Complete atrioventricular block, shock, and hyperkalemia induced by toxic adenoma of the thyroid gland

The case of a 74-year-old woman with toxic thyroid adenoma, presenting as complete heart block, is described. Upon admission the patient was in a state of circulatory collapse with metabolic acidosis and hyperkalemia. After initiation of right ventricular pacing the circulatory and metabolic disorders rapidly normalized without any other specific therapy. Since treatment and attainment of the euthyroid state the patient has had no conduction delays or arrhythmias. Complete heart block in thyrotoxicosis is uncommon and previous reports relate to its occurrence in Graves' disease, usually complicated by infectious disorders. This is the only case known to us of complete heart block in toxic thyroid adenoma.