34:6 DISEASES OF THE HEART. 



from a gelatinous to a semi-cartilaginous consistence, and leads to per- 

 manent thickening and rigidity of the valves, and the retraction and 

 shrinking of the thickened valves, in which chalky masses often form, 

 are much the most common causes of valvular disease of the heart. 

 WTien the vegetations grow old, calcification may also take place in 

 them, so that irregular lobulated masses, of stony hardness, cover the 

 shapeless valves. While the anatomical alterations hitherto described 

 are the most common results of endocarditis, there may appear as less 

 usual accompaniments of the disease 



1. Laceration of the endocardium. This may readily be accounted 

 for, from the relaxation and softening which the endocardium under 

 goes. It is the chordae tendinese which give way with the greatest 

 frequence ; and it is easy to see that the proper tension of the valve 

 during systole must then be materially interfered with. In other 

 cases the valve itself tears ; in others, one surface of a valve alone is 

 torn ; the blood which penetrates through the rent, causing the oppo- 

 site surface of the endocardium to bulge in the form of a sac, consti- 

 tuting an aneurism of the valve. *It is rare for the endocardium to give 

 way at any point in the muscular wall of the heart although, should 

 this happen (but only in such a case), it may be possible for the sub- 

 stance of the heart-wall to take part in the inflammation for the blood 

 to force its way into the rupture, and more or less to tear asunder the 

 cardiac muscles, so as to produce an acute aneurism of the heart, a 

 rounded, circumscribed sac, seated upon the wall of the heart, as an 

 appendage, bounded at its entrance by torn and ragged endocardium, 

 its wall consisting of the forcibly separated fibres of the muscular sub- 

 stance of the organ. 



2. The adhesions of the chordae tendinese, and of the edges of the 

 valves either to one another or to the wall of the heart, to which en- 

 docarditis sometimes gives rise, are of quite as much importance, and 

 produce consequences quite as grave, as do the lacerations ; for, by 

 adhesion of the edges of the valves, or of the chordae tendineae to 

 one another, the auriculo-ventricular orifice becomes very much con- 

 tracted ; and, by adhesion of the valves or chordae tendineae with the 

 heart-wall, closure of the mitral orifice during systole of the ventri- 

 cle is rendered impracticable. We shall discuss this subject more fully 

 while treating of valvular disease. If we reflect that the heart is in 

 constant action, and that during the formation of these adhesions the 

 parts must have been in a constant state of alternate contact and sep- 

 aration, the formation of these adhesions will appear more dilncult tc 

 account for than any other anatomical change which occurs in endo- 

 carditis. 



In ulcerative endocarditis there are irregularly-shaped, abruptly- 



