The protective action of quinidin against the onset of paroxysmal auricular fibrillation and tachycardia.

Abstract

(1) A female, age 23, with mitral stenosis and insufficiency of rheumatic etiology, predisposed to paroxysms of auricular tachycardia, never failed, when not previously subjected to the influences of other drugs, to have a paroxysm of auricular tachycardia following 2 injections of 1 cc. of epinephrin, 15 minutes apart. 1 When quinidin sulphate, 0.2 grams, twice daily, was administered previously, a paroxysm failed to appear upon exhibition of epinephrin in the same manner. This was performed twice. The first time after 6 weeks of this quinidin therapy, and 7 days later during which time no quinidin was administered, a paroxysm of tachycardia followed the exhibition of epinephrin as described. Fourteen weeks of quinidin therapy followed this and at the end of this time no paroxysm appeared after the epinephrin, yet five days later during which time no quinidin was administered, a paroxysm of tachycardia followed administration of the epinephrin.

(2) A male, age 65, with arteriosclerotic heart disease, subject to attacks of paroxysmal auricular fibrillation during a period of normal sinus rhythm, was similarly treated with epinephrin. Auricular fibrillation appeared with very little change of rate about 15 minutes after the 2nd injection of epinephrin. Quinidin was utilized to re-establish the normal sinus rhythm, which reappeared 12 hours after administering 0.2 grams every two hours. The dosage was then reduced to 0.2 grams four times daily. After four days administration of quinidin in this manner, during which time the normal sinus rhythm prevailed, epinephrin exhibited in the same manner was not followed by alteration of the rhythm controlling the heart beat. It appears as if quinidine offers a protection to the heart against the inception of paroxysmal auricular tachycardia and fibrillation induced by means of epinephrin.