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The effects of a decrease in plasma pH, bicarbonate and sodium on the electrocardiographic pattern are compared with those produced by elevation of scrum potassium and lithium in the dog. The electrocardiographic alterations were found to be similar in form and progression. The alterations can be correlated with those found in isolated nerve and muscle preparations.

This report is intended to contribute to an understanding of the natural morbidity of patients with chronic rheumatic heart disease in the third, fourth, and fifth decades of life. The (lata should prove useful in a consideration of the criteria for surgical intervention.T1HE recent emphasis on early surgical intervention for patients with chronic rheumatic valvular disease has made the need for basic data concerning the natural history of this conditioii of practical importance.Data regarding the natural morbidity of patients with chronic rheumatic heart disease in the third, fourth, and fifth decades of life are presented. This information should prove useful in evaluating the effects of surgical intervention on the natural morbidity and mortality of the disease.

The effects of an increase in plasma pH, bicarbonate and sodium on the electrocardiogram of the normal dog have been compared with those produced by a decrease in plasma potassium. The eleetrocardiographie alterations in these experimentally induced situations were found to be similar in form and progression. I N THE preceding paper it was shown that electrocardiographic changes similar to those produced by an excess of plasma potassium can follow disturbances of other electrolytes. 1 The present experiments were designed (1) to define the effects of a decreased plasma potassium and increased pH and bicarbonate individually and collectively on the electrocardiogram, and (2) to attempt to clarify the mechanism responsible for the alterations in myocardial function which occur in conditions of hypochloremic, hypokalemic alkalosis. METHODS AND MATERIALSEighteen experiments were performed on 12 female mongrel clogs, anesthetized with sodium pentobarbital. The procedures and methods were the same as those described in the preceding communication.1 Respiratory alkalosis was induced by overventilation with room air or oxygen. Aide J by Grants from the American Heart Association and The National Heart Institute, National Institutes of Health.Dr. Magida is a Post-Doctorate Research Fellow, National Heart Institute, United States Public Health Service, Bcthesda, Md.This work was done during Dr. Roberts' tenure of a Research Fellowship of the American Heart Association.Received for publication Dec. 15, 1952. RESULTSInfusion of Sodium Bicarbonate. Figure 1 illustrates the effect of the infusion of sodium bicarbonate at a rate of 1.2 mEq. per minute over a period of three and one-half hours. Similar results were obtained in five experiments. It is seen that the anticipated rise in plasma pH and bicarbonate is accompanied by elevation of plasma sodium and a fall in potassium concentration. Serial electrocardiograms show the following: tachycardia; T-wave alterations which consisted of increased duration and change in direction, followed by increased amplitude and finally peaking; S-T segment alterations characterized either by elevation or depression; increased amplitude of the P wave. In three experiments sodium bicarbonate was infused at the rate of 4.0 mEq. per minute over a two-hour period. With such rapid rates of infusion the electrocardiogram showed peaking and increased amplitude of the T wave and terminal loss of the P wave, development of a nodal or ventricular rhythm and ultimate disintegration of the ventricular complex.Infusion of Sodium Hydroxide. In three experiments sodium hydroxide was infused with the purpose of determining the amount of alkali which could be neutralized by the body buffer systems and to study the effect of this alkali on the electrocardiogram. The effect of sodium hydroxide, infused at a rate of 1 mEq. per minute is illustrated in figure 2.