92 PRACTICE OF MEDICINE. 



Morbid sounds of the heart. — Unnatural sounds may be called 

 murmurs ; and they are of two kinds ; the exocardial, produced 

 external to the heart, that is to say, in the pericardium ; and the 

 endocardial^ produced in the heart itself. 



The endocardial murmurs have a blowing character, the ezocar- 

 dial give the idea of friction. 



" The endocardial murmur," says Dr. Latham, " is not only dif- 

 ferent in kind from the natural sounds of the heart, but it takes their 

 place, and is heard in their stead. It comes exactly where the first 

 sound, or where the second, or where both sounds should be. It 

 keeps strict time with the systole or with the diastole of the heart, 

 or with both. 



" The exocardial murmur, too, is different in kind from the natural 

 sounds of the heart. But it does not take the place of them ; it is 

 not heard in their stead. In proportion as it is louder, it obscures 

 or overpowers the natural sounds. But the natural sounds are still 

 apt to reach the ear through the exocardial murmur ; and when they 

 do not reach the ear, it is because they are imperceptible under the 

 circumstances, not because they cease to exist." 



Endocardial murmurs (i. e., murmurs within the heart) are caused 

 by peculiar vibrations of the columns of blood which pass through 

 the heart; and these vibrations may depend, — 1st, upon an unnatu- 

 rally thin quality^ and deficient quantity of the bbod, as in the mur- 

 murs heard after hemorrhage ; 2ndly, on disease of the valvular 

 orifices of the heart, offering obstacles to the passage of the blood. 



A murmur caused by the passage of the blood through a diseased 

 valvular orifice may be direct or regurgitant ; that is, may be pro- 

 duced during the flow of the blood along its natural channel, if con- 

 tracted ; or during its regurgitation, which will happen if the diseased 

 valve is unable to shut properly. 



In order to ascertain which valve is diseased, notice must betaken 

 of the time at which the murmur is heard ; — of the pait of the 

 ^iJPcordial space ivhere it is heard most loudly ; and of the direction 

 vn which it is conveyed the farthest. 



Valvular disease of the right side of the heart is very rare indeed ; 

 and the diagnosis of it from disease on the left side is a matter of 

 some uncertainty. The following observations, therefore, chiefly 

 apply to the aortic and mitral valves. 



When a single endocardial murmur is heard during the systole of 

 the heart, its seat is most probably the aortic valve, which is thick- 

 ened, so as to impede the blood in its exit from the heart and to 

 throw it into vibration. 



When a single murmur is heard, coincident with the heart's 

 diastole^ this also may be produced by a diseased aortic valve, if so 

 diseased as to be incapable of closing, and permit the blood to regur- 

 gitate into the ventricle. 



