title: Second and third degree atrioventricular block with Graves' disease: a case report and review of the literature.
abstract: A previously healthy woman experienced Adams-Stokes attacks ten weeks after the initiation of antithyroid medication for Graves' disease. The patient manifested advanced atrioventricular (A-V) block requiring a temporary transvenous pacemaker. The site of heart block was localized to the A-V node by utilizing a His bundle electrogram. With control of the hyperthyroid state, normal A-V conduction was restored. Review of the literature identified twenty-five additional cases of second or third degree A-V block associated with Graves' disease, ten of whom had Adams-Stokes syncope or convulsive seizures. The A-V nodal block was reversible with cure of the primary endocrine disease. It is postulated that excessive thyroid hormone has a direct effect on the cardiac conduction system, specifically, the region of the A-V node and bundle of His. Recommendations are made regarding the recognition and management of patients at risk for developing heart block associated with Graves' disease.
mesh_terms: D000219:Adams-Stokes Syndrome / Q000503:physiopathology; D000328:Adult; D001145:Arrhythmias, Cardiac / Q000175:diagnosis; D004562:Electrocardiography; D005260:Female; D006111:Graves Disease / Q000150:complications*; D006327:Heart Block / Q000209:etiology*; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D006980:Hyperthyroidism / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial