Morphologic Changes in the Heart in Experimental Myxedema

Cardiac enlargement and changes indicative of low voltage in the electrocardiogram have long been recognized as a part of the clinical picture of myxedema in the human being. The mechanism of the production of these signs is not well understood. With the introduction of the operation of total thyroidectomy as a therapeutic measure in chronic heart disease,1a knowledge of the exact nature of the changes which occur in the heart as a result of myxedema becomes of vital importance. With this in mind, experiments were planned which would enable us to study the effects of long-standing myxedema experimentally induced in animals. In the medical literature on the subject there is some confusion as to whether there are specific pathologic changes in the heart muscle in myxedema and still greater confusion as to whether these changes are responsible for the increase in the size of the heart and the changes