HYPERTROPHY OF THE HEART. 327 



we listen at the middle of the third costal cartilage ; for that of the 

 tricuspid, at the lower end of the sternum, on a level with the fourth 

 intercostal space. 



The mitral sounds are less distinctly audible at the spot in the 

 thorax corresponding to the situation of the mitral valve, but can be 

 heard and isolated better at the region of the apex, which lies about 

 in the third intercostal space, an inch and a half from the left border 

 of the sternum. This is owing to the fact that the mitral valve is 

 separated from the anterior wall of the chest by the right side of the 

 heart, and from the lateral wall by the lung. These media are poorly 

 adapted for the transmission of the sounds of the mitral to the ear, or 

 for their isolation from the sounds arising in the right side of the heart. 

 On the other hand, the apex, which belongs to the left ventricle alone, 

 and which lies immediately in contact with the wall of the thorax, is 

 well calculated to isolate the tones of the mitral, and to conduct them 

 to the ear. 



The sounds and murmurs which arise in the various orifices of the 

 heart are often heard, with greater distinctness, at other points than 

 those just mentioned. This is sometimes owing to an elevated or de- 

 pressed attitude of the diaphragm, or to displacement of the medias- 

 tinum, and sometimes, indeed, no reason for the variation can be 

 assigned. In order not to be led into error of diagnosis by such 

 irregularities in determining the source of a murmur, we must not 

 attach too much diagnostic importance to the situation of the point 

 where the sound is most plainly audible, but should rather rely upon 

 the concomitant signs of enlargement of one or other portion of the 

 heart. 



To save repetition, we shall defer the discussion of the differential 

 diagnosis of hypertrophy and dilatation of the heart, and of pericardial 

 exudation, etc., until we shall have learned the symptoms of the latter 

 diseases. 



PROGNOSIS. Of all diseases of the heart, hypertrophy admits of 

 the best prognosis, if we accept the narrowest meaning of the term 

 which we have assigned to it. In many instances, in which we shall 

 find hypertrophy as a complication of other diseases of the heart, the 

 compensatory hypertrophy actually mitigates the danger of the chief 

 disease. . J 



Patients with simple hypertrophy of the heart may live to a great 

 age. If they die early, death is generally due to haemorrhagic effu- 

 sions into the brain or lungs, for the prevention of which occurrences 

 a careful treatment and a judicious regimen do not seem to be with- 

 out efficacy. The prognosis, however, is often rendered more gra\e 

 by the occurrence of a consecutive degeneration of the substance cf 





