420 THE CIRCULATORY SYSTEM. 



INFLAMMATION. (Pericarditis.) 



Pericarditis is rarely primary, but is usually secondary to infectious 

 diseases, such as pneumonia, pleurisy, tuberculosis, typhoid fever, endo- 

 carditis, and pysemia. It may follow injuries and is frequently associ- 



FIG. 218. FIBRINOUS PERICARDITIS. 

 The pericardial sac is laid open and the heart is seen covered with an irregular villous layer of flbrin. 



ated with rheumatism or inflammation of the kidneys. It may be exu- 

 dative or productive in character. 



Exudative Pericarditis. It is convenient to distinguish in exudative 

 pericarditis Skfibrinous, a sero-fibrinous, and a, purulent form. 



FIBRINOUS AND SERO-FIBRINOUS PERICARDITIS. In the earlier 

 stages or lighter forms of fibriuous pericarditis, the whole surface or 

 portions of the pericardium may be dull or slightly roughened from a 

 delicate fibriuous pellicle, more or less hypersemic and often studded with 

 minute petechiae. Later, if the exudate accumulate, the entire surface 

 of the pericardium may be covered with a net-like layer of thick masses 

 of fibrin. This may cover both the visceral and parietal surfaces and 

 is often beset with irregular villosities (Fig. 218). Fibrinous adhesions 

 may form between the two layers. There is usually some serous fluid 

 as well as leucocytes mingled with the fibrin. 



Serum may accumulate in considerable quantity sero-Jibrinous peri- 

 carditis. The pericardial sac may be greatly distended with this form of 



