366 DISEASES OF THE HEART. 



the valve is torn. Still oftener, it is the chordae tendinese that have 

 given way, and it can be distinctly recognized that the latter, which 

 are usually thickly covered by the vegetations previously described, 

 are inverted by the regurgitating stream of blood, and made to flap 

 backward into the auricle. More rarely, the tendons are adherent to 

 the wall of the heart, so as to prevent the valve-tips from approaching 

 one another. Finally, as more or less extensive tendinous degenera- 

 tion of the papillary muscles not unfrequently constitutes a minor 

 source of the disorder, and where neither these nor other anatomical 

 alterations are found to account for an insufficience which has notori- 

 ously existed, it is most probable that some invisible change in these 

 muscles has been the cause of the symptoms. The lesions, which the 

 cavities and walls of the heart exhibit in cases of insufficience, are 

 equally characteristic and interesting. The left auricle, into which the 

 blood is first driven during systole, is always a good deal enlarged, and 

 its walls are considerably thickened. The pulmonary artery and vein 

 are in like manner dilated, as is also the right heart, both ventricle and 

 auricle. The right ventricle, whose task is enormously increased, be- 

 comes so much hypertrophied that its walls grow as thick as those of 

 the left. If cut open, they do not collapse as before, but the cut gapes 

 as it would do if made in the left ventricle. There is almost always a 

 moderate degree of dilatation of the left ventricle, into which, as we 

 have seen, the blood pours under greatly-increased pressure. 



In insufficience of the mitral valve, the valve-tips are shortened ; 

 in constriction of the orifice, they have generally grown narrower, and 

 this contraction of the valvular ring is the most common cause of im- 

 pediment to the flow of the blood from auricle to ventricle. It rarely 

 happens, however that the valves thus thickened by endocarditis, and 

 in which new connective tissue is growing, contract in one direction 

 alone ; they almost always become narrowed and shorter simultane- 

 ously, so that stenosis and insufficience appear together. In other 

 cases, the lower edges of the valve-tips, or of the chordae tendineae, 

 are so intimately united, that the valve takes the shape of a funnel, 

 broad toward the auricle, and ending toward the ventricle in a narrow 

 opening, through which it is often almost impossible to pass the tip of 

 the finger. The vegetations, which often cover the valve in the form 

 of hard, wart-like concretions, may also contribute to occlusion of the 

 orifice. 



Dilatation of the left auricle, and of the pulmonary arteries and 

 veins, is also a constant accompaniment of stenosis of the mitral, and 

 fche walls of the dilated chambers exhibit hypertrophy similar to what 

 we have described above. The left ventricle, however, is in a condi- 

 tion opposite to that which we find in insufficience. Instead of being 



