626 The Heart in Myxedema 



due to disagreement as to what constitutes "congestive failure." In the writer's 

 opinion "congestive faikue" as seen in myxedema is a very different thing 

 from the congestive failure of chronic valvular disease of the heart. In con- 

 gestive heart failure: (1) the general picture is dynamic— for example, rest- 

 lessness, tachypnea, tachycardia, loud heart sounds, great cardiac activity; (2) 

 shortness of breath occurs with orthopnea; (3) the heart is practically always 

 enlarged; (4) blood volume is increased; (5) venous pressure is elevated; (6) 

 pulmonary congestion is almost constant; (7) an enlarged tender liver is fre- 

 cjuent; (8) cyanosis is usual; (9) edema is dependent; (10) and finally, digitalis 

 is helpful but thyroid is not. 



In myxedema: (1) the general picture is hypodynamic— for example, leth- 

 argy, slow respiration, bradycardia, faint heart sounds, sluggish cardiac action; 

 (2) shortness of breath occurs on exertion but there is no orthopnea; (3) the 

 heart is not always enlarged; (4) blood volume is decreased; (5) venous pres- 

 sure is usually not elevated; (6) pulmonary congestion is infrequent; (7) an 

 enlarged tender liver is infrequent; (8) cyanosis is infrequent; (9) edema is 

 widely distributed; (10) and finally, reversion to normal is complete with 

 thyroid therapy. 



Since the characteristic changes in the electrocardiogram may be present in 

 myxedema with a heart of normal size or, of even greater importance, a heart 

 of apparently normal size that does not become smaller with thyroid therapy, 

 and since sluggish cardiac movement usually accompanies these electrocardio- 

 graphic changes, it would seem that these two latter signs are of fundamental 

 diagnostic importance and that they usually precede cardiac enlargement. 

 Electrocardiographic changes are practically always found when the BMR 

 falls below —25. Under thyroid therapy the cardiac pulsations may become 

 normal before the electrocardiogram returns to normal. 



The division (Escamilla, Lisser and Shepardson"") of "cardiac complications" 

 in myxedema into three groups: (1) atony without decompensation, (2) atony 

 with decompensation, (3) atony with decompensation and arteriosclerosis, 

 has the advantage of simplicity and the virtue of indicating the progressive 

 nature of the damage to the heart in myxedema of long duration, but it intro- 

 duces the controversial words "decompensation" and "complications." It 

 seems clear that heart changes are part of the pictine of myxedema and not 

 a separate cardiac entity or complication. 



The following is a classification of myxedema based upon the changes in 

 the heart: 



1. Myxedema with normal heart size and normal electrocardiogram. 



2. Myxedema with the heart normal in size but with sluggish pulsations and 

 characteristic electrocardiographic changes both of which return to normal 

 with thyroid therapy. (Not infrequent.) 



3. Myxedema with the heart enlarged but, rarely, the electrocardiogram 

 normal. (The larger the heart and the lower the basal metabolic rate the more 

 frequently the electrocardiogram is abnormal.) 



