Endocrine Abstracts

Cardiac arrhythmias in thyrotoxicosis are usually seen as sinus tachycardia and atrial fibrillation but conduction abnormalities in the form of heart blocks do occur in rare instances. We present here four hyperthyroid patients with complete heart blocks. Cases 1 and 2 are young women diagnosed with Graves’ disease who both experienced syncope and were seen to have 3rd degree atrio-ventricular block. Case 3 is a young woman who presented with palpitations, fever and shortness of breath. Her 12 lead ECG showed diffuse ST-segment elevation consistent with pericarditis and complete heart block. Case 4 is a young male with enlarged anterior neck mass and hyperthyroid symptoms who was not cleared for thyroidectomy due to 3rd degree AV block. Development of conduction problems in hyperthyroidism can be due to overwhelming thyroid hormones per se and contributed by acute infections, use of rate control drugs, electrolyte imbalances, and cardiac anomalies. Resolution of clinical, electrophysiological, and biochemical abnormalities occurred in our patients after achieving euthyroidism.