326 DISEASES OF THE CIRCULATORY SYSTEM. 



also become thick and rigid, and interfere with the function of 

 the valves. The dense cicatricial connective tissue may be- 

 come infiltrated with lime salts. 



In some cases the inflammatory process may be chronic 

 from the first. This is especially liable to occur in persons of 

 advanced years, and also in connection with chronic alcoholism, 

 syphilis, and gout, which are active factors also in producing 

 general arterio-sclerosis. The alterations in the valves lead to 

 stenosis, an obstruction to the flow of blood ; or insufficiency, 

 when the valves cannot close, and thus prevent the regurgita- 

 tion of the blood. A valve may be both stenotic and insuf- 

 ficient. 



Either condition necessarily leads to imperfect circulation 

 of the blood through the heart. The natural result of the in- 

 creased work thrown upon the heart-muscle is hypertrophy. 

 When this compensatory hypertrophy fails, most serious 

 changes occur in the various organs. The lungs become 

 cedematous and gradually indurated, as the result of an in- 

 creased proliferation of the interstitial connective tissue. The 

 pulmonary vessels are distended, even varicose ; thrombi may 

 form, as the result of the sluggish circulation. The liver, 

 spleen and kidneys are enlarged by reason of their passive 

 congestion. The countenance becomes cyanosed from the 

 stagnation of the circulation and lessened oxidation ; there 

 are serous effusions into the peritoneal, pleural, and pericardial 

 sacs and general oedema of the subcutaneous tissue and skin. 

 The mucous membrane of the gastro-intestinal tract is swollen 

 and redematous. 



Pericarditis. 



Inflammation of the pericardium may be a primary affection, 

 occurring in connection with rheumatism and Bright's disease, 

 and various acute infectious fevers, as pneumonia, typhoid, 

 scarlet fever, influenza, and puerperal septicaemia; or much 

 less frequently it may be a secondary affection resulting from 

 the extension of an inflammatory process from neighboring 

 structures to the pericardium. 



The membrane first becomes dull and lustreless. The 

 character of the exudate varies, usually purely serous, but 

 sometimes hemorrhagic or seropurulent. The opposed sur- 



