The Thermode--an Electrode for Demonstrating the T-Wave Change due to Delayed Repolarization of the Ventricle*

Summary In the teaching of electrocardiography, it is desirable to demonstrate the meaning of the T wave. In the normal human subject it is not easy to produce T wave changes. For this reason any experimental method has considerable value. This paper describes a simple method of demonstrating the effect of delayed and enhanced recovery of the ventricles by the use of a hollow electrode or thermode, which can be cooled or warmed. In use, the thermode is placed in contact with the surface of the left ventricle of an experimental animal. While recording the ECG from the right forelimb and thermode (with the usual conventions, e.g., negativity of thermode produces a downward deflection), the passage of cold water causes the T wave to move downward; then passing warm water through the thermode causes the inverted T wave in sequence to become smaller, isoelectric, then upward.