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[Hyperthyroidism and atrioventricular heart block (author's transl)]
Insights
Thyrotoxicosis can cause heart conduction disturbances like atrioventricular block. This study suggests thyroid hormone directly affects the heart, resolving with treatment, and contraindicating beta-blocker use.
Area of Science:
- Cardiology
- Endocrinology
- Electrophysiology
Background:
- Thyrotoxicosis, a state of excess thyroid hormone, can lead to various cardiovascular complications.
- Atrioventricular block, a disruption in heart's electrical conduction, is an unusual but reported complication of hyperthyroidism.
Abstract:
Two cases of thyrotoxicosis including a first-degree heart block are reported; a study of action potentials of the bundle of His was achieved in the second case. The association atrioventricular block-hyperthyroidism is unusual but does not seem to be a pure coincidence. The direct effect of thyroid hormon on the myocardium is supposed to be responsible for the conduction disturbance; its disappearance with the cure of the thyrotoxicosis is a favourable argument for a relation of causality. The therapeutic consequence of this association is to exclude completely the use of betablockers.