Cyclic sinus node dysfunction in a patient with hyperthyroidism.

Abstract

In a 54-year-old woman with hyperthyroidism, episodic sinus node dysfunction (SND) recurred in a cyclic fashion. The SND occurred suddenly during normal sinus rhythm and progressed to marked sinus bradycardia; occasionally, sinus arrest developed with or without ventricular escape beats. A 1-mg dose of intravenous atropine sulfate suppressed the occurrence transiently. After a 200-mg dose of propylthiouracil and a 20-mg dose of prednisolone every six hours, the SND was completely abolished within 21 hours. It is probable that, together with a pathologic process induced by hyperthyroidism, the autonomic nervous system participated in our patient's episodic SND.