Abstract
Summary
Results obtained with isolated dog hearts do not necessarily apply to human beings, yet certain points in this paper may be considered when a combination of drugs is contemplated. The myocardial depression produced by quinidine can be counteracted with ouabain. Quinidine, in relatively large doses, neither decreased nor increased the dose of ouabain that produced ventricular fibrillation. This finding is in harmony with the results of Weiss and Hatcher(7) obtained with intact cats. Furthermore, quinidine alone, under the present experimental conditions produced no premature ventricular beats, ventricular tachycardia or ventricular fibrillation in intact dogs or isolated hearts. Procaine amide depressed the myocardium to a much lesser extent than quinidine, but in big doses it produced ventricular ectopic rhythms. Yet even these arrhythmia-producing doses of procaine amide do not influence the lethal dose of ouabain. The same thing seems to be true of mercurials. It would thus appear that the arrhythmia-producing properties of different drugs are not necessarily additive and that the danger of producing ventricular fibrillation by the combination of such drugs is perhaps exaggerated.
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