium, and the external field so produced was measured by electrodes located within a radius of 10 mm. from the centrally stimulated point. In 104 experiments in 10 dogs the external field so produced was negligible until propagation reached either the epicardial or endocardial surfaces. If it is assumed that propagated intramural activity is temporarily a closed electromotive surface, then the data presented suggest that there is a uniform difference in potential across this surface. Since there is no fundamental difference in the wavefront characteristics of closed electromotive surfaces and those which present boundaries on the epicardial or endocardial surfaces, these data strongly suggest that there is a uniform difference in potential across all propagated wavefronts in normal ventricular muscle.