ELECTROCARDIOGRAPHIC CHANGES INDUCED BY COOLING OR WARMING THE INNER SURFACE OF THE DOG'S VENTRICLE

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Abstract
The temp. of the endocardial surface of the dog''s ventricle was changed by the introduction into the ventricle, by arterial catheterization, of Ringer''s soln. at various temperatures. Cooling the inside of the left apex changed the form of, and widened the QRS complex and also caused conspicuous increase in the height and width of the T waves. Warming had opposite but less striking effects on the T wave, and changed the form of the QRS complex. Ringer''s soln. at body temp. caused no changes. In other expts., cooling the inner surface of the right ventricles caused similar T wave changes, but reverse effects on the form of the QRS complex. Cooling the basal left endocardial surface caused inversion and usually widening of the T waves. These expts. have demonstrated that procedures, the preponderant effect of which should be to change the temp. of the endocardial ventricular surface, produce T-wave changes of the kind which theoretical considerations have led us to expect. It is reasonable to suppose, therefore, that the electrical effects were, in fact, brought about by a change in rate of repolarrzation of the endocardial surface. If this conclusion be justified, it follows that changes in the electrical state of the subendocar-dial muscle surface play a part in the genesis of the electrocardiogram.