DISEASES OF THE HEART. — VALVULAR DEEECTS. 291 



the veins and in the pulmonary circulation, causing cyanosis, dropsy, 

 &c. Meanwhile these extreme symptoms are warded off for a long 

 time by the dilatation of the left heart which accompanies its hyper- 

 trophy ; this enables it to accommodate an abnormally large amount of 

 blood and adapts it to receive a part of that which has just been driven 

 out of it. This dilatation is a result, not of the insufficiency, but of the 

 stenosis ; but it makes amends for the insufficiency just as hypertrophy 

 obviates the dangers of stenosis. All these methods of spontaneous 

 compensation however, have their limits. Supposing the obstruction at 

 the aortic orifice to be complete, it is clear that the utmost degree of 

 hypertrophy and dilatation would not suffice to obviate the imminent fall 

 of tension in the aortic system. Now cases of stenosis occur which are 

 really not far removed from complete occlusion of the aortic orifice. 



Fig. 93. 



.•• /r.i 



•' .\ 



■••■..,-••■■' •■^;-^ 



Hypertrophy of right ventricle. Heart in situ. References as 

 in previous figure. Dotted line represents outline of hyper- 

 trophied right ventricle. 



/5. Stenosis and Insufficiency ofthe Mitral Volvo (figs. 93 and 90). 



Stenosis of the mitral orifice impairs the facility with which the 

 blood normally flows into the left ventricle during the cardiac diastole. 

 The blood stagnates in the left auricle. This stagnation causes a 

 pressure in its interior analogous to the increase of systolic pressure 

 upon the inner surface of the left ventricle in stenosis of the aortic 

 orifice. The left auricle indeed, under such circumstances, is prone to 

 undergo dilatation, which is however, always associated with some 



