Abstract
Sufficient evidence is now at hand to indicate that in a certain number of patients suffering from fibrillation of the auricles (about 50 per cent.), oral administration of quinidine sulphate serves to restore the normal rhythm. It is the purpose of this communication to record the mechanism of the heart's action which has been observed in the first eleven patients who have received quinidine in this hospital.
Five hundred and seven electrocardiograms taken on eleven patients have been measured and analyzed. After a preliminary dose of .2 to .4 gm. of quinidine to test for the presence of an idiosyncrasy to members of the cinchona group, .4 gm. of the drug has been given by mouth, in gelatin capsules, either three times daily or every two hours, until either the establishment of normal rhythm or the appearance of untoward symptoms indicated cessation of therapy. No more than 2.0 gm. of quinidine were administered in twenty-four hours, though treatment has been continued daily for as long as ten days.
Electrocardiograms were taken in some instances as often as every five minutes during the time when a change in rhythm was anticipated. Usually curves were made at two-hour intervals on the days on which the drug was given, and at least daily throughout the periods of observation.
Cases in which the Normal Mechanism was Restored.-Three patients received ten courses of quinidine. Restoration of the normal mechanism was accomplished nine times. The first effect noted was usually an acceleration of ventricular rate. This was followed at times by the appearance of premature beats, arising more commonly in the right, but occasionally in the left ventricle, and at times in both. If electrocardiograms were taken at sufficiently frequent intervals, the transitional mechanisms in the common order of their appearance were : coarse fibrillation, impure flutter, flutter, and normal rhythm.
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