An Experimental Study on the Origin of T-Waves Based on Determinations of Effective Refractory Period from Epicardial and Endocardial Aspects of the Ventricle

The effective refractory period was determined at the surface and in the deeper layers of the dog heart and was correlated with the surface T-waves. A small delay in recovery of cardiac excitability appeared at the surface when T-waves were negative and in the deeper layers when T-waves were positive. Acute injury produced by ligation of the coronary artery caused a marked acceleration of recovery in the deeper layers, sometimes extending to the surface.