Electrocardiographic changes associated with experimental alterations in blood potassium in cats

Abstract

The increasing interest in electrocardiographic abnormalities which are not due to structural changes in the myocardium has prompted our study of the effect of potassium on the electrocardiogram. An intimate relationship of potassium to automatism and to bioelectric phenomena seems fairly certain, in the light of current knowledge, and numerous investigators have studied the effects of potassium on heart muscle strips, the intact heart, and heart-lung preparations. Electrocardiograms with concomitant potassium determinations on the intact, unanesthetized subject following potassium administration are rare. Wiggers 1 produced electrocardiographic changes similar to those due to coronary occlusion by applying with a brush a 20 per cent solution of potassium chloride directly to the ventricle of the dog. Wiggers and his associates 2, 3 described electrocardiographic changes in dogs following intravenous and intracardiac injections of potassium chloride. These changes varied with the amount of potassium chloride injected and with the site and speed of injection. Concentrations of serum potassium were not determined. Harris and Levin 4 noted slowing of the human heart and slight diminution in the height of the P waves following the administration of 5 c.c. of 5 per cent potassium chloride solution. They conclude that there is no relation between electrocardiographic changes and concentration of potassium in the serum, but from the data presented this conclusion does not seem justified. In five experiments on four dogs, Winkler, Hoff, and Smith 5 found marked changes in the electrocardiogram, with eventual cardiac arrest, following the intravenous administration of 1.12 per cent potassium chloride solution at the rate of 10 c.c. per minute. In the present study the potassium chloride was given intraperitoneally because Zwemer and Truszkowski 6 had found that this procedure gave more predictable results and smoother blood potassium curves.