408 DISEASES OF THE PERICARDIUM. 



uises there sometimes is a peculiarity observable about the veins of the 

 aeck. We see, namely, when the sternum, after having been drawn 

 down by the systolic movement, springs back again with the diastole, 

 thereby creating an expansion of the chest, that the veins collapse. 

 En Friedreicffs case this phenomenon only lasted for a limited time, 

 and ceased as the action of the heart, and with it the systolic depres- 

 sion, grew more feeble. Thus, in solitary cases, physical examination 

 may inform us of the existence of pericardial adhesion. In the major- 

 ity of instances, however, the statement of Skoda, in the first edition 

 of his book, still holds good, that "no symptoms are discoverable, 

 through percussion and auscultation, which can be ascribed to adhe- 

 sion of the heart and pericardia." 



CHAPTER III. 



HYDROPERICARDIUM. 



ETIOLOGY. Hydropericardium depends upon an increase of the 

 normal liquor pericardii, a transudation which contains but little albu- 

 men. We have already seen how a decrease in the size of the heart, 

 by reducing the pressure upon the pericardium from within, results in 

 an increase in quantity of the liquid in the sac. The same thing takes 

 place when the lungs become adherent to the pericardium and are 

 reduced in volume, either from atrophy, failure to regain their normal 

 size after absorption of a pleuritic effusion, or contraction from chronic 

 pneumonia. This form of hydropericardium is analogous to the in- 

 crease in the amount of cerebro-spinal liquid which takes place in 

 atrophy of the b^ain, and, as the latter is called hydrocephalus ex 

 vacuo, so hydropericardium ex vacuo would be a suitable name for 

 the former. 



A second form of hydropericardium is that which arises from an 

 obstruction of the veins of the right heart. An abnormal pressure is 

 thus thrown upon the pericardial veins, and dropsy of the sac results 

 just as it takes place in other serous sacs, or in the subcutaneous cel- 

 lular tissue. The collections of water in the pericardium arising in 

 valvular disease of the mitral, emphysema, cirrhosis of the lungs, and 

 m other diseases in which the right side of the heart is overloaded, 

 all belong under this head. In all these cases dropsy may be of earlier 

 occurrence in the pericardium than in any other part of the body. 



It is otherwise in the third form, in which dropsy of the pericar- 

 dium, like that of other organs and structures, is to be regarded as the 

 effect of a " dropsical crasis." Appearing in diseases in which the 

 blood has a tendency to lose its albumen, and for its serum to trans- 



