Hyperthyroidism and Heart Block

7/03/02

Question: Can hyperthyroidism be a cause of heart block?

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Unique Identifier:4074593

Authors: Kramer MR. Shilo S. Hershko C.

Title: Atrioventricular and sinoatrial block in thyrotoxic crisis.

Source: British Heart Journal. 54(6):600-2, 1985 Dec.

Abstract: A 55 year old woman in thyrotoxic crisis developed atrial fibrillation, atrioventricular block, and sinoatrial block in rapid succession. All of these abnormalities resolved completely after antithyroid treatment. This course of events illustrates the profound effect of thyroid hormones on cardiac function. In view of the potential aggravation of atrioventricular conduction disturbance by beta adrenergic blocking agents, thyrotoxic patients should be carefully screened for electrocardiographic evidence of conduction disturbance before the administration of such drugs.

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Unique Identifier:6161353

Authors: Miller RH. Corcoran FH. Baker WP.

Title: Second and third degree atrioventricular block with Graves' disease: a case report and review of the literature. [Review] [53 refs]

Source: Pacing & Clinical Electrophysiology. 3(6):702-11, 1980 Nov.

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. [References: 53]

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Unique Identifier:1156072

Authors: Campus S. Rappelli A. Malavasi A. Satta A.

Title: Heart block and hyperthyroidism. Report of two cases.

Source: Archives of Internal Medicine. 135(8):1091-5, 1975 Aug.

Abstract: In two patients with hyperthyroidism who had no signs of heart disease, first-degree heart block with tall and large P waves occurred. In one patient, a left bundle-branch block and transient complete heart block with Stokes-Adams episodes also occurred, although there was no verifiable evidence of acute inflammatory disease.