The Heart in the Experimental Hyperthyroidism With Special Reference to Its Histology

introduction It is generally known that cardiac disturbances occur in patients suffering from goitre, in not only the exophthalmic type, but also apparently simple goitre, and that cardiac weakness is one of the most frequent causes of sudden death. The subject is, therefore, one of great interest to clinical and experimental investigators. These cardiac disturbances may occasionally be caused by pressure of the tumor upon neighboring structures—venous or respiratory obstruction, or mechanical affection of the smypathetic or vagus nerves (“mechanical goitre heart”—A. Kocher). In the majority of the cases, however, they may be attributed to a certain kind of intoxication, concerning the etiology of which there is a diversity of opinion. Bircher has claimed that the cardiac disturbances associated with endemic goitre are due, not to the goitre itself, but to the general intoxication which is responsible for the changes in the thyroid glands. Most observers believe, however, that the cardiac manifestations associated with goitre arise for the most part from thyroid intoxication (especially in Graves’ disease)and chiefly from an excessive stimulation of the cardiac accelerator nerves.