428 



THE CIRCULATORY SYSTEM. 



roma, thrombosis, or embolus of one of the coronary arteries, whereby a 

 portion of the heart wall is deprived of nourishment and degenerates. Or 

 rupture of a branch of one of the coronary arteries may induce rupture 

 of the heart wall. Acute and chronic myocarditis, with or without the 

 formation of abscess or cardiac aneurism, or the presence of tumors in the 

 heart wall, or hydatids, may lead to rupture. ' 



3. In rare cases rupture is associated with stenosis of the aorta and 

 dilatation of the heart cavities. 



4. Eupture of the papillary muscles and tendons may be due to fatty 

 degeneration or inflammatory or ulcerative processes. 



ATROPHY. 



Atrophy of the walls of the heart may be accompanied with no change 

 in the size of its cavities; or with dilatation ("passive dilatation ") ; or, 



more frequently, with diminution 

 in the size of the cavities. 



The atrophy involves most 

 frequently all the cavities of the 

 heart, but may be confined to one 

 or more of them. 



The muscular tissue appears 

 normal, or may be brown from the 

 presence of little granules of pig- 

 ment in the muscle fibres, which 

 are sometimes present in large 

 numbers brown atrophy; or the 

 muscle fibres may undergo fatty 

 degeneration ; or there may be an 

 abnormal accumulation of fat 

 beneath the pericardium ; or there 

 may be a peculiar gelatinous 

 material beneath the pericardium 



this consists of fat which has undergone mucous degeneration. The 

 heart may be so much atrophied as to weigh only four ounces. 



Atrophy of the heart may be congenital ; it may be associated with 

 repeated haemorrhages or wasting diseases, or senility, with chronic peri- 

 carditis, with effusion, with obstructive lesions of the coronary arteries, 

 with chronic myocarditis, or mitral stenosis. 



Atrophy of the Pericardial Fat Tissue not infrequently occurs in per- 

 sons emaciated by chronic disease, and then the usual situations of the 

 fat are occupied by a tissue resembling mucous tissue in its gross charac- 

 ters. Microscopical examination shows that in this atrophic fat the fat 

 cells have largely lost their contents, and the whole tissue has undergone 

 a partial reversion to its embryonic form (see Fig. 226). 



'Consult Councilman, "On Sudden Deaths due to the Heart." Boston Med. and 

 Surg. Journal, November 9th, 1893. 



FIG. 228. ATROPHIC PERICARDIAL FAT TISSUE. 



From a young person dead of carcinoma of the stom- 

 ch and peritoneum. Stained with osmic acid and 



